Rate Of Deacetylation Research Articles

Mechanism of Heterogeneous Alkaline Deacetylation of Chitin: A Review.

This review provides an analysis of experimental results on the study of alkaline heterogeneous deacetylation of chitin obtained by the authors and also published in the literature. A detailed analysis of the reaction kinetics was carried out considering the influence of numerous factors: reaction reversibility, crystallinity and porosity of chitin, changes in chitin morphology during washing, alkali concentration, diffusion of hydroxide ions, and hydration of reacting particles. A mechanism for the chitin deacetylation reaction is proposed, taking into account its kinetic features in which the decisive role is assigned to the effects of hydration. It has been shown that the rate of chitin deacetylation increases with a decrease in the degree of hydration of hydroxide ions in a concentrated alkali solution. When the alkali concentration is less than the limit of complete hydration, the reaction practically does not occur. Hypotheses have been put forward to explain the decrease in the rate of the reaction in the second flat portion of the kinetic curve. The first hypothesis is the formation of "free" water, leading to the hydration of chitin molecules and a decrease in the reaction rate. The second hypothesis postulates the formation of a stable amide anion of chitosan, which prevents the nucleophilic attack of the chitin macromolecule by hydroxide ions.

The Influence of Concentration Chitosan of A Shell Snail to Lower Levels of BOD and COD on Waste Laundry

Disposal of laundry waste directly in the river is the cause of high river pollution. Laundry wastewater resulted in an increase in BOD and COD parameters so that it had a negative impact on ecosystem life. The coagulation process using chemicals can reduce BOD and COD parameters in wastewater but have negative effects on health. Chitosan from snail shells can be used as an alternative coagulant that is environmentally friendly because it contains about 70% - 80% chitin. This study aims to synthesize chitosan biocoagulants from snail shells and to test the effectiveness of snail shell chitosan in the treatment of laundry wastewater. Fourier Transform Infra-Red (FTIR) analysis showed that the deacetylation rate of chitosan obtained was 78.06%. Coagulation was carried out on wastewater using variable concentrations and stirring speed. The results showed that the optimum dose of snail shell chitosan biocoagulant was at a concentration of 0.4%. At this dose, the coagulant can bind to the most optimal contaminants so that it can reduce the BOD and COD values ​​in laundry waste and the Fast Stirring Speed ​​of 100 rpm is the optimum stirring speed because large speeds will produce excessive shear forces and prevent the desired floc arrangement.

Comparative Microbial Conversion of Deoxynivalenol and Acetylated Deoxynivalenol in Different Parts of the Chicken Intestine as Detected In Vitro and Translated to the In Vivo Situation.

To assess potential differences in the intestinal microbial metabolism of deoxynivalenol (DON) and its acetylated forms 3-Ac-DON and 15-Ac-DON, in vitro anaerobic incubations with intestinal contents from chickens were conducted. Quantitative microbiota characterization was obtained by 16S rRNA sequencing. The data showed substantial differences in the level of different toxin conversions by the microbiota from the different intestinal segments. The transformation rate of DON to its metabolite DOM-1 decreased in the order of cecum > ileum > jejunum, and caecum contents could completely transform DON to DOM-1 within 24 h. However, no transformation appeared in the duodenum. For 3-Ac-DON, the deacetylation rate decreased as follows: duodenum > caecum > ileum > jejunum, and 100% deacetylation was observed in the duodenum within 24 h. The deacetylation of 15-Ac-DON decreased in the order of cecum > duodenum > ileum with no transformation in the jejunum. Some genera may contribute to the transformation of the toxins. Based on the in vitro kinetic parameters and their scaling to the in vivo situation, it was concluded that in the chicken small intestine, the deconjugation of both 3-Ac-DON and 15-Ac-DON will not likely be completed upon full transit. Whether this also holds for humans remains to be established.

Combined Metabolic and Chemical (CoMetChem) Labeling Using Stable Isotopes-a Strategy to Reveal Site-Specific Histone Acetylation and Deacetylation Rates by LC-MS.

