Romanowsky staining: history, recent advances and future prospects from a chemistry perspective

Romanowsky staining was an important methodological breakthrough in diagnostic hematology and cytopathology during the late 19th and early 20th centuries; it has facilitated for decades the work of biologists, hematologists and pathologists working with blood cells. Despite more than a century of studying Romanowsky staining, no systematic review has been published that explains the chemical processes that produce the "Romanowsky effect" or "Romanowsky-Giemsa effect" (RGE), i.e., a purple coloration arising from the interaction of an azure dye with eosin and not due merely to their simultaneous presence. Our review is an attempt to build a bridge between chemists and biomedical scientists and to summarize the available data on methylene blue (MB) demethylation as well as the related reduction and decomposition of MB to simpler compounds by both light and enzyme systems and microorganisms. To do this, we analyze modern data on the mechanisms of MB demethylation both in the presence of acids and bases and by disproportionation due to the action of light. We also offer an explanation for why the RGE occurs only when azure B, or to a lesser extent, azure A is present by applying experimental and calculated physicochemical parameters including dye-DNA binding constants and electron density distributions in the molecules of these ligands. Finally, we discuss modern techniques for obtaining new varieties of Romanowsky dyes by modifying previously known ones. We hope that our critical literature study will help scientists understand better the chemical and physicochemical processes and mechanisms of cell staining with such dyes.

Resonant Raman scattering on graphene: SERS and gap-mode TERS

Nanoscale deformations and corrugations occur in graphene-like two-dimensional materials during their incorporation into hybrid structures and real devices, such as sensors based on surface-enhanced Raman scattering (SERS-based sensors). The structural features mentioned above are known to affect the electronic properties of graphene, thus highly sensitive and high-resolution techniques are required to reveal and characterize arising local defects, mechanical deformations, and phase transformations. In this study, we demonstrate that gap-mode tip-enhanced Raman Scattering (gm-TERS), which offers the benefits of structural and chemical analytical methods, allows variations in the structure and mechanical state of a two-dimensional material to be probed with nanoscale spatial resolution. In this work, we demonstrate locally enhanced gm-TERS on a monolayer graphene film placed on a plasmonic substrate with specific diameter gold nanodisks. SERS measurements are employed to determine the optimal disk diameter and excitation wavelength for further realization of gm-TERS. A significant local plasmonic enhancement of the main vibrational modes in graphene by a factor of 100 and a high spatial resolution of 10 nm are achieved in the gm-TERS experiment, making gm-TERS chemical mapping possible. By analyzing the gm-TERS spectra of the graphene film in the local area of a nanodisk, the local tensile mechanical strain in graphene was detected, resulting in a split of the G mode into two components, G+ and G-. Using the frequency split in the positions of G+ and G- modes in the TERS spectra, the stress was estimated to be up to 1.5%. The results demonstrate that gap-mode TERS mapping allows rapid and precise characterization of local structural defects in two-dimensional materials on the nanoscale.

Diverse prognostic value of the GTn promoter polymorphism in squamous cell and adeno carcinoma of the oesophagus

The basal transcription of heme oxygenase-1 (HO-1) regulation is dependent upon a GT repeat germ line polymorphism (GTn) in the promoter of the HO-1 gene. We determined the prognostic value of HO-1 promoter polymorphism on the natural postoperative course of complete resected oesophageal cancer. Genomic DNA from 297 patients was amplified by polymerase chain reaction and sequenced. The results were correlated with clinicopathological parameters, disseminated tumour cells in bone marrow (DTC) and clinical outcome. Depending on short allele with <25 and long allele with ≥25, GTn repeats three genotypes (SS, SL and LL) were defined. A diverse role of GTn was evident in squamous cell carcinoma (SCC) and adenocarcinoma (AC). In SCC, the SS genotype presented less advanced tumours with lower rate DTC in bone marrow and relapse compared with L-allele carriers. In contrast, AC patients with the SS genotype displayed a complete opposing tumour characteristic. The disease-free (DFS) and overall survival (OS) in SCC patients was markedly reduced in LL genotypes (p < 0.001). In AC contrarily the SS genotype patients displayed the worst DFS and OS (p < 0.001). GTn is a strong prognostic factor with diverse prognostic value for recurrence and survival in AC and SCC.

Single nucleotide polymorphism in esophageal cancer related gene 1: an analysis in resected oral squamous cell carcinoma patients

Esophageal cancer related gene 1 (ECRG1) is a novel candidate tumor suppressor gene in human esophageal squamous cells. Overexpression of ECRG1 protein inhibits tumor cell proliferation. Genetic polymorphisms in coding sequences of the gene may cause functional alterations of the gene product and be associated with higher cancer risk and disease phenotypes. A single nucleotide polymorphism (SNP) (Arg290Gln) found in the coding region of ECRG1 might play a role in susceptibility to esophageal squamous cell carcinoma. This study examined SNPs in ECRG1 in a similar tumor type (oral squamous cell carcinoma; OSCC) and investigated the relationship between SNPs in ECRG1 and the clinical outcome of patients with OSCC. DNA samples of 137 OSCC patients were analyzed for SNP genotypes Arg/Arg, Arg/Gln and Gln/Gln in the coding region (exon 8) of ECRG1. SNP genotypes Arg/Arg were found in 70 (51%), Arg/Gln in 60 (43%) and Gln/Gln in 7 (5%) patients. There was no significant association between genotypes and survival (p=0.77) or relapse free survival (p=0.32). The Gln/Gln genotype had the best survival (not significant) probably due to rare cases of SNP Gln/Gln genotype. Genotype Arg/Arg might be a potential negative prognostic marker in OSCC, but more studies with higher patient numbers are required.

