Plant cell wall inspired xyloglucan/cellulose nanocrystals aerogels produced by freeze-casting.

Cellulose nanocrystals (CNC) and xyloglucan (XG) were used to construct new aerogels inspired by the hierarchical organization of wood tissue, i.e., anisotropic porous cellular solid with pore walls containing oriented and stiff cellulose nanorods embedded in hemicellulose matrix. Aerogels with oriented or disordered pores were prepared by directional and non-directional freeze-casting from colloidal dispersions of XG and CNC at different ratios. XG addition induced a clear improvement of the mechanical properties compared to the CNC aerogel, as indicated by the Young modulus increase from 138 kPa to 610 kPa. The addition of XG changed the pore morphology from lamellar to alveolar and it also decreased the CNC orientation (the Hermans' orientation factor was 0.52 for CNC vs 0.36-0.40 for CNC-XG). The aerogels that contained the highest proportion of XG also retained their structural integrity in water without any chemical modification. These results open the route to biobased water-resistant materials by an easy and green strategy based on polymer adsorption rather than chemical crosslinking.

Microfluidics assisted generation of innovative polysaccharide hydrogel microparticles.

Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles: - Janus hydrogel microparticles made of pectin­pectin (homo Janus) and pectin­alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin. - Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid­fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid­liquid interface. These new and original hydrogel microparticles will open up opportunities for studying relationships between combined enzymatic hydrolysis and active release for Janus particles and relationships between shape and swelling behaviour for anisotropic pectin microparticles.

Tuning the architecture of cellulose nanocrystal-poly(allylamine hydrochloride) multilayered thin films: influence of dipping parameters.

Multilayered thin films consisting of alternating cationic polyelectrolyte, poly(allylamine hydrochloride) (PAH), and anionic cellulose nanocrystals (CNs) were constructed using the dipping procedure by screening different experimental parameters: the drying step between each layer adsorption, the dipping time, the ionic strength of the PAH solution, and the concentration of CNs dispersion. We showed that the drying process and the ionic strength of PAH solution were crucial parameters for the successful construction of 8-bilayer films. Film thickness is mainly influenced by dipping time and CN concentration when using the dipping procedure without drying. Two architectures of adsorbed CN layers-a single or a double layer of CNs-were revealed on the basis of the thickness increment per bilayer, depending on experimental conditions. The layer adsorption process was investigated in real-time using quartz crystal microbalance with dissipation (QCM-D) experiments in an aqueous environment or by incorporating a drying step. On the basis of in situ construction of PAH-CN films in wet media, QCM-D data were indicative of highly hydrated films for which the progressive layer stacking is disturbed or prevented. QCM-D monitoring of CNs and PAH layer adsorption was monitored by incorporating a drying process. The impact of experimental parameters on PAH-CN multilayered construction and on CN layer configuration is discussed. This study offers new opportunities for tailoring the architecture of CN-based multilayer films.

Aggregation during coniferyl alcohol polymerization in pectin solution: a biomimetic approach of the first steps of lignification.

Coniferyl alcohol was polymerized in pectin solution in order to mimic the lignification that is the final step of biosynthesis of plant cell wall. Dehydrogenated polymers (DHP = coniferyl alcohol polymers = synthetic lignin) interact with pectin to form hydrophobic clusters as monitored by pyrene fluorescence spectroscopy. The structure of these clusters was studied during the polymerization of synthetic lignin by static and quasielastic light scattering and small angle neutron scattering experiments. We show that synthetic lignin and pectin contribute to the same clusters, but the inner structure of these clusters is very heterogeneous and displays three phases. One observes a segregation between well separated pectin and lignin rich phases at length scales below approximately 30 nm. As a corollary of this segregation, clusters embody a large amount of solvent. On average, the density of the polymer rich phase (lignin plus pectin) inside clusters increases while its specific surface area decreases throughout the polymerization process. These results are discussed with respect to in vivo lignification of the plant cell wall.

Association behaviour of lignins and lignin model compounds studied by multidetector size-exclusion chromatography.

SEC elution curves of spruce milled wood lignin (MWL) and guaiacyl lignin polymer models (G-DHPs) in N,N-dimethylformamide (DMF) exhibited a bimodal elution profile. Light scattering measurements indicated that these elution profiles were due to association effects between the molecules. This became apparent from the determination of high molar masses in the range 10(5)-10(8) g/mol. To study this effect, MWL and DHP were fractionated by precipitation in tetrahydrofuran (THF). The THF-insoluble fractions were found to be the fractions corresponding to the apparent high molar mass part of the DMF elution profiles. The THF-soluble fractions proved to be the less-associated fractions, with lower apparent molecular mass. The individual fractions proved to be rather stable in DMF. Accordingly, the bimodal elution profiles of the starting materials were not the result of an equilibrium between associated and molecular dispersed molecules but of different structures exhibiting a specific and stable association pattern. The different fractions were further characterised by SEC in THF after acetylation to determine molar masses in molecular disperse solutions.

Spinal anaesthesia in a child with hypoplastic left heart syndrome.