Histone acetylation is an important, reversible post-translational protein modification and a hallmark of epigenetic regulation. However, little is known about the dynamics of this process, due to the lack of analytical methods that can capture site-specific acetylation and deacetylation reactions. We present a new approach that combines metabolic and chemical labeling (CoMetChem) using uniformly 13C-labeled glucose and stable isotope-labeled acetic anhydride. Thereby, chemically equivalent, fully acetylated histone species are generated, enabling accurate relative quantification of site-specific lysine acetylation dynamics in tryptic peptides using high-resolution mass spectrometry. We show that CoMetChem enables site-specific quantification of the incorporation or loss of lysine acetylation over time, allowing the determination of reaction rates for acetylation and deacetylation. Thus, the CoMetChem methodology provides a comprehensive description of site-specific acetylation dynamics.

Sirtuins as molecular targets, mediators, and protective agents in metal-induced toxicity.

Metal dyshomeostasis, and especially overexposure, is known to cause adverse health effects due to modulation of a variety of metabolic pathways. An increasing body of literature has demonstrated that metal exposure may affect SIRT signaling, although the existing data are insufficient. Therefore, in this review we discuss the available data (PubMed-Medline, Google Scholar) on the influence of metal overload on sirtuin (SIRT) signaling and its association with other mechanisms involved in metal-induced toxicity. The existing data demonstrate that cadmium (Cd), mercury (Hg), arsenic (As), lead (Pb), aluminium (Al), hexavalent chromium (CrVI), manganese (Mn), iron (Fe), and copper (Cu) can inhibit SIRT1 activity. In addition, an inhibitory effect of Cd, Pb, As, and Fe on SIRT3 has been demonstrated. In turn, metal-induced inhibition of SIRT was shown to affect deacetylation of target proteins including FOXO, PGC1α, p53 and NF-kB. Increased acetylation downregulates PGC1α signaling pathway, resulting in cellular altered redox status and increased susceptibility to oxidative stress, as well as decreased mitochondrial biogenesis. Lower rates of LKB1 deacetylation may be responsible for metal-induced decreases in AMPK activity and subsequent metabolic disturbances. A shift to the acetylated FOXO results in increased expression of pro-apoptotic genes which upregulates apoptosis together with increased p53 signaling. Correspondingly, decreased NF-kB deacetylation results in upregulation of target genes of proinflammatory cytokines, enzymes, and cellular adhesion molecules thus promoting inflammation. Therefore, alterations in sirtuin activity may at least partially mediate metal-induced metabolic disturbances that have been implicated in neurotoxicity, nephrotoxicity, cardiotoxicity, and other toxic effects of heavy metals.

Species Differences in in vitro and Estimated in vivo Kinetics for Intestinal Microbiota Mediated Metabolism of Acetyl-deoxynivalenols.

Deoxynivalenol (DON) and its acetylated derivatives 3-acetyl-DON (3-Ac-DON) and 15-acetyl-DON (15-Ac-DON) are important mycotoxins of concern in the modern food chain. The present study reveals that the rate of de-acetylation in in vitro anaerobic fecal incubations decreased in the order rat > mouse > human > pig for 3-Ac-DON, and mouse > human > rat > pig for 15-Ac-DON. The ratio between the de-acetylation rate of 3-Ac-DON and 15-Ac-DON varies with the species. Scaling of the kinetic parameters to the in vivo situation results in catalytic efficiencies decreasing in the order human > rat > pig > mouse for 3-Ac-DON and human > pig > rat > mouse for 15-Ac-DON. The results obtained indicate that in mice, 3-Ac-DON can be fully deconjugated while 15-Ac-DON cannot. In rats, pigs, and humans, both 3-Ac-DON and 15-Ac-DON can be totally transformed by gut fecal microbiota during the estimated intestinal residence time. A correlation analysis between the deacetylation rate and the relative abundance of the microbiome suggests Lachnospiraceae may be involved in the deacetylation process. It is concluded that interspecies differences in deacetylation of acetylated DONs exist but that in risk assessment assumption of complete intestinal deconjugation provides an adequate approach.

Exifone Is a Potent HDAC1 Activator with Neuroprotective Activity in Human Neuronal Models of Neurodegeneration.

