Hierarchical Self-Assembly of Amphiphilic ß-C-Glycosylbarbiturates into Multiresponsive Alginate-Like Supramolecular Hydrogel Fibers and Vesicle Hydrogel.

Ordered molecular self-assembly of glycoamphiphiles has been regarded as an attractive, practical and bottom-up approach to obtain stable, structurally well-defined, and functional mimics of natural polysaccharides. This study describes a versatile and rational design of carbohydrate-based hydrogelators through N,N'-substituted barbituric acid-mediated Knoevenagel condensation onto unprotected carbohydrates in water. Amphiphilic N-substituted ß-C-maltosylbarbiturates self-assembled into pH- and calcium-triggered alginate-like supramolecular hydrogel fibers with a multistimuli responsiveness to temperature, pH and competitive metal chelating agent. In addition, amphiphilic N,N'-disubstituted ß-C-maltosylbarbiturates formed vesicle gels in pure water that were scarcely observed for glyco-hydrogelators. Finally, barbituric acid worked as a multitasking group allowing chemoselective ligation onto reducing-end carbohydrates, structural diversity, stimuli-sensitiveness, and supramolecular interactions by hydrogen bonding.

Robotic right hepatectomy for giant hepatocellular adenoma - With video.

BACKGROUND: The safety and efficiency of mini-invasive approach for liver resection have been confirmed. However, laparoscopic approach suffers from several limits due to technical difficulties particularly for voluminous tumor. Robotic approach could improve accessibility of these difficult tumors. METHODS: A 29-year-old woman was treated for a giant telangiectasic adenoma [1] of the right liver measuring 20 cm. RESULTS: A robotic anatomical right hepatectomy was decided [2]. Da Vinci X robot was used. The procedure was performed with a second surgeon positioned between the patient's legs using suction/irrigation device and ultrasonic dissector through laparoscopic ports [3]. A first hilar approach allows individualization of right hepatic artery and portal vein. Robotic irrigated bipolar coagulation and laparoscopic ultrasonic dissector was used for parenchymal transection. Operation time was 290 min, and estimated blood loss was 150 ml. Postoperative course was uneventful. The patient was discharged on postoperative day eight. CONCLUSIONS: Robotic approach could improve accessibility to minimally invasive liver resection of voluminous tumor.

Expeditious Synthesis of C-Glycosyl Barbiturate Ligands of Bacterial Lectins: From Monomer Design to Glycoclusters and Glycopolymers.

The approach developed here offers a straightforward and efficient access to ß- C-glycosyl barbiturate ligands, spanning from glycomimetics to multivalent C-neoglycoconjugates, with the aim of deciphering structural parameters impacting the binding to pathogenic lectins. We reinvestigated the Knoevenagel condensation of barbituratic acid on protecting-group free carbohydrates and successfully designed sodium and 5,5-disubstituted N, N-dimethyl barbiturate forms of D-galactose, L-fucose, melibiose, 2'-fucosyllactose, and maltose and evaluated their binding affinity by isothermal titration calorimetry with LecA (galactose-binding lectin) and LecB (fucose-binding lectin) from Pseudomonas aeruginosa and RSL (fucose-binding lectin) from Ralstonia solanacearum. The barbiturate ring was shown to be detrimental for binding to LecA ( KD in mM range) and even more to LecB (noninteraction) while RSL is much more tolerant especially in the presence of an aromatic group ( KD in µM range). However, distancing the barbiturate ring from the recognition carbohydrate residue by using oligosaccharides increased affinity up to low micromolar range. Extension of our convenient synthetic approach led in two steps to melibiose-based C-glycosyl barbiturate cluster and C-glycosyl barbiturate glycopolymers exhibiting a dramatic enhancement of binding avidity for LecA.

Highly concentrated collagen solutions leading to transparent scaffolds of controlled three-dimensional organizations for corneal epithelial cell colonization.

This study aimed at controlling both the organization and the transparency of dense collagen scaffolds making use of the lyotropic mesogen properties of collagen. Cholesteric or plywood-like liquid crystal phases were achieved using mixtures of acetic and hydrochloric acids as solvents. The critical pH at which the switch between the two phases occurred was around pH = 3. The use of the two acids led to fibrillated collagen I scaffolds, whose visual aspect ranged from opaque to transparent. Rheological investigations showed that viscoelastic properties of the plywood-like solutions were optimized for molding due to faster recovery. They also confirmed the correlation between the elastic modulus and the diameter of collagen fibrils obtained after fibrillogenesis under ammonia vapor. Human corneal epithelial cells, grown from donor limbal explants, were cultured both on transparent plywood-like matrices and on human amniotic membranes for 14 days. The development of corneal epithelium and the preservation of epithelial stem cells were checked by optical microscopy, colony formation assay, immuno-fluorescence and quantitative polymerase chain reaction. A higher level of amplification of limbal stem cells was obtained with collagen matrices compared with amniotic membranes, showing the high biocompatibility of our scaffolds. We therefore suggest that collagen solutions presenting both plywood-like organization and transparency might be of interest for biomedical applications in ophthalmology.

