Vertical ordering sensitivity of solid supported DPPC membrane to alamethicin and the related loss of cell viability.

BACKGROUND: Experimental studies of antimicrobial peptides interacting with lipid membranes recently attracted growing interest due to their numerous biomedical applications. However, the influence of such peptides on the structural organisation of lipid membranes in connection with the actual cell response still remains an elusive issue. METHODS: X-ray diffraction was employed on detecting the sensitivity of the periodical spacing of dipalmitoyl-phosphatidyl-choline stacked as solid-supported bilayers to the presence of varying amounts of the peptide alamethicin in a wide range of peptide-to-lipid molar ratios. These results were then correlated with the effects of alamethicin on biological membranes in vitro as observed by optical microscopy and microculture tetrazolium assay on the tumour cells HeLa to provide a comprehensive and quantitative analysis of these effects, based on a dose-response relationship. RESULTS: The experiments allowed correlating the periodical spacing and the peptide-to-lipid molar ratio on alamethicin-dipalmitoyl-phosphatidyl-choline samples. Two different trends of periodical spacing vs. peptide-to-lipid molar ratio clearly appeared at low and high hydration levels, showing intriguing non-linear profiles. Unexpected correspondences were observed between the peptide-to-lipid molar ratio range where the changes in dipalmitoyl-phosphatidyl-choline structure occur and the alamethicin doses which alter the viability and the plasma membrane morphology of HeLa. CONCLUSIONS: Alamethicin might induce either mechanical or phase changes on dipalmitoyl-phosphatidyl-choline bilayers. Such easily accessible ordering information was well-calibrated to predict the alamethicin doses necessary to trigger cell death through plasma membrane alterations. GENERAL SIGNIFICANCE: This benchmark combined study may be valuable to predict bioeffects of several antimicrobial peptides of biomedical relevance.

Detection of postoperative pseudoaneurysms following abdominal aortic aneurysm repair in Behçet's disease by MRA.

We report the development of two anastomotic pseudoaneurysms in a patient with Behçet's disease eighteen months after abdominal aortic aneurysm repair. Major asymptomatic vascular complications should be suspected in patients with Behçet's disease with a history of vascular surgery and treated expediently due to the risk of rupture. Magnetic resonance angiography, contrast-enhanced computed tomography or ultrasound scanning should be performed at least every 6 months after vascular surgery.

[Role of ultrasonography in the control of patients receiving perioperative total parenteral nutrition]. / Ruolo dell'ecografia nel controllo di pazienti sottoposti a nutrizione parenterale totale perioperatoria.

BACKGROUND: On the basis of personal experience and literature, this study has been carried out in order to clarify the impact of ultrasonography on the diagnosis and prevention of hepatobiliary complications Total Parenteral Nutrition (TPN)-related. METHODS: Between April 1995-April 1997 in the Department of General Surgery-University of Catanzaro, 18 adult patients submitted to major thoracic or abdominal surgery, underwent to TPN for perioperative time (range: 9-55 days). In these patients ultrasonography was performed at pre-established days in pre- and postoperative time in order to diagnose precociously the possibility of hepatobiliary complications. RESULTS: Ultrasonography showed: 3 cases of hepatic steatosis, 5 cases of steatosis and gallbladder biliary sludge, 2 cases of gallbladder biliary sludge alone, 1 case of gallbladder biliary sludge with microlithiasis, 1 case of acute acalculous cholecystitis. The other 6 patients presented only little laboratory tests alterations, but normal ultrasonographic findings. CONCLUSIONS: Therefore it is underlined the importance of systematic ultrasonographic follow-up of patients on TPN as a non invasive method in the early diagnosis of hepatobiliary complications TPN-related. The good compliance of the patients to this instrumental investigation and the not excessive increase of their management's costs are also underlined.

[Routine broncho-myo-plasty after pneumonectomy]. / Bronco-mio-plastica di principio dopo pneumonectomia.

Bronchopleural fistula is certainly the most important and specific complication following total pneumonectomy. In order to reduce this risk a systematic protection of bronchial suture by means of muscular flap transposition is suggested. The authors report 15 cases of total pneumonectomy for lung cancer at different localization. In all the patients a bronchomuscular plasty was used to protect the bronchial suture. The anterolateral body of latissimus dorsi, when it was possible, was preferred for the following reasons: 1) it makes the suture of the main bronchus greatly resistant; 2) it makes easier the obliteration of the pleural cavity; 3) its transposition is rapid and easy. In only one case a diaphragmatic flap was transposed together with its vascular and nervous system giving rise to a phrenic paralysis. Although few cases are reported, the results are successful and encourage the application of this procedure in future.

[Recurrent biliary calculi]. / La calcolosi biliare plurirecidiva.

The Authors report two cases of recurrent bile duct stones and discuss about the diagnosis and treatment of this infrequent disease. Although diagnostic and management procedures are similar to those commonly used in all types of biliary stones, therapeutical options may be different in relation to the different clinical pictures. The Authors strongly suggest that bilioenteric anastomosis and endoscopic sphincterotomy are the best procedures to assure a correct and definitive treatment of recurrent biliary stones. However, the adoption of different diagnostic and therapeutic approaches, rather than univocal schemes, is recommended.