A molecular study of modern oil paintings: investigating the role of dicarboxylic acids in the water sensitivity of modern oil paints

The 20th century has seen a significant evolution in artists'' paint formulation and technology which is likely to relate to the new conservation challenges frequently presented by modern oil paintings, including unpredictable water- and solvent-sensitivity. This study examined the molecular causes and mechanisms behind these types of modern oil paint vulnerability. Research performed up to now has suggested a correlation between the occurrence of water sensitivity and the presence of relatively high amounts of extractable free dicarboxylic acids. To explore this further, as well as the influence of paint formulation, a set of model paint samples, produced in 2006 using commercial tube paints to which known amounts of additives were added, were analysed. The samples were tested for water sensitivity by aqueous swabbing and characterised using transmission Fourier Transform-Infra Red spectroscopy (FTIR) to determine the molecular composition of the main paint constituents, High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), to identify the type(s) of drying oils used as binders, and Gas Chromatography-Mass Spectrometry (GC-MS) using a recently developed analytical procedure that can discriminate and quantify free fatty and dicarboxylic acids, as well as their corresponding metal soaps (carboxylates of fatty and dicarboxylic acids). The results indicated that the addition of small amounts of additives can influence the water sensitivity of an oil paint, as well as its molecular composition. Additionally the nature of the ionomeric/polymeric network appears to be a significant determining factor in the development of water sensitivity.

Quantitative mass spectrometry was used to investigate the role played by dicarboxylic acids in the water sensitivity of modern oil paints.     

Lysyl-tRNA Synthetase (KRS) Expression in Gastric Carcinoma and Tumor-Associated Inflammation

Background

Lysyl-tRNA synthetase (KRS) is an aminoacyl-tRNA synthetase (ARS) that is essential for protein synthesis during ligation of specific amino acids to their cognate tRNAs. Aberrant expression of ARSs is associated with various human cancers.

Methods

Using immunohistochemical detection, the present study analyzed the clinical relevance of KRS expression in tumor cells and tumor-associated inflammatory cells (TAI) in 457 patients who underwent curative radical surgery and standard adjuvant therapy and who were observed on long-term follow-up.

Results

High expression of KRS in tumor cells (tumor–KRS(+)) was noted in 43.3 % (198 of 457) of cases. High expression of KRS in tumor-associated inflammatory cells (TAI–KRS(+)) including macrophages/monocytes, CD4-positive T cells, and/or neutrophils was observed in 37.2 % (170 of 457) of cases. Status of KRS in the tumor and TAI revealed an association with the known clinicopathological parameters for prognosis of gastric cancer. Tumor–KRS(+) status correlated to shorter overall survival, especially in stage III to IV cancers (P = 0.003), while TAI–KRS(+) status correlated significantly to longer overall survival in gastric cancer (P = 0.049). Cases with tumor–KRS(+) and TAI–KRS(?) status showed significantly reduced survival rates compared to those of other cases (P = 0.010), and status of tumor–KRS(+) and TAI–KRS(?) was revealed as an independently poor prognostic factor of overall survival (P = 0.001).

Conclusions

KRS-related inflammation can be identified in a subset of gastric cancer. This may be a possible mechanism of immune surveillance against tumor progression. In addition, expression status of KRS in tumor and TAI may be an independent prognostic marker for gastric cancer patients.     

HLA-DRB1*1502 allele,subtype of DR15, is associated with susceptibility to ulcerative colitis and its progression

HLA-DRB1 allele typing was performed by the PCR-RFLP method on 59 ulcerative colitis (UC) patients and 136 healthy controls. Phenotypic frequencies of HLA-B52 and DR2 were significantly increased among the UC patients, serologically. DNA typing of HLA-DRB1 revealed that the genotypic frequency of DRB1*1502 was higher in UC than in the controls (49.2% vs 17.6%;P<0.0001). In the analysis of clinical parameters, 82.8% of patients bearing DRB1*1502 were treated with corticosteroids. DRB1*1501 and DRB1*1502 differ in only one amino acid at residue 86 (valine vs glycine), and 66% of the UC patients carried two glycines at position 86 in the HLA-DR-chain (vs 51% of control;P<0.05). These observations suggest that the presence of Gly-86 in the HLA-chain and surrounding amino acid sequence of HLA-DRB1*1502 is strongly associated with susceptibility to UC.