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Background: Preanalytical variables, such as sample collection, handling, transport, and storage, may affect patient results. The number of errors in the preanalytical phase may decrease by following standardized procedures. Methods: A retrospective analysis (2001–2005) of results obtained through the Spanish Society of Clinical Chemistry and Molecular Pathology Quality Assessment Program for the Preanalytical Phase has been carried out to summarize data regarding the main factors affecting the preanalytical phase quality. In such a program, participants are asked to register rejections and causes for rejection of routine or stat samples usually and locally collected at their laboratories. Results: Results discussed refer to 105 laboratories. Of the 4,715,132 tubes expected to be received during the data collection period among participating laboratories and according to determinations included by clinicians in the request form, 32,977 (0.699%) offered a cause for rejection. Whole blood-EDTA samples and serum samples accounted for 75.6% of all samples collected among laboratories, although they only corresponded to 55.8% of all registered rejections. In total, 81% of rejections arose as a result of the following reasons: “specimen not received” (37.5%), “hemolysis” (29.3%), and “clotted sample” (14.4%). Moreover, plasma-citrate-erythrocyte sedimentation rate exhibited the highest percentage of rejection (1.473%), whereas the lowest rate corresponded to whole blood-EDTA (0.381%). Conclusions: Overall percentage of rejection is similar to previously published data. As some of the included variables have turned out to be irrelevant, the program has been simplified from the year 2006 onwards. Clin Chem Lab Med 2008;46:849–54. [ABSTRACT FROM AUTHOR]

Background: Ibrutinib, a first-in-class inhibitor of Bruton's tyrosine kinase, is approved for the treatment of various B-cell malignancies and chronic graft-versus-host disease. Based on encouraging preclinical data, safety and efficacy of ibrutinib combined with companion drugs for advanced renal cell carcinoma (RCC), gastric/gastroesophageal junctional adenocarcinoma (GC), and colorectal adenocarcinoma (CRC) were evaluated., Methods: Ibrutinib 560 mg or 840 mg once daily was administered with standard doses of everolimus for RCC, docetaxel for GC, and cetuximab for CRC. Endpoints included determination of the recommended phase 2 dose (RP2D) of ibrutinib in phase 1b and efficacy (overall response rate [ORR] for GC and CRC; progression-free survival [PFS] for CRC) in phase 2., Results: A total of 39 (RCC), 46 (GC), and 50 (RCC) patients were enrolled and received the RP2D. Safety profiles were consistent with the individual agents used in the study. Confirmed ORRs were 3% (RCC), 21% (GC), and 19% (CRC). Median (90% CI) PFS was 5.6 (3.9-7.5) months in RCC, 4.0 (2.7-4.2) months in GC, and 5.4 (4.1-5.8) months in CRC., Conclusions: Clinically meaningful increases in efficacy were not observed compared to historical controls; however, the data may warrant further evaluation of ibrutinib combinations in other solid tumours., Trial Registration: ClinicalTrials.gov, NCT02599324., (© 2023. The Author(s).)

Background: Preterm infants born earlier than 32 weeks of gestational age (GA) often need red blood cell (RBC) transfusions, which have been associated with an increased incidence of complications of prematurity, due to changes in tissue oxygenation. Transfusion of umbilical cord blood (UCB) could be beneficial for this group. The aims of this study were: (i) to determine the RBC transfusion needs in infants <32 weeks in Hospital Clinic of Barcelona; (ii) to identify the target GA group that would benefit most from UCB transfusion; and (iii) to assess the current availability of UCB as a potential source of RBC transfusion for these premature infants in our tertiary referral blood bank., Material and Methods: A retrospective observational study was performed on infants born at <32 weeks GA, divided into two groups: (i) extremely low gestational age neonates (ELGAN) (from 23 0 to 27 6 weeks) and (ii) very preterm neonates (VPN) (from 28 0 to 31 6 weeks). Their complications and transfusion rates were compared. Processing and availability of UCB samples in the reference blood bank were assessed., Results: Overall, 1,651 infants <32 weeks GA were admitted in the study period. While 12.5% of VPN received at least one RBC transfusion, the percentage increased to 60% among the ELGAN. Retinopathy of prematurity and bronchopulmonary dysplasia were diagnosed more frequently in the ELGAN group (p<0.001) than in the VPN group. The annual average volume of RBC transfusion in our study group was 1.35 L (95% CI: 1.07-1.64). The reference blood bank was able to produce 16 L (95% CI: 14-18) of UCB-RBC per year., Conclusion: Considering the data obtained about RBC transfusion needs and morbidities, the ELGAN group has been identified as the target group that would benefit most from UCB-RBC transfusions. We have demonstrated that our blood bank is able to produce enough RBC from UCB. Randomised control trials are warranted to study the potential benefits of UCB compared to adult blood for RBC transfusions.

