Accuracy of preoperative automatic measurement of the liver volume by CT-scan combined to a 3D virtual surgical planning software (3DVSP).

BACKGROUND: Liver volumetry is a critical component of safe hepatic surgery, in order to minimize the risk of postoperative liver failure. Liver volumes can be calculated routinely using the time-consuming gold standard method of manual volumetry. The current work sought to evaluate an alternative automatic technique based on a novel 3D virtual planning software, and to compare it to the manual technique. METHODS: A prospective study of patients undergoing liver resection was conducted. Every patient had a pre and 2-day postoperative CT-scan. For each patient, total, remnant and resected volumes were calculated manually and automatically. Planes of resection were verified by a hepatobiliary surgeon and compared with postoperative volumes. Paired t-tests and correlation coefficients were calculated. RESULTS: A major hepatectomy was carried out in 36/43 patients. The automatic TLV (1,759 mL) and the manual TLV (1,832 mL) were significantly different (p < 0.001), but extremely highly correlated (r = 0.989). The percentages of preoperative RLV (manual 58.5%, automatic 58.9%) were similar, with an excellent correlation of 0.917. The preoperative RLV were matched with the 2-day postoperative RLV showing a significant difference (p = 0.0301). The resected volumes using both techniques (871 and 832 mL) were compared with the resected specimen volume (670 mL), showing a significant difference (p < 0.001) but a high degree of correlation (r = 0.874). CONCLUSION: The 3D virtual surgical planning software is accurate and reliable in determining the total liver and future remnant liver volumes. This technique demonstrates a good correlation with the manual technique. Future work will be required to confirm these findings and to evaluate the clinical value of the three-dimensional planning platform.

Surgical management of symptomatic hydatid liver disease: experience from a Western centre.

BACKGROUND: Hydatid liver cysts are rare in North America. The objective of this study was to determine the optimal surgical management for hydatid liver cysts treated outside endemic areas. METHODS: We reviewed the cases of consecutive patients who underwent management of hydatid liver cysts. Radical liver resections were compared with other types of procedures. Clinical presentation, investigations, perioperative outcomes and longterm follow-up were evaluated. We evaluated disease recurrence using the Kaplan- Meier method. RESULTS: Forty patients underwent surgery for hydatid liver cysts. Most patients had single (68%) right-sided (46%) cysts with a median size of 10 cm. Most (83%) underwent liver resection with or without drainage/marsupialization. Radical liver resection was carried out in 60% (19 major, 5 minor). Additional procedures were required in 50% (biliary fistulization 30%, diaphragmatic fistulization 20% or paracaval location/ fusion 8%). Postoperative complications occurred in 48%. The median follow-up was 39 months. The 3-year recurrence-free survival was significantly different between patients who had radical resection and those who had other procedures (100% v. 71%, p = 0.002). CONCLUSION: The surgical management of hydatid liver cysts in North America remains rare and challenging and is frequently associated with fistulizing complications. Excellent long-term outcomes are best achieved using principles of radical liver resection that are familiar to North American surgeons.

CONTEXTE: L'hydatidose (kyste hydatique du foie) est une affection rare en Amérique du Nord. Cette étude visait à déterminer quelle était la meilleure façon de prendre en charge cette maladie à l'extérieur de zones où elle est endémique. MÉTHODES: On a revu les cas de patients consécutifs traités pour des kystes hydatiques du foie. L'ablation radicale du foie a été comparée à d'autres types d'intervention. Le tableau clinique, les examens exploratoires, les résultats périopératoires et le suivi de longue durée ont été évalués. On a aussi évalué la récurrence de la maladie en utilisant la méthode Kaplan­Meier. RÉSULTATS: Quarante patients avaient été opérés pour des kystes hydatiques du foie. La plupart présentaient des kystes simples (68 %) dans le foie droit (46 %), qui mesuraient en moyenne 10 cm de diamètre. La plupart (83 %) avaient subi une résection hépatique avec ou sans drainage ou marsupialisation. Une résection radicale a été pratiquée chez 60 % des patients (19 cas majeurs, 5 cas mineurs). D'autres interventions se sont avérées nécessaires dans 50 % des cas (fistulisation dans les voies biliaires 30 %, fistulisation dans le diaphragme 20 %, localisation paracave ou fusion 8 %). Des complications postopératoires sont survenues dans 48 % des cas. La durée moyenne du suivi a été de 39 mois. On a observé une différence significative entre le taux de survie sans récidive sur 3 ans entre les patients ayant subi une résection radicale et ceux ayant subi une autre intervention (100 % c. 71 %, p = 0.002). CONCLUSION: En Amérique du Nord, le traitement chirurgical de l'hydatidose reste rare, difficile et souvent compliqué par une fistulisation. La résection hépatique radicale, que les chirurgiens nord-américains maîtrisent bien, est l'intervention permettant d'obtenir les meilleurs résultats à long terme.

Effect of organic and inorganic acids on concentrated chitosan solutions and gels.

Rheological properties of concentrated chitosan aqueous solutions and gels in the presence of different organic and inorganic acids were investigated. Viscosities of the solutions increased with polymer concentration and degree of ionization. Strong gels were obtained at pH around 2 with oxalic, phosphoric and sulfuric acids. Gelation was favored by simple and short chain length acids and was governed by ionic interactions. The gels could be distinguished from solutions by the frequency independence of their dynamic moduli and their high apparent activation energy for flow.

Physical gelation of chitosan in the presence of beta-glycerophosphate: the effect of temperature.

