Gábor Méhes

Red Cells, Hemoglobin, Heme, Iron, and Atherogenesis

Objective—We investigated whether red cell infiltration of atheromatous lesions promotes the later stages of atherosclerosis. Methods and Results—We find that oxidation of ferro (FeII) hemoglobin in ruptured advanced lesions occurs generating ferri (FeIII) hemoglobin and via more extensive oxidation ferrylhemoglobin (FeIII/FeIV=O). The protein oxidation marker dityrosine accumulates in complicated lesions, accompanied by the formation of cross-linked hemoglobin, a hallmark of ferrylhemoglobin. Exposure of normal red cells to lipids derived from atheromatous lesions causes hemolysis and oxidation of liberated hemoglobin. In the interactions between hemoglobin and atheroma lipids, hemoglobin and heme promote further lipid oxidation and subsequently endothelial reactions such as upregulation of heme oxygenase-1 and cytotoxicity to endothelium. Oxidative scission of heme leads to release of iron and a feed-forward process of iron-driven plaque lipid oxidation. The inhibition of heme release from globin by haptoglobin and sequestration of heme by hemopexin suppress hemoglobin-mediated oxidation of lipids of atheromatous lesions and attenuate endothelial cytotoxicity. Conclusion—The interior of advanced atheromatous lesions is a prooxidant environment in which erythrocytes lyse, hemoglobin is oxidized to ferri- and ferrylhemoglobin, and released heme and iron promote further oxidation of lipids. These events amplify the endothelial cell cytotoxicity of plaque components.

Heterogeneity of Prostate-Specific Membrane Antigen (PSMA) Expression in Prostate Carcinoma with Distant Metastasis

Prostate-specific membrane antigen (PSMA) is a transmembrane protein that is overexpressed in advanced stage prostate adenocarcinomas. As a novel target for in vivo prognostic and therapeutic approaches, the distribution pattern of PSMA in primary and metastatic tumors is of significant interest. In this study we addressed the cellular distribution and heterogeneity of PSMA expression. Paraffin-embedded sections of 51 patients with primary prostate carcinoma and distant metastases were evaluated. Immunohistochemistry was used to determine the cellular localization, staining intensity and positive cell fraction which were related to tumor type and growth pattern. We demonstrated differences in the intracellular localization of the PSMA immunostaining which seem to be related to the tumor differentiation pattern. A significant number of the primary tumors (7/51) and metastases (6/51) presented with highly heterogeneous PSMA expression and in further 2 primary, and 8 metastatic tumors the staining was in the negative range (<10% positive tumor cells). A direct correlation between histological parameters and PSMA expression could not be demonstrated. Our findings clearly support the feasibility but also direct to potential failures of PSMA-targeted in vivo diagnostic and therapeutic approaches in prostate cancer patients with distant metastasis.

The age and genomic integrity of neurons after cortical stroke in humans

It has been unclear whether ischemic stroke induces neurogenesis or neuronal DNA rearrangements in the human neocortex. Using immunohistochemistry; transcriptome, genome and ploidy analyses; and determination of nuclear bomb test–derived 14C concentration in neuronal DNA, we found neither to be the case. A large proportion of cortical neurons displayed DNA fragmentation and DNA repair a short time after stroke, whereas neurons at chronic stages after stroke showed DNA integrity, demonstrating the relevance of an intact genome for survival.

Solid and papillary epithelial neoplasm arising in heterotopic pancreatic tissue of the mesocolon

Aim—Solid and papillary epithelial neoplasm (SPEN) is an uncommon pancreatic tumour. Very rarely it has also been described outside the pancreas, usually arising from heterotopic pancreatic tissue. This report summarises all the published extrapancreatic SPENs and documents the sixth such case arising from heterotopic pancreatic tissue of the transverse mesocolon in a 15 year old girl. Methods/Results—Histological and immunohistochemical examination revealed typical papillary and solid areas composed of columnar, cuboidal, and round cells, which were focally positive for vimentin, cytokeratin, neurone specific enolase, carcinoembryonic antigen, α1-antitrypsin, α1-antichymotrypsin, and negative for neuroendocrine markers (neurofilament, PGP 9.5, chromogranin A, synaptophysin, and S100), p53, and oestrogen and progesterone receptors. Electron microscopy showed scant zymogen but no neurosecretory granules. In agreement with the flow cytometric result of diploidy, comparative genomic hybridisation (CGH) did not reveal loss or gain of genetic material, and the in situ hybridisation analysis of the RB1 and p53 genes revealed no abnormality in the 13q and 17p arms. Conclusions—Immunohistochemical and electron microscopic data support exocrine differentiation. The CGH and the flow cytometric results suggest a subtle, yet unknown genetic change, rather than a large genetic alteration. RB1 and p53 in situ hybridisation ruled out the role of deletion at these sites in the pathogenesis of SPEN. Interestingly, review of the published and the present heterotopic pancreatic SPENs identified the mesocolon as the most common anatomical site (four of six), despite the very rare occurrence of ectopic pancreatic tissue at this site.

Automated fluorescent in situ hybridization (FISH) analysis of t(9;22)(q34;q11) in interphase nuclei

For chronic myeloid leukemia, the FISH detection of t(9;22)(q34;q11) in interphase nuclei of peripheral leukocytes is an alternative method to bone marrow karyotyping for monitoring treatment. With automation, several drawbacks of manual analysis may be circumvented. In this article, the capabilities of a commercially available automated image acquisition and analysis system were determined by detecting t(9;22)(q34;q11) in interphase nuclei of peripheral leukocytes.