Genomic instability caused by a deficiency in the DNA damage response and repair has been linked to age-related cognitive decline and neurodegenerative diseases. Preventing genomic instability that ultimately leads to neuronal death may provide a broadly effective strategy to protect against multiple potential genotoxic stressors. Recently, the zinc-dependent class I histone deacetylase (HDAC1) has been identified as a critical factor for protecting neurons from deleterious effects of DNA damage in Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). Translating these observations to a novel neuroprotective therapy for AD, ALS, and FTD may be advanced by the identification of small molecules capable of increasing the deacetylase activity of HDAC1 selectively over other structurally similar HDACs. Here, we demonstrate that exifone, a drug previously shown to be effective in treating cognitive deficits associated with AD and Parkinson's disease, the molecular mechanism of which has remained poorly understood, potently activates the deacetylase activity of HDAC1. We show that exifone acts as a mixed, nonessential activator of HDAC1 that is capable of binding to both free and substrate-bound enzyme, resulting in an increased relative maximal rate of HDAC1-catalyzed deacetylation. Exifone can directly bind to HDAC1 based upon biolayer interferometry assays with kinetic and selectivity profiling, suggesting that HDAC1 is preferentially targeted compared to other class I HDACs and the kinase CDK5, which have also been implicated in neurodegeneration. Consistent with a mechanism of deacetylase activation intracellularly, the treatment of human induced pluripotent stem cell (iPSC)-derived neuronal cells resulted in globally decreased histone acetylation. Moreover, exifone treatment was neuroprotective in a tauopathy patient iPSC-derived neuronal model subject to oxidative stress. Taken together, these findings reveal exifone as a potent activator of HDAC1-mediated deacetylation, thereby offering a lead for novel therapeutic development aiming to protect genomic integrity in the context of neurodegeneration and aging.

KARAKTERISTIK DAN NILAI SUN PROTECTING FACTOR (SPF) KITOSAN DARI TULANG SOTONG (Sephia officinalis)

Cuttlefish (sepia officinalis) have internal shells commonly called cuttlebones which produce more chitin than shrimp shells and crab skins. The purpose of this study was to determine the characteristics of chitosan from cuttlebone including the degree of deacetylation, water content, solubility, organoleptic test (color, odor, texture) as well as testing the value of chitosan protecting the sun protection factor. Chitosan is made in 3 stages, namely deproteination, demineralization, and deacetylation. Deproteination with 4% NaOH at 100 ° C for 60 minutes. Demineralization at room temperature using 1M HCl solution for 120 minutes. Deacetylation using 50% NaOH concentration at 100 ° C for 60 minutes. Chitosan characterization includes the degree of deacetylation, moisture content, solubility, organoleptic test (color, odor, texture). Testing the value of sun protection factor using a UV-VIS spectrophotometer read at wavelengths from 290 to 320 nm. Characteristics of chitosan produced according to chitosan standards used in industry with a deacetylation rate of 71%, yield 31%, moisture content of 0.93%, soluble in acetic acid2% solution, white odorless and powdery. Chitosan with a concentration of 3% gives the value of sun protecting factor 9 as a potential sunscreen that provides maximum protection power.

Cerebrospinal fluid composition after duraplasty with different substitutes in early and late postoperative periods (an experimental study)

Objective. To study cerebrospinal fluid (CSF) changes after the duraplasty with autologous fascia, collagen-based material and chitin-chitosan membrane in early and late postoperative periods. Materials and methods. Chitosan-based films were made out of 3 % solution of chitosan for the research. We used 200 kDa chitosan (deacetylation rate 80–90 %) to produce chitin-chitosan membrane by using solvent evaporation method. For enhancing mechanical properties and reducing the degradation, chitin particles were added to the chitosan solution. Chitosan and chitin ratio was 80/20. The chitin/chitosan solution in Petri dishes was being dried out during 3 days at room temperature. Cerebrospinal fluid composition has been studied after the duraplasty with autofascia, collagen-based material and innovative chitosan-based graft in early and late postoperative periods. The duraplasty was performed by applying these materials to 90 Chinchilla rabbits breed. Animals were divided into three groups: I group — duraplasty using the fascia lata autograft, II group — duraplasty with the collagen-based material, III group — duraplasty using the chitin-chitosan membrane. The animals in the II and III groups were divided into 2 subgroups: A — plasty without fixing the material, B — plasty with fixing the material using atraumatic suture. CSF composition was studied before and after the operation had been performed in 2 weeks, 2 and 6 months. Results. The results of our study demonstrated the increase in density and protein level, the decrease in рН and glucose level and the extreme increase of cells, mostly neutrophils after the use of fascia lata for dural closure. At the same time, there were no substantial changes after dural closure with artificial collagen- and chitosan-based materials, the CSF composition normalized in 2 months after operation. Conclusion. The use of autologous fascia for duraplasty leads to an acute response of the cerebrospinal fluid in the early postoperative period and to residual pleocytosis. The chitosan-based graft application was followed by no complications at 6 months after surgery and only slight CSF response in the early postoperative period. There wasn’t any significant difference in CSF composition in chitosan- and the collagen-based material usage. Given the lack of changes in SCF tests between suture and no suture graft fixation except for a slight increase in erythrocyte number in the early postoperative period, the choice of material fixation method is entirely dependent on the clinical situation and does not affect the cerebrospinal fluid state.

