Hyaluronic acid and oxidized regenerated cellulose prevent adhesion reformation after adhesiolysis in rat models.

Postsurgical adhesion formation is the most common complication in abdominal and pelvic surgery. Adhesiolysis is the most commonly applied treatment for adhesion formation but is often followed by adhesion reformation. Therefore, an efficient strategy should be adopted to solve these problems. This study aimed to explore whether hyaluronic acid and oxidized regenerated cellulose (ORC) could prevent adhesion formation and reformation. Thirty female Sprague Dawley rats were randomly divided into three groups (n=10 each) and subjected to different treatments during the first and second surgery. The control group was treated with isotonic sodium chloride, the ORC group was treated with ORC (1.5×1 cm), and the medical sodium hyaluronate (MSH) group was treated with 1% MSH (0.5 mL). At 2 weeks after the first surgery, adhesion scores in the MSH group (1.90±0.99) and the ORC group (1.40±0.97) were significantly lower than those in the control group (3.00±0.82) (P=0.005). Similarly, 2 weeks after the second surgery, adhesion scores in the MSH group (2.00±0.82) and the ORC group (1.50±1.27) were significantly lower than those in the control group (3.50±0.53) (P=0.001). In addition, body weights in the MSH group and the ORC group did not change significantly, whereas the control group showed a consistent decrease in body weight during the experiment. Histological examination revealed that inflammatory infiltration was involved in both adhesion formation and reformation. In conclusion, hyaluronic acid and ORC were both efficient in reducing adhesion formation and reformation in the rat model.

Enzymatic cellulose oxidation is linked to lignin by long-range electron transfer.

Enzymatic oxidation of cell wall polysaccharides by lytic polysaccharide monooxygenases (LPMOs) plays a pivotal role in the degradation of plant biomass. While experiments have shown that LPMOs are copper dependent enzymes requiring an electron donor, the mechanism and origin of the electron supply in biological systems are only partly understood. We show here that insoluble high molecular weight lignin functions as a reservoir of electrons facilitating LPMO activity. The electrons are donated to the enzyme by long-range electron transfer involving soluble low molecular weight lignins present in plant cell walls. Electron transfer was confirmed by electron paramagnetic resonance spectroscopy showing that LPMO activity on cellulose changes the level of unpaired electrons in the lignin. The discovery of a long-range electron transfer mechanism links the biodegradation of cellulose and lignin and sheds new light on how oxidative enzymes present in plant degraders may act in concert.

Effects of lytic polysaccharide monooxygenase oxidation on cellulose structure and binding of oxidized cellulose oligomers to cellulases.

In nature, polysaccharide glycosidic bonds are cleaved by hydrolytic enzymes for a vast array of biological functions. Recently, a new class of enzymes that utilize an oxidative mechanism to cleave glycosidic linkages was discovered; these enzymes are called lytic polysaccharide monooxygenases (LPMO). These oxidative enzymes are synergistic with cocktails of hydrolytic enzymes and are thought to act primarily on crystalline regions, in turn providing new sites of productive attachment and detachment for processive hydrolytic enzymes. In the case of cellulose, the homopolymer of ß-1,4-d-glucose, enzymatic oxidation occurs at either the reducing end or the nonreducing end of glucose, depending on enzymatic specificity, and results in the generation of oxidized chemical substituents at polymer chain ends. LPMO oxidation of cellulose is thought to produce either a lactone at the reducing end of glucose that can spontaneously or enzymatically convert to aldonic acid or 4-keto-aldose at the nonreducing end that may further oxidize to a geminal diol. Here, we use molecular simulation to examine the effect of oxidation on the structure of crystalline cellulose. The simulations highlight variations in behaviors depending on the chemical identity of the oxidized species and its location within the cellulose fibril, as different oxidized species introduce steric effects that disrupt local crystallinity and in some cases reduce the work needed for polymer decrystallization. Reducing-end oxidations are easiest to decrystallize when located at the end of the fibril, whereas nonreducing end oxidations readily decrystallize from internal cleavage sites despite their lower solvent accessibility. The differential in decrystallization free energy suggests a molecular mechanism consistent with experimentally observed LPMO/cellobiohydrolase synergy. Additionally, the soluble oxidized cellobiose products released by hydrolytic cellulases may bind to the active sites of cellulases with different affinities relative to cellobiose itself, which potentially affects hydrolytic turnover through product inhibition. To examine the effect of oxidation on cello-oligomer binding, we use thermodynamic integration to compute the relative change in binding free energy between the hydrolyzed and oxidized products in the active site of Family 7 and Family 6 processive glycoside hydrolases, Trichoderma reesei Cel7A and Cel6A, which are key industrial cellulases and commonly used model systems for fungal cellulases. Our results suggest that the equilibrium between the two reducing end oxidized products, favoring the linear aldonic acid, may increase product inhibition, which would in turn reduce processive substrate turnover. In the case of LMPO action at the nonreducing end, oxidation appears to lower affinity with the nonreducing end specific cellulase, reducing product inhibition and potentially promoting processive cellulose turnover. Overall, this suggests that oxidation of recalcitrant polysaccharides by LPMOs accelerates degradation not only by increasing the concentration of chain termini but also by reducing decrystallization work, and that product inhibition may be somewhat reduced as a result.

