Accumulation of carbapenem resistance mechanisms in VIM-2-producing Pseudomonas aeruginosa under selective pressure.

Pseudomonas aeruginosa has the potential to achieve resistance to carbapenems via the acquisition of carbapenemase-encoding genes, the downregulation of the OprD porin, the overexpression of efflux systems and the overproduction of cephalosporinases. One hundred and fifty carbapenem-non-susceptible isolates from 2008 to 2010 were screened for carbapenemase production, OprD porin loss, efflux pumps overexpression and inducible AmpC beta-lactamase production. For comparison reasons, the presence of the same mechanisms was also assessed in a previous collection of 30 carbapenem-non-susceptible P. aeruginosa isolated between 2003 and 2005. Results showed the accumulation of various resistance mechanisms among VIM-2 producers isolated between 2008 and 2010 with a parallel considerable increase in imipenem MIC90 and the geometric mean of the MIC values of imipenem and meropenem between the two study groups. The accumulation of carbapenem resistance mechanisms highlights the potential of this formidable pathogen for evolutionary success under antibiotic selective pressure.

Frequent presence of incomplete HPV16 E7 ORFs in lung carcinomas: memories of viral infection.

BACKGROUND: HPV16 E6/E7 oncoproteins are critical for cervical carcinogenesis. The corresponding oncogenes are also detected in head and neck cancer, but in lung cancer their presence is strongly debated. PCR-based detection protocols amplify different target sequences. OBJECTIVES: To examine the frequency of different length HPV16 E7 segments in lung carcinomas. STUDY DESIGN: We designed four different amplification schemes for the detection of overlapping segments of the HPV16 E7 ORF, all suitable for specific HPV detection in cervical carcinoma. In two schemes, the entire E7 ORF was targeted while in the remaining schemes internal, smaller sequences were targeted. In total, 76 specimens were used; 29 lung carcinoma specimens, 16 non-cancerous lung tissue specimens from the same patients and 31 bronchial washings from different lung cancer patients. RESULTS: Amplification of the entire HPV16 E7 ORF, using two protocols, demonstrated the absence of the specific HPV16 E7 sequences (74 samples either tested negative by the first PCR protocol or false positive by the second, based on sequencing or AvaII or PvuII digestion). However, both schemes targeting smaller E7 segments revealed the frequent presence of HPV16 E7 sequences in lung carcinoma specimens (14/23 positive by either scheme). CONCLUSIONS: HPV16 E7 sequences are frequently observed in lung carcinomas. Decreasing the size of PCR-target sequences increases the detection frequency, possibly indicating the presence of incomplete viral ORFs. Restriction endonuclease analysis is critical for verifying the reliability of the detection of these sequences.

Rat liver endoplasmic reticulum protein kinases.

1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal proteins solubilized with Triton X-100 were analyzed by means of ion exchange chromatography. 2. Protein kinase activity was detected in the column fractions using specific assays for cAMP-dependent protein kinase, cGMP-dependent protein kinase, protein kinase C, Ca2+/calmodulin-dependent protein kinase and casein kinases. 3. Fractions with protein kinase activity were further analyzed by SDS-polyacrylamide gel electrophoresis. 4. The results indicate that cAMP-dependent protein kinase type I and II, casein kinases I and II, protein kinase C proenzymes I and II and Ca2+/calmodulin kinase II are associated with the membranes of endoplasmic reticulum (ER).

Altered cellular interactions between endothelial cells and nonenzymatically glucosylated laminin/type IV collagen.

Laminin and type IV collagen are two major basement membrane glycoproteins. In previous studies it has been shown that nonenzymatic glucosylation induces structural alterations of these macromolecules and also reduces their ability to self-associate. In the present study, endothelial cells were tested for their ability to adhere and spread on nonenzymatically glucosylated laminin and type IV collagen. Adhesion and spreading were reduced when glucosylated macromolecules were used as substrates. Glucosylation-induced changes in adhesion and spreading may be an important initial event signaling other phenotypic modifications of cells in the microvasculature and may be a crucial factor in order to understand the pathogenesis of diabetic microangiopathy at the molecular level.