Functional role of water in membranes updated: A tribute to Träuble.

The classical view of a cell membrane is as a hydrophobic slab in which only nonpolar solutes can dissolve and permeate. However, water-soluble non-electrolytes such as glycerol, erythritol, urea and others can permeate lipid membranes in the liquid crystalline state. Moreover, recently polar amino acid's penetration has been explained by means of molecular dynamics in which appearance of water pockets is postulated. According to Träuble (1971), water diffuses across the lipid membranes by occupying holes formed in the lipid matrix due to fluctuations of the acyl chain trans-gauche isomers. These holes, named "kinks" have the molecular dimension of CH2 vacancies. The condensation of kinks may form aqueous spaces into which molecular species of the size of low molecular weight can dissolve. This molecular view can explain permeability properties considering that water may be distributed along the hydrocarbon chains in the lipid matrix. The purpose of this review is to consolidate the mechanism anticipated by Träuble by discussing recent data in literature that directly correlates the molecular state of methylene groups of the lipids with the state of water in each of them. In addition, the structural properties of water near the lipid residues can be related with the water activity triggering kink formation by changes in the head group conformation that induces the propagation along the acyl chains and hence to the diffusion of water.

Microthermodynamic interpretation of fluid states from FTIR measurements in lipid membranes: a Monte Carlo study.

Fourier transform infrared spectroscopy (FTIR) is usually employed to obtain transition temperatures of lipids and lipid mixtures and the effect on it of several effectors, such as cholesterol. However, no interpretation of the molecular information provided by the frequency shift to higher values observed at Tc is available. In this article, we demonstrate that data obtained by means of FTIR measurements contain information about the microscopic thermodynamics of the lipid-phase transition. By means of Monte Carlo simulation, we have been able to show that the frequency shift from low to high values can be taken as a two-state transition of molecular constituents in a lattice rearrangement. According to the model, at temperatures below Tc all of the groups are defined in the lowest-energy state defined by the lowest frequency value and therefore they are all connected in a gel lattice. Above Tc, some groups may reach different energy states depending on the restrictions imposed on the groups. Ideally, when all of the groups are able to reach the highest frequency, a fully "fluid" state is reached, which is a disordered state. If we take this hypothetical state as a reference, it is possible to show that the higher states become less accessible. The model is suitable for describing the effect of cholesterol, which is able to dump the phase transition and is congruent with previous data denoting that in the so-called fluid phase the first four to five methylene groups remain in the gel state even above Tc. The frequency value attained above Tc depends on the nature of the lipid acyl chain.

Structural and thermodynamic properties of water-membrane interphases: significance for peptide/membrane interactions.

Water appears as a common intermediary in the mechanisms of interaction of proteins and polypeptides with membranes of different lipid composition. In this review, how water modulates the interaction of peptides and proteins with lipid membranes is discussed by correlating the thermodynamic response and the structural changes of water at the membrane interphases. The thermodynamic properties of the lipid-protein interaction are governed by changes in the water activity of monolayers of different lipid composition according to the lateral surface pressure. In this context, different water populations can be characterized below and above the phase transition temperature in relation to the CH2 conformers' states in the acyl chains. According to water species present at the interphase, lipid membrane acts as a water state regulator, which determines the interfacial water domains in the surface. It is proposed that those domains are formed by the contact between lipids themselves and between lipids and the water phase, which are needed to trigger adsorption-insertion processes. The water domains are essential to maintain functional dynamical properties and are formed by water beyond the hydration shell of the lipid head groups. These confined water domains probably carries information in local units in relation to the lipid composition thus accounting for the link between lipidomics and aquaomics. The analysis of these results contributes to a new insight of the lipid bilayer as a non-autonomous, responsive (reactive) structure that correlates with the dynamical properties of a living system.

Surface and hysteresis properties of lipid interphases composed by head group substituted phosphatidylethanolamines.

This work analyzes the surface properties of PE-containing membranes modified at the head group region by the addition of methyl and ethyl residues at or near the amine group. These residues alter the lipid-lipid and lipid-water interactions by changes in the hydrogen bonding capability and the charge density of the amine group thus affecting the electrostatic interaction. The results obtained by measuring the dipole potential, the zeta potential, the area per lipid and the compressibility properties allow to conclude that the H-bonding capability prevails in the lipid-lipid interaction. The non polar groups attached to the C2-carbon of the ethanolamine chain introduces a steric hindrance against compression and increases the dipole potential. The analysis of areas suggests that lipids with methylated head groups have a much larger compressibility at expense of the elimination of hydration water, which is congruent with the broader extent of the hysteresis loop.