Absence of H- and K-ras oncogene mutations in sporadic medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) occurs sporadically (sMTC) or as part of the inherited cancer syndrome, multiple endocrine neoplasia type 2 (MEN 2). While the occurence of the MEN 2 syndrome is associated with mutations in the RET protooncogene, the reason for carcinogenesis in sMTC still remains unclear. Ras is a frequently mutated oncogene in a broad spectrum of human tumors and has been found in about 50% of follicular, papillary or anaplastic thyroid carcinomas. The purpose of this study was to determine, whether mutations in the ras oncogene could play a possible role in the carcinogenesis of sMTC. In this study we analyzed 15 sMTC for mutations in the hotspots codon 12, 13 and 61 of the H- and K-ras oncogene. We used the direct sequencing technique. In none of the examined tumors we were able to detect a mutation in the codon 12, 13 and 61 of the H-ras and K-ras oncogene. Based upon these results, we conclude that H- and K-ras do not play an important role in the carcinogenesis of sMTC.

No correlation between RET immunostaining and the codon 918 mutation in sporadic medullary thyroid carcinoma

INTRODUCTION

Medullary thyroid carcinoma (MTC) occurs sporadically or as part of the inherited cancer syndrome, multiple endocrine neoplasia (MEN) type 2. The MEN2 gene has been identified as the RET proto-oncogene. Mutations in the RET proto-oncogene are associated with the pathogenesis of MTC. Approximately 23-40% of sporadic MTCs (sMTCs) have a somatic RET codon 918 mutation within the catalytic core of the tyrosine kinase, which is a mutation found in over 98% of all MEN 2B cases as a germline mutation.

METHODS

In order to elucidate the role of this mutation, we examined 40 sMTCs for the codon 918 mutation. Simultaneously, we looked for overexpression of the RET protein by means of immunohistochemistry with a newly developed RET antibody.

RESULTS

In 8 of 40 tumors (20%), we were able to find a RET codon 918 mutation. Nine of 40 tumors (22.5%) showed immunoreactivity with the RET antibody.

CONCLUSION

The presence of the somatic RET codon 918 mutations did not correlate with the presence of positive RET immunostaining.

27-bp deletion in the ret proto-oncogene as a somatic mutation associated with medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) occurs as a sporadic tumor or in connection with the inherited cancer syndromes of multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Missense RET proto-oncogene mutations of one of cysteine codons in exons 10 and 11 are found in the majority of families with MEN 2A and or familial MTC. In MEN 2B, mutations at codon 918, exon 16, have been identified in most of the affected individuals. In a significant amount of sporadic MTC somatic codon 918 mutations appear. In addition to these, a 6-bp deletion including codon 630 and a 24-bp deletion including codon 634 combined with a 6-bp insertion have been observed. We report on a 27-bp deletion in exon 10 as a somatic mutation associated with a sporadic medullary thyroid carcinoma.

[Detection of H-ras and K-ras in tumors of gastrointestinal-pancreatic system]

The Gastro-Entero-Pancreatic System (GEP) defined a group of highly differentiated neuroendocrine tumors (Insulinomas, Gastrinomas, PP-omas, Somatostatinomas, Carcinoids). In this kind of tumors the multistage carcinogenesis is really unknown. Activated ras oncogenes could play an important role in initiation or process of carcinogenesis in different human cancers. The purpose of our study was to determe if H-ras or K-ras play a role in the carcinogenesis of GEP tumors. 20 paraffin embedded tumor tissues (1 Vipom, 1 Somatostatinom, 10 Carcinoids, 1 Gastrinoma, 4 livermetastasis of a Carcinoid, 3 Insulinomas) were analysed immunohistologic of H-ras and K-ras oncogene protein expression. Immunohistologic investigations showed a H-ras expression in 65% (13/20). K-ras protein could detected in 10% (2/20). On the basis of these data H-ras oncogene expression could play a role in the multistage carcinogenesis of GEP tumors.

[Somatic ret proto-oncogene mutations in sporadic C-cell carcinoma of the thyroid gland]

Germline mutations of the RET proto-oncogene localized on chromosome 10q11.2 are the underlying cause of hereditary medullary thyroid carcinoma. In MEN 2A and FMTC, mutations can be found in exons 10, 11, 13 or 14. MEN 2B is characterized by a specific mutation in exon 16. In a significant number of sporadic MTC somatic mutations in codon 918 (exon 16) are detectable. Some rare sporadic MTC present somatic mutations in codons 611, 634, 768 and 883. Recently, deletion-insertion of the RET proto-oncogene in exon 11 and a deletion in exon 10 has been found. RET proto-oncogene mutations are not only responsible for the development of the familial MTC, but may also play an important role in the pathogenesis of sporadic MTC. However, the prognostic relevance of these somatic events is still unclear.