Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a key tool for the analysis of biological tissues. It provides spatial and quantitative information about different types of analytes within tissue sections. Despite the increasing improvements of this technique, the low detection sensitivity of some compounds remains an important challenge to overcome. Poor sensitivity is related to weak ionization efficiency, low abundance of analytes and matrix ions, or endogenous interferences. On-tissue chemical derivatization (OTCD) has proven to be an important solution to these issues and is increasingly employed in MALDI MSI studies. OTCD reagents, synthesized or commercially available, have been essentially used for the detection of small exogenous or endogenous molecules within tissues. Optimally, an OTCD reaction is performed in mild conditions, in an acceptable range of time, preserves the integrity of the tissues, and prevents the delocalization. In addition to their reactivity with a targeted chemical function, some OTCD reagents can also be used as a matrix, which simplifies the sample preparation procedure. In this review, we present an exhaustive overview of OTCD reagents and methods used in MALDI MSI studies.The argument concerning the exact minimum number of examined lymph nodes (ELNs) has continued for a long time among various regions, and no consensus has been reached for stratified pathological T stages for data to date. Data from 4607 pN0 patients with gastric cancer were analyzed. Kaplan-Meier analysis showed the similar overall survival (OS) outcomes among the 3 groups (ELNs ≤ 15, 16 ≤ ELNs ≤ 29 and ELNs ≥ 30, P = .171). However, the ELNs ≥ 30 group had a better disease-free survival (DFS) outcome compared with the others (all P less then .05). An increased ELN group (ELNs ≥ 30) showed an improved OS only for pT3 patients (hazard ratio [HR] = 0.397, 95% confidence interval (CI) 0.182-0.866, P = .020), while an improved DFS for pT3 patients (HR = 0.362, 95%CI 0.152-0.860, P = .021) and pT4 patients (HR = 0.484, 95%CI 0.277-0.844, P = .011) in the multivariate analysis. A well discriminated and calibrated nomogram was constructed to predict the probability of the OS and DFS, with the C-index for OS and DFS prediction of 0.782 (95%CI 0.735 to 0.829) and 0.738 (95%CI 0.685 to 0.791), respectively. This study provides new and useful insights into the impact of ELN count on reducing stage migration and postoperative recurrence of pN0 patients with gastric cancer in 2000-2017. In conclusion, a larger number of ELNs is suggested for surgeons to prolong the prognosis of pN0 gastric cancer, especially for pT3 patients. To describe the incidence, demographics, diagnostic clinical manifestations and long-term outcomes of juvenile dermatomyositis (JDM) in Maori and Pacific Island compared to European children. A chart review was conducted of children with JDM seen by the Starship Rheumatology service between 2000 and 2020. Diagnostic clinical manifestations, demographics, disease course and significant complications were collated. The incidence, clinical manifestations and severity of JDM were determined and compared between ethnic groups, in particular Maori and Pacific Island, and European children. The overall incidence of JDM was 0.24/100 000 per year with no significant ethnic variation. Maori children were less likely to achieve a clinical response (71 vs. https://www.selleckchem.com/products/m344.html 100%, P= 0.08), Maori and Pacific less likely to achieve clinical remission (56 vs. 40%, P= 0.69), with Maori (71 vs. 44%, P= 0.37) and Maori and Pacific (60 vs. 44%, P= 0.69) children more likely to follow a chronic course compared to European children. Calcinosis (50 vs. 13%, P= 0.07), cutaneous vasculopathy (30 vs. 0%, P= 0.05) and interstitial lung disease (30 vs. 6%, P= 0.26) were more common in Maori and Pacific compared to European children. The incidence of JDM among a cohort of New Zealand children was established, with Maori and Pacific children more likely to experience a chronic continuous disease course, calcinosis, cutaneous vasculopathy and interstitial lung disease compared to European children. The incidence of JDM among a cohort of New Zealand children was established, with Maori and Pacific children more likely to experience a chronic continuous disease course, calcinosis, cutaneous vasculopathy and interstitial lung disease compared to European children.The purpose of this study was to evaluate oxygen-enhanced pulmonary imaging at 0.55 T with 3D stack-of-spirals ultrashort-TE (UTE) acquisition. Oxygen-enhanced pulmonary MRI offers the measurement of regional lung ventilation and perfusion using inhaled oxygen as a contrast agent. Low-field MRI systems equipped with contemporary hardware can provide high-quality structural lung imaging by virtue of the prolonged T2 *. Fortuitously, the T1 relaxivity of oxygen increases at lower field strengths, which is expected to improve the sensitivity of oxygen-enhanced lung MRI. We implemented a breath-held T1 -weighted 3D stack-of-spirals UTE acquisition with a 7 ms spiral-out readout. Measurement repeatability was assessed using five repetitions of oxygen-enhanced lung imaging in healthy volunteers (n = 7). The signal intensity at both normoxia and hyperoxia was strongly dependent on lung tissue density modulated by breath-hold volume during the five repetitions. A voxel-wise correction for lung tissue density improved the repeatability of percent signal enhancement maps (coefficient of variation = 34 ± 16%). Percent signal enhancement maps were compared in 15 healthy volunteers and 10 patients with lymphangioleiomyomatosis (LAM), a rare cystic disease known to reduce pulmonary function. We measured a mean percent signal enhancement of 9.0 ± 3.5% at 0.55 T in healthy volunteers, and reduced signal enhancement in patients with LAM (5.4 ± 4.8%, p = 0.02). The heterogeneity, estimated by the percent of lung volume exhibiting low enhancement, was significantly increased in patients with LAM compared with healthy volunteers (11.1 ± 6.0% versus 30.5 ± 13.1%, p = 0.01), illustrating the capability to measure regional functional deficits.