Are we overestimating the permanence of cellulose triacetate cinematographic films? A mathematical model for the vinegar syndrome

Among the earliest signs of degradation in cellulose triacetate cinematographic films is the generation of acetic acid due to hydrolytic deacetylation of the polymer, marked by an increase in the acidity of the films and emissions of acetic acid leading to a characteristic vinegar odour. We propose a mathematical model for predicting the onset of the vinegar syndrome which accounts for the autocatalytic effect of acetic acid on the deacetylation reaction. Model parameters are estimated from previously published experimental data from other research groups. These show free acidity changes in cellulose triacetate films subjected to accelerated ageing at temperatures of 70–100 °C. The model is validated against a different set of previously published experimental data of cellulose triacetate films aged at 21 °C and 35 °C, at 20, 35 and 50% relative humidity. The model demonstrates good quantitative agreement with the published experimental data. Predictions of film permanence at lower temperatures, similar to those present in the archives in which the films are typically stored, are made and compared with the predictions of film conservation guidelines. The results indicate that film permanence may be overestimated by existing guidelines, which do not account for autocatalysis in their modelling of the deacetylation rate. Our results suggest that cold storage, a common film conservation strategy, may be less effective at inhibiting degradation than previously thought. As cold storage typically requires film to be kept in confined spaces with limited air movement, conditions which promote autocatalysis, the inclusion of autocatalysis in our model is highly applicable to simulating this environment.

Potential of Chitosan From Local Crab (Portunus Pelagicus) to Enhance Storability of Musa Paradisiaca L.

Potential waste of local crab carapace (Portunus pelagicus) as a source of chitosan as an active layer that can protect bananas has been studied. The process in this study consists of three stages. The first stage was the isolation of chitin through deproteinization process using 2.0 N NaOH solution with a ratio of 1:6 w/v and demineralization process using 1.5 N HCl solution with a ratio of 1:12 w/v. The second stage is the deacetylation stage using 50% NaOH solution with a ratio of 1:20 w/v. Fourier Transform Infra-Red (FTIR) Spectroscopy is used to determine the degree of deacetylation. The third stage is the banana coating application using chitin solution to determine the shelf life of bananas with variations in levels of 2, 2.5, 3 and 3,5 % w/v by immersion method for one hour. It was found that carapace crab, a part that was underutilized from crab, gave rise to chitin deacetylation with a deacetylation rate of 62.11%; pH 8.9 and water content of 7.677%. Chitosan-based coatings are applied to fresh bananas and are found to increase fruit firmness, and inhibit browning. The results show that chitosan-coated bananas have a longer storage time. The application of chitin deacetylated (chitosan) as fruit banana coater found that higher coater levels extend the shelf life of bananas with the best coater content is 3% b/v. It results in a shelf life of bananas for up to 12 days, this is longer than bananas without chitosan layer which only has a shelf life of four days. Increased coating rates have a positive effect on the shelf life of bananas. This study shows that waste from carapace crabs can be used to form active layers that can preserve fruit.

