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Brian Searle Profile
Brian Searle

@briansearle

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Career Scientist in Quantitative Health Sciences at @MayoClinic and @proteome_sw into immuno-oncology, proteomics, mass spectrometry & bioinformatics (he/him)

Rochester, MN
Joined October 2009
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@briansearle
Brian Searle
2 months
People have asked about how MAP-MS works so here's a tweetorial on @teerap16's new preprint: MAP-MS takes advantage of parallelization in a trapping MS, collecting Orbitrap MS1s with 2x the dynamic range by differentially amplifying parts of the ion beam.
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@briansearle
Brian Searle
2 months
MAP-MS produces precursor quantification with half the coefficient of variation versus "normal" 1e6 MS1s and 1/3rd compared to "common" 3e6 MS1s. This is huge for people doing DDA-based quantification!
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@briansearle
Brian Searle
2 months
What is the end result? A small (~10%) increase in detections using both DDA and DIA for free on existing hardware (no upgrades or software required). The REAL improvement is much, much more consistent MS1 quantification with match-between-runs.
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@briansearle
Brian Searle
2 months
Tangent: people ask how different MAP-MS is from BoxCar, but it’s more like MSX since it hides ion accumulation inside MS2s “consequence-free”. BoxCar takes multiple long transients to improve dynamic range, which eats up MS2 time. BoxCar produces better MS1s at significant cost!.
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@briansearle
Brian Searle
2 months
MAP-MS provides a roadmap for making better use of the ion beam. To accelerate open science, our raw data ( is already public. We've also uploaded the Exploris 480 .meth method files so you can start experimenting immediately!
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searlelab.org
MAP-MS Multiple Accumulation Precursor Mass Spectrometry (MAP-MS) Description MAP-MS takes advantage of parallelization in a trapping MS. I...
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@briansearle
Brian Searle
2 months
Ok, but does this screw up intensities? It turns out: no. The variable fill logic already adjusts peak intensity as ions/second based on the actual ion injection time. The resulting MAP-MS MS1 appears like “normal” tSIM MS1s to all downstream tools. No programming needed!.
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@briansearle
Brian Searle
2 months
Instead of multiplexing different windows together, MAP-MS multiplexes the entire precursor range. At first this seems strange, but the benefit is to variably fill each range for a different length of time, allowing the instrument to spend more time on "empty" m/z regions.
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@briansearle
Brian Searle
2 months
In 2013, the MacCoss lab showed a way to combine multiple groups of ions in a single spectrum to improve multiplexing with DIA to narrow isolation windows (, which morphed into the popular staggering technique. MAP-MS does the same, but for precursors.
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nature.com
Nature Methods - A multiplexing strategy for data-independent acquisition (DIA)-based mass spectrometry addresses the limitation of low precursor selectivity to make DIA more practical for peptide...
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@briansearle
Brian Searle
2 months
In a hybrid Q-Orbitrap, parallelization still occurs: while one ion batch is measured, a new batch is accumulated. The Orbi's small capacity means MS1s accumulate in 1-2 ms, wasting the rest of the ion beam. MAP-MS accumulates pieces of the MS1 mass range in a single spectrum.
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@briansearle
Brian Searle
2 months
Orbitraps are slow with limited ion capacity. As such, parallel processing has long been part of how Orbitraps work. Since the Fusion Tribrid, while the Orbitrap was busy measuring precursors, the ion trap collects serial MS2s (ie the classic Senko paper:
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@briansearle
Brian Searle
3 months
RT @OhioStatePIIO: New research in @NatureComms on rapid assay development for low input targeted #proteomics using a versatile linear ion….
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@briansearle
Brian Searle
7 months
RT @MaisamHaijaMD: So proud of @V_Akshintala well deserved! We are going to do great things for the diagnosis and management of #pancreatit….
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@briansearle
Brian Searle
7 months
RT @cincykidspcc: @briansearle w/ @OSUWexMed presenting his work on urine proteomics as identifiers of chronic #pancreatitis biomarkers. Hi….
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@briansearle
Brian Searle
8 months
RT @MaisamHaijaMD: A wonderful lecture by ⁦@briansearle⁩ on #proteomic #applications in #childhood #pancreatitis, next phase #collaboration….
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@briansearle
Brian Searle
9 months
Come join the OSU proteomics community! We're hiring a senior staff scientist at @OhioStatePIIO run by @Zihai to direct a mass spec proteomics facility to monitor immune proteins in cancer. A great opportunity for independent MS researchers! DM for details
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Brian Searle
10 months
RT @dschweppe1: Great seeing this big collaborative effort come together with @lea_starita, @Nobu_Hamazaki, @JShendure, and led by @riddhim….
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@briansearle
Brian Searle
11 months
This should be an exciting, educational lecture on ion traps! I am really looking forward to moderating audience questions for Philip during his talk tomorrow. Come join us!.
@hupo_org
Human Proteome
11 months
Register today for this powerful webinar organized by HUPO’s ETC – “The Past, Present and Future of Quadrupole Ion Trap Mass Spectrometers in Proteomics” Speaker Philip M. Remes, PhD – Thurs. Sept. 12 at 9 am PDT, 12 pm EDT, 5 pm CET, 12 am CST
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@briansearle
Brian Searle
1 year
RT @OhioStatePIIO: Kudos to the team of @briansearle, @ArianaShannon, et al. Using a linear ion trap with 1ng total protein on column, they….
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@briansearle
Brian Searle
1 year
RT @ArianaShannon: Come see the Searle lab at ASMS Anaheim #asms2024
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@briansearle
Brian Searle
1 year
RT @kermitmurray: (BioRxiv All) Hybrid Quadrupole Mass Filter Radial Ejection Linear Ion Trap and Intelligent Data Acquisition Enable Highl….
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