Molecular mass and molecular-mass distribution of TEMPO-oxidized celluloses and TEMPO-oxidized cellulose nanofibrils.

Native wood cellulose was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and the fibrous TEMPO-oxidized celluloses (TOCs) thus obtained were disintegrated in water to prepare TOC nanofibrils (TOCNs). The carboxyl groups of TOCs and TOCNs were methyl-esterified, and the methylated samples were dissolved in 8% LiCl/N,N-dimethylacetamide for size-exclusion chromatography/multiangle laser-light scattering (SEC-MALLS) analysis to obtain their molecular-mass (MM) values and MM distributions (MMDs). The results showed that remarkable depolymerization occurred in TOCs and TOCNs and depended on the oxidation and sonication conditions. Because single peaks without bimodal patterns were observed in the MMDs for all of the TOC and TOCN samples, depolymerization may have randomly occurred on whole cellulose molecules and oxidized cellulose molecules in the microfibrils during these treatments. Compared with the MM values obtained by SEC-MALLS, the intrinsic viscosities of TOCs dissolved in 0.5 M copper ethylenediamine solution provided lower MM values owing to depolymerization during the dissolution and postreduction processes.

Regulation of postprandial blood metabolic variables by TEMPO-oxidized cellulose nanofibers.

Wood cellulose was converted to individual nanofibers of approximately 4 nm width and 380-570 nm average length by TEMPO-mediated oxidation. The TEMPO-oxidized cellulose nanofibers (TOCNs) were orally administered with glucose and glyceryl trioleate to mice and postprandial responses of blood glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), and triglycerides were studied. Both blood insulin and GIP concentrations were decreased by TOCN with a carboxyl content and aspect ratio of 1.2 mmol g(-1) and 120, respectively, in dose-dependent manners (0-0.3 mg g(-1) body weight). Of the TOCNs examined, that with a carboxyl content and aspect ratio of 1.2 mmol g(-1) and 120, respectively, was the most effective in reducing postprandial blood glucose, plasma insulin, GIP, and triglyceride concentrations. Thus, TOCNs were found to exhibit characteristic biological activities when administered to mice and may have potential applications in biomedical fields for human health.

Effects of oxidized regenerated methylcellulose on lymphocyst formation and peritoneum in gynecologic cancer patients.

HYPOTHESIS: The role of oxidized regenerated methylcellulose (ORC) in the lymphocyst formation after systematic lymphadenectomy. METHODS AND STUDY DESIGN: This was a retrospective case-control study. Patients with gynecologic cancer who underwent systematic lymphadenectomy from May 2000 to April 2006 were considered. Retroperitoneal "no closure" method was performed in all patients. Two groups were identified according to ORC use. The lymphocysts were evaluated via ultrasonography/computed tomography/magnetic resonance imaging between the third and sixth months after surgery. RESULTS: The overall lymphocyst incidence was found to be 75 (29.8%) of 252, and lymphocyst incidence in the ORC and control groups was 45 (30%) of 150 and 30 (29.4%) of 102, respectively. The mean (SD) total number of extracted lymph nodes in the ORC group was 27.5 (10.6), which was significantly higher than that in the control group (22.1 [10.8]; P = 0.001). Duration of drain was significantly longer in the ORC group (P = 0.028). However, when confounding variables were included into the binary logistic regression analysis for the prediction of the duration of drains, only the stage of disease predicted the duration of drains. CONCLUSIONS: Use of ORC does not seem to affect lymphocyst formation. Oxidized regenerated methylcellulose use does not affect the duration of drains, hence ORC does not seem to pose a stimulatory effect on the peritoneum.