Hypoplastic left heart syndrome (HLHS), a complex congenital heart disease, is the most common lethal cardiac defect in neonates. Its treatment includes cardiac transplantation and/or surgical palliation. Associated extracardiac congenital abnormalities are exceptional. We report the case of a neonate with HLHS and anorectal atresia who required urgent surgical management to relieve intestinal obstruction. The surgery was successfully performed under spinal anaesthesia.

Equation of state data for iron at pressures beyond 10 Mbar.

We present equation of state points for iron, in the pressure range 10-45 Mbar, the first obtained with laser-driven shock waves. The experiment has been performed with the high energy laser Phebus, optically smoothed with Kinoform phase plates. Our results double the set of existing experimental data at very high pressures showing good agreement with the predictions of the quotidian equation of state model and with previous results.

[Self-poisoning with Datura stramonium. 3 case reports]. / Intoxication volontaire par Datura stramonium. 3 observations.

BACKGROUND: Datura stramonium is a hallucinogenic plant that causes serious poisoning. Due to its easy availability and strong anticholinergic properties, substance users and teens may use Datura stramonium as a drug. Consumption of any part of the plant can result in severe toxicity. CASE REPORTS: 3 cases of acute self-poisoning by ingestion of Datura stramonium are reported. The patients presented with a typical anticholinergic syndrome: agitation, confusion, hallucinations and combative behaviour; all of them had mydriasis, but dry mouth and tachycardia were less common. All these 3 subjects had a good prognosis but have required hospitalisation because of severe psychiatric derangement with agitated behaviour. The patients were favourably managed with only symptomatic treatment. DISCUSSION: This article reviews the clinical syndrome associated with the toxicity. The severity of hallucinations and confusion, associated with pupillary dilation, flushing, dry mouth, and tachycardia, are related with Datura intoxication. Symptomatic treatment is efficient. CONCLUSION: Primary care physicians might be informed about the abuse of Datura stramonium, often associated with substance misuse, and the need to educate risk-patients.

Influence of pectins on the solubility and the molar mass distribution of dehydrogenative polymers (DHPs, lignin model compounds).

Dehydrogenation polymers (DHPs, lignin model compounds) were synthesized in the presence of increasing pectin concentrations using two different methods. The first method ('Zutropfverfahren', ZT) consists in the slow adding of monomers whereas in the second method ('Zulaufverfahren', ZL) all the reactants are added simultaneously. DHPs solubility increases with the pectin concentration in the ZT experiments and remains stable in the ZL experiments. Covalent bonds between pectin and DHP are formed during ZT polymerization resulting in lignin carbohydrate complex (LCC) which keeps the unbound DHPs in solution by the formation of aggregate or micelle-like structures. In contrast LCC are not formed during the ZL process which behave like the DHP reference. The ZT DHP molar masses increase observed is attributed to the reactivity of the high molar mass polymer solubilized by the LCC whereas ZL higher molar mass polymers are precipitated out of the solution and cannot react further.

Synthesis, characterisation and water sorption properties of pectin-dehydrogenation polymer (lignin model compound) complex.

Coniferyl alcohol was polymerised in the presence of pectin and a pectin-DHP complex was isolated. Characterisation of the complex has demonstrated that DHP (20% wt) was covalently linked by ester bonds to the pectin. The water sorption behaviour of the pectin-DHP complex was determined at several relative vapour pressures and compared with those obtained on pectin, DHP and a blend of both polymers in the same proportion as in the complex. The complex exhibited a lower hydrophilicity resulting from three associated phenomena: grafting, pectin-DHP interactions and the formation of a chemical network.

[Serotonin syndrome in acute poisoning with antidepressive agents]. / Syndrome sérotoninergique lors d'une intoxication aiguë aux antidépresseurs.

We report a case of severe serotonin syndrome after self-poisoning with two antidepressant drugs, paroxetine (a selective inhibitor of serotonin reuptake) and moclobemide (a reversible inhibitor of MAO-A). The serotonin syndrome is characterized by neuromuscular, behavioural, and autonomic changes. It occurs with the use of drugs able to increase serotonergic transmission in brain by acting on biosynthesis, reuptake, catabolism or release of serotonin. Treatment is symptomatic. The incidence of severe cases seems to have increased, probably due to the use of new antidepressant "specific" inhibitors of the serotonin reuptake.

[Analgesia with intra-articular injection of buprenorphine after surgery of the shoulder]. / Analgésie par injection intra-articulaire de buprénorphine après chirurgie de l'épaule.

The effect of 10 ml of intra-articular buprenorphine (0.30 mg) or normal saline on postoperative pain after shoulder surgery was studied in a randomized, prospective, double-blind study in 30 ASA I-II patients receiving general anaesthesia. The pain scores (Five Point Scale ranging from "no pain" to "unbearable pain" and Visual Analog Pain Scale) 1, 2, 3, 4, 6 and 24 hours after surgery, time to first analgesic use and total 6-hours and 24-hours analgesic requirements were recorded. VAPS was significantly lower in the buprenorphine group compared with placebo-treated patients one hour after surgery (p < 0.05). The time to first analgesic use was longer and total 6-h opioid requirements were lower in the buprenorphine group when compared with the control group (p < 0.05). No significant differences were detected in total 24-h analgesic requirements between the two groups. These results indicate that intra-articular injection of buprenorphine after shoulder surgery provides short analgesia. This effect may be mediated by systemic absorption.

