Minor groove recognition is important for the transcription factor PhoB: a surface plasmon resonance study.

The two-component regulatory system PhoR/PhoB induces the expression of several genes in response to phosphate starvation in Escherichia coli. In order to quantify these protein-DNA interactions and to study the time-resolved dynamics of the binding mechanism, the specific recognition of different oligonucleotide duplexes by the DNA-binding domain of PhoB (PhoB(DBD)) was analyzed using surface plasmon resonance. In addition the two point mutants PhoB(DBD)D196A and PhoB(DBD)R219A were obtained and the DNA recognition in comparison to the wildtype PhoB(DBD) was investigated. Aspartic acid 196 and arginine 219 mediate specific minor groove interactions. All results reveal that at high PhoB(DBD)-concentrations all recognition sequences of the pho box are occupied. Decreasing the protein amount results in a mixture of free oligonucleotides and DNA molecules occupied by two WT-PhoB(DBD). Moreover, the SPR results indicate that both binding site segments, the TGTCA-motif and the A/T-rich minor groove, are essential for the binding process. A comparison of different regulons additionally proved the dependency of the recognition process on the base composition of the minor groove.

VCD studies on cyclic peptides assembled from L-α-amino acids and a trans-2-aminocyclopentane- or trans-2-aminocyclohexane carboxylic acid.

The increasing interest in peptidomimetics of biological relevance prompted us to synthesize a series of cyclic peptides comprising trans-2-aminocyclohexane carboxylic acid (Achc) or trans-2-aminocyclopentane carboxylic acid (Acpc). NMR experiments in combination with MD calculations were performed to investigate the three-dimensional structure of the cyclic peptides. These data were compared to the conformational information obtained by electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectroscopy. Experimental VCD spectra were compared to theoretical VCD spectra computed quantum chemically at B3LYP/6-31G(d) density functional theory (DFT) level. The good agreement between the structural features derived from the VCD spectra and the NMR-based structures underlines the applicability of VCD in studying the conformation of small cyclic peptides.

False aneurysm of the pulmonary artery induced by a Swan-Ganz catheter: clinical presentation and radiologic management.

OBJECTIVE: This study evaluates retrospectively the clinical presentation, radiographic findings, and angiographic management of false aneurysm of the pulmonary artery resulting from Swan-Ganz catheter placement. MATERIALS AND METHODS: Over a 4-year period, seven false aneurysms of the pulmonary artery were diagnosed in five patients (four women, one man) who were 67-81 years old. All five patients underwent Swan-Ganz catheter placement to monitor cardiac surgery--coronary artery bypass grafting in four and mitral valve replacement in one. All patients were anticoagulated. For five patients, we reviewed the medical records and the results of chest radiography, digital subtraction pulmonary angiography, and pulmonary artery embolization. For two patients, we reviewed the results of CT scanning. RESULTS: Non-life-threatening hemoptysis was noted in all cases and occurred in three patients after the Swan-Ganz catheter had been removed (elapsed time of 1-19 days). Chest radiographs revealed a pulmonary infiltrate in one patient and a pulmonary mass in two patients. The results were unremarkable in the other two patients. CT depicted two false aneurysms of the pulmonary artery as round masses with eccentrically enhanced lumina circumscribed by thrombosis. Pulmonary angiography revealed a single false aneurysm in three patients and two false aneurysms in two patients. All false aneurysms were localized in segmental or subsegmental branches of the right middle pulmonary artery (n = 4) or the right lower pulmonary artery (n = 3). All patients were successfully treated with transcatheter steel-coil embolization. CONCLUSION: Even when the chest radiograph appears unremarkable, patients clinically suspected of developing a false aneurysm of the pulmonary artery after Swan-Ganz catheter placement require enhanced CT or pulmonary angiography to establish the diagnosis. False aneurysms of the pulmonary artery can be treated at the time of pulmonary angiography by steel-coil embolization.

[Comparative study of cefixime versus amoxicillin-clavulanic acid combination in the oral treatment of urinary tract infections in children]. / Etude comparant le céfixime à l'association amoxicilline-acide clavulanique dans le traitement par voie orale des infections urinaires de l'enfant.

BACKGROUND: Acute febrile infections suggestive of pyelonephritis require treatment by broad-spectrum antibiotics capable of reaching significant tissue levels. This study compares efficacy and safety of cefixime with amoxycillin + clavulanic acid in urinary tract infections. POPULATION AND METHODS: Fifty seven children aged 5 months to 14 years treated for urinary tract infection in ten pediatric centres for a period of 10 months had been randomly included in the study. Thirty (22 girls and eight boys) were given cefixime and 27 (24 girls and three boys) amoxycillin-clavulanate. Efficacy was evaluated in only 36 patients whose bacteria were susceptible to both antibiotics (26 pyelonephritis and ten cystitis). RESULTS: Sixteen patients out of the 19 given cefixime recovered vs. 14 out of the 17 given amoxycillin-clavulanate with no significant difference between both groups. Bacteria were more often susceptible to cefixime (100% of cases) than to amoxycillin-clavulanate (69%) (p < or = 0.0001). Safety was good and comparable in both groups. CONCLUSION: Cefixime given per os seems effective and safe in treating urinary tract infections. These results have to be confirmed by further studies.