To investigate the nature and origin of the antibacterial activity of the lytic phage ϕAB2 toward Acinetobacter baumannii, we successfully isolated and characterized a novel phage lysozyme (endolysin) from ϕAB2 and named it LysAB2. To analyze antibacterial activity of LysAB2, the complete LysAB2 and two deletion derivatives were constructed, purified and characterized. Zymographic assays showed that only the intact LysAB2 could lyse the peptidoglycan of A. baumannii and the Staphylococcus aureus cell wall. Antibacterial analysis also showed that only the intact LysAB2 retained the complete bactericidal activity. When applied exogenously, LysAB2 exhibited a broad bacteriolytic activity against a number of Gram-negative and Gram-positive bacteria. Thermostability assays indicated that LysAB2 was stable at 20∼40 °C. Its optimal pH was 6.0, and it was active from pH 4 to 8. Scanning electron microscopy revealed that exposure to 500 μgml(-1) LysAB2 for up to 60 min caused a remarkable modification of the cell shape of the bacteria. Treating bacteria with LysAB2 clearly enhanced permeation of the bacterial cytoplasmic membrane. These results indicate that LysAB2 is an effective lysozyme against bacteria, and they suggest that it is a good candidate for a therapeutic/disinfectant agent to control nosocomial infections caused by multiple drug-resistant bacteria.

A retrospective study of 36 patients with xanthogranulomatous pyelonephritis who underwent nephrectomy at our hospital was performed. The disease occurred most frequently in middle-aged women with a history of recurrent urinary tract disorder. There were 2 cases of focal xanthogranulomatous pyelonephritis, 2 associated with emphysematous pyelonephritis, 2 that manifested as fistula formation between the colon or skin, and 1 with deep sinus formation into the hip joint that presented as septic arthritis. Flank pain and fever were the most frequent complaints. Escherichia coli (67%) and Proteus mirabilis (26%) were the most common organisms isolated from the voided urine, kidney and blood stream. Cephalothin plus gentamicin or tobramycin were the drugs of choice before surgical intervention.

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Nicotinamide N-methyltransferase (NNMT) was recently identified as one clear cell renal cell carcinoma (ccRCC)-associated gene by analyzing full-length complementary DNA-enriched libraries of ccRCC tissues. The aim of this study is to investigate the potential role of NNMT in cellular invasion. A strong NNMT expression is accompanied with a high invasive activity in ccRCC cell lines, and small interfering RNA-mediated NNMT knockdown effectively suppressed the invasive capacity of ccRCC cells, whereas NNMT overexpression markedly enhanced that of human embryonic kidney 293 (HEK293) cells. A positive correlation between the expression of NNMT and matrix metallopeptidase (MMP)-2 was found in ccRCC cell lines and clinical tissues. The treatment of blocking antibody or inhibitor specific to MMP-2 significantly suppressed NNMT-dependent cellular invasion in HEK293 cells. Furthermore, SP-1-binding region of MMP-2 promoter was found to be essential in NNMT-induced MMP-2 expression. The specific inhibitors of PI3K/Akt signaling markedly decreased the binding of SP1 to MMP-2 promoter as shown by chromatin immunoprecipitation assay. We also demonstrated that PI3K/Akt pathway plays a role in NNMT-dependent cellular invasion and MMP-2 activation. Moreover, short hairpin RNA-mediated knockdown of NNMT expression efficiently inhibited the growth and metastasis of ccRCC cells in non-obese diabetic severe combined immunodeficiency mice. Taken together, the present study suggests that NNMT has a crucial role in cellular invasion via activating PI3K/Akt/SP1/MMP-2 pathway in ccRCC.

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