[The intravascular transfer of glycine during percutaneous kidney surgery]. / Passage intravasculaire du glycocolle lors de la chirurgie rénale percutanée.

Transurethral prostatic resection using a 1.5% glycine solution causes a well known clinical and metabolic syndrome called TURP-syndrome. Recent development of percutaneous renal surgery is responsible of several similar accidents. In a prospective study of 150 patients (mean age: 35 +/- 10) subjected to a percutaneous nephrolithotomy, the natremia and the amino acid content of the plasma were measured preoperatively and immediately postoperatively by chromatography. The study shows that there is a post-nephrolithotomy syndrome in two per cent. This syndrome contains a hemodilution with hyponatremia and reabsorption of irrigation fluid. Glycolemia, serinemia and threoninemia increase significantly. These modifications have a good correlation between them except for the natremia. Variability of results in this study and in the literature is explained by difficulty and duration of surgery, volume of glycol used, increasing intrarenal pressures and sudden opening of vessels peroperatively. The gravity of post-nephrolithotomy syndrome requires to change the irrigate solute and use normal saline solution when it is possible.

[Use of propofol in 1350 anesthetized patients for electroconvulsive therapy]. / Utilisation du propofol lors de 1,350 anesthésies pour sismothérapie.

Propofol was used for 1,350 sessions of electro-convulsive therapy (ECT). After 0.5 mg of intravenous atropine, patients received 1 to 1.5 mg.kg-1 bolus of propofol over a period of 20 seconds or less. This was convenient for loss of the eye-lash reflex. A bolus of 15 to 20 mg suxamethonium was given, in non allergic patients, to prevent trauma from the seizure. The patient was hyperventilated with pure oxygen through a facial mask. The electric shock was delivered bitemporally after a dental protection had been inserted. For each patient, the following data were noted: sex, use of tricyclic antidepressant drugs, atopy, amount of administered propofol and the effective intensity of the electric shock. The 99 patients were given 16.27 +/- 14 ECT sessions. Among them 26 took antidepressant drugs and 34 were atopic. There was no difference, except for weight, between the 25 men and 74 women. The mean dose of propofol was 1.37 +/- 0.3 mg.kg-1. The dose decreased with increasing age. There was no statistical relationship between the amount of propofol and intensity of the electric shock required to set off a seizure. The use of antidepressant drugs, and atopy did not influence the required amount of propofol. Speed of injection seemed to be the determining factor for narcosis with low doses of propofol. Hyperoxia and hypocapnia induced by hyperventilating with pure oxygen seemed to facilitate occurrence and duration of seizures. Although propofol has been said to reduce the length of seizures, there is controversy concerning the ECT efficacy criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

[Propofol and etomidate: a comparative study in emergency anesthesia in ASA I and II patients]. / Propofol et étomidate: étude comparative en anesthésie d'urgence chez des patients ASA I et II.

The use of propofol and etomidate in emergency anaesthesia is studied in 39 patients ASA I and 11 patients ASA II. After premedication, the narcosis is induced and maintained either by iterative injections or by continued infusion. Concerning haemodynamic changes, the diastolic blood pressure decreases in propofol group without any deleterious effect for these patients. Recovering time is the same in the two groups. The time for recovering memorization is significantly shorter in the propofol group. The use of these two drugs is fully justified in an emergency situation with preference for propofol in case of preoperative haemodynamic stability.

[Study of cerebral energy metabolism and development of postanoxia coma]. / Exploration du métabolisme énergétique cérébral et évolution des comas postanoxiques.

An open prospective study of brain energy metabolism was carried out in 20 consecutive cases of coma occurring after cardiopulmonary arrest (CPA) of various causes. Mean age was 54 years and mean duration of CPA 2.75 min, with a mean of 11 min for resuscitation. Brain energy metabolism was compared with clinical course, electroencephalogram (EEG), and neurological outcome. All the patients were given the usual intensive care: intermittent positive pressure ventilation, haemodynamic control, sedation with benzodiazepines, neuromuscular paralysis, anticonvulsants, mannitol. A clinical examination and an EEG were carried out daily, 4 h after all drugs which might interfere with these investigations or brain energy metabolism had been stopped (except for anticonvulsants). Successive measurements of the cerebral arteriovenous oxygen (C (a - v) O2) and glucose (C (a - v)gluc) contents were made. The oxygen glucose index (OGI) was calculated according to Cohen's formula. The first set of measurements were carried out within the first 30 h after CPA. The last measurements were made a few hours before death or recovery, or stabilization of the coma. Patients were assigned to 2 groups according to their neurological outcome: group R (n = 8), patients who recovered consciousness; group D (n = 12), patients who developed brain death or a vegetative state - Safar's cerebral performance category 4. During the first 30 h, there was no relationship between clinical course, EEG and cerebral outcome. Half of the patients died or recovered within 72 h.(ABSTRACT TRUNCATED AT 250 WORDS)