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Employment of fluorophore-tagged alkyl and aryl iodides permitted detection of persistent surface intermediates during their direct insertion to commercially available zinc powder. The sensitivity of this subensemble microscopy technique enabled structure-reactivity studies in the formation of intermediates that are present in quantities sufficiently low as to have been undetected previously by traditional ensemble analytical techniques. These surface intermediates were transformed by lithium chloride, leading to the assignment of the mechanistic role of lithium chloride as changing the rate-determining step in the reaction by lowering the barrier for solubilization of these otherwise persistent surface organometallic intermediates. The temperature dependence/qualitative barrier of the direct insertion step was determined independently from the solubilization step and from the barrier for the overall reaction. Detection of these zinc surface intermediates at the single-molecule level, i.e., of individual surface organometallic species, has been achieved for the first time. Energy dispersive X-ray spectroscopy (EDS) measurements of the elemental composition of the surface of the zinc powder determined that lithium chloride does not clean the surface of the oxides; instead, pretreatment of the surface with TMSCl effects partial removal of surface oxides after the 2 h pretreatment time previously reported in the empirically optimized synthetic procedure. Current limitations of this microscopy approach are also determined and discussed with respect to the addition of solid reagents during in operando imaging. Characterization of the resulting soluble fluorophore-tagged organozinc/LiCl complex by ¹H NMR spectroscopy, mass spectrometry, and fluorescence spectroscopy provided insight into its solution dynamics and chemical exchange processes. [ABSTRACT FROM AUTHOR]

Sjögren's Disease (SjD) is a systemic autoimmune disease without a clear etiology or effective therapy. Utilizing unbiased single-cell and spatial transcriptomics to analyze human minor salivary glands in health and disease we developed a comprehensive understanding of the cellular landscape of healthy salivary glands and how that landscape changes in SjD patients. We identified novel seromucous acinar cell types and identified a population of PRR4+CST3+WFDC2 - seromucous acinar cells that are particularly targeted in SjD. Notably, GZMK +CD8 T cells, enriched in SjD, exhibited a cytotoxic phenotype and were physically associated with immune-engaged epithelial cells in disease. These findings shed light on the immune response's impact on transitioning acinar cells with high levels of secretion and explain the loss of this specific cell population in SjD. This study explores the complex interplay of varied cell types in the salivary glands and their role in the pathology of Sjögren's Disease.

Identifying cell types and states remains a time-consuming, error-prone challenge for spatial biology. While deep learning is increasingly used, it is difficult to generalize due to variability at the level of cells, neighborhoods, and niches in health and disease. To address this, we developed TACIT, an unsupervised algorithm for cell annotation using predefined signatures that operates without training data. TACIT uses unbiased thresholding to distinguish positive cells from background, focusing on relevant markers to identify ambiguous cells in multiomic assays. Using five datasets (5,000,000-cells; 51-cell types) from three niches (brain, intestine, gland), TACIT outperformed existing unsupervised methods in accuracy and scalability. Integrating TACIT-identified cell types with a novel Shiny app revealed new phenotypes in two inflammatory gland diseases. Finally, using combined spatial transcriptomics and proteomics, we discovered under- and overrepresented immune cell types and states in regions of interest, suggesting multimodality is essential for translating spatial biology to clinical applications., Competing Interests: Conflict of interest: The authors had access to the study data and reviewed and approved the final manuscript. Although the authors view each of these as noncompeting financial interests, KMB, QTE, BFM, and BMW are all active members of the Human Cell Atlas; furthermore, KMB is a scientific advisor at Arcato Laboratories. All other authors declare no competing interests.

Essentially no information is known about the behavior of individual molecular catalysts under reaction conditions. This is a result of the averaging inherent to traditional analytical techniques. Herein, a combined fluorescence microscopy and 1 H NMR spectroscopy study reveals that unique (that is, non-ensemble averaged) distributions and time-variable kinetics from molecular ruthenium catalysts within growing polynorbornene occur and are detectable between 10 -9  m and 10 -6  m of substrate, surprisingly just 1000-fold less concentrated than a typical laboratory bench-scale reaction. The kinetic states governing single-turnover events are determinable by overlay of the signal arising from individual monomer insertion reactions with that from polymer growth from neighboring catalysts., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Catalytic cycles are typically depicted as possessing time-invariant steps with fixed rates. Yet the true behavior of individual catalysts with respect to time is unknown, hidden by the ensemble averaging inherent to bulk measurements. Evidence is presented for variable chemical kinetics at individual catalysts, with a focus on ring-opening metathesis polymerization catalyzed by the second-generation Grubbs' ruthenium catalyst. Fluorescence microscopy is used to probe the chemical kinetics of the reaction because the technique possesses sufficient sensitivity for the detection of single chemical reactions. Insertion reactions in submicron regions likely occur at groups of many (not single) catalysts, yet not so many that their unique kinetic behavior is ensemble averaged., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)