University of Texas Health Science Center at Houston
Recent publications
Major neurological and psychiatric diseases affect females and males differently, suggesting that inherent sex-biased biological factors affect disease incidence and progression. These factors are grouped into two major groups, hormones secreted by the gonads, and genes unequally encoded on X and Y sex chromosomes in the two sexes. Numerous rodent models of these diseases have been used to dissect the relative contributions of sex hormones and sex chromosomes, and studies of humans bear strongly on the factors that might account for the sex differences. Examples of research progress in this area are reviewed for multiple sclerosis and autoimmune diseases, stroke, Alzheimer's Disease, Parkinson's Disease, and autism spectrum disorder. The study of sex differences offers novel perspectives in the discovery of factors that may be targeted in the clinic to alleviate the burden of these diseases.
Benign cardiac masses are a rare entity and are characterized by their propensity to present under the guise of clinical manifestations also associated with other more common and lethal syndromes. Apart from this, the majority of patients with benign cardiac masses are asymptomatic, and detection is often incidental or at postmortem. Imaging and biopsy are the mainstay of diagnosis for such masses; therefore, an appreciation of the surgical features thereof is vital. The majority of benign cardiac masses can be curatively treated by prompt surgical excision.
When no single outcome is sufficient to capture the multidimensional impairments of a disease, investigators often rely on multiple outcomes for comprehensive assessment of global disease status. Methods for assessing covariate effects on global disease status include the composite outcome and global test procedures. One global test procedure is the O’Brien’s rank-sum test, which combines information from multiple outcomes using a global rank-sum score. However, existing methods for the global rank-sum do not lend themselves to regression modeling. We consider sensible regression strategies for the global percentile outcome (GPO), under the transformed linear model and the monotonic index model. Posing minimal assumptions, we develop estimation and inference procedures that account for the special features of the GPO. Asymptotics are established using U-statistic and U-process techniques. We illustrate the practical utilities of the proposed methods via extensive simulations and application to a Parkinson’s disease study.
Glioblastoma (GBM) is a common and aggressive brain cancer that accounts for 60% of adult brain tumors. Anti-angiogenesis therapy is an attractive option due to the high vasculature density of GBM. However, the best-known anti-angiogenic therapeutics, bevacizumab, and aflibercept, have failed to show significant benefits in GBM patients. One of the reasons is the limited brain penetration of antibody-based therapies due to existence of the blood-brain barrier (BBB), which is further strengthened by the blood vessel normalization effects induced by anti-angiogenic therapies. To investigate if increased drug concentration in the brain by transferrin receptor (TfR)-mediated delivery across the BBB can enhance efficacy of anti-angiogenic antibody therapies, we first identified an antibody that binds to the apical domain of the mouse TfR and does not compete with the natural ligand transferrin (Tf) binding to TfR. Then, we engineered two bispecific antibodies fusing a vascular endothelial growth factor (VEGF)-Trap with the TfR-targeting antibody. Characterization of the two bispecific formats using multiple in vitro assays, which include endocytosis, cell surface and whole-cell TfR levels, human umbilical vein endothelial cell growth inhibition, and binding affinity, demonstrated that the VEGF-Trap fused with a monovalent αTfR (VEGF-Trap/moAb4) has desirable endocytosis without the induction of TfR degradation. Peripherally administered VEGF-Trap/moAb4 improved the brain concentration of VEGF-Trap by more than 10-fold in mice. The distribution of VEGF-Trap/moAb4 was validated to be in the brain parenchyma, indicating the molecule was not trapped inside the vasculature. Moreover, improved VEGF-Trap brain distribution significantly inhibited the angiogenesis of U-87 MG GBM tumors in a mouse model.
