Ultraflextreme maldi tof instrument

Profiles of myocardial cryosections of each individuals were acquired using an UltrafleXtreme MALDI-TOF instrument (Bruker Daltonics, Bremen, Germany). For each cryosection, 20 average spectra were collected (resulting from a sum of 10,000 spectra).
For the comparative analysis of individuals peaks between control and electrical shock groups in the “near” and “far” regions, non-parametric Wilcoxon statistic test was used. Masses were considered statistically differential between groups if the p value was < 0.01 with a Fold Change (FC) ratio between the mean normalized intensity values > 1.5 or < 0.66. Receiver operating characteristic (ROC) curves were generated and masses with areas under the curve (AUC) > 0.8 were specially retained.

The cell-free supernatant was collected from a 200 mL culture of strain DHA6, acidified using 2 M HCl (pH 2.0), and kept overnight at 4 °C. After incubation, CLPs were precipitated through centrifugation at 14,000 rpm for 20 min at 4 °C, re-dissolved in methanol (pH 7.0), and dried using a rotary vacuum [42 (link)]. The dried CLPs were subsequently dissolved in dimethyl sulfoxide (DMSO; Sigma-Aldrich, St. Louis, MO, USA) at 100 μg/mL for further experimental use.
The CLPs produced by strain DHA6 were characterized using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)-mass spectrometry (MS) method [43 (link),44 (link)]. DHA6 was cultured in tryptic soy broth medium at 28 ± 2 °C for 48 h, and a single colony was suspended in a matrix solution (10 mg/mL cyano-4-hydroxycinnamic acid in 70% water, 30% acetonitrile, and 0.1% trifluoroacetic acid). The bacterial samples were homogenized, and 1 μL of the solution was spotted onto a MALDI-TOF MTP 384 objective plate (Bruker Daltonik GmbH, Leipzig, Germany). After air-drying, MALDI-TOF-mass spectra were recorded using a Bruker Ultraflextreme MALDI-TOF instrument (Bruker, Bremen, Germany) equipped with a Smartbeam laser operating at a 2-kHz repetition rate. Spectra were acquired in positive linear ion mode within the mass range of 300 to 3000 Dalton (Da).