Determination of features indicating progression in atypical squamous cells with undetermined significance: human papillomavirus typing and DNA ploidy analysis from liquid-based cytologic samples.

The Bethesda System of cervical cytologic findings introduced the term ASCUS (atypical squamous cells of undetermined significance) to cover the broad zone separating normal cytomorphology from definitive squamous intraepithelial lesions (SILs). The management of patients with ASCUS is particularly problematic as approximately 10% of ASCUS patients develop SIL and 1 per 1000 develop cervical carcinoma.

Epstein-Barr virus prevalence in oral squamous cell cancer and in potentially malignant oral disorders in an eastern Hungarian population

We tested 65, 44, and 116 patients with oral squamous cell cancer (OSCC), oral leukoplakia (OL), and oral lichen planus (OLP) against 68 age-matched controls for the presence of Epstein-Barr virus (EBV). Apparently healthy mucosa was simultaneously sampled and examined in all patients. Paraffin-embedded tissue sections of all EBV-positive patients with OSCC were examined for latent membrane protein-1 (LMP-1) expression (demonstrable in most EBV-associated malignancies) using immunohistochemistry. The prevalence of EBV in the controls and in OSCC, OL, and OLP lesions was 19.1%, 73.8%, 29.5%, and 46.6%, respectively, and 66.2%, 22.7%, and 31.9% in the healthy mucosa of patients, respectively. The prevalence of EBV in OSCC patients was significantly higher than in controls or in respective samples of the other two patient groups both in the lesion and in the healthy mucosa. Comparisons including only patients with EBV-negative lesions yielded similar results. Lesions of patients with OLP, but not of patients with OL, differed significantly from controls in EBV prevalence. In OSCC, LMP-1 expression was not detected, and EBV carriage was not significantly associated with any risk factors and did not influence the outcome. Although a high prevalence of EBV was found in OSCC, comparable carriage rates on healthy mucosa of patients indicated that an aetiological role of EBV is unlikely.

Chromosome Abnormalities with Prognostic Impact in B-cell Chronic Lymphocytic Leukemia

The detailed analysis of the biologic features led to a rapid increase in clinically relevant information in CLL. The recognition of the prognostic role of IgVH hypermutation status and related phenotypic changes (CD38, ZAP-70 expression) as well as of chromosome abnormalities defined by cytogenetic analysis enabled a refined classification of the disease. Improvements in karyotyping and the introduction of fluorescence in situ hybridization (FISH) in routine hematological diagnostics raised the detection rate of chromosomal aberrations to approx. 60–80% in CLL. Among them, deletions of 17p and 11q have been associated with unfavorable prognosis. The deletion of the p53 locus (17pl3) was described as the strongest independent predictor for aggressive behavior, resistance to chemotherapy and early death. On the contrary, an isolated deletion at 13ql4 or a normal karyotype was related with a long survival. Classical and molecular cytogenetic analysis became an important tool for individual risk estimation. Unlike any other approaches, cytogenetic monitoring reflects the genetic heterogeneity and clonal growth dynamics during the course of the disease.

HGF-Promoted Motility in Primary Human Melanocytes Depends on CD44v6 Regulated via NF-kappa B, Egr-1, and C/EBP-beta

The regulation of CD44v6, a variant of the CD44 family of glycosylated adhesion molecules, through hepatocyte growth factor (HGF) has implications for motility in primary human melanocytes. We show that exposure of primary human melanocytes to HGF results in an increase of CD44v6 expression. Immunostaining of melanocytic lesions revealed low cytoplasmic positivity of CD44v6 in some nevi but high membranous expression in primary cutaneous melanomas, and cutaneous and lymph node metastases. HGF-dependent CD44v6 regulation in melanocytes is NF-kappaB dependent because BAY 11-7082, an inhibitor of NF-kappaB activation, but not interference with the mitogen-activated protein kinase or phosphatidylinositol 3-kinase cascade, antagonized HGF-induced CD44v6 expression. NF-kappaB-mediated transcriptional regulation of CD44v6 involves the transcription factors Egr-1 and CCAAT enhancer-binding protein-beta (C/EBP-beta). In gel shift assays, the initial binding of p100/p52 NF-kappaB, C/EBP-beta, and Egr-1 to the CD44 promoter experienced reshuffling toward increased affinity of C/EBP-beta after HGF stimulation. A blocking antibody to CD44v6 decreased HGF-induced c-Met phosphorylation as well as enhanced random- and site-directed migration. Our data show that HGF-induced motility in primary human melanocytes depends on c-Met-CD44v6 interaction, and that HGF-enhanced CD44v6 expression is required for motility and transcriptional upregulation of CD44v6, presumably mediated through a complex comprising NF-kappaB/C/EBP-beta and Egr-1.

Human papillomavirus typing and DNA ploidy determination of squamous intraepithelial lesions in liquid‐based cytologic samples

Infection by high‐risk human papillomavirus (HPV) plays a role in the evolution of cervical carcinoma. Cellular atypia and consecutive DNA content alterations in cytologic samples are consequences of a preexisting viral infection.