Stabilization of Collagen Fibrils by Gelatin Addition: A Study of Collagen/Gelatin Dense Phases.

Collagen and its denatured form, gelatin, are biopolymers of fundamental interest in numerous fields ranging from living tissues to biomaterials, food, and cosmetics. This study aims at characterizing mixtures of those biopolymers at high concentrations (up to 100 mg·mL-1) at which collagen has mesogenic properties. We use a structural approach combining polarization-resolved multiphoton microscopy, polarized light microscopy, magnetic resonance imaging, and transmission electron microscopy to analyze gelatin and collagen/gelatin dense phases in their sol and gel states from the macroscopic to the microscopic scale. We first report the formation of a lyotropic crystal phase of gelatin A and show that gelatin must structure itself in particles to become mesogenic. We demonstrate that mixtures of collagen and gelatin phase segregate, preserving the setting of the pure collagen mesophase at a gelatin ratio of up to 20% and generating a biphasic fractal sample at all tested ratios. Moreover, differential scanning calorimetric analysis shows that each protein separates into two populations. Both populations of gelatins are stabilized by the presence of collagen, whereas only one population of collagen molecules is stabilized by the presence of gelatin, most probably those at the interface of the fibrillated microdomains and of the gelatin phase. Although further studies are needed to fully understand the involved mechanism, these new data should have a direct impact on the bioengineering of those two biopolymers.

Probing the 3D structure of cornea-like collagen liquid crystals with polarization-resolved SHG microscopy.

This work aims at characterizing the three-dimensional organization of liquid crystals composed of collagen, in order to determine the physico-chemical conditions leading to highly organized structures found in biological tissues such as cornea. To that end, we use second-harmonic generation (SHG) microscopy, since aligned collagen structures have been shown to exhibit intrinsic SHG signals. We combine polarization-resolved SHG experiments (P-SHG) with the theoretical derivation of the SHG signal of collagen molecules tilted with respect to the focal plane. Our P-SHG images exhibit striated patterns with variable contrast, as expected from our analytical and numerical calculations for plywood-like nematic structures similar to the ones found in the cornea. This study demonstrates the benefits of P-SHG microscopy for in situ characterization of highly organized biopolymers at micrometer scale, and the unique sensitivity of this nonlinear optical technique to the orientation of collagen molecules.

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments.

This paper presents the correlative imaging of collagen denaturation by nonlinear optical microscopy (NLO) and nanoscale infrared (IR) spectroscopy to obtain morphological and chemical information at different length scales. Such multiscale correlated measurements are applied to the investigation of ancient parchments, which are mainly composed of dermal fibrillar collagen. The main issue is to characterize gelatinization, the ultimate and irreversible alteration corresponding to collagen denaturation to gelatin, which may also occur in biological tissues. Key information about collagen and gelatin signatures is obtained in parchments and assessed by characterizing the denaturation of pure collagen reference samples. A new absorbing band is observed near the amide I band in the IR spectra, correlated to the onset of fluorescence signals in NLO images. Meanwhile, a strong decrease is observed in Second Harmonic signals, which are a structural probe of the fibrillar organization of the collagen at the micrometer scale. NLO microscopy therefore appears as a powerful tool to reveal collagen degradation in a non-invasive way. It should provide a relevant method to assess or monitor the condition of collagen-based materials in museum and archival collections and opens avenues for a broad range of applications regarding this widespread biological material.

Tunable asymmetric catalysis through ligand stacking in chiral rigid rods.

Chiral benzene-1,3,5-tricarboxamide (BTA) ligands, comprising one diphenylphosphino group and one or two remote chiral 1-methylheptyl side chains, were evaluated in the rhodium-catalyzed asymmetric hydrogenation of dimethyl itaconate. Despite the fact that the rhodium atom and the chiral center(s) are separated by more than 12 covalent bonds, up to 82% ee was observed. A series of control and spectroscopic experiments confirmed that the selectivity arises from the formation of chiral helical polymers by self-association of the BTA monomers through noncovalent interactions. The addition of a phosphine-free chiral BTA, acting as a comonomer for the chiral BTA ligands, increases the level of enantioselectivity (up to 88% ee). It illustrates how the selectivity of the reaction can be increased in a simple fashion by mixing two different BTA monomers. The concept was further probed by performing the same experiment with an achiral BTA ligand, i.e. a phosphine-functionalized BTA that contains two remote octyl side chains. It afforded an encouraging 31% ee, thus demonstrating the catalytically relevant transfer of chirality between the self-assembled units. It constitutes a unique example of the sergeants-and-soldiers principle applied to catalysis.

Chronic inflammatory diseases of the bowel: diagnosis and follow-up.