Connected and isolated CH2 populations in acyl chains and its relation to pockets of confined water in lipid membranes as observed by FTIR spectrometry.

Analysis of the band corresponding to the frequency of vibrational symmetric stretching mode of methylene groups in the lipid acyl chains and the bands of water below and above the phase transition of different lipids by Fourier transform infrared spectroscopy gives strong support to the formation of confined water pockets in between the lipid acyl chains. Our measures and analysis consolidate the mechanism early proposed by Traüble, in the sense that water is present in kinks formed by trans-gauche isomers along the hydrocarbon tails. The formation of these regions depends on the acyl lipid composition, which determines the presence of different populations of water species, characterized by its degree of H bond coordination in fluid saturated or unsaturated lipids. The free energy excess due to the reinforcement of the water structure along few water molecules in the adjacencies of exposed membrane residues near the phase transition is a reasonable base to explain the insertion and translocation of polar peptides and amino acid residues through the biomembrane on thermodynamic and structural grounds.

Oligoarginine vectors for intracellular delivery: role of arginine side-chain orientation in chain length-dependent destabilization of lipid membranes.

Arginine-rich peptides receive increased attention due to their capacity to cross different types of membranes and to transport cargo molecules inside cells. Even though peptide-induced destabilization has been investigated extensively, little is known about the peptide side-chain and backbone orientation with respect to the bilayer that may contribute to a molecular understanding of the peptide-induced membrane perturbations. The main objective of this work is to provide a detailed description of the orientation of arginine peptides in the lipid bilayer of PC and negatively charged PG liposomes using ATR-IR spectroscopy and molecular modeling, and to relate these orientational preferences to lipid bilayer destabilization. Molecular modeling showed that above the transition temperature arginine side-chains are preferentially solvent-directed at the PC/water interface whereas several arginine side-chains are pointing towards the PG hydrophobic core. IR dichroic spectra confirmed the orientation of the arginine side chains perpendicular to the lipid-water interface. IR spectra shows an randomly distributed backbone that seems essential to optimize interactions with the lipid membrane. The observed increase of permeation to a fluorescent dye is related to the peptide induced-formation of gauche bonds in the acyl chains. In the absence of hydrophobic residues, insertion of side-chains that favors phosphate/guanidium interaction is another mechanism of membrane permeabilization that has not been further analyzed so far.

[Frontal sinusitis, mucocele and subperiosteal superolateral orbit abscess]. / Sinusite frontale, mucocèle et abcès orbitaire supérolatéral.

INTRODUCTION: Periorbital infection following pansinusitis is a rare complication which can lead to irreversible orbital and intracranial consequences. Chandler classified them in 1970. OBSERVATION: An eight-year-old child presented with a subperiosteal superolateral abscess. The initial flu-like syndrome developed into pansinusitis resisting to usual treatment. Palpebral edema and major exophthalmia then appeared requiring CT scan and MRI, which confirmed a subperiosteal abscess. DISCUSSION: A subperiosteal abscess is a serious condition requiring an early diagnosis and a medical or surgical treatment adapted to the severity. Chandler's classification gives the opportunity to adapt management to the infection's gravity. Ethmoiditis may be complicated by periorbital abscesses found usually in the superointernal quadrant. Medical imaging and surgical treatment confirmed a superolateral periorbital abscess and a frontal mucocele. This case illustrates the possibility of communication between frontal sinus and orbital cavity. During frontal sinus infection, pre-existing mucocele may become super-infected and induce a periorbital abscess.

Role of guanidyl moiety in the insertion of arginine and Nalpha-benzoyl-L-argininate ethyl ester chloride in lipid membranes.