Structural and biological evaluation of new chitosan membrane for dural closure

Objective: to study the structural and biological evaluation of chitin-chitosan based membrane for dura mater replacement. Materials and methods. Chitosan-based films were made out of 3% solution of chitosan for the research. We used 200, 500 and 700 kDa chitosan (deacetylation rate 80–90 %) to produce chitin-chitosan membrane by using solvent evaporation method. For enhancing mechanical properties and reducing the degradation, chitin particles were added to the chitosan solution. Chitosan and chitin ratio was 80/20. The chitin/chitosan solution in Petri dishes was dried out during 3 days at room temperature. To obtain information about the structure of membrane surface and cross-section scanning, electron microscopy was performed. Hydrolytic degradation was studied by pouring into SBF solution. To determine the rate of enzymatic degradation, trypsin solution was used. To determine the mass loss percentage, we measured the sample weight after 7, 14, 21, 30 and 60 days after being in the appropriate solutions. Relative elongation and strength were measured by digital dynamometer to study membranes mechanical properties such as the strength and elasticity. MLO-A5 cells were used to assess biocompatibility of new materials. Results. Macroscopic view of obtained samples has shown their relative transparency with impregnation of chitin particle that elevated over the membrane surface without any diversity between different chitosan molecular weight samples. Due to scanning electron microscopy, principal diversity between the samples of different molecular weight has being seen: rough pore surface at 200 and 500 kDa and flat with minimal roughness surface of 700 kDa membranes. Cross-section of 500 and 700 kDa membranes are dense with no pores, but 200 kDa membrane are sponge like and it can be prediction for fluid sorption and cell migration during healing process. Chitin-chitosan membranes are biocompatible and degrade in aqueous and enzymatic solutions. Due to polysaccharide nature of chitosan and chitin, enzymatic degradation has shown higher trend compare to the hydrolytic ones. 200 kDa membrane degrades faster with final mass loss 83.2 % and completely due to porous structure that allows fluid sorption. Membrane mechanical parameters strongly depend on their structure. 200 kDa membrane has shown 2-fold higher elongation compared to 500 kDa and 3-fold — compared to 700 kDa ones. The compensation of mechanical forces ensured by porous structure is better than in dense ones. Tensile strength was in 2-fold better in 200 kDa membranes than in 500 and 700 kDa ones. Cell culture experiment has shown the better adhesion at the 3 rd day for 200 kDa membrane and minimal cell adhesion for 700 kDa membrane, probably due to smooth surface. The reduction rate between all samples and PCT control differ a lot, except for 200 kDa membrane that has the same proliferation rate as TCP. Conclusion. Chitin-chitosan membranes, made from different molecular weight chitosan, are transparent and has appropriate structure for being used as a dura mater substitute. They are biocompatible and degrade in aqueous and enzymatic solutions. Due to porous structure, excellent mechanical properties as well as better cell adhesion and proliferation, 200 kDa chitosan membrane is more applicable for neurosurgical issues.

Kinetic Analysis of Cellulose Acetate/Cellulose II Hybrid Fiber Formation by Alkaline Hydrolysis

Cellulose acetate (CA) can be converted to cellulose II through a deacetylation process using ethanolic NaOH solution. Infrared spectroscopy was used to observe the degree of acetylation by comparing the absorption intensities of C═O and C–O stretches. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis, which only measures a few microns into the fiber diameter, was compared with FTIR, which measures the whole fiber cross-section. Steady deacetylation of the whole fiber over 180 min was observed with FTIR to eventual complete deacetylation. In comparison, ATR-FTIR shows deacetylation occurring more rapidly to complete deacetylation after 90 min, indicating rapid deacetylation of the CA fiber periphery. Data were fitted to a pseudo-second order kinetic model, with high correlation (R² > 0.99), and it was observed that the deacetylation rate (k₂) observed with ATR-FTIR (−0.634 min⁻¹) was twice as rapid as the deacetylation rate observed with FTIR (−0.315 min⁻¹). IR observations were in agreement with the analysis of fiber cross-sections by confocal microscopy, where it was observed that changes in fiber morphology occurred with treatment time and progressive hydrolysis of cellulose acetate to cellulose II. A differential fiber chemical composition was created within the CA fiber cross-section; after 5 min, the outer regions of the fiber cross-section are hydrolyzed to cellulose II and this hydrolysis increases heterogeneously with time to complete hydrolysis after 180 min and conversion to cellulose II. These results indicate the potential to produce fibers with a differential periphery/core structure, which can be accurately designed according to the relative degrees of cellulose II/CA required for specific applications by varying the treatment time in application of this model.

