The role of charges near the pore mouth has been discussed in theoretical work about ion channels. To introduce new negative charges in a channel protein, amino groups of porin from Rhodobacter capsulatus 37b4 were succinylated with succinic anhydride, and the precise extent and sites of succinylations and structures of the succinylporins determined by mass spectrometry and X-ray crystallography. Molecular weight and peptide mapping analyses using matrix-assisted laser desorption-ionization mass spectrometry identified selective succinylation of three lysinet-amino groups (Lys-46, Lys-298, Lys-300) and the N-terminal a-amino group. The structure of a tetra-succinylated porin (TS-porin) was determined to 2.4 A and was generally found unchanged in comparison to native porin to form a trimeric complex. All succinylated amino groups found in a mono/di-succinylated porin (MS-porin) and a TS-porin are localized at the inner channel surface and are solvent-accessible: Lys-46 is located at the channel constriction site, whereas Lys-298, Lys-300, and the N-terminus are all near the periplasmic entrance of the channel. The Lys-46 residue at the central constriction loop was modeled as succinyl-lysine from the electron density data and shown to bend toward the periplasmic pore mouth. The electrical properties of the MS-and TS-porins were determined by reconstitution into black lipid membranes, and showed a negative charge effect on ion transport and an increased cation selectivity through the porin channel. The properties of a typical general diffusion porin changed to those of a channel that contains point charges near the pore mouth. The single-channel conductance was no longer a linear function of the bulk aqueous salt concentration. The substantially higher cation selectivity of the succinylated porins compared with the native protein is consistent with the increase of negatively charged groups introduced. These results show tertiary structure-selective modification of charged residues as an efficient approach in the structure-function evaluation of ion channels, and X-ray crystallography and mass spectrometry as complementary analytical tools for defining precisely the chemically modified structures.

In cell extracts of Lactobacillus delbriickii ssp. lactis DSM7290 a peptidase with the ability to hydrolyse Phe-P-naphthylamide (Phe-P-NA) and His-P-NA could be detected. Escherichia coli lacking the enzyme activity in an enzymic plate assay was used to screen high-copy-number and lowcopy-number plasmid libraries of size-fractionated Lnctobacillus DNA. Clones with the desired phenotype were detected, and the gene, designated pepiV, was further subcloned and sequenced. A large open reading frame of 2529 nucleotides is predicted to encode a protein of 843 amino acids (95 358 Da). Comparison of the pepN gene from Lb. delbriickii ssp. lactis DSM7290 indicates that it is homologous to genes of the family of Zn"-metallohydrolases and PepN shows identity with the active centre Zn*'-binding motif of these enzymes. The substrate Lys-p-NA is more effectively cleaved than Phe-P-NA or His-P-NA which were used for screening in E. coli. The cloned yepN gene was efficiently overexpressed in E. coli and subcloning of the gene in Lactobacillus casei resulted in a moderate ovcrcxpression of approximately 20-fold. The pepN gene product was purified from the pepN-deficient E. coli strain CM89, using the substrate Lys-p-nitroanilide (Lys-NHPh) in the assay procedure. In a four-step procedure including streptomycin sulfate precipitation, anion-exchange chromatography and gel filtration the peptidase was purified to electrophoretic homogeneity.

Purpose Given the uncertainty with regard to the effectiveness of pelvic nodal irradiation (PNI) for prostate cancer, we aimed to determine whether patients with prostate cancer who are treated with PNI are at a higher risk of developing radiation-related lymphopenia (RRL). Methods and materials The electronic charts of 886 consecutive patients treated with radiation therapy for prostate cancer between 2006 and 2018 at our institution were retrospectively analyzed. Qualifying patients were those with total lymphocyte counts within 1 year before and 3 to 24 months after the start of radiation therapy. Lymphopenia was the primary outcome, and overall survival and biochemical progression-free survival were secondary outcomes. Results Thirty-six patients with and 95 patients without PNI qualified for inclusion. In the PNI cohort, 61.1% of patients developed RRL (median follow-up total lymphocyte count < 1000 cells/μL) versus 26.3% of non-PNI patients ( P < .001). On univariate analysis, initial prostate-specific antigen level, baseline lymphopenia, treatment modality, PNI status, increased planned target volume, and androgen deprivation therapy administration were all significant predictors of RRL ( P < .05). On multivariate analysis, PNI status was a significant predictor of RRL (hazard ratio [HR], 3.42; 95% confidence interval [CI], 1.22-9.61; P < .001), as were initial prostate-specific antigen values (HR, 1.05; 95% CI, 1.00-1.11; P = .006) and baseline lymphopenia (HR, 8.32; 95% CI, 2.19-31.6; P = .007). RRL was not predictive for biochemical progression-free survival, distant metastasis, or overall survival on multivariate analysis, but the number of events was likely insufficient for these analyses. Conclusions The higher risk of RRL among patients with PNI comports with other papers that show that increased treatment volumes are associated with higher rates of RRL. Mounting evidence for the adverse effects of RRL on clinical outcomes supports the significance of our findings and suggests that further studies are needed on RRL as a potential harm of PNI that may affect the interpretation of results from clinical trials of PNI.

In a double-blind multicentre study the efficacy and safety of a single-dose treatment with pefloxacin (800 mg) was compared with a five-day treatment regimen of 960 mg co-trimoxazole twice daily in the therapy of acute uncomplicated cystitis in women. In order to maintain blindness, patients in the pefloxacin group received placebo to complement the full number of tablets. Nine centres were involved; 155 patients received pefloxacin and 161 patients received co-trimoxazole. Of these, 140 patients treated with pefloxacin and 145 with co-trimoxazole were considered valid for efficacy and safety analysis. At the first follow-up, after seven to ten days, 97.1% of the pefloxacin group and 95.2% of the co-trimoxazole group were bacteriologically cured. At the second follow-up visit, after 28 to 42 days, the urine culture was negative in 95.0% of the pefloxacin group and 90.3% of the co-trimoxazole group. A single dose of 800 mg pefloxacin was demonstrated to be as safe and at least as effective as a five-day regimen of co-trimoxazole in the treatment of uncomplicated cystitis.

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