Triggering receptor expressed on myeloid cells 2 (TREM2) plays a crucial role in regulating microglial functions and removal of amyloid plaques in Alzheimer's disease (AD). However, therapeutics based on this knowledge have not been developed due to the low antibody brain penetration and weak TREM2 activation. In this study, we engineered a TREM2 bispecific antibody to potently activate TREM2 and enter the brain. To boost TREM2 activation, we increased the valency of bivalent anti-TREM2 Ab2 IgG to tetra-variable domain immunoglobulin (TVD-Ig), thus improving the EC50 of amyloid-β oligomer (oAβ)-lipid microglial phagocytosis by more than 100-fold. Ab2 TVD-Ig treatment also augmented both microglia migration toward oAβ and microglia survival by 100-fold over the bivalent IgG antibody. By targeting the transferrin receptor (TfR), the brain-penetrating Ab2 TVD-Ig/αTfR bispecific antibody realized broad brain parenchyma distribution with a 10-fold increase in brain antibody concentration. Ab2 TVD-Ig/αTfR treatment of 5-month-old 5XFAD mice significantly boosted microglia-plaque interactions and enhanced amyloid plaque phagocytosis by microglia. Thus, potent TREM2 activation by a multivalent agonist antibody coupled with TfR-mediated brain entry can boost microglia clearance of amyloid plaques, which suggests the antibody has potential as an AD treatment.List of abbreviations AD: Alzheimer's disease; Ab: antibody; APOE: apolipoprotein E; Aβ: amyloid beta; BBB: blood-brain barrier; BLI: bio-layer interferometry; CNS: central nervous system; CSF: colony-stimulating factor; CytoD: cytochalasin d; DAM: microglia type associated with neurodegenerative diseases; DAP12: DNAX-activation protein 12; TVD-Ig: tetra-variable domain immunoglobulin; ECD: extracellular domain; ELISA: enzyme-linked immunoassay; ESC: embryonic stem cell; hMGLs: human embryonic stem cell-derived microglia-like lines; IBA1: ionized calcium-binding adaptor molecule 1; ITAM: immunoreceptor tyrosine-based activation motif; KiH: knob-into-hole; NFAT: nuclear factor of activated t-cells; PC: phosphatidylcholine; PK: pharmacokinetics; PS: phosphatidylserine; pSYK: phosphorylated spleen tyrosine kinase; scFv: single-chain variable fragment; SEC: size-exclusion chromatography; sTREM2: soluble triggering receptor expressed on myeloid cells 2; SYK: spleen tyrosine kinase; TfR: transferrin receptor; TREM2: triggering receptor expressed on myeloid cells 2.
and insurance companies facilitated this increase by amending restrictions that had previously limited telemedi-cine use. 2 Although research suggests that telemedicine has the potential to decrease costs and increase access to health care, there are vulnerable groups at risk for experiencing tele-medicine disparities if a health equity lens is not used to implement future telemedicine use. The primary risk factor of COVID-19 mortality is age; therefore, many health care settings used telemedicine as an alternative to reduce potential exposure to older patients. Unfortunately, older adults are the least likely to use technology, such as telemedicine. 1 As an example, my parents were asked to switch their health care appointments to telemedicine throughout the COVID-19 pandemic. They did not own a computer , and the only device they owned with a camera was their smartphone. As low-income older adults, they did not have the money to purchase technology that was not a necessity before the pandemic. Fortunately, my classes started being delivered online during the COVID-19 pandemic and I was able to travel to them, so they had access to my laptop. We knew that eventually I would have to leave; therefore, we made the decision to purchase a laptop with a camera. The access to technology problem was solved with the purchase; however , they did not know how to download and use videoconference applications. Throughout numerous days, I educated my parents on how to download different applications and use them until they felt empowered to be able to use them without me. My parents were able to independently attend their health care sessions through telemedicine, and we have weekly videoconference family gatherings now. However, public health and policymakers cannot hope that people will be able to access technology, have money to purchase up-to-date technology , and have people to help educate them on how to use technology. Barriers to telemedicine implementation include lack of technology and digital literacy. 3 Although researchers have quickly attempted to study and publish about telemedicine, there has not been an equivalent amount of increase in digital literacy research. This is emphasized by a PubMed search of "digital liter-acy" between 2020 and 2021 that found only 573 publications compared with 14 597 publications for "telemedicine or telehealth." Additionally, only three "digital literacy" studies have been registered on clinicaltrials.gov since January 1, 2020, whereas 560 "telemedicine or tele-health" studies have been registered. It is imperative that public health study inequities associated with tele-medicine to make sure that the increase of telemedicine does not widen the current health disparities. Previous evidence suggests that barriers to telemedicine can be overcome by interventions that increase perceived self-efficacy through education. 3,4 Additionally, the association of disability and poverty with telemedicine use should inform policymakers to ensure that technological devices with disability accommodations are covered as medical necessity. 5 There is a growing need for public health to ensure that the advantages of telemedicine are implemented in an equitable manner so that people like my parents are not left behind.
