We present the geoBoundaries Global Administrative Database (geoBoundaries): an online, open license resource of the geographic boundaries of political administrative divisions (i.e., state, county). Contrasted to other resources geoBoundaries (1) provides detailed information on the legal open license for every boundary in the repository, and (2) focuses on provisioning highly precise boundary data to support accurate, replicable scientific inquiry. Further, all data is released in a structured form, allowing for the integration of geoBoundaries with large-scale computational workflows. Our database has records for every country around the world, with up to 5 levels of administrative hierarchy. The database is accessible at http://www.geoboundaries.org, and a static version is archived on the Harvard Dataverse.

Expressed prostatic secretions (EPS), also called post digital rectal exam urines, are proximal fluids of the prostate that are widely used for diagnostic and prognostic assays for prostate cancer. These fluids contain an abundant number of glycoproteins and extracellular vesicles secreted by the prostate gland, and the ability to detect changes in their N-glycans composition as a reflection of disease state represents potential new biomarker candidates. Methods to characterize these N-glycan constituents directly from clinical samples in a timely manner and with minimal sample processing requirements are not currently available. In this report, an approach is described to directly profile the N-glycan constituents of EPS urine samples, prostatic fluids and urine using imaging mass spectrometry for detection. An amine reactive slide is used to immobilize glycoproteins from a few microliters of spotted samples, followed by peptide N-glycosidase digestion. Over 100 N-glycan compositions can be detected with this method, and it works with urine, urine EPS, prostatic fluids, and urine EPS-derived extracellular vesicles. A comparison of the N-glycans detected from the fluids with tissue N-glycans from prostate cancer tissues was done, indicating a subset of N-glycans present in fluids derived from the gland lumens. The developed N-glycan profiling is amenable to analysis of larger clinical cohorts and adaptable to other biofluids.

Sialic acid isomers attached in either α2,3 or α2,6 linkage to glycan termini confer distinct chemical, biological, and pathological properties, but they cannot be distinguished by mass differences in traditional mass spectrometry experiments. Multiple derivatization strategies have been developed to stabilize and facilitate the analysis of sialic acid isomers and their glycoconjugate carriers by high-performance liquid chromatography, capillary electrophoresis, and mass spectrometry workflows. Herein, a set of novel derivatization schemes are described that result in the introduction of bioorthogonal click chemistry alkyne or azide groups into α2,3and α2,8-linked sialic acids. These chemical modifications were validated and structurally characterized using model isomeric sialic acid conjugates and model protein carriers. Use of an alkyne-amine, propargylamine, as the second amidation reagent effectively introduces an alkyne functional group into α2,3-linked sialic acid glycoproteins. In tissues, serum, and cultured cells, this allows for the detection and visualization of Nlinked glycan sialic acid isomers by imaging mass spectrometry approaches. Formalin-fixed paraffinembedded prostate cancer tissues and pancreatic cancer cell lines were used to characterize the numbers and distribution of alkyne-modified α2,3-linked sialic acid N-glycans. An azide-amine compound with a poly(ethylene glycol) linker was evaluated for use in histochemical staining. Formalin-fixed pancreatic cancer tissues were amidated with the azide amine, reacted with biotin-alkyne and copper catalyst, and sialic acid isomers detected by streptavidin-peroxidase staining. The direct chemical introduction of bioorthogonal click chemistry reagents into sialic acid-containing glycans and glycoproteins provides a new glycomic tool set to expand approaches for their detection, labeling, visualization, and enrichment.

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Identifying distinct biomarkers of DCIS and determining the invasive potential of DCIS are of great clinical importance. N-linked glycans present on the cell surface of DCIS lesions and surrounding stroma are potential biomarkers of disease and tissue, but remain largely unexplored. An N-glycan targeted imaging mass spectrometry (IMS) approach was initiated to identify N-glycans associated with DCIS and progression in clinical FFPE tissues. A cohort of pathologist annotated DCIS and IDC tissues with a range of disease severity as well as the RAHBT TMA DCIS cohort were evaluated. The RAHBT cohort contains primary DCIS lesions with known long-term outcomes and serves as a good sample set to identify early markers indicating progressive potential, while the DCIS and IDC large tissue biopsies provide information on distinct glycan profiles when DCIS has progressed to IDC. Initially, tissue samples containing DCIS alone or both DCIS and IDC were processed for N-glycan MALDI-IMS analysis, the goal being to establish a consensus panel of each analyte and determine distinct profiles of DCIS when alone vs. when IDC was present. For N-glycans, a peak list of 54 N-glycans was selected for evaluation of each DCIS only tissue, as well as the mixed DCIS/IDC tissues. By highest intensity, the major DCIS-associated glycans were in the high-mannose and paucimannose structure categories. Additionally, a series of tri- and tetra-antennary multi-fucosylated glycans were also detected specifically in the DCIS lesions. In tissues containing both IDC and DCIS lesions, the high mannose glycans were also detected in the IDC regions, and GlcNAc-bisected glycans were seen elevated in these as compared to DCIS-only tissues. For samples in the RAHBT TMA cohort (progressors N=43; non-progressors N=78), the bisected N-glycans seen elevated with IDC were also seen to be significantly increased in the RAHBT samples that would eventually progress to IDC. Additional analyses to evaluate N-glycan isomer distributions for fucosylated and sialylated glycan species are also ongoing. The cumulative N-glycan data will be assessed with the extensive spatial genomic, transcriptomic and immunohistological data already generated for the same samples in the RAHBT cohort. This novel combination of multi-enzymatic digests with histopathology annotations represents an extensive multi-dimensional profile of DCIS and a novel tissue biomarker discovery approach. Citation Format: Elizabeth N. Wallace, Grace Grimsley, Siri H. Strand, Robert Michael Angelo, Graham Colditz, E. Shelley Hwang, Robert West, Jeffrey R. Marks, Peggi M. Angel, Richard R. Drake. Characterizing N-glycan profiles of DCIS progression using tissue imaging MALDI mass spectrometry [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr PR010.