Approximately one fourth of cases of inflammatory bowel disease (IBD) occur during childhood and children are more prone than their adult counterparts to have severe disease at presentation. To investigate these diseases MR imaging is no longer an emerging tool. Numerous reviews and articles have been published on this topic underlying the advances of imaging but also the complexity and the financial impact on management of such diseases. In children it seems reasonable to consider US as the first imaging examination to perform, especially when the diagnosis of IBD is unknown. However, we believe that recent and future technical progress, especially the ability of MR to display reproducible data, and the need for gold standard evaluation of new medical therapies will increase the role of MR enterography.

Clinical experience with retrievable Günther Tulip vena cava filters.

PURPOSE: To report clinical experience with retrievable Günther Tulip filters from implantation to retrieval and their status in nonretrieved situations. METHODS: Seventy-five Günther Tulip filter implantations were performed in 71 patients (43 women; mean age 55 years). Indications for filter placement were pulmonary embolism (PE) or iliofemoral deep vein thrombosis (DVT) in patients with a contraindication to anticoagulation (43, 61%) or perioperative PE prophylaxis (28, 39%) in patients with confirmed iliofemoral DVT. Retrieval procedures were planned for each patient. Patients with nonretrieved filters were followed with plain radiography and duplex sonography. RESULTS: Technical success of filter insertion was 97.3% (73/75). Eighteen (25%) patients died from unrelated causes prior to retrieval attempts, and 6 other patients were too critically ill for a retrieval procedure. Of 49 (67%) planned retrieval attempts, 14 (19%) filters could not be removed owing to large trapped thrombi. The mean implantation period for the 35 (48%) retrieved filters was 8.2 days (range 1-13). Delivery tilt was observed in 12 (16%) filters and during retrieval attempts in 1 more case. For 9 nonretrieved filters, tilt and migration were observed in 22% at a mean follow-up of 30 months, but no venous thrombosis was assessed. CONCLUSIONS: Our data confirm the clinical efficacy of the Günther Tulip filter during implantation and the feasibility of its retrieval. Further long-term follow-up should be conducted on nonretrieved filters to confirm our results.

[Evaluation of non-enhanced spiral CT in the assessment of renal colic: prospective series of 81 patients]. / Evaluation du scanner hélicoïdal non injecté dans la prise en charge des coliques néphrétiques: série prospective de 81 malades.

OBJECTIVE: For many years, intravenous urography has been the first-line investigation for renal colic. Since the middle of the 1990s, non-enhanced spiral CT has become a more efficient, less invasive and less expensive alternative to IVU. The aim of this study was to compare non-enhanced spiral CT and IVU in the assessment of renal colic and to evaluate the possibility of exclusive CT assessment in this disease. MATERIAL AND METHODS: Prospective study including 81 patients all undergoing urgent non-enhanced spiral CT, while the first 30 patients were investigated by non-enhanced spiral CT and IVU. RESULTS: Comparison of IVU versus CT: better sensitivity of CT for the diagnosis of renal colic (96% vs 92%) and for the detection of stones (95% vs 59%). CT diagnosis: A definitive diagnosis of renal colic was established in 72/81 patients: stone visualized in 64 cases and post colic syndrome in 8 cases, while the other 9 patients presented a non-urological abdominal disease. DISCUSSION: Comparison of our series with results reported in the literature confirms the superiority of CT over IVU with better visualization of the stone at a lower cost, with a shorter examination time, without injection and allowing the detection of non-urological disease. Analysis of CT signs emphasizes the importance of secondary signs for the diagnosis of renal colic (dilatation, perirenal or ureteric oedema, rim sign). Delayed excretion demonstrated by IVU and not directly evaluable by non-enhanced CT is no longer an argument in favour of IVU as first-line examination for the assessment of renal colic. CONCLUSION: The superiority of CT for the diagnosis of renal colic has now been demonstrated. Renal colic can now be assessed exclusively by first-line non-enhanced helical CT. IVU or contrast-enhanced CT may be indicated in rare cases when there is a doubt about the diagnosis on non-enhanced CT.

[Imaging strategy for cervical spine injury]. / Stratégies d'imagerie des traumatismes du rachis cervical.

MAKING THE DIAGNOSIS: Exploration strategies when faced with a suspected spine injury have improved with the recent development of new imaging techniques (notably the helical CT scan). A selection must be made between the techniques available in order to optimise diagnostic habits. THE FUNDAMENTAL POINTS: The clinical examination identifies the small group of patients that does not require radiographic exploration. When cervical lesions exist, they are often multiple and layered. This justifies the fact that, if an exploration of the cervical spine is proposed, it should be complete and include the upper and lower hinges. The quality of the standard images (face, profile, mouth open) varies greatly. Their negative quality and predictive value decreases when the severity of the injury increases. PARTICULAR EXAMINATIONS: Scanning is the most efficient technique for not only detecting but also formally eliminating an injury. Its indications should therefore be extended but also limited to a selected population. The MRI is currently a second line examination, indicated for any suspicion of a neurological lesion, notably of the bone marrow. Lesions of the ligaments are often missed and should be systematically searched for using dynamic imaging. These can be done at distance from the injury.