Comprehensive analysis of the immune and prognostic implication of MASP1 in stomach adenocarcinoma.

OBJECTIVE: Stomach adenocarcinoma (STAD) is the major cancer worldwide with high morbidity and mortality rate. Late diagnosis and limited treatment options of STAD lead to disease progression, spread, and metastasis. Therefore, finding a new biomarker to diagnosis and treatment is very important for STAD in clinical practice. MATERIALS AND METHODS: The clinical data, transcriptome data and CCLE data were downloaded from TCGA database and CCLE database, respectively. TIMER website, TISIDB website and CIBERSORT methodology were used to analyse immune infiltration. R software and R package were used to analyse gene difference expression, determine co-expression genes, conduct gene enrichment analyses, construct a prognostic signature and establish nomogram. RESULTS: MASP1 was decreased in STAD compared with normal tissue at the mRNA level (p < 0.001). The enrichment analysis showed that mismatch repair (MMR) was related to the MASP1 gene. Up-regulation of MAPS1 expression was positively associated with dendritic cells (p < 0.01), neutrophils (p < 0.05), macrophages (p < 0.001), CD4+ T cells (p < 0.001) and B cells (p < 0.05). A four-gene prognostic signature was determined based on MASP1-related immunomodulators. The prognostic signature was an independent prognostic predictor in STAD. Finally, we established a nomogram to forecast survival and the nomogram has a good prediction accuracy. CONCLUSIONS: In STAD, MASP1 is closely related to immunity. MASP1 has the potential to positively regulate the abundance of immune cells. The MASP1-related prognosis signature and nomogram can accurately predict the survival of patients with STAD. Therefore, MASP1 is likely to be a diagnosis and promising immunotherapy target spot in STAD clinical practice.

Determination of nicotine and cotinine in human plasma by liquid chromatography-tandem mass spectrometry with atmospheric-pressure chemical ionization interface.

Here we report a sensitive liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method capable of quantifying nicotine down to 1 ng/ml and cotinine to 10 ng/ml from 1.0 ml of human plasma. The method was validated over linear ranges of 1.0-50.0 ng/ml for nicotine and 10.0-500.0 ng/ml for cotinine, using deuterated internal standards. Compounds were simply extracted from alkalinized human heparinized plasma with methylene chloride, reconstituted into a solution of acetonitrile, methanol and 10 mM ammonium acetate (53:32:15, v/v) after the organic phase was dried down, and analyzed on the LC-MS-MS, which is a PE Sciex API III system equipped with a Keystone BDS Hypersil CI8 column and atmospheric pressure chemical ionization (APCI) interface. The between-run precision and accuracy of the calibration standards were < or = 6.42% relative standard deviation (R.S.D.) and < or = 11.8% relative error (R.E.) for both nicotine and cotinine. The between-run and within-run precision and accuracy of quality controls, (2.5, 15.0, 37.5 ng/ml for nicotine and 25.0, 150.0, 375.0 ng/ml for cotinine), were < or = 6.34% R.S.D. and < or = 7.62% R.E. for both analytes. Sample stabilities in chromatography, in processing and in biological matrix were also investigated. This method has been applied to pharmacokinetic analysis of nicotine and cotinine in human plasma.