Guanidyl moieties of both arginine (Arg) and N(alpha)-benzoyl-L-argininate ethyl ester chloride (BAEE) are protonated in all environments studied, i.e., dry solid state, D(2)O solutions, and dry and hydrated lipids as suggested by DFT(B3LYP)/6-31+G(d,p) calculations. Arg and BAEE are able to insert in the lipid interphase of both DMPC and DOPC monolayers as revealed by the observed decrease in the membrane dipole potential they induce. The larger decrease in the dipole potential induced by BAEE, compared to Arg, can be explained partially by the higher affinity of the hydrophobic benzoyl and ethyl groups for the membrane phase, which allows an easier insertion of this molecule. FTIR studies indicate that the guanidyl moiety of Arg is with all probability facing the hydrophobic part of the lipids, whereas in BAEE this group is facing the water phase. Zeta potential measurements provide a direct evidence that Arg orients in the lipid interphase of phosphatidylcholine (PC) bilayers with the negative charged carboxylate group (-COO-) toward the aqueous phase.

Structural and dynamical surface properties of phosphatidylethanolamine containing membranes.

The hydration of solid dimyristoylphosphatidylethanolamine (DMPE) produces a negligible shift in the asymmetric stretching frequency of the phosphate groups in contrast to dimyristoylphosphatidylcholine (DMPC). This suggests that the hydration of DMPE is not a consequence of the disruption of the solid lattice of the phosphate groups as occurs in DMPC. The strong lateral interactions between NH(3) and PO(2)(-) groups present in the solid PEs remain when the lipids are fully hydrated and seem to be a limiting factor for the hydration of the phosphate group hindering the reorientation of the polar heads. The lower mobility is reflected in a higher energy to translocate the phosphoethanolamine (P-N) dipoles in an electrical field. This energy is decreased in the presence of increasing ratios of PCs of saturated chains in phosphoethanolamine monolayer. The association of PC and PE in the membrane affecting the reorientation of the P-N groups is dependent of the chain-chain interaction. The dipole potentials of PCs and PEs mixtures show different behaviors according to the saturation of the acyl chain. This was correlated with the area in monolayers and the hydration of the P-N groups. In spite of the low hydration, DMPE is still able to adsorb fully hydrated proteins, although in a lower rate than DMPC at the same surface pressure. This indicates that PE interfaces possess an excess of surface free energy to drive protein interaction. The relation of this free energy with the low water content is discussed.

[The Hôtel-Dieu de Lyon, the most beautiful hospital in the kingdom during the reign of Louis XV]. / L'Hôtel-Dieu de Lyon, le plus bel hôpital du Royaume à l'époque de Louis XV.

The Hôtel-Dieu was built between 1741 and 1761 on the banks of the Rhône, composed of a magnificent two-story facade, and the whole crowned by a dome which added to the glory of the city. For this grandiose and costly project, Soufflot was called in. The Hôtel-Dieu became the best hospital in the realm. The healthcare personnel consisted of 130 hospitaller sisters and 50 brothers under the guidance of the chaplains. Eight to ten journeymen surgeons, forefathers of the interns, were spread throughout the wards. The principal surgeon chosen by the rectors became, after 6 years of practice, a fully qualified surgeon, or a 'surgeon gaining mastery', and could then practice freely in the city. In 1755, 1300 patients were hospitalized in the old and new buildings.

[Percy at the battle of Eylau]. / Percy à la bataille d'Eylau.

The battle of Eylau was the bloodiest of the Napoleonic era: around 40,000 Russian and French victims littered the battlefield. It was icy cold. Percy, in charge of the army's health service, was horrified "at the view of corpses heaped in the snow," and organized first aid for the numerous wounded.

[Gaspard II Bartholin and the vulvovaginal gland]. / Gaspard II Bartholin et la glande vulvovaginale.

Born in 1655 in Copenhagen to a renowned family, Gaspard Bartholin had the good fortune during his stay in Paris to meet Joseph Guichard du Verney, a French anatomist who had discovered the glandula vestibuloris major. Back in Copenhagen he was appointed professor of anatomy at the age of 21 described the physiology of the glandula vestibuloris major, later known as Batholin's gland. Ennobled, laden with honours, he was later appointed personal physician to the king of Denmark until his death in 1738.

[An unusual anomaly : cervical spondylolysis in an adult]. / Une anomalie exceptionnelle: la spondylolyse cervicale chez l'adulte.

A case of spondylolysis with exceptional involvement of the cervical spine is reported. The lesion turned out to be a defect in the pars interarticularis of a cervical vertebra. Such cases generally involve the sixth vertebra. Spondylolysis is asymptomatic more often than not. Positive diagnosis is supported by an analysis of the anatomic structures on radiographs and CT-scans. Differential diagnoses include congenital lesion (articular dysplasia) is always found, there is no argument allowing the assertion that cervical spondylolysis is a congenital condition rather than secondary to stress fractures.