In situ detoxification and continuous cultivation of dilute-acid hydrolyzate to ethanol by encapsulated S. cerevisiae.

Dilute-acid lignocellulosic hydrolyzate was successfully fermented to ethanol by encapsulated Saccharomyces cerevisiae at dilution rates up to 0.5h(-1). The hydrolyzate was so toxic that freely suspended yeast cells could ferment it continuously just up to dilution rate 0.1h(-1), where the cells lost 75% of their viability measured by colony forming unit (CFU). However, encapsulation increased their capacity for in situ detoxification of the hydrolyzate and protected the cells against the inhibitors present in the hydrolyzate. While the cells were encapsulated, they could successfully ferment the hydrolyzate at tested dilution rates 0.1-0.5h(-1), and keep more than 75% cell viability in the worst conditions. They produced ethanol with yield 0.44+/-0.01 g/g and specific productivity 0.14-0.17 g/(gh) at all dilution rates. Glycerol was the main by-product of the cultivations, which yielded 0.039-0.052 g/g. HMF present in the hydrolyzate was converted 48-71% by the encapsulated yeast, while furfural was totally converted at dilution rates 0.1 and 0.2h(-1) and partly at the higher rates. Continuous cultivation of encapsulated yeast was also investigated on glucose in synthetic medium up to dilution rate 1.0 h(-1). At this highest rate, ethanol and glycerol were also the major products with yields 0.43 and 0.076 g/g, respectively. The experiments lasted for 18-21 days, and no damage in the capsules was detected.

Ethanol fermentation of acid-hydrolyzed cellulosic pyrolysate with Saccharomyces cerevisiae.

Acid-hydrolysis of cellulosic pyrolysate to glucose and its fermentation to ethanol were investigated. The maximum glucose yield (17.4%) was obtained by the hydrolysis with 0.2 mol/l sulfuric acid using autoclaving at 121 degrees C for 20 min. The fermentation by Saccharomyces cerevisiae of a hydrolysate medium containing 31.6 g/l glucose gave 14.2 g/l ethanol after 24 h, whereas the fermentation of the medium containing 31.6 g/l pure glucose gave 13.7 g/l ethanol after 18 h. The results showed that acid-hydrolyzed pyrolysate could be used for ethanol production. Different nitrogen sources were evaluated and the best ethanol concentration (15.1 g/l) was achieved by single urea. S. cerevisiae (R) was obtained by adaptation of S. cerevisiae to the hydrolysate medium for 12 times, and 40.2 g/l ethanol was produced by it in the fermentation with the hydrolysate medium containing 95.8 g/l glucose, which was about 47% increase in ethanol production compared to its parent strain.

Ethanol fermentation of acid-hydrolyzed cellulosic pyrolysate with Saccharomyces cerevisiae.

The acid hydrolysis of cellulosic pyrolysate to glucose and its fermentation to ethanol were investigated. The maximum glucose yield (17.4%) was obtained by the hydrolysis with 0.2 mol sulfuric acid per liter pyrolysate using autoclaving at 121 degrees C for 20 min. The fermentation by Saccharomyces cerevisiae of a hydrolysate medium containing 31.6 g/l glucose gave 14.2 g/l ethanol in 24 h, whereas the fermentation of the medium containing 31.6 g/l pure glucose gave 13.7 g/l ethanol in 18 h. The results showed that the acid-hydrolyzed pyrolysate could be used for ethanol production. Different nitrogen sources were evaluated and the best ethanol concentration (15.1 g/l) was achieved by single urea. S. cerevisiae (R) was obtained by adaptation of S. cerevisiae to the hydrolysate medium for 12 times, and 40.2 g/l ethanol was produced by S. cerevisiae (R) in the fermentation with the hydrolysate medium containing 95.8 g/l glucose, which was about 47% increase in ethanol production compared to its parent strain.

Noncovalent immobilization of bovine serum albumin on oxidized cellulose.