Background: First-line therapy for advanced oesophageal cancer is currently limited to fluoropyrimidine plus platinum-based chemotherapy. We aimed to evaluate the antitumour activity of pembrolizumab plus chemotherapy versus chemotherapy alone as first-line treatment in advanced oesophageal cancer and Siewert type 1 gastro-oesophageal junction cancer., Methods: We did a randomised, placebo-controlled, double-blind, phase 3 study across 168 medical centres in 26 countries. Patients aged 18 years or older with previously untreated, histologically or cytologically confirmed, locally advanced, unresectable or metastatic oesophageal cancer or Siewert type 1 gastro-oesophageal junction cancer (regardless of PD-L1 status), measurable disease per Response Evaluation Criteria in Solid Tumors version 1.1, and Eastern Cooperative Oncology Group performance status of 0-1, were randomly assigned (1:1) to intravenous pembrolizumab 200 mg or placebo, plus 5-fluorouracil and cisplatin (chemotherapy), once every 3 weeks for up to 35 cycles. Randomisation was stratified by geographical region, histology, and performance status. Patients, investigators, and site staff were masked to group assignment and PD-L1 biomarker status. Primary endpoints were overall survival in patients with oesophageal squamous cell carcinoma and PD-L1 combined positive score (CPS) of 10 or more, and overall survival and progression-free survival in patients with oesophageal squamous cell carcinoma, PD-L1 CPS of 10 or more, and in all randomised patients. This trial is registered with ClinicalTrials.gov, NCT03189719, and is closed to recruitment., Findings: Between July 25, 2017, and June 3, 2019, 1020 patients were screened and 749 were enrolled and randomly assigned to pembrolizumab plus chemotherapy (n=373 [50%]) or placebo plus chemotherapy (n=376 [50%]). At the first interim analysis (median follow-up of 22·6 months), pembrolizumab plus chemotherapy was superior to placebo plus chemotherapy for overall survival in patients with oesophageal squamous cell carcinoma and PD-L1 CPS of 10 or more (median 13·9 months vs 8·8 months; hazard ratio 0·57 [95% CI 0·43-0·75]; p<0·0001), oesophageal squamous cell carcinoma (12·6 months vs 9·8 months; 0·72 [0·60-0·88]; p=0·0006), PD-L1 CPS of 10 or more (13·5 months vs 9·4 months; 0·62 [0·49-0·78]; p<0·0001), and in all randomised patients (12·4 months vs 9·8 months; 0·73 [0·62-0·86]; p<0·0001). Pembrolizumab plus chemotherapy was superior to placebo plus chemotherapy for progression-free survival in patients with oesophageal squamous cell carcinoma (6·3 months vs 5·8 months; 0·65 [0·54-0·78]; p<0·0001), PD-L1 CPS of 10 or more (7·5 months vs 5·5 months; 0·51 [0·41-0·65]; p<0·0001), and in all randomised patients (6·3 months vs 5·8 months; 0·65 [0·55-0·76]; p<0·0001). Treatment-related adverse events of grade 3 or higher occurred in 266 (72%) patients in the pembrolizumab plus chemotherapy group versus 250 (68%) in the placebo plus chemotherapy group., Interpretation: Compared with placebo plus chemotherapy, pembrolizumab plus chemotherapy improved overall survival in patients with previously untreated, advanced oesophageal squamous cell carcinoma and PD-L1 CPS of 10 or more, and overall survival and progression-free survival in patients with oesophageal squamous cell carcinoma, PD-L1 CPS of 10 or more, and in all randomised patients regardless of histology, and had a manageable safety profile in the total as-treated population., Funding: Merck Sharp & Dohme., Competing Interests: Declaration of interests J-MS reports research funding to the institution by Merck Sharp & Dohme (MSD; a subsidiary of Merck), AstraZeneca, and Ono Pharmaceuticals, during the conduct of the study. LS reports research funding to the institution by MSD, grants from Beijing Xiantong Biomedical Technology, Qily Pharmaceutical, Zaiding Pharmaceutical, Jacobio Pharmaceuticals, and Beihai Kangcheng Medical Technology, and consulting fees from HARBOUR and Merck, during the conduct of the study. MAS reports funding to the institution from MSD, Bristol Myers Squibb (BMS), and Oncolys BioPharma, during the conduct of the study. PE reports funding to the institution from MSD, during the conduct of the study, and personal fees from MSD, AstraZeneca, Celgene, Daiichi Sankyo, Five Prime, Lilly, Loxo, Taiho, Takeda, and Zymeworks, outside of the submitted work. AA reports funding to the institution from MSD, BMS, and Bayer Pharmaceuticals, during the conduct of the study, and personal fees from MSD and BMS, and personal fees for advisory role from Merck Serono and Servier, outside of the submitted work. TD reports funding to the institution from MSD, Daiichi Sankyo, Sumitomo Dainippon, AbbVie, Novartis, Boehringer Ingelheim, Taiho Pharmaceutical, Merck Serono, BMS, Pfizer, Lilly, Kyowa Hakko, Kirin, and IQVIA, during the conduct of the study, and personal fees for consulting or advisory role from MSD, Daiichi Sankyo, Amgen, Sumitomo Dainippon, Taiho Pharmaceutical, Takeda, AbbVie, Novartis, Bayer, Boehringer Ingelheim, Rakuten Medical, and BMS, and honoraria from Ono Pharmaceutical, Astellas Pharma, Oncolys BioPharma, Taiho Pharmaceutical, and Otsuka, outside of the submitted work. TK reports funding to the institution from MSD, Ono Pharmaceutical, Shionogi, Astellas Amgen Bio Pharma, and Taiho Pharmaceutical, during the conduct of the study, and personal fees from MSD, Ono Pharmaceutical, Merck, Astellas Pharma, BMS, and Oncolys BioPharma, outside of the submitted work. J-PM reports funding to the institution from MSD, during the conduct of the study, and honoraria from MSD, Bayer, and BMS, outside of the submitted work. ZL reports funding to the institution from MSD, during the conduct of the study. S-BK reports funding to the institution from MSD, Novartis, and Sanofi-Genzyme, during the conduct of the study, and personal fees for consulting or advisory role from Dae Hwa Pharmaceutical, ISU Abxis, and Daiichi-Sankyo, outside of the submitted work. BCC reports funding to the institution from MSD, Novartis, Bayer, AstraZeneca, MOGAM Institute, Dong-A ST, Champions Oncology, Janssen, Yuhan, Ono, Dizal Pharma, AbbVie, Medpacto, G Innovation, Eli Lilly, Blueprint Medicines, and Interpark Bio Convergence, fees for consulting or advisory role from Novartis, AstraZeneca, Boehringer Ingelheim, Roche, BMS, Ono, Yuhan, Pfizer, Eli Lilly, Janssen, Takeda, MSD, Janssen, Medpacto, Blueprint Medicines, KANAPH Therapeutic, Brigebio Therapeutics, Cyrus Therapeutics, and Guardant Health, stock ownership in TheraCanVac, Gencurix, Bridgebio Therapeutics, KANAPH Therapeutic, Cyrus Therapeutics, and Interpark Bio Convergence, personal fees for Board of Directorship from Gencurix and Interpark Bio Convergence, royalties from Champions Oncology, and is the founder of DAAN Biotherapeutics, outside of the submitted work. MAM reports funding to the institution from MSD, during the conduct of the study, and consultancy for MSD, BMS, Servier, and Lilly, and honoraria from BMS, Servier, and Amgen, outside of the submitted work. EG reports funding to the institution from MSD, during the conduct of the study, and personal fees from MSD, BMS, Servier, and Roche, outside of the submitted work. HH reports funding to the institution from MSD, during the conduct of the study, and grants from AstraZeneca, Daiichi Sankyo, Dainippon Sumitomo Pharma, Merck Biopharma, MSD, Taiho, Chugai, Eisai, LSK BioPharma, Incyte, Pfizer, Boehringer Ingelheim, Beigene, Ono, BMS, and Astellas, and personal fees from Daiichi Sankyo, Dainippon Sumitomo Pharma, Lilly, Merck Biopharma, MSD, Taiho, Chugai, Ono, BMS, Yakult Honsha, Sanofi, Takeda, and Kyowa Hakko Kirin, outside of the submitted work. CF reports funding to the institution from MSD, during the conduct of the study, and grants and non-financial support from National Comprehensive Cancer Network, Taiho Oncology, Pfizer, and AstraZeneca, outside of the submitted work. AT reports funding to the institution from MSD, during the conduct of the study, and grants from Taiho Pharmaceutical, Chugai Pharmaceutical, Eli Lilly Japan, Merck Biopharma, Takeda Pharmaceutical, Sanofi, Ono Pharmaceutical, Kyowa Hakko Kirin, Eisai, Toray Medical, Daiichi Sankyo, Bayer Yakuhin, Shionogi, Pfizer, and Yakult Honsha, and personal fees from Taiho Pharmaceutical, Chugai Pharmaceutical, Eli Lilly, BMS, Merck Biopharma, Takeda Pharmaceutical, and Sanofi, outside of the submitted work. WM, S-HL, PS, LA, and VCO report funding to the institution from MSD, during the conduct of the study. QL, SS, and PB are employees and hold stock in MSD. KK reports funding to the institution from MSD, during the conduct of the study, and research funding from Ono, BMS, Beigene, Shionogi, Merck Biopharma, Oncolys Biopharma, and Chugai, outside of the submitted work., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Analysis of X-ray absorption spectroscopy data often involves the removal of artifacts or glitches from the acquired signal, a process commonly known as deglitching. Glitches result either from specific orientations of monochromator crystals or from scattering by crystallites in the sample itself. Since the precise energy - or wavelength - location and the intensity of glitches in a spectrum cannot always be predicted, deglitching is often performed on a per spectrum basis by the analyst. Some routines have been proposed, but they are prone to arbitrary selection of spectral artifacts and are often inadequate for processing large data sets. Here, a statistically robust algorithm, implemented as a Python program, for the automatic detection and removal of glitches that can be applied to a large number of spectra, is presented. It uses a Savitzky-Golay filter to smooth spectra and the generalized extreme Studentized deviate test to identify outliers. Robust, repeatable, and selective removal of glitches is achieved using this algorithm.