[Brief history of the hospital bed]. / Petite histoire du lit d'hôpital.

Start as simple litter for several patients in the Middle-Age, the hospital's bed had progressively change to the first mechanical beds in the XIX century.

Acetabular anatomy and the relationship with pelvic vascular structures. Implications in hip surgery.

Most direct vascular trauma occurring during hip surgery results from injury to pelvic vascular structures which are not visible during the procedures of reaming, drilling holes or the fixation of screws. In this study, 5 pelves of fresh cadavers were injected with a radiopaque mixture and were visualised with a scanner according to 5 predetermined sections. Bone depth of the acetabulum was measured in each section. A calculation was made describing the minimal distance separating the inner cortex from the principal pelvic vessels. After an anatomic dissection of each pelvis, the relationship between the vessels and screws of the fixation cup, implanted identically on the quadranted acetabulum, was observed. The screws placed in the anterior and inferior quadrants and the center of the acetabulum endangered the external iliac v. and a. and the obturator pedicle. The depth of the periacetabular bone was greater in the superior and posterior quadrants. The inferior gluteal, pudendal and superior gluteal aa. were more than ten mm from the posterior wall. Conversely, the external iliac and obturator pedicles came in contact with the osseous surface on which they lay. A projection of the vessels on the acetabulum was made, and the reproducible character of the acetabular-quadrant system was verified. The superior quadrant offers all the characteristics of a vascular safe zone. A knowledge of these anatomic relationships explain vascular trauma in pelvic fractures and helps to prevent vascular injury in hip surgery.

Results of passive and active immunization directed against ferric aerobactin in experimental enterobacterial infections in mice and chickens.

Production of aerobactin has been reported to be a virulence factor in members of the family Enterobacteriaceae. To investigate the protection afforded by humoral immunity directed towards aerobactin in infectious diseases caused by aerobactin-producing strains, we tested the efficacy of mAbAERO1, a murine monoclonal antibody directed to ferric aerobactin, which, in vitro, was found to impair the growth of aerobactin-dependent strains of Enterobacteriaceae under iron-limited conditions. The mortality of mice experimentally infected with the aerobactin-producing strains Escherichia coli V2019 (LD50 = 3.5 x 10(5) CFU/mice) or Klebsiella pneumoniae Caroli (LD50 = 1.3 CFU/mice) was not reduced when 1 mg of mAbAERO1 was injected intravenously 1 h before or 1 h after bacterial challenge. Nor was mortality reduced after challenge with either E. coli V2019 or K. pneumoniae Caroli, even though the active immunization of mice with purified FeAero (ferric aerobactin) conjugated with thyroglobulin as followed by a rise in systemic anti-FeAero antibodies. Lastly, chicks born of hens immunized with FeAero showed evidence of antibody transmission towards FeAero, but were not protected when challenged with E. coli MT78, an aerobactin-producing strain highly virulent for chickens. Therefore, under the experimental conditions tested, humoral immunity against aerobactin appeared to play only a minor role in protection against infections caused by aerobactin-producing members of the family Enterobacteriaceae. However, other experimental models should be tested to confirm these observations.

[Hippocrates' heritage from Lyons]. / L'héritage lyonnais d'Hippocrate.

Hippocrates' influence is known in Lyons as soon as the time of the Renaissance, after the discovery of printing. Symphorien Champier and later chiefly Rabelais translated texts of the Cos master and had them edited by the first printers. Hippocrates' influence is moreover evident in Rabelais' work. In the XIXth century, surgeon major Pétrequin published the first book devoted to Hippocrates's surgery. More recently, Professor Pierre Delore has been a convinced supporter of neo-hippocratic medicine of which he developed the chief principles in his works.

The upper end of the femur: dimensions of the endosteal canal.

Based on a prospective study of 30 right or left femurs removed in a continuous series in the anatomy department, a study was made of the dimensions of the endosteal canal of the upper end of the femur. The femora were analysed by means of 12 CT scans below the lesser trochanter. The sections were numbered and the dimensional parameters calculated by computer, using an original plan. The results were subjected to descriptive and correlative analysis. From these dimensional findings it appeared that the anatomy of the upper end of the femur is not random; morphotypic models exist and the laws of a normal model are regulated by a mathematical equation.