Krzysztof Bielawski

Allelic length of a CA dinucleotide repeat in the egfr gene correlates with the frequency of amplifications of this sequence--first results of an inter-ethnic breast cancer study.

Overexpression of the epidermal growth factor receptor (EGFR) is a common finding in invasive breast cancer and represents a potential target for new treatment options. However, little is known about the parameters that might indicate a potential clinical response for these anti‐EGFR‐based therapies. In order to gain further insights into the interplay between the length of a CA‐SSR I repeat in intron 1 of egfr, copy numbers of this untranslated regulatory sequence, and protein expression, the present study investigated breast cancers from Germans and Japanese patients by microsatellite analysis, quantitative 5′ nuclease assay by egfr enzyme‐linked immunosorbent assay (ELISA), and comparative genomic hybridization (CGH). Japanese breast cancer patients displayed significantly longer alleles for the CA‐SSR I repeat (p < 0.001), associated with significantly lower EGFR expression (mean 65 versus 36 fmol/mg membrane protein). Allelic imbalance (restricted to CA‐SSR I) was observed in 55% of the informative Japanese breast cancers compared with only 34% of the German breast cancer reference group. Using a quantitative 5′ nuclease assay for egfr, a significantly higher percentage of Japanese breast cancer patients revealed amplifications of the CA‐SSR I repeat (p < 0.01). Japanese patients with these amplifications were characterized by a significantly higher EGFR content compared with the German breast cancer patients (p < 0.05). These data show, on the one hand, that the correlation of EGFR overexpression and an inherited CA repeat polymorphism within intron 1 of egfr is a general finding in breast cancer, as has been shown previously. On the other hand, the data demonstrate clearly for the first time an interaction between the length of a polymorphism in intron 1 of egfr as an inherited genetic factor and the frequency of egfr amplification, as an acquired genetic factor, both factors contributing to EGFR overexpression in breast cancer. This new knowledge about mechanisms of regulation of EGFR expression might serve as an additional basis for evaluating anti‐EGFR‐based therapies. Copyright

Superoxide dismutase is upregulated in Staphylococcus aureus following protoporphyrin-mediated photodynamic inactivation and does not directly influence the response to photodynamic treatment

BackgroundStaphylococcus aureus, a major human pathogen causes a wide range of disease syndromes. The most dangerous are methicillin-resistant S. aureus (MRSA) strains, resistant not only to all β-lactam antibiotics but also to other antimicrobials. An alarming increase in antibiotic resistance spreading among pathogenic bacteria inclines to search for alternative therapeutic options, for which resistance can not be developed easily. Among others, photodynamic inactivation (PDI) of S. aureus is a promising option. Photodynamic inactivation is based on a concept that a non toxic chemical, called a photosensitizer upon excitation with light of an appropriate wavelength is activated. As a consequence singlet oxygen and other reactive oxygen species (e.g. superoxide anion) are produced, which are responsible for the cytotoxic effect towards bacterial cells. As strain-dependence in photodynamic inactivation of S. aureus was observed, determination of the molecular marker(s) underlying the mechanism of the bacterial response to PDI treatment would be of great clinical importance. We examined the role of superoxide dismutases (Sod) in photodynamic inactivation of S. aureus as enzymes responsible for oxidative stress resistance.ResultsThe effectiveness of photodynamic inactivation towards S. aureus and its Sod isogenic mutants deprived of either of the two superoxide dismutase activities, namely SodA or SodM or both of them showed similar results, regardless of the Sod status in TSB medium. On the contrary, in the CL medium (without Mn++ ions) the double SodAM mutant was highly susceptible to photodynamic inactivation. Among 8 clinical isolates of S. aureus analyzed (4 MRSA and 4 MSSA), strains highly resistant and strains highly vulnerable to photodynamic inactivation were noticed. We observed that Sod activity as well as sodA and sodM transcript level increases after protoporphyrin IX-based photodynamic treatment but only in PDI-sensitive strains.ConclusionsWe confirmed that porphyrin-based photokilling efficacy is a strain-dependent phenomenon. We showed that oxidative stress sensitivity caused by the lack of both Sod enzymes can be relieved in the presence of Mn ions and partially in the presence of Fe ions. The fact that Sod activity increase is observed only in PDI-susceptible cells emphasizes that this is probably not a direct factor affecting S. aureus vulnerability to porphyrin-based PDI.

Genetic variability of hepatitis B virus isolates in Poland

There is very limited knowledge about the genetic variability of HBV strains circulating in the population of Polish chronically infected HBV patients. The aim of this study was to analyse the phylogenetic relatedness and polymorphism in some functional domains of HBV genome among chronically infected patients from northern Poland. Fifty-one serum samples were included to analysis of HBV genomes due to the viral load sufficient for DNA preparation and sequencing. The sequences of the rt polymerase/S and preC/BCP regions of those isolates were analysed, compared to genome sequences of different variants of HBV from GenBank database and genetic relatedness of Polish genotypes to known reference strains was estimated. A phylogenetic tree of 41 analysed genotype A isolates as well as 8 genotype D strains was constructed showing relationship to know reference strains. Two isolates, initially classified as genotype F turned to be related to genotype H, newly described genotype deriving from genotype F, a very rare genotype in Europe. HBV genotypes’ distribution pattern in Poland and phylogenetic relatedness seems to be different from our Eastern neighbours. Due to the fact that Poland is still ethnically uniform country, it is interesting to explore molecular epidemiology of HBV infections in our population.

Isolation and characterization of the restriction endonuclease PpeI from Phormidium persicinum

PpeI is a type II restriction endonuclease isolated from cyanobacterial strainPhormidium persicinum. The endonuclease PpeI, an isoschizomer of ApaI, recognizes the hexanucleotide sequence (5’t-GGGCC/C-3’t) and cleaves, after the second C, producing four nucleotide 3’t-cohesive ends.

Hepatitis D, B and C virus (HDV/HBV/HCV) coinfection as a diagnostic problem and therapeutic challenge

Coinfection with hepatitis D virus (HDV) in chronic hepatitis B is associated with more rapid progression to liver cirrhosis. We present two cases of infection with hepatitis D, B and C viruses. Both male patients were primarily diagnosed as infected with hepatitis B virus (HBV) and hepatitis C virus (HCV), HBsAg-positive and anti-HCV-positive. The first patient was treated with interferon, lamivudine and pegylated interferon. A full virological and biochemical response was achieved. The second patient was treated with interferon and ribavirin, lamivudine and twice with pegylated interferon. In the ultrasound elastography progression of liver fibrosis to F4 was described. HDV infection should be considered in patients with HBV minireplication, high activity of aminotransferases and progression of liver disease despite a good virological response to anti-HBV treatment. Efficacy of interferon in HDV infection is severely limited.

SACNI, AN ISOSCHIZOMER OF BANII ISOLATED FROM STREPTOMYCES ACHROMOGENES RECOGNIZES THE 5-'GRGCY/C SEQUENCE

SacNI, an isoschizomer of the restriction endonuclease, BanII [Sugisaki et al., Nucleic Acids Res. 10 (1982) 5747-5752], has been isolated from Streptomyces achromogenes N-J-H. SacNI recognizes the palindromic sequence, 5-GRGCY/C, and cleaves within the recognition sequence, generating a 3 protruding RGCY end (where R = A or G, and Y = C or G).