The fate of copper (Cu) in rivers impacted by acid drainage remains poorly studied in waters with comparatively low Al and Fe concentrations. This work addresses the role of confluences in controlling the physical and chemical fate of Cu in a system with total molar ratio Cu/Al > 0.2 and Cu/Fe > 0.15. Two consecutive confluences were studied in the upper Mapocho watershed, a densely populated basin with intensive mining located in the Chilean Andes. The inflow had acidic conditions with seasonal variations and Cu up to 9 mg L -1 . Lability measurements with diffusive gradient in thin films showed that Cu entered as a dissolved labile form. However, downstream from the confluences a higher pH shifted Cu toward nonlabile compounds and solid phases enriched with Cu. Measurements of x-ray absorption spectroscopy of freshly formed particles showed that composition was dominated by sorbed Cu and Cu(OH) 2 (s) precipitates, with a higher proportion of sorbed Cu downstream from confluences when pH < 5. Particle size distributions (PSD) measured in field showed that downstream from the confluences the total volume and average diameter of the suspended particles grew progressively, with estimated mean settling velocities increasing from 0.3 to 4.2 cm s -1 . As a result, 7-30% of the influent Cu was removed from the river flow. These results highlight that shifts in chemical partition and PSDs in river confluences and the hydrodynamic environments at the river reach level control the mobility of Cu in systems with high Cu/Al and Cu/Fe., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Stannous fluoride (SnF 2 ) is a compound present in many commercially available dentifrices; however, oxidative decomposition negatively impacts its efficacy. Stannous oxidation is often mitigated through the addition of complexing agents or sources of sacrificial stannous compounds. The authors have found that the addition of zinc phosphate significantly improved stannous stability more effectively than other stabilization methods. The authors evaluated the chemical speciation of stannous compounds within a variety of formulations using x-ray absorption near edge spectroscopy (XANES), a technique never used before in this manner. These data were compared and correlated with several antimicrobial experiments., Methods: XANES data of various commercially available compounds and Colgate Total SF were performed and analyzed against a library of reference compounds to determine the tin chemical speciation. The antibacterial assays used were salivary adenosine triphosphate, short-interval kill test, plaque glycolysis, and anaerobic biofilm models., Results: XANES spectra showed a diverse distribution of tin species and varying degrees of SnF 2 oxidation. In vitro antimicrobial assessment indicated significant differences in performance, which may be correlated to the differences in tin speciation and oxidation state., Conclusions: Driven by the excipient ingredients, SnF 2 dentifrices contain a distribution of tin species in either the SnF 2 or Sn(IV) oxidation state. The addition of zinc phosphate provided significant robustness against oxidation, which directly translated to greater efficacy against bacteria., Practical Implications: The choice of inactive ingredients in a dentifrice with active SnF 2 can dramatically impact product stability., (Copyright © 2019 American Dental Association. Published by Elsevier Inc. All rights reserved.)

Identifying and quantifying the processes governing the mobilization of metals during resuspension events is key to assessing long-term metals efflux from sediments and associated ecological impacts. We investigated the effects of sediment resuspension on the mobilization and chemical speciation of zinc in two-week-long batch experiments using metal-contaminated sediments from Lake DePue (IL, USA). Measurements of dissolved zinc and sulfate allowed us to characterize the kinetics of metal sulfide dissolution and the resulting net release of zinc to the aqueous phase. X-ray absorption spectroscopy (XAS) provided direct insights into the chemical speciation of iron and zinc and their dynamic transformations during resuspension. While ZnS rapidly oxidized during resuspension, dissolved zinc increased only after two days of resuspension. We proposed a kinetic model to explain changes in the chemical speciation of zinc during these experiments as constrained by the dissolved species concentrations and chemical speciation as informed by XAS. Only 15% of the zinc mobilized was released to the aqueous phase while the remaining fraction repartitioned the solid phase either as a carbonate precipitate or as a sorbed species. Our results show that zinc sorption onto particle surfaces and reprecipitation of zinc minerals limit zinc solubility during resuspension of metal-sulfide sediments., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The consumption of alcohol and drugs of abuse among pregnant women has experienced a significant increase in the last decades. Suitable maternal nutritional status is crucial to maintain the optimal environment for fetal development but if consumption of alcohol or drugs of abuse disrupt the intake of nutrients, the potential teratogenic effects of these substances increase. Despite evidence of the importance of nutrition in addicted pregnant women, there is a lack of information on the effects of alcohol and drugs of abuse on maternal nutritional status; so, the focus of this review was to provide an overview on the nutritional status of addicted mothers and fetuses. Alcohol and drugs consumption can interfere with the absorption of nutrients, impairing the quality and quantity of proper nutrient and energy intake, resulting in malnutrition especially of micronutrients (vitamins, omega⁻3, folic acid, zinc, choline, iron, copper, selenium). When maternal nutritional status is compromised by alcohol and drugs of abuse the supply of essential nutrients are not available for the fetus; this can result in fetal abnormalities like Intrauterine Growth Restriction (IUGR) or Fetal Alcohol Spectrum Disorder (FASD). It is critical to find a strategy to reduce fetal physical and neurological impairment as a result of prenatal alcohol and drugs of abuse exposure combined with poor maternal nutrition. Prenatal nutrition interventions and target therapy are required that may reverse the development of such abnormalities., Competing Interests: The authors declare no conflict of interest.

The identity and structure of tin(ii)-fluoride complexes formed in aqueous solutions is determined by combining X-ray absorption spectroscopy, thermodynamic modeling and quantum mechanical calculations. Spectroscopic measurements confirm the presence of 3 stannous fluoride complexes, SnF+, SnF02 and SnF3-, with mean Sn-F bond distances that increase linearly, from 1.98 to about 2.04 Å, as a function of the coordination number. Computational ab initio calculations indicate that the stannous fluoride complexes form localized σs-p bonds, with the stereochemically active lone pair of the Sn(ii) atom distorting the geometry of the complexes. In addition, the SnF3- complex exhibits loosely coordinated water, which is removed upon addition of glycerol to lower the solvent activity. Our results provide spectroscopic confirmation of the stannous fluoride complexes proposed in the literature, and explain why glycerol additions stabilize solutions of Sn(ii) against oxidation.