Human histone deacetylase 6 shows strong preference for tubulin dimers over assembled microtubules

Human histone deacetylase 6 (HDAC6) is the major deacetylase responsible for removing the acetyl group from Lys40 of α-tubulin (αK40), which is located lumenally in polymerized microtubules. Here, we provide a detailed kinetic analysis of tubulin deacetylation and HDAC6/microtubule interactions using individual purified components. Our data unequivocally show that free tubulin dimers represent the preferred HDAC6 substrate, with a KM value of 0.23 µM and a deacetylation rate over 1,500-fold higher than that of assembled microtubules. We attribute the lower deacetylation rate of microtubules to both longitudinal and lateral lattice interactions within tubulin polymers. Using TIRF microscopy, we directly visualized stochastic binding of HDAC6 to assembled microtubules without any detectable preferential binding to microtubule tips. Likewise, indirect immunofluorescence microscopy revealed that microtubule deacetylation by HDAC6 is carried out stochastically along the whole microtubule length, rather than from the open extremities. Our data thus complement prior studies on tubulin acetylation and further strengthen the rationale for the correlation between tubulin acetylation and microtubule age.

Effects of low–frequency ultrasound on heterogenous deacetylation of chitin

The effects of low frequency ultrasound to the heterogeneous deacetylation of chitin from the shell of white shrimp (Penaeus vannamei) were examined. The deacetylation process was carried out in the range of NaOH concentrations from 35% to 65% (w/w) with and without the ultrasound in the frequency of 37kHz, RMS=300W. The chitosan obtained was characterized in the degree of deacetylation, solubility, FT-IR and X-ray diffraction. The results showed that the behaviors of the deacetylation in two cases, with and without ultrasound, were similar but the ultrasound enhanced the deacetylation rate and therefore reduced the time of the reaction to get the same degree of deacetylation. The role of ultrasound in the process showed more clearly in the low concentration of sodium hydroxide, below 45% (w/w). At the higher concentration of sodium hydroxide, the influence of ultrasound on facilitating deacetylation decreased significantly, however, ultrasound was still keeping on its improving effect on the solubility of the chitosan obtained. The data from FT-IR and X-ray diffraction did not show any considerable change in structure of both kinds of chitosan. This study showed the potential of using low frequency ultrasound in enhancing the deacetylation of chitin for reducing the chemical consumption.

Experimental evaluation of new chitin-chitosan graft for duraplasty.

Natural materials such as collagen and alginate have promising applications as dural graft substitutes. These materials are able to restore the dural defect and create optimal conditions for the development of connective tissue at the site of injury. A promising material for biomedical applications is chitosan-a linear polysaccharide obtained by the deacetylation of chitin. It has been found to be nontoxic, biodegradable, biofunctional and biocompatible in addition to having antimicrobial characteristics. In this study we designed new chitin-chitosan substitutes for dura mater closure and evaluated their effectiveness and safety. Chitosan films were produced from 3 % of chitosan (molar mass-200, 500 or 700 kDa, deacetylation rate 80-90%) with addition of 20% of chitin. Antimicrobial effictively and cell viability were analysed for the different molar masses of chitosan. The film containing chitosan of molar mass 200 kDa, had the best antimicrobial and biological activity and was successfully used for experimental duraplasty in an in vivo model. In conclusion the chitin-chitosan membrane designed here met the requirements for a dura matter graft exhibiting the ability to support cell growth, inhibit microbial growth and biodegradade at an appropriate rate. Therefore this is a promising material for clinical duroplasty.

Optimization of Deacetylation Process for Regenerated Cellulose Hollow Fiber Membranes

Cellulose acetate (CA) hollow fibers were spun from a CA+ Polyvinylpyrrolidone (PVP)/N-methyl-2-pyrrolidone (NMP)/H2O dope solution and regenerated by deacetylation. The complete deacetylation time of 0.5 h was found at a high concentration (0.2 M) NaOH ethanol (96%) solution. The reaction rate of deacetylation with 0.5 M NaOH was faster in a 50% ethanol compared to a 96 vol.% ethanol. The hydrogen bond between CA and tertiary amide group of PVP was confirmed. The deacetylation parameters of NaOH concentration, reaction time, swelling time, and solution were investigated by orthogonal experimental design (OED) method. The degree of cross-linking, the residual acetyl content, and the PVP content in the deacetylated membranes were determined by FTIR analysis. The conjoint analysis in the