Colorectal cancer (CRC) is among the most common malignancies with limited treatments other than surgery. The tumor microenvironment (TME) profiling enables the discovery of potential therapeutic targets. Here, we profile 54,103 cells from tumor and adjacent tissues to characterize cellular composition and elucidate the potential origin and regulation of tumor-enriched cell types in CRC. We demonstrate that the tumor-specific FAP ⁺ fibroblasts and SPP1 ⁺ macrophages were positively correlated in 14 independent CRC cohorts containing 2550 samples and validate their close localization by immuno-fluorescent staining and spatial transcriptomics. This interaction might be regulated by chemerin, TGF-β, and interleukin-1, which would stimulate the formation of immune-excluded desmoplasic structure and limit the T cell infiltration. Furthermore, we find patients with high FAP or SPP1 expression achieved less therapeutic benefit from an anti-PD-L1 therapy cohort. Our results provide a potential therapeutic strategy by disrupting FAP ⁺ fibroblasts and SPP1 ⁺ macrophages interaction to improve immunotherapy.
Germline mutations in BRCA1 or BRCA2 exist in ~2–7% of breast cancer patients, which has led to the approval of PARP inhibitors in the advanced setting. We have previously reported a phase II neoadjuvant trial of single agent talazoparib for patients with germline BRCA pathogenic variants with a pathologic complete response (pCR) rate of 53%. As nearly half of the patients treated did not have pCR, better strategies are needed to overcome treatment resistance. To this end, we conducted multi-omic analysis of 13 treatment naïve breast cancer tumors from patients that went on to receive single-agent neoadjuvant talazoparib. We looked for biomarkers that were predictive of response (assessed by residual cancer burden) after 6 months of therapy. We found that all resistant tumors exhibited either the loss of SHLD2, expression of a hypoxia signature, or expression of a stem cell signature. These results indicate that the deep analysis of pre-treatment tumors can identify biomarkers that are predictive of response to talazoparib and potentially other PARP inhibitors, and provides a framework that will allow for better selection of patients for treatment, as well as a roadmap for the development of novel combination therapies to prevent emergence of resistance.
The brain, particularly the ventromedial hypothalamic nucleus (VMH), has been long known for its involvement in glucose sensing and whole-body glucose homeostasis. However, it is still not fully understood how the brain detects and responds to the changes in the circulating glucose levels, as well as brain-body coordinated control of glucose homeostasis. In this review, we address the growing evidence implicating the brain in glucose homeostasis, especially in the contexts of hypoglycemia and diabetes. In addition to neurons, we emphasize the potential roles played by non-neuronal cells, as well as extracellular matrix in the hypothalamus in whole-body glucose homeostasis. Further, we review the ionic mechanisms by which glucose-sensing neurons sense fluctuations of ambient glucose levels. We also introduce the significant implications of heterogeneous neurons in the VMH upon glucose sensing and whole-body glucose homeostasis, in which sex difference is also addressed. Meanwhile, research gaps have also been identified, which necessities further mechanistic studies in future.