In order to determine the ability of 1,2-dipalmitoyl phosphatidylcholine (DPPC) and 1,2-dioleoyl phosphatidylglycerol (DOPG) to host peptide sequences belonging to the E2 protein of GBV virus C/Hepatitis G virus, the behaviour of Langmuir monolayers formed by these phospholipids and E2 (12-26), E2 (354-363) and E2 (chimeric) peptide sequences was analysed from data of surface pressure (π) versus area per molecule (A) isotherms, compression modulus (C s -1 ), excess Gibbs energy of mixing (ΔG exc ) and total Gibbs energy of mixing (ΔG mix ). Three different behaviours were observed. Mixed films of E2 (12-26) with DPPC or DOPC showed negative values for the excess thermodynamic functions, and thus attractive interactions between mixed films components are greater than in ideal films. Mixtures of E2 (354-363) with DPPC or DOPG, exhibited positive values of excess functions, evidencing weaker interactions in the mixed films in relation to those of pure components. Finally, positive and negative excess functions were observed in E2 (chimeric)/DPPC or DOPG mixed films, depending on their composition. In short, the interaction between the phospholipids used in this work as models of cell membranes and E2 peptides varies with the type of phospholipid and the nature of the peptide (size, bulky, hydrophobicity and electric charge)., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Corrosion of copper pipes may release high amounts of copper into the water, exceeding the maximum concentration of copper for drinking water standards. Typically, the events with the highest release of copper into drinking water are related to the presence of biofilms. This article reviews this phenomenon, focusing on copper ingestion and its health impacts, the physicochemical mechanisms and the microbial involvement on copper release, the techniques used to describe and understand this phenomenon, and the hydrodynamic effects. A conceptual model is proposed and the mathematical models are reviewed., Competing Interests: The authors declare no conflict of interest.

Using a metadynamics approach, we investigate the potential of mean force for Na + permeation inside a cyclic peptide nanotube (CPN) with modified interior as a function of ion position, coordination number, and lumen chemistry. We show that functionalizing the lumen of a CPN with a methyl-benzoic acid group introduces non-periodic variations in the internal energy of the nanotube, which dictate the overall free energy roughness during the permeation of Na + . These non-periodic variations arise from the structural dynamics of the functional group, where changes in the dihedral angles induced by the proximity of the ion give rise to conformational changes that increase landscape roughness and thereby decrease transport rate. Our computational framework emphasizes the advantages of using the coordination number as a collective variable to investigate the available conformations during ion permeation through CPNs, and reveals new structure-function relations for chemically tunable CPNs, paving the way for rational design of nano-porous systems with tunable selectivity and flux.

CPT-11 and SN-38 are camptothecins with strong antitumor activity. Nevertheless, their severe side effects and the chemical instability of their lactone ring have questioned the usual forms for its administration and have focused the current research on the development of new suitable pharmaceutical formulations. This work presents a biophysical study of the interfacial interactions of CPT-11 and SN-38 with membrane mimetic models by using monolayer techniques and Differential Scanning Calorimetry. The aim is to get new insights for the understanding of the bilayer mechanics after drug incorporation and to optimize the design of drug delivery systems based on the formation of stable bilayer structures. Moreover, from our knowledge, the molecular interactions between camptothecins and phospholipids have not been investigated in detail, despite their importance in the context of drug action. The results show that neither CPT-11 nor SN-38 disturbs the structure of the complex liposome bilayers, despite their different solubility, that CPT-11, positively charged in its piperidine group, interacts electrostatically with DOPS, making stable the incorporation of a high percentage of CPT-11 into liposomes and that SN-38 establishes weak repulsive interactions with lipid molecules that modify the compressibility of the bilayer without affecting significantly neither the lipid collapse pressure nor the miscibility pattern of drug-lipid mixed monolayers. The suitability of a binary and a ternary lipid mixture for encapsulating SN-38 and CPT-11, respectively, has been demonstrated., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Mixed monolayers of E2(279-298), a synthetic peptide belonging to the structural protein E2 of the GB virus C (GBV-C), formerly know as hepatitis G virus (HGV), and the phospholipids dipalmitoylphosphatidyl choline (DPPC) and dimiristoylphosphatidyl choline (DMPC),which differ in acyl chains length, were obtained at the A/W interface (monolayers of extension) in order to provide new insights on E2/phospholipids interaction. Analysis of the surface pressure-area isotherms, Brewster angle microscopy images, relative thickness, and mean areas per molecule has allowed us to establish the conditions under which the mixed components of the monolayer are miscible or immiscible and know how the level of the E2/phospholipid interaction varies with the composition of the mixed films, the surface pressure, and the hydrocarbon chains length of the phospholipids. The steric hindrance caused by the penetration of the polymer strands into the more or less ordered hydrocarbon chains of the phospholipids was suggested to explain the differences in the peptide interaction with the phospholipids studied. Therefore, the novelty of results obtained with the Langmuir film balance technique, supplemented with BAM images allow us to achieve a deeper understanding of the interaction.

