-BMAP18 Antimicrobial Peptide Is Active , Resists to Pulmonary Proteases but Loses Its Activity in a Murine Model of Lung Infection.

The spread of antibiotic resistant-pathogens is driving the search for new antimicrobial compounds. Pulmonary infections experienced by cystic fibrosis (CF) patients are a dramatic example of this health-care emergency. Antimicrobial peptides could answer the need for new antibiotics but translating them from basic research to the clinic is a challenge.

The Mechanism of Killing by the Proline-Rich Peptide Bac7(1-35) against Clinical Strains of Pseudomonas aeruginosa Differs from That against Other Gram-Negative Bacteria.

infections represent a serious threat to worldwide health. Proline-rich antimicrobial peptides (PR-AMPs), a particular group of peptide antibiotics, have demonstrated activity against strains. Here we show that the mammalian PR-AMP Bac7(1-35) is active against some multidrug-resistant cystic fibrosis isolates of By confocal microscopy and cytometric analyses, we investigated the mechanism of killing against strain PAO1 and three selected isolates, and we observed that the peptide inactivated the target cells by disrupting their cellular membranes.

Methods for Elucidating the Mechanism of Action of Proline-Rich and Other Non-lytic Antimicrobial Peptides.

A distinct group of antimicrobial peptides kills bacteria by interfering with internal cellular functions and without concurrent lytic effects on cell membranes. Here we describe some methods to investigate the mechanisms of action of these antimicrobial peptides. They include assays to detect the possible temporal separation between membrane permeabilization and bacterial killing events, to assess the capacity of antimicrobial peptides to cross the bacterial membranes and reside in the cytoplasm, and later to inhibit vital cell functions such as DNA transcription and protein translation.

Inner membrane proteins YgdD and SbmA are required for the complete susceptibility of to the proline-rich antimicrobial peptide arasin 1(1-25).

Arasin 1 from the spider crab is a proline-rich antimicrobial peptide (PR-AMP), which kills target bacteria by a non-membranolytic mechanism. By using a fluorescent derivative of the peptide, we showed that arasin 1 rapidly penetrates into cells without membrane damage. To unravel its mode of action, a knockout gene library of was screened and two types of mutants with a less susceptible phenotype to the arasin 1 fragment (1-23) were found.

Non-Membrane Permeabilizing Modes of Action of Antimicrobial Peptides on Bacteria.

Antimicrobial peptides (AMPs) are a large class of innate immunity effectors with a remarkable capacity to inactivate microorganisms. Their ability to kill bacteria by membranolytic effects has been well established. However, a lot of evidence points to alternative, non-lytic modes of action for a number of AMPs, which operate through interactions with specific molecular targets.

Proteolytic activity of Escherichia coli oligopeptidase B against proline-rich antimicrobial peptides.

Oligopeptidase B (OpdB) is a serine peptidase widespread among bacteria and protozoa that has emerged as a virulence factor despite its function has not yet been precisely established. By using an OpdB-overexpressing Escherichia coli strain, we found that the overexpressed peptidase makes the bacterial cells specifically less susceptible to several proline-rich antimicrobial peptides known to penetrate into the bacterial cytosol, and that its level of activity directly correlates with the degree of resistance. We established that E.

Enteric YaiW is a surface-exposed outer membrane lipoprotein that affects sensitivity to an antimicrobial peptide.

yaiW is a previously uncharacterized gene found in enteric bacteria that is of particular interest because it is located adjacent to the sbmA gene, whose bacA ortholog is required for Sinorhizobium meliloti symbiosis and Brucella abortus pathogenesis. We show that yaiW is cotranscribed with sbmA in Escherichia coli and Salmonella enterica serovar Typhi and Typhimurium strains. We present evidence that the YaiW is a palmitate-modified surface exposed outer membrane lipoprotein.

Functional and structural study of the dimeric inner membrane protein SbmA.

SbmA protein has been proposed as a dimeric secondary transporter. The protein is involved in the transport of microcins B17 and J25, bleomycin, proline-rich antimicrobial peptides, antisense peptide phosphorodiamidate morpholino oligomers, and peptide nucleic acids into the Escherichia coli cytoplasm. The sbmA homologue is found in a variety of bacteria, though the physiological role of the protein is hitherto unknown.

Functional characterization of SbmA, a bacterial inner membrane transporter required for importing the antimicrobial peptide Bac7(1-35).

SbmA is an inner membrane protein of Gram-negative bacteria that is involved in the internalization of glycopeptides and prokaryotic and eukaryotic antimicrobial peptides, as well as of peptide nucleic acid (PNA) oligomers. The SbmA homolog BacA is required for the development of Sinorhizobium meliloti bacteroids within plant cells and favors chronic infections with Brucella abortus and Mycobacterium tuberculosis in mice. Here, we investigated functional features of SbmA/BacA using the proline-rich antimicrobial peptide Bac7(1-35) as a substrate.

Elective bone marrow transplantation in a child with X-linked hyper-IgM syndrome presenting with acute respiratory distress syndrome.

We describe a 10-month-old boy diagnosed with X-linked hyper-IgM syndrome (XHIM) after suffering from life-threatening acute respiratory distress syndrome (ARDS) caused by Pneumocystis carinii pneumonia (PCP), although his previous clinical history and first level laboratory tests investigating immunological function did not indicate immunodeficiency. When the patient's overall condition was good, elective bone marrow transplantation from an HLA-matched older brother was performed successfully. We describe how correct diagnosis and successful treatment were made possible thanks to the involvement of a network of specialists.

Resistance to vecuronium in a term neonate.

We report a case of resistance to curarization in a term neonate undergoing surgery. The dosage of vecuronium required to obtain satisfactory muscular blockade and cessation of spontaneous breathing efforts was more than 10-fold the normal one. The operation was delayed for 90 min The mechanism of this marked resistance is unknown, but some possible hypotheses are presented, focusing on the neonate's poor intrauterine growth and an abnormality in pharmacodynamics.

[Modified technique of Waters for retrograde intubation. Apropos of a case of difficult intubation].

The authors describe a case of impossible intubation by classical means in an obese 37-yr old woman, affected with encephalopathy, hydrocephalus and severe psychomotor retardation. After failure of intubation by classical methods using a flexible introducer, the patient was intubated by Waters retrograde technique using an epidural catheter passed through the thyrocricoid membrane and recovered in the mouth. Following this guide the endotracheal tube passed the glottis fairly easily with the help of a flexible "mouse tail-ended" introducer (C-Mettro, Cook, 19.

[Value of HME antibacterial filters in neonatal and pediatric anesthesia. Comparison with traditional heating humidifiers].

HME (heat-moisture exchangers) filters (Hygrobaby DAR) have been compared with classical humidifiers (Bennett Cascade Humidifier) with regard to heating and humidification of inspired gases in anaesthetized neonates and infants. 28 young patients (2 days-12 months) have been randomized into two groups. Though traditional heaters-humidifiers offer slightly higher performances in terms of temperature and moisture, HME-filters appear to be a better choice from cost, handiness and safety considerations.