Congenital diaphragmatic hernia (CDH) is a rare birth defect characterized by incomplete closure of the diaphragm and herniation of fetal abdominal organs into the chest that results in pulmonary hypoplasia, postnatal pulmonary hypertension owing to vascular remodelling and cardiac dysfunction. The high mortality and morbidity rates associated with CDH are directly related to the severity of cardiopulmonary pathophysiology. Although the aetiology remains unknown, CDH has a polygenic origin in approximately one-third of cases. CDH is typically diagnosed with antenatal ultrasonography, which also aids in risk stratification, alongside fetal MRI and echocardiography. At specialized centres, prenatal management includes fetal endoscopic tracheal occlusion, which is a surgical intervention aimed at promoting lung growth in utero. Postnatal management focuses on cardiopulmonary stabilization and, in severe cases, can involve extracorporeal life support. Clinical practice guidelines continue to evolve owing to the rapidly changing landscape of therapeutic options, which include pulmonary hypertension management, ventilation strategies and surgical approaches. Survivors often have long-term, multisystem morbidities, including pulmonary dysfunction, gastroesophageal reflux, musculoskeletal deformities and neurodevelopmental impairment. Emerging research focuses on small RNA species as biomarkers of severity and regenerative medicine approaches to improve fetal lung development. Congenital diaphragmatic hernia is a rare birth defect associated with cardiopulmonary complications and high mortality and morbidity. This Primer describes the epidemiology and mechanisms of congenital diaphragmatic hernia and discusses diagnosis, management and quality of life for patients.
Background Microglia plays crucial roles in Alzheimer’s disease (AD) development. Triggering receptor expressed on myeloid cells 2 (TREM2) in association with DAP12 mediates signaling affecting microglia function. Here we study the negative regulation of TREM2 functions by leukocyte immunoglobulin-like receptor subfamily B member 2 (LILRB2), an inhibitory receptor bearing ITIM motifs. Methods To specifically interrogate LILRB2-ligand (oAβ and PS) interactions and microglia functions, we generated potent antagonistic LILRB2 antibodies with sub-nanomolar level activities. The biological effects of LILRB2 antagonist antibody (Ab29) were studied in human induced pluripotent stem cell (iPSC)–derived microglia (hMGLs) for migration, oAβ phagocytosis, and upregulation of inflammatory cytokines. Effects of the LILRB2 antagonist antibody on microglial responses to amyloid plaques were further studied in vivo using stereotaxic grafted microglia in 5XFAD mice. Results We confirmed the expression of both LILRB2 and TREM2 in human brain microglia using immunofluorescence. Upon co-ligation of the LILRB2 and TREM2 by shared ligands oAβ or PS, TREM2 signaling was significantly inhibited. We identified a monoclonal antibody (Ab29) that blocks LILRB2/ligand interactions and prevents TREM2 signaling inhibition mediated by LILRB2. Further, Ab29 enhanced microglia phagocytosis, TREM2 signaling, migration, and cytokine responses to the oAβ-lipoprotein complex in hMGL and microglia cell line HMC3. In vivo studies showed significantly enhanced clustering of microglia around plaques with a prominent increase in microglial amyloid plaque phagocytosis when 5XFAD mice were treated with Ab29. Conclusions This study revealed for the first time the molecular mechanisms of LILRB2-mediated inhibition of TREM2 signaling in microglia and demonstrated a novel approach of enhancing TREM2-mediated microglia functions by blocking LILRB2-ligand interactions. Translationally, a LILRB2 antagonist antibody completely rescued the inhibition of TREM2 signaling by LILRB2, suggesting a novel therapeutic strategy for improving microglial functions.
Transcription factors play a fundamental role in cardiovascular adaptation to stress. Nuclear receptor subfamily 4 group A member 2 (NR4A2; NURR1) is an immediate-early gene and transcription factor with a versatile role throughout many organs. In the adult mammalian heart, and particularly in cardiac myocytes, NR4A2 is strongly up-regulated in response to beta-adrenergic stimulation. The physiologic implications of this increase remain unknown. In this study, we aimed to interrogate the consequences of cardiac NR4A2 up-regulation under normal conditions and in response to pressure overload. In mice, tamoxifen-dependent, cardiomyocyte-restricted overexpression of NR4A2 led to cardiomyocyte hypertrophy, left ventricular dilation, heart failure, and death within 40 days. Chronic NR4A2 induction also precipitated cardiac decompensation during transverse aortic constriction (TAC)-induced pressure overload. Mechanistically, NR4A2 caused adult cardiac myocytes to return to a fetal-like phenotype, with a switch to glycolytic metabolism and disassembly of sarcomeric structures. NR4A2 also re-activated cell cycle progression and stimulated DNA replication and karyokinesis but failed to induce cytokinesis, thereby promoting multinucleation of cardiac myocytes. Activation of cell cycle checkpoints led to induction of an apoptotic response which ultimately resulted in excessive loss of cardiac myocytes and impaired left ventricular contractile function. In summary, myocyte-specific overexpression of NR4A2 in the postnatal mammalian heart results in increased cell cycle re-entry and DNA replication but does not result in cardiac myocyte division. Our findings expose a novel function for the nuclear receptor as a critical regulator in the self-renewal of the cardiac myocyte and heart regeneration.