The interaction between a peptide sequence from GB virus C E1 protein (E1P8) and its structural analogs (E1P8-12), (E1P8-13), and (E1P8-21) with anionic lipid membranes (POPG vesicles and POPG, DPPG or DPPC/DPPG (2:1) monolayers) and their association with HIV-1 fusion peptide (HIV-1 FP) inhibition at the membrane level were studied using biophysical methods. All peptides showed surface activity but leakage experiments in vesicles as well as insertion kinetics in monolayers and lipid/peptide miscibility indicated a low level of interaction: neither E1P8 nor its analogs induced the release of vesicular content and the exclusion pressure values (πe) were clearly lower than the biological membrane pressure (24-30 mN m(-1)) and the HIV-1 FP (35 mN m(-1)). Miscibility was elucidated in terms of the additivity rule and excess free energy of mixing (GE). E1P8, E1P8-12 and E1P8-21 (but not E1P8-13) induced expansion of the POPG monolayer. The mixing process is not thermodynamically favored as the positive GE values indicate. To determine how E1 peptides interfere in the action of HIV-1 FP at the membrane level, mixed monolayers of HIV-1 FP/E1 peptides (2:1) and POPG were obtained. E1P8 and its derivative E1P8-21 showed the greatest HIV-1 FP inhibition. The LC-LE phase lipid behavior was morphologically examined via fluorescence microscopy (FM) and atomic force microscopy (AFM). Images revealed that the E1 peptides modify HIV-1 FP-lipid interaction. This fact may be attributed to a peptide/peptide interaction as indicated by AFM results. Finally, hemolysis assay demonstrated that E1 peptides inhibit HIV-1 FP activity., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The development of peptide fusion inhibitors based on short synthetic peptides represents a promising option in the fight against HIV-1 infection, especially in individuals infected with multiresistant HIV-1 strains. GBV-C has the beneficial effect of retarding the progression of AIDS in people who are co-infected with both the GBV-C and HIV viruses. In previous works, the E1(22-39) GBV-C sequence (E1P8lin) was found to be capable of inhibiting the interaction of HIV-1 FP with bilayers and its cyclic analogue (E1P8cyc) showed a higher anti-HIV-1 activity. In the present work, in an attempt to gain a better understanding of the interaction of E1P8 peptides with HIV-1 FP, we analyzed direct interactions between peptides at the molecular level. Our results support that E1P8cyc might be more potent at blocking HIV-1 entry than E1P8lin as a consequence of the structure induced in the complex formed with HIV-1 FP, which is able to modify the conformation adopted by this functional domain of the HIV-1 gp41 protein in target cell membranes., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Microbially influenced corrosion (MIC) is recognized as an unusual and severe type of corrosion that causes costly failures around the world. A microbial biofilm could enhance the copper release from copper plumbing into the water by forming a reactive interface. The biofilm increases the corrosion rate, the mobility of labile copper from its matrix and the detachment of particles enriched with copper under variable shear stress due to flow conditions. MIC is currently considered as a series of interdependent processes occurring at the metal-liquid interface. The presence of a biofilm results in the following effects: (a) the formation of localized microenvironments with distinct pH, dissolved oxygen concentrations, and redox conditions; (b) sorption and desorption of labile copper bonded to organic compounds under changing water chemistry conditions; (c) change in morphology by deposition of solid corrosion by-products; (d) diffusive transport of reactive chemical species from or towards the metal surface; and (e) detachment of scale particles under flow conditions. Using a multi-technique approach that combines pipe and coupon experiments this paper reviews the effects of microbial biofilms on the corrosion of copper plumbing systems, and proposes an integrated conceptual model for this phenomenon supported by new experimental data., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Three synthetic peptide sequences of 18 amino acid each, corresponding to different fragments of the E2 capsid protein of GB virus C (GBV-C): SDRDTVVELSEWGVPCAT (P45), GSVRFPFHRCGAGPKLTK (P58) and RFPFHRCGAGPKLTKDLE (P59) have been characterized in order to find a relationship between their physicochemical properties and the results obtained in cellular models. Experiments were performed in presence and absence of the HIV fusion peptide (FP-HIV) due to the evidences that GBV-C inhibits AIDS progression. P45 peptide showed lower surface activity and less extent of penetration into 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS) (3:2, mol/mol) lipid monolayers than P58 and P59. However, P45 peptide presented higher capacity to inhibit FP-HIV induced cell-cell fusion than the other two sequences. These results were supported by fluorescence anisotropy measurements which indicated that P45 had a significant effect on the inhibition of FP-HIV perturbation of liposomes of the same lipid composition. Finally, atomic force microscopy (AFM) studies have evidenced the modification of the changes induced by the FP-HIV in the morphology of lipid bilayers when P45 was present in the medium., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The physical chemistry properties and interactions of E2 (125-139) and E2 (120-139) peptide sequences from GB virus C with model cell membranes were investigated by means of several biophysical techniques in order to gain better understanding of the effect of peptide length and lipid charge on membrane binding. The peptides, having one net negative charge at the pH of the assays, interacted with monolayers of all the phospholipids regardless of the charge but with more extent with the cationic DPTAP thus indicating that the interaction had both a hydrophobic and an electrostatic component as has been observed for other peptides of the same family. The peptides were able to leakage contents of liposomes and showed fluorescence energy transfer in vesicles depending on the vesicles lipid composition. On another hand, circular dichroism has shown that the peptides exist mainly as a mixture of disordered structure and β-type conformations in aqueous solution but diminished its unstructured content, folding preferentially into α-helical conformation upon interaction with hydrophobic solvents or positively charged lipid surfaces. Altogether, results of this work indicate that the peptides interact at a surface level, penetrate into bilayers composed of fluid lipids and that conformational changes could be responsible for this effect., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Four peptide sequences corresponding to the E1 protein of GBV-C: NCCAPEDIGFCLEGGCLV (P7), APEDIGFCLEGGCLVALG (P8), FCLEGGCLVALGCTICTD (P10) and QAGLAVRPGKSAAQLVGE (P18) were studied as they were capable of interfering with the HIV-1 fusion peptide (HIV-1 FP). In this work, the surface properties of the E1 peptide sequences are investigated and their physicochemical characterization is done by studying their interaction with model membranes; moreover, their mixtures with HIV-1 FP were also studied in order to observe whether they are capable to modify the HIV-1 FP interaction with model membranes as liposomes or monolayers. Physicochemical properties of peptides (pI and net charge) were predicted showing similarities between P7 and P8, and P10 and HIV-1 FP, whereas P18 appears to be very different from the rest. Circular dichroism experiments were carried out showing an increase of the percentage of α-helix of P7 and P8 when mixed with HIV-1 FP corroborating a conformational change that could be the cause of their inhibition ability. Penetration experiments show that all the peptides can spontaneously insert into phospholipid membranes. Analysis of compression isotherms indicates that the peptides interact with phospholipids and the E1 peptides modify the compression isotherms of HIV-1 FP, but there is one of the peptides that excelled as the best candidate for inhibiting the activity of HIV-1 FP, P7, and therefore, that could be potentially used in future anti-HIV-1 research., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Five peptide sequences corresponding to the E1 protein of GBV-C [NCCAPEDIGFCLEGGCLV (P7), APEDIGFCLEGGCLVALG (P8), FCLEGGCLVALGCTICTD (P10), QAGLAVRPGKSAAQLVGE (P18), and AQLVGELGSLYGPLSVSA (P22)] were synthesized because they were capable of interfering with the HIV-1 fusion peptide (HIV-1 FP)-vesicle interaction. In this work the interaction of these peptides with the HIV-1 FP, as well as with membrane models, was analyzed to corroborate their inhibition ability and to understand if the interaction with the fusion peptide takes place in solution or at the membrane level. Several studies were carried out on aggregation and membrane fusion, surface Plasmon resonance, and conformational analysis by circular dichroism. Moreover, in vitro toxicity assays, including cytotoxicity studies in 3T3 fibroblasts and hemolysis assays in human red blood cells, were performed to evaluate if these peptides could be potentially used in anti-HIV-1 therapy. Results show that P10 is not capable of inhibiting membrane fusion caused by HIV-1 and it aggregates liposomes and fuses membranes, thus we decided to discard it for futures studies. P18 and P22 do not inhibit membrane fusion, but they inhibit the ability of HIV-1 FP to form pores in bilayers, thus we have not discarded them yet. P7 and P8 were selected as the best candidates for future studies because they are capable of inhibiting membrane fusion and the interaction of HIV-1 FP with bilayers. Therefore, these peptides could be potentially used in future anti-HIV-1 research., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

