Biology subjects

Pomper, M. G.

Publications and source records attributed to Pomper, M. G..

5 recordsLinked to original sources

bioRxiv2023

In-bore MRI-compatible Transrectal Ultrasound and Photoacoustic Imaging

Prostate cancer (PCa) is known as one of the most prevalent and fatal cancer types. This report describes an MRI-compatible photoacoustic/ultrasound (PA/US) imaging platform to improve the diagnosis of PCa. In the proposed solution, PA imaging, which offers real-time, non-ionizing imaging with high sensitivity and specificity, is combined with MRI, aiming to overcome PAs limited field of view (FOV) and make PA scalable for translation to clinical settings. Central to the design of the system is a reflector-based transrectal probing mechanism composed of MRI-compatible materials. The linear transducer with a center hole for optical fiber delivery can be mechanically actuated to form a multi-angled scan, allowing PA/US imaging from varied cross-sectional views. Performance assessment was carried out in phantom and ex-vivo settings. We confirmed the MRI compatibility of the system and demonstrated the feasibility of its tri-modal imaging capability by visualizing a tubing phantom containing contrast agents. The ex-vivo evaluation of targeted tumor imaging capability was performed with a mouse liver sample expressing PSMA-positive tumors, affirming the systems compatibility in spectroscopic PA (sPA) imaging with biological tissue. These results support the feasibility of the in-bore MRI-compatible transrectal PA and US and the potential clinical adaptability.

bioengineering↗

bioRxiv2022

The SARS-CoV-2 spike protein binds and modulates estrogen receptors

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein binds angiotensin-converting enzyme 2 (ACE2) at the cell surface, which constitutes the primary mechanism driving SARS-CoV-2 infection. Molecular interactions between the transduced S and endogenous proteins likely occur post-infection, but such interactions are not well understood. We used an unbiased primary screen to profile the binding of full-length S against >9,000 human proteins and found significant S-host protein interactions, including one between S and human estrogen receptor alpha (ER). After confirming this interaction in a secondary assay, we used bioinformatics, supercomputing, and experimental assays to identify a highly conserved and functional nuclear receptor coregulator (NRC) LXD-like motif on the S2 subunit and an S-ER binding mode. In cultured cells, S DNA transfection increased ER cytoplasmic accumulation, and S treatment induced ER-dependent biological effects and ACE2 expression. Noninvasive multimodal PET/CT imaging in SARS-CoV-2-infected hamsters using [18F]fluoroestradiol (FES) localized lung pathology with increased ER lung levels. Postmortem experiments in lung tissues from SARS-CoV-2-infected hamsters and humans confirmed an increase in cytoplasmic ER expression and its colocalization with S protein in alveolar macrophages. These findings describe the discovery and characterization of a novel S-ER interaction, imply a role for S as an NRC, and are poised to advance knowledge of SARS-CoV-2 biology, COVID-19 pathology, and mechanisms of sex differences in the pathology of infectious disease.

immunology↗

bioRxiv2021

Forebrain Shh overexpression improves cognitive function in a Down syndrome mouse model and euploid littermates

People with Down syndrome (DS) have intellectual disability, early-onset dementia, and cerebellar hypoplasia. Trisomic cerebellar granule cell precursors from Ts65Dn, a mouse model of DS, had a deficit in mitogenic response to Sonic hedgehog (Shh) in vitro, and newborn Ts65Dn mice received a single subcutaneous injection of the Shh signaling agonist SAG had normalized cerebellar morphology and improved spatial learning and hippocampal synaptic plasticity at adult. However, cognitive effects of Shh overexpression in vivo and where SAG acts to improve cognitive outcomes of trisomy are unknown. Here, we created an inducible human Shh (hShh) knock-in mouse, TRE-bi-hShh-Zsgreen1 (TRE-hShh), expressing dually-lipidated Shh-Np in the presence of transactivator (tTA). Double transgenic mice, Camk2a-tTA;TRE-hShh (Camk2a-hShh) and Pcp2-tTA;TRE-hShh (Pcp2-hShh), increased Shh signaling in forebrain and cerebellum, respectively. Forebrain Shh overexpression normalized hyperactivity, and spatial learning and memory deficits in 3-month-old Ts65Dn, while Shh overexpression in cerebellum had no effect. Further, Camk2a-hShh delayed early-onset severe cognitive impairment in 7-month-old Ts65Dn and enhanced spatial cognition in euploid (Eu) and showed no effect on the longevity of Eu or Ts65Dn, and MRI demonstrated that Pcp2-hShh mitigated disproportionately small cerebellum in Ts65Dn. Finally, Ts65Dn at postnatal day 6 had reduced Gli1 levels in hippocampus and cerebellum, which could be at least partially rescued by Camk2a-hShh and Pcp2-hShh, respectively. Our findings suggest restoration of impaired Shh signaling in forebrain from the perinatal and early postnatal period improves cognitive function.

neuroscience↗

bioRxiv2018

Chemogenetic ligands for translational neurotheranostics

Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) are a popular chemogenetic technology for manipulation of neuronal activity in uninstrumented awake animals with potential for precision medicine-based clinical theranostics. DREADD ligands developed to date are not appropriate for such translational applications. The prototypical DREADD agonist clozapine N-oxide (CNO) lacks brain entry and converts to clozapine. The second-generation DREADD agonist, Compound 21 (C21), was developed to overcome these limitations. We found that C21 has low brain penetrance, weak affinity, and low in vivo DREADD occupancy. To address these drawbacks, we developed two new DREADD agonists, JHU37152 and JHU37160, and the first dedicated positron emission tomography (PET) DREADD radiotracer, [18F]JHU37107. JHU37152 and JHU37160 exhibit high in vivo DREADD potency. [18F]JHU37107 combined with PET allows for DREADD detection in locally-targeted neurons and at their long-range projections, enabling for the first time, noninvasive and longitudinal neuronal projection mapping and potential for neurotheranostic applications.

neuroscience↗

bioRxiv2017

PET studies of the glial cell marker TSPO in psychosis patients - a meta-analysis using individual participant data

BackgroundAccumulating evidence suggests that the immune system may be an important target for new treatment approaches in schizophrenia. Positron emission tomography (PET) and radioligands binding to the translocator protein (TSPO), which is expressed in glial cells in brain including immune cells, represents a potential method for patient stratification and treatment monitoring. This study examined if patients with first episode psychosis and schizophrenia had altered TSPO levels as compared to healthy control subjects.\n\nMethodsPubMed was searched for studies comparing patients with psychosis to healthy controls using second-generation TSPO radioligands. The outcome measure was distribution volume (VT), an index of TSPO levels, in frontal cortex (FC), temporal cortex (TC) and hippocampus (HIP). Bayes factors (BF) were applied to examine the relative support for higher, lower or no-change of TSPO levels in patients as compared to healthy controls.\n\nResultsFive studies, with 75 patients with first-episode psychosis or schizophrenia and 77 healthy control subjects were included. BF showed strong support for lower patient VT relative to no-change (all BF>32) or relative to an increase (all BF>422) in all brain regions. From the posterior distributions, mean patient-control differences in standardized VT values were -0.48 for FC (95% credible interval (CredInt)=-0.88 to -0.09), -0.47 for TC (CredInt=-0.87 to -0.07) and -0.63 for HIP (CredInt=-1.00 to -0.25).\n\nDiscussionThe observed reduction of TPSO in compared to control subjects in patients may correspond to altered function or lower density of brain immune cells. Future studies should focus on investigating the underlying biological mechanisms and their relevance for treatment.

immunology↗