Immobilization of bovine serum albumin (BSA) on oxidized cellulose (OC) containing carboxylic groups, a biocompatible and bioresorbable polymer, was investigated in water and different buffer solutions (pH 2-7) at 5 degrees C. The maximum amounts of BSA loaded on OC in pH 2, 3, 4, 6, and 7 buffer media were 9.82, 10.52, 8.86, 9.16, 6.05, and 2.69% (w/w), respectively. In water, the corresponding value was 9.82%. The release study was performed on powder, pellet and suspension (in castor and sesame oils) dosage forms of OC-BSA immobilization products prepared in water and pH 2 buffer, in pH 7.4 phosphate buffer at 37 degrees C. The results revealed the release of BSA to be the fastest from oil suspensions, intermediate from powders, and slowest from pellets. In conclusion, the results presented suggest that OC has the potential to be used as an immobilizing matrix for BSA and other proteins in water and pH 2-4 buffer solutions.

Acidity is involved in the development of neuropathy caused by oxidized cellulose.

Recently we demonstrated that oxidized cellulose (OC), a surgical topical hemostatic agent, induces subjacent nerve fiber degeneration by a diffusible chemical mechanism. Since OC is highly acidic, we examined the role of acidity in the development of neuropathy by OC in this study. Fifteen minutes' exposure to culture media containing OC (2 mg/ml, pH 3.47 or 10 mg/ml, pH 2.57) suppressed the subsequent neurite outgrowth of precultured rat DRG neurons in vitro. However, the neurotoxicity of OC disappeared when the pH of the media was restored to 7.42. Topical application of 20 mg OC lowered the pH in the subperineurium of the adjacent rat sciatic nerve to around 3, and kept it below 4 for 2 h in vivo. Application of 0.1 ml neutralized physiological saline containing 40 mg OC did not produce pathological changes in the adjacent rat sciatic nerve in vivo, in contrast to the marked subperineurial nerve damage by direct application of 20 or 40 mg OC observed in our previous study. These results strongly indicate that local neurotoxicity of OC is due to its high acidity. Further care is needed to avoid direct application of large amounts of OC to peripheral nerve.

In vivo degradation of oxidized, regenerated cellulose.

Oxidized, regenerated cellulose (ORC) was surgically implanted on the uterine horns of rabbits, and its biodegradation was studied in vivo. Samples of peritoneal lavages, serum, and urine were collected during the degradation process and analyzed for carbohydrate components utilizing high-performance liquid chromatography with pulsed amperometric detection (h.p.l.c.-p.a.d.). Degradation was rapid, and oligomeric products were evident primarily in the peritoneal fluid from the implantation site, with no apparent accumulation in either the serum or the urine. The size distribution and the amount of the oligomeric products decreased after day one, and by day four peritoneal lavages were essentially free of oligomers. The structure of the products formed was consistent with the lability of the polymer in solution, and the kinetics of degradation paralleled the results of the previously reported in vitro studies. Rabbit peritoneal macrophages, when incubated with ORC in vitro were observed to readily ingest and hydrolyze the polymeric material. A mechanism of degradation consisting of chemical depolymerization, followed by enzymatic hydrolysis mediated by glycosidases endogenous to peritoneal macrophages, is proposed.

Surgicel: its fate following implantation.

Surgicel, a local haemostatic gauze, is claimed to consist of oxidised regenerated cellulose. It is a polyanion, the functional unit of which is termed polyanhydroglucuronic acid. The ability of tissues to absorb Surgicel and its inherent haemostatic properties have been extensively investigated. This study was undertaken a) to determine the time required for absorption of Surgicel from implantation sites in the chest wall muscles of rats, and b) to establish mechanisms for its removal. Data derived from sequential uronic acid assays, histochemistry using the stain alcian blue, and transmission electron microscopy of implanted Surgicel were interpreted to reveal that Surgicel consists of at least two active components. These are a soluble uronic acid component which is lost after 6 h, and a fibrous component which persists. The latter material resembles Surgicel in the electron microscope and is still evident at the implantation site at 48 h post-implantation. Moreover, Surgicel can be characterized in vitro into at least two components according to its solubility under dissociative salt conditions (4M guanidinium chloride). A residual fibrous material could then be hydrolysed with 0.3N sodium hydroxide. We postulate that the absorption of the former salt soluble uronate in vivo is by early degradation and/or systemic clearance, whilst removal of the fibrous material requires phagocytosis.