One way to gain information about the fusogenic potential of virus-derived synthetic peptides is to examine their interfacial properties and subsequently to study them in monolayers and bilayers. Here, we characterize the physicochemical surface properties of the peptide E1(64-81), whose sequence is AQLVGELGSLYGPLSVSA. This peptide is derived from the E1 structural protein of GBV-C/HGV which was previously shown to inhibit leakage of vesicular contents caused by the HIV-1 fusion peptide (HIV-1 FP). Mixed isotherms of E1(64-81) and HIV-1 FP were obtained and their Brewster angle microscopy (BAM) and atomic force microscopy (AFM) images showed that the peptide mixture forms a different structure that is not present in the pure peptide images. Studies with lipid monolayers (1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) and 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG)) show that both peptides interact with all the lipids assayed but the effect that HIV-1 FP has on the monolayers is reduced in the presence of E1(64-81). Moreover, differential scanning calorimetry (DSC) experiments show the capacity of HIV-1 FP to modify the properties of the bilayer structure and the capacity of E1(64-81) to inhibit these modifications. Our results indicate that E1(64-81) interacts with HIV-1 FP to form a new structure, and that this may be the cause of the previously observed inhibition of the activity of HIV-1 FP by E1(64-81)., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The aim of this study was to identify proteins that could inhibit the activity of the peptide sequence representing the N-terminal of the surface protein gp41 of HIV, corresponding to the fusion peptide of the virus (HIV-1 FP). To do this we synthesized and studied 58 peptides corresponding to the envelope protein E1 of the hepatitis G virus (GBV-C). Five of the E1 synthetic peptides: NCCAPEDIGFCLEGGCLV (P7), APEDIGFCLEGGCLVALG (P8), FCLEGGCLVALGCTICTD (P10), QAGLAVRPGKSAAQLVGE (P18) and AQLVGELGSLYGPLSVSA (P22) were capable of inhibiting the leakage of vesicular contents caused by HIV-1 FP. A series of experiments were carried out to determine how these E1 peptides interact with HIV-1 FP. Our studies analyzed the interactions with and without the presence of lipid membranes. Isothermal titration calorimetry revealed that the binding of P7, P18 and P22 peptides to HIV-1 FP is strongly endothermic, and that binding is entropy-driven. Gibbs energy for the process indicates a spontaneous binding between E1 peptides and HIV-1 FP. Moreover, confocal microscopy of Giant Unilamellar Vesicles revealed that the disruption of the lipid bilayer by HIV-1 FP alone was inhibited by the presence of any of the five selected peptides. Our results highlight that these E1 synthetic peptides could be involved in preventing the entry of HIV-1 by binding to the HIV-1 FP. Therefore, the continued study into the interaction between GBV-C peptides and HIV-1 FP could lead to the development of new therapeutic agents for the treatment of AIDS., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Thrombospondin-1 (TSP-1) is a protein involved in angiogenesis and tumor metastasis. In a previous study, a tridecapeptide sequence of TSP-1B [KRFKQDGGWSHWG] was synthesized and its biological activity was determined as well as the activity of three related sequences TSPB-(E), TSPB-(S), and TSPB-(Abu)(6). These peptides were tested for activity on the cell growth of three human carcinoma cells lines and only TSPB-(Abu)(6) increased proliferation of MCF7 and HT-29. The main aim of this study was to perform physicochemical measurements, in a comparative way, to determine if the differences in activity could be related to physicochemical properties. Peptides were characterised by HPLC capacity factors, UV, fluorescence, and CD spectra (either in buffer solution or in the presence of lipid vesicles), surface activity, and aggregation. Moreover, the interaction of these peptides with phospholipids was determined through their penetration in monolayers of DPPC, PG, or PS as well as their miscibility in mixed monolayers. Besides, using liposomes as model membranes, the affinity of these peptides for phosphatidylcholine was measured with vesicles labeled with fluorescent markers (TMA-DPH, laurdan, pyrene). Results show that these molecules are highly hydrophilic and their surface activity is low. Mixed monolayers indicate that there is almost no miscibility. Besides, its presence does not modify noticeably the microviscosity of bilayers. Moreover, UV and fluorescence spectra of peptides were not affected by the presence of lipids in the media but CD spectra recorded in TFE/water (1/1) resulted in small changes for TSPB, TSPB-(E), and TSPB-(S) peptides. On the contrary CD spectra of TSPB-(Abu)(6) derivatives were clearly much more sensitive to the polarity of the environment. According to these data the biological activity of peptide with a cyclic aspartimide moiety at position 6 could be related to a specific conformational change in the peptide chain promoted by a hydrophobic membrane-like environment., (Copyright © 2011 Elsevier Inc. All rights reserved.)

E1(145-162), a peptide corresponding to the structural protein E1 of the GB virus C, has been shown earlier to bind at pH 7.4 to vesicles containing 1,2-dimyiristoyl-sn-glycero-3-phospho-rac-(1-glycerol)] (DMPG) and 1,2-dimyiristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipids. To deepen the understanding of the interaction of E1(145-162) with the lipid membrane, in this paper, we report a detailed study of the surface properties of peptide, miscibility properties, and behavior of mixed monomolecular films of it and three phospholipids DMPG, DMPC, and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPG). These studies were performed using the Langmuir balance by means of surface adsorption studies, surface pressure-mean molecular area compression isotherms, and penetration kinetics. The Brewster angle microscopy (BAM) was used to study the morphological properties of pure peptide and the mixed monolayers. The results show us that the peptide showed surface activity concentration dependent when injected beneath a buffered solution (HEPES/NaCl, pH 7.4). This tendency to accumulate into the air/water interface confirms its potential capacity to interact with membranes; the higher penetration of peptide into phospholipids is attained when the monolayers are in the liquid expanded state and the lipids are charged negatively maybe due to its negative electric charge that interacts with the positive global charge of the peptide sequence. The area per molecule values obtained suggested that the main arrangement structure for E1(145-162) peptide is the alpha-helical at the air-water interface that agreed with computational prediction calculations. Miscibility studies indicated that mixtures become thermodynamically favored at low peptide molar fraction.

The physicochemical characterization of the peptide sequence E1(145-162) corresponding to the structural protein E1 of the hepatitis G virus was done by studying its interaction with model membranes. Small unilamellar vesicles (SUVs) of dimyristoylphosphatidylglycerol or dimyristoylphosphatidylcholine were chosen as mimetic membranes. Peptide incorporation and location in the phospholipid bilayer was investigated by fluorescence anisotropy with SUVs labeled with diphenylhexatriene (DPH) or trimethylammonium-DPH. The addition of the peptide E1(145-162) showed significant changes in the anisotropy values of the probe located at the air/water interface. These results indicate that the peptide E1(145-162) preferably interacts with the lipid surface without penetrating inside the bilayer. A series of fluorescence experiments based on tryptophan peptide fluorescence were modeled by means of multivariate curve resolution-alternating least squares (MCR-ALS) algorithm to further study the peptide interaction with bilayers at different temperatures. The preliminary results obtained with MCR-ALS showed how the peptide concentration decay is directly linked to the appearance of a new specie, which corresponds to the lipid-peptide binding. These results provide useful information for the design of synthetic immunopeptides that can be incorporated into a liposomal system with potential to promote a direct delivery of the membrane-incorporated immunogen to the immunocompetent cells, thus increasing the immuno response from the host.

The GB virus C/hepatitis G virus (GBV C/HGV) is a Flaviviridae member that despite its non pathogenicity, has become of great interest given that it could inhibit the replication of the human immunodeficiency virus (HIV). Therefore, a better knowledge of the virus peptides involved in the cellular membrane fusion mechanism has become our aim. The selected peptide, named E2(347-363), corresponds to the GBV-C/HGV E2 protein and has been synthesized in order to study its interaction with in vitro membrane models. Two phospholipids, varying the charge and the unsaturations of the hydrocarbon chain have been chosen: 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (sodium salt) (DOPG). For our porpoise, we have used the Langmuir monolayer technique and Brewster angle microscopy (BAM) to gain deeper insight into the peptide/lipid interactions. The results obtained allow us to argue in favour of considering E2(347-363) a success candidate for developing further experiments in order to determine its potential role in the GBV C/HGV virus/cell membrane fusion process.

Docetaxel (DCT) is an antineoplastic drug for the treatment of a wide spectrum of cancers. DCT surface properties as well as miscibility studies with l-alpha-dipalmitoyl phosphatidylcholine (DPPC), which constitutes the main component of biological membranes, are comprehensively described in this contribution. Penetration studies have revealed that when DCT is injected under DPPC monolayers compressed to different surface pressures, it penetrates into the lipid monolayer promoting an increase in the surface pressure. DCT is a surface active molecule able to decrease the surface tension of water and to form insoluble films when spread on aqueous subphases. The maximum surface pressure reached after compression of a DCT Langmuir film was 13 mN/m. Miscibility of DPPC and DCT in Langmuir films has been studied by means of thermodynamic properties as well as by Brewster angle microscopy (BAM) analysis of the mixed films at the air-water interface, concluding that DPPC and DCT are miscible and they form non-ideally mixed monolayers at the air-water interface. Helmholtz energies of mixing revealed that no phase separation occurs. In addition, Helmholtz energies of mixing become more negative with decreasing areas per molecule, which suggests that the stability of the mixed monolayers increases as the monolayers become more condensed. Compressibility values together with BAM images indicate that DCT has a fluidizing effect on DPPC monolayers.

Traditional studies of copper release in plumbing systems assume that the water extracted from a pipe follows a plug-type flow and that the pipe surface does not interact with the bulk water under flow conditions. We characterized actual stagnation-flushing cycles in a household pipe undergoing corrosion in the presence of a microbial biofilm. The mass of copper released in 10 experiments was on average 8 times the value estimated by using the plug-flow assumption. The experimental copper release pattern was explained by an advection-diffusion model only if a high copper concentration occurs near the pipe surface after stagnation. Microscopic examination of the pipe surface showed a complex assemblage of biotic and abiotic features. X-ray diffraction analyses identified only malachite, while X-ray absorption spectroscopy also revealed cupric hydroxide and cuprite. These results indicate that the surface serves as a storage compartment of labile copper that may be released under flow conditions. Thus, the diffusive transport from the pipe surface to the bulk during stagnation is not the only control of the flux of copper to the tap water when porous reactive microstructures cover the pipe. Our results highlight the need for models that consider the interaction between the hydrodynamics, chemistry, and structure at the solid-water interface to predict the release of corrosion byproducts into drinking water.

Three hydrophobic derivatives of GHK peptide containing either N-terminal hexanoyl, decanoyl or myristoyl acyl moieties were synthesized. The binding of these peptidolipids to phospholipid bilayers as well as their hemolytic activity were determined. Moreover, the influence of these peptidolipids on several physicochemical properties of liposomes was studied. Binding experiments indicate a high affinity of these peptidolipids for lipids ordered in liposomes. Nevertheless, this interaction does not promote the release of entrapped carboxyfluorescein. Experiments carried out by the asymmetric membrane method (NBD-PE/dithionite) and quenching studies (PC-pyrene/KI) indicate that this association has a protective effect suggesting that the hydrophobic moiety inserts in the external part of the bilayer and the peptide chain remains protruding from the surface hindering the entrance or the approach of reactants to it. The microviscosity of DPPC bilayers determined using TMA-DPH as fluorescent marker was not affected by the presence of peptidolipids. Besides, results indicate that myristoyl-GHK produces total hemolysis at 2.5x10(-4)M but decanoyl and hexanoyl derivatives at 5x10(-4)M induce only 10% of hemolysis.

The peptide corresponding to the sequence (279-298) of the Hepatitis G virus (HGV/GBV-C) E2 protein was synthesized, and surface activity measurements, pi-A compression isotherms, and penetration of E2(279-298) into phospholipid monolayers spread at the air-water interface were carried out on water and phosphate buffer subphases. The results obtained indicated that the pure E2(279-298) Langmuir monolayer exhibited a looser packing on saline-buffered than on pure water subphase and suggest that the increase in subphase ionic strength stabilizes the peptide monolayer. To better understand the topography of the monolayer, Brewster angle microscopy (BAM) images of pure peptide monolayers were obtained. Penetration of the peptide into the pure lipid monolayers of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) and into mixtures of dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) at various initial surface pressures was investigated to determine the ability of these lipid monolayers to host the peptide. The higher penetration of peptide into phospholipids is attained when the monolayers are in the liquid expanded state, and the greater interaction is observed with DMPC. Furthermore, the penetration of the peptide dissolved in the subphase into these various lipid monolayers was investigated to understand the interactions between the peptide and the lipid at the air-water interface. The results obtained showed that the lipid acyl chain length is an important parameter to be taken into consideration in the study of peptide-lipid interactions.

Two peptides based on the active SIKVAV sequence were synthesized and hydrophobically modified through attachment of a myristoyl residue to the amino terminal group. A comparative study was carried out on the physicochemical properties of both parent and hydrophobically modified structures. Properties studied were hydrophobicity, surface activity, spreadability on aqueous surfaces, penetration in lipid monolayers, aggregation and haemolytic activity. Results obtained indicate that myristoyl containing peptides form micelles at 10(-6) M concentration, whereas parent peptides start to aggregate at 10(-5) M. All of them are able to spread on aqueous surfaces forming stable monolayers. Concerning their haemolytic activity only one of the sequences promotes a partial lysis of erythrocytes after 30 min incubation at 37 degrees C and 10(-5) M concentration in the media.

A useful approach to get information about the potential fusogenic ability of virus synthetic peptides is the study of its interfacial properties and subsequent study in mono- and bilayers. In this work, we have characterized by means of physicochemical tools (i.e. compression isotherms and surface activity) the sequence 267-284, LLGTEVSEVLGGAGLTGG, derived from the E2 structural protein of HGV/GBV-C. The adsorption of the peptide at the air/water interface was monitored by following the increase in surface pressure as a function of time at two different pH values: 5 and 7. Parameters such as surface excess or molecular area were calculated from the equation of Gibbs. The peptide showed a tendency to migrate to the surface of a saline-buffered solution. It formed stable monolayers at the air/water interface giving a compression isotherm with a shape consistent with that of some alpha-helical peptide conformations. Brewster angle microscopy (BAM) showed that through compression the peptide formed multilayers. The studies with lipid monolayers (DPMC, DMPC/DMPG, and DMPC/DMTAP) showed that the peptide interacts with all the lipids assayed producing a marked disrupting effect upon them. In these effects electrostatic interactions seem to have some participation.

Using the Langmuir technique, we have studied the properties at the air/water interface and the interaction of the hepatitis G virus synthetic peptide E1(53-66) and its palmitoyl derivative with membrane phospholipids. These phospholipids had different characteristics referring to the net charge and saturation of the acyl chain. The palmitoyl derivative was more stable at the air/water interface and in the kinetic at constant area measurements showed higher incorporation to the monolayer. The interaction was higher for saturated phospholipids and those with a negative net charge. When the peptides were in the subphase, they produced changes in the miscibility of mixed monolayers composed of DPPC/DPPG or DOPC/DOPG. It can be deduced from the results obtained that electrostatic interactions play a major role, but when the peptide is derivatized with the palmitoyl chain, hydrophobic interactions are added to the former ones. The interaction is also influenced by the saturation of the acyl chain.

With the aim of better understanding the fusion process mediated by the envelope proteins of the hepatitis G virus (HGV/GBV-C), we have investigated the interaction with model membranes of two overlapping peptides [(267-284) and (279-298)] belonging to the E2 structural protein. The peptides were compared for their ability to perturb lipid bilayers by means of different techniques such as differential scanning calorimetry and fluorescence spectroscopy. Furthermore, the conformational behaviour of the peptides in different membrane environments was studied by Fourier-transform infrared spectroscopy and circular dichroism. The results showed that only the E2(279-298) peptide sequence was able to bind with high affinity to negatively charged membranes, to permeabilize efficiently negative lipid bilayers, to induce haemolysis, and to promote inter-vesicle fusion. This fusogenic activity could be related to the induced peptide conformation upon interaction with the target membrane.

A peptide sequence, stearoyl-GESIKVAVS(NH2), related to a laminin fragment, has been synthesized. Formation of aggregates was controlled by titrating a sodium anilinonaphthalene sulphonate (ANS) solution with peptide and recording fluorescence intensity increases. The results show that this system experiences a sudden increase in fluorescence at peptide concentrations around 2.5 x 10(-4) mol/L. The interaction of this hydrophobic peptide with DPPC vesicles has been studied using fluorescence techniques. Its influence on the microviscosity of bilayers was determined by studying polarization/temperature dependence for ANS and diphenyl hexatriene (DPH) fluorescent probes. With both markers the presence of peptide promotes a clear increase in anisotropy values. This indicates a rigidifying effect. Leakage studies carried out with liposomes loaded with carboxyfluorescein (CF) indicate a stabilizing effect of the peptide on bilayers, in agreement with results obtained with fluorescent probes., (Copyright 2005 John Wiley & Sons, Ltd.)

The name HGV/GBV-C remains as an acronym for hepatitis G virus (HGV) and GB virus-C (GBV-C), strain variants of this enveloped RNA virus independently but simultaneously discovered in 1995. Nowadays there is no evidence that it causes hepatitis in humans either during initial infection or after long-term carriage, but it has been recently related with HIV regarding the inhibition of progression to AIDS. The overall genomic organization of HGV/GBV-C is similar to that of hepatitis C virus (HCV) and other members of the Flavivirus family in Hepacivirus genus. Although a stretch of conserved, hydrophobic amino acids within the envelop glycoprotein of HCV has been proposed as the virus fusion peptide, the mode of entry of GBV-C/HGV into target cells is at present unknown. In the present work, sequences derived from the structural E2-protein of HGV/GBV-C have been selected by means of semiempirical methods and then synthesized manually following solid-phase methodologies. Their ability to induce perturbations in model membranes has been analysed by measuring the penetration of such peptides in lipid monolayers and by a series of experiments based on tryptophan peptide fluorescence emission spectra. Besides, release of vesicular contents to the medium was monitored by the ANTS/DPX assay. The membrane destabilization properties of these peptides was found very related with the length of the sequence., (Copyright 2005 John Wiley & Sons, Ltd.)

The interaction with phospholipid bilayers of two synthetic peptides with sequences corresponding to a segment next to the native N-terminus and an internal region of the E2 structural hepatitis G virus (HGV/GBV-C) protein [E2(7-26) and E2(279-298), respectively] has been characterized. Both peptides are water soluble but associate spontaneously with bilayers, showing higher affinity for anionic than zwitterionic membranes. However, whereas the E2(7-26) peptide is hardly transferred at all from water to the membrane interface, the E2(279-298) peptide is able to penetrate into negatively charged bilayers remaining close to the lipid/water interface. The nonpolar environment clearly induces a structural transition in the E2(279-298) peptide from random coil to alpha-helix, which causes bilayer perturbations leading to vesicle permeabilization. The results indicate that this internal segment peptide sequence is involved in the fusion of HGV/GBV-C to membrane.

The present study was undertaken to examine the physicochemical properties of three overlapping peptides belonging to the E2 envelope protein of Hepatitis G virus (GBV-C/HGV) and its interaction with phospholipid biomembrane models using biophysical techniques. We describe our findings concerning the surface activity and the interaction of the peptides with monolayers and liposomes composed of the zwitterionic phospholipids dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine (DMPC) and a mixture of DMPC with the anionic phospholipid dimyristoylphosphatidylglycerol. The results inform about the effect of the chain length on their interaction with biomembrane models. The longest chain peptide interacts in a higher extent with all the phospholipid studied as a result of a combination of hydrophobic and electrostatic forces.

The physicochemical properties of three peptides belonging to the beta-interferon (beta-IFN) molecule, -beta-IFN(13-20), beta-IFN(40-47) and beta-IFN(109-116)-, which have been described to be antigenic epitopes of the neutralising antibodies responsible of the failure of the Multiple Sclerosis therapy, and their palmitoylated derivatives were analysed. Peptides were synthesised by solid-phase methodologies and characterized by amino acid analysis, analytical high-performance liquid chromatography and electrospray mass spectrometry. The activity of free and derivatized peptides was determined. In order to know how the synthesised peptides were able to interact with membrane models, studies of kinetics of penetration at constant area and compression isotherms were carried out. Moreover, differential scanning calorimetry (DSC) was used to investigate the thermotropic phase properties of binary mixtures of dipalmitoylphosphatidylcholine (DPPC) or dipalmitoylphosphatidylglicerol (DPPG) with the peptides.

The interaction of the hepatitis G synthetic peptide E2(99-118) with cell membrane phospholipids of different characteristics such as dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) was studied by Langmuir isotherms. Epifluorescence microscopy and Atomic force microscopy (AFM) was also used to study interactions with DPPC. Compression isotherms of DPPC/E2(99-118) and DPPG/E2(99-118) mixed monolayers showed negative deviation from ideallity consistent with the existence of attractive interactions. The incorporation of the peptide in DPPC monolayer was also confirmed in epifluorescence microscopy and AFM studies. The peptide retarded the formation of DPPC domains and did not let the phospholipid get organized. No important differences in the interactions with DPPC (neutral) or DPPG (anionic) were found, thus suggesting that electrostatics forces do not have a predominant influence in these interactions., (Copyright 2004 Elsevier B.V)

The present work examines the relationship between the antimicrobial activity of novel arginine-based cationic surfactants and the physicochemical process involved in the perturbation of the cell membrane. To this end, the interaction of these surfactants with two biomembrane models, namely, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) multilamellar lipid vesicles (MLVs) and monolayers of DPPC, 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] sodium salt (DPPG), and Escherichia coli total lipid extract, was investigated. For the sake of comparison, this study included two commercial antimicrobial agents, hexadecyltrimethylammonium bromide and chlorhexidine dihydrochloride. Changes in the thermotropic phase transition parameters of DPPC MLVs in the presence of the compounds were studied by differential scanning calorimetry analysis. The results show that variations in both the transition temperature (Tm) and the transition width at half-height of the heat absorption peak (deltaT1/2) were consistent with the antimicrobial activity of the compounds. Penetration kinetics and compression isotherm studies performed with DPPC, DPPG, and E. coli total lipid extract monolayers indicated that both steric hindrance effects and electrostatic forces explained the antimicrobial agent-lipid interaction. Overall, in DPPC monolayers single-chain surfactants had the highest penetration capacity, whereas gemini surfactants were the most active in DPPG systems. The compression isotherms showed an expansion of the monolayers compared with that of pure lipids, indicating an insertion of the compounds into the lipid molecules. Owing to their cationic character, they are incorporated better into the negatively charged DPPG than into zwitterionic DPPC lipid monolayers.