When adding beta-glycerophosphate (beta-GP), a weak base, to chitosan aqueous solutions, the polymer remains in solution at neutral pH and room temperature, while homogeneous gelation of this system can be triggered upon heating. It is therefore one of the rare true physical chitosan hydrogels. In this study, physicochemical and rheological properties of chitosan solutions in the presence of acetic acid and beta-GP were investigated as a function of temperature in order to gain a better understanding of the gelation mechanisms. The gel structure formed at high temperature was only partially thermoreversible upon cooling to 5 degrees C because of the existence of remaining associations, confirmed by the spontaneous recovery of the gel after breakup at low temperature. Increasing temperature had no effect on the pH values of this system, while conductivity (and calculated ionic strength) increased. Values from the pH measurements were used to estimate the degree of protonation of each species as a function of temperature. The decreasing ratio of -NH3+ in chitosan and -OPO(O-)2 in beta-GP suggested reduced chitosan solubility along with a diminution of ionic interactions such as ionic bridging with increasing temperature. On the other hand, the increased ionic strength as a function of temperature, in the presence of beta-GP, enhanced screening of electrostatic repulsion and increased hydrophobic effect, resulting in favorable conditions for gel formation. Therefore, our study suggests that hydrophobic interactions and reduced solubility are the main driving force for chitosan gelation at high temperature in the presence of beta-GP.

Synthesis and characterization of new permanently charged poly(amidoammonium) salts and evaluation of their DNA complexes for gene transport.

A new series of linear and permanently charged poly(amidoammonium) salts were synthesized in order to investigate the influence of their ionic and hydrophobic contents on both the cytotoxicity and the transfection mediated by polycation-DNA complexes. The poly(amidoammonium) salts were prepared by chemical modification of a parent poly(amidoamine) containing two tertiary amino groups per structural unit: one incorporated into the main chain and the other fixed at the end of a short bismethylene spacer. The permanent charges were introduced through a quaternization reaction involving iodomethane or 1-iodododecane as an alkylating agent. Under appropriate conditions, the methylation reaction was found to be regioselective, allowing the quaternization of either the side chains or both the side chains and the backbone. Under physiological salt conditions (150 mM NaCl), all of the poly(amidoammonium) salts self-assembled with DNA to form complexes. High proportions of highly quaternized polycation provided better defined morphology to the polycation-DNA complexes. Complexes formed from unquaternized polycation were less cytotoxic than branched poly(ethyleneimine) (25 kDa). At high polycation-DNA weight ratios, the introduction of permanent charges generated a significant increase in the cytotoxicity, but no patent correlation could be established with the amount and the position of the permanent charges. Only complexes formed from polycations with quaternized backbone were able to generate significant gene expression, which was putatively attributed to a better defined toroidal-like morphology together with a higher stability, as suggested by zeta potential measurements. The incorporation of dodecane side chains on highly charged polycations severely amplified the cytotoxicity so that, in return, the transfection level was dramatically affected.

Inhibitory Effect of Organic Acids upon Meat Spoilage Bacteria.

The relative ability of acetic, benzoic, citric, lactic, propionic, and sorbic acids to inhibit the growth of six common meat spoilage bacteria ( Brochothrix thermosphacta , Carnobacterium piscicola , Lactobacillus curvatus , Lactobacillus sake , Pseudomonas fiuorescens , and Serratia liquefaciens ) was compared under otherwise optimum conditions (BHI or MRS broths; 20°C). Because of their low solubility in the growth media, benzoic and sorbic acids could only be used in low concentrations (below 0.15% [wt/vol]) and did not efficiently inhibit bacterial growth. All other acids totally inhibited growth at concentrations ranging from 0.1 % to 1% (wt/vol). On a weight basis, acetic acid was found to be the most inhibitory, followed by propionic. lactic, and citric acid, while the order of efficiency was reversed (citric> lactic> propionic> acetic) when the acid concentrations were expressed on a molar basis or when the acid effectiveness was evaluated relative to the concentration of undissociated molecules. Overall, the lactobacilli were the bacteria most resistant to the action of organic acids, followed by P. fiuorescens and S. liquefaciens , while B. thermosphacta and C. piscicola were considerably more sensitive.

Structure determination of the exopolysaccharide produced by Lactobacillus rhamnosus strains RW-9595M and R.

Exopolysaccharides (EPSs) were isolated and purified from Lactobacillus rhamnosus strains RW-9595M, which has been shown to possess cytokine-stimulating activity, and R grown under various fermentation conditions (carbon source, incubation temperature and duration). Identical (1)H NMR spectra were obtained in all cases. Molecular masses were determined by gel permeation chromatography. The primary structure was elucidated using chemical and spectroscopic techniques. Organic acid, monosaccharide and absolute configuration analyses gave the following composition: pyruvate, 1; D-glucose, 2; D-galactose, 1; and l-rhamnose, 4. Methylation analysis indicated the presence of three residues of 3-linked rhamnose, and one residue each of 2,3-linked rhamnose, 2-linked glucose, 3-linked glucose and 4,6-linked galactose. The EPS was submitted to periodate oxidation followed by borohydride reduction. Monosaccharide analysis of the resulting polysaccharide gave the new composition: rhamnose, 4; and glucose, 1. Methylation analysis confirmed the loss of the 2-linked glucose and 4,6-linked galactose residues. On the basis of one- and two-dimensional (1)H and (13)C NMR data, the structure of the native EPS was consistent with the following heptasaccharide repeating unit: [3Rha alpha-3Glc beta-3[Gal4,6(R)Py alpha-2]Rha alpha-3Rha alpha-3Rha alpha-2Glc alpha-](n) where Rha corresponds to rhamnose (6-deoxymannose) and Py corresponds to pyruvate acetal. Complete (1)H and (13)C assignments are reported for the native and the corresponding pyruvate-hydrolysed polysaccharide. Electrospray MS and MS/MS data are given for the oligosaccharide produced by Smith degradation.