Background Neuroblastic tumors arise from primitive sympathetic ganglion cells and are the most common extracranial solid tumor of childhood. Ganglioneuroma is the most well-differentiated, benign subtype and comprises less than 1% of all soft tissue tumors. One to 5% of these occur in the head and neck, including the parapharyngeal space. It is uncommon to find a physically detectable, neoplastic parapharyngeal space mass in a child. Case report A 7-year-old boy presented with a painless left neck mass. Imaging revealed a 2.6 × 2.7 × 6.1 cm left parapharyngeal space mass. Fine-needle aspiration suggested a ganglioneuroma. The patient developed compressive symptoms, notably pain, thus the decision was made to surgically resect. The tumor was excised transcervically, preserving the great vessels, phrenic and cranial nerves. Postoperatively, the patient developed a mild ipsilateral Horner’s syndrome, suggesting the mass to be a ganglioneuroma of the sympathetic chain. Conclusions Cervical ganglioneuromas typically present as slow-growing masses that cause compressive symptoms or are found incidentally. Resection is reserved for those with significant symptoms and is often complicated by Horner’s syndrome. In the review of literature, there are 23 reported cases of ganglioneuroma in the head/neck with a median age of 17 years. Eight of these occurred in the para/retropharyngeal spaces. Of these, five presented as an asymptomatic neck mass, two presented with compressive symptoms, and one was discovered incidentally. It is important to consider ganglioneuroma in the workup of pediatric neck masses, even in young children. Asymptomatic masses should be monitored for symptomatic transformation, and excision should be considered.
Study objective The rate of cesarean delivery is increasing globally but the risk of perioperative organ injury associated with cesarean delivery is not well defined. The objective of this study was to determine the risk of postpartum acute kidney injury, a peripartum complication defined by an acute decrease in kidney function, associated with cesarean delivery compared to vaginal delivery. Setting Population-based discharge database. Patients The Optum Clinformatics® Data Mart was queried for parturients that underwent cesarean or vaginal delivery between January 2016 to January 2018. Using a propensity score model based on 27 antepartum characteristics, we generated a final matched cohort of 116,876 parturients. Intervention/Exposure Cesarean delivery as the mode of delivery. Measurements The risk of acute kidney injury associated with each delivery mode and the effect of acute kidney injury on the length of hospital stay for parturients. Main results The matched cohort consisted of 116,876 deliveries, with 58,438 cases in each group. In the cesarean delivery group, the incidence of postpartum acute kidney injury was 24.5 vs. 7.9 per 10,000 deliveries in the vaginal delivery group (adjusted odds ratio = 3; 95% CI, 2.13–4.22; P < .001). The median of the length of hospital stay [interquartile range] was longer by 50% in parturients who developed postpartum acute kidney injury after vaginal delivery (3 [2–4] days vs. those who did not, 2 [2, 3] days; P < .001) and by 67% after cesarean delivery (5 [4–7] days vs. 3 [3, 4] days; P < .001). Conclusions Cesarean delivery is associated with a significantly increased risk of postpartum acute kidney injury as compared to vaginal delivery. The development of postpartum acute kidney injury is associated with prolonged length of hospital stay.
Primary failure of eruption (PFE) is a rare disorder defined as incomplete tooth eruption despite the presence of a clear eruption pathway. PFE is known to be caused by rare variants in the parathyroid hormone 1 receptor gene (PTH1R). Although several PTH1R variants have been reported, the etiology of PFE remains unclear. However, important studies that help elucidate the pathology of PFE have recently been published. The purpose of this review is to summarize current treatment options, clinical symptoms or phenotypes for diagnosis, genetic information including solid evidence in mouse disease models and disease-specific induced pluripotent stem cells, thus approaching the etiology of PFE from the perspective of the latest research.
Huntington’s disease (HD) is a rare neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. Inflammasomes are multiprotein complexes capable of sensing pathogen-associated and damage-associated molecular patterns, triggering innate immune pathways. Activation of inflammasomes results in a pro-inflammatory cascade involving, among other molecules, caspases and interleukins. NLRP3 (nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain-containing 3) is the most studied inflammasome complex, and its activation results in caspase-1 mediated cleavage of the pro-interleukins IL-1β and IL-18 into their mature forms, also inducing a gasdermin D mediated form of pro-inflammatory cell death, i.e. pyroptosis. Accumulating evidence has implicated NLRP3 inflammasome complex in neurodegenerative diseases. The evidence in HD is still scant and mostly derived from pre-clinical studies. This review aims to present the available evidence on NLRP3 inflammasome activation in HD and to discuss whether targeting this innate immune system complex might be a promising therapeutic strategy to alleviate its symptoms.
The Mexican state of Tamaulipas serves as a migration waypoint into the US. Here, we determined the contribution of immigrants to TB burden in Tamaulipas. TB surveillance data from Tamaulipas (2006–2013) was used to conduct a cross-sectional characterization of TB immigrants (born outside Tamaulipas) and identify their association with TB treatment outcomes. Immigrants comprised 30.8% of TB patients, with > 99% originating from internal Mexican migration. Most migration was from South to North, with cities adjacent to the US border as destinations. Immigrants had higher odds of risk factors for TB [older age (≥ 65 year old, OR 2.4, 95% CI 2.1, 2.8), low education (OR 1.3, 95% CI 1.2, 1.4), diabetes (OR 1.2, 95% CI 1.1, 1.4)], or abandoning treatment (adjusted OR 1.2, 95% CI 1.0, 1.5). There is a need to identify strategies to prevent TB more effectively in Tamaulipas, a Mexican migration waypoint.
Delayed cerebral ischemia (DCI) continues to be a sequela of aneurysmal subarachnoid hemorrhage (aSAH) that carries significant morbidity and mortality. Aside from nimodipine, no therapeutic agents are available to reduce the incidence of DCI. Pathophysiologic mechanisms contributing to DCI are poorly understood, but accumulating evidence over the years implicates several factors. Those have included microvessel vasoconstriction, microthrombosis, oxidative tissue damage, and cortical spreading depolarization as well as large vessel vasospasm. Common to these processes is red blood cell leakage into the cerebrospinal fluids (CSF) and subsequent lysis which releases hemoglobin, a central instigator in these events. This has led to the hypothesis that early blood removal may improve clinical outcome and reduce DCI. This paper will provide a narrative review of the evidence of hemoglobin as an instigator of DCI. It will also elaborate on available human data that discuss blood clearance and CSF drainage as a treatment of DCI. Finally, we will address a recent novel device that is currently being tested, the Neurapheresis CSF Management System™. This is an automated dual-lumen lumbar drainage system that has an option to filter CSF and return it to the patient.
In this series of talks and the accompanying panel session, leaders from the Society of Asian Academic Surgeons discuss issues faced by Asian Americans and the importance of the role of mentors and allyship in professional development in the advancement of Asian Americans in leadership roles. Barriers, including the model minority myth, are addressed. The heterogeneity of the Asian American population and disparities in healthcare and in research, specifically as relates to Asian Americans, also are examined.
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4,266 members
Dean Forrest Sittig
  • School of Biomedical Informatics
Anne Marie Krachler
  • Department of Microbiology and Molecular Genetics
David Morton Low
  • Division of Management, Policy and Community Health
Benson Mwangi
  • Department of Psychiatry and Behavioral Sciences
Leomar Y Ballester
  • Department of Pathology and Laboratory Medicine
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Giuseppe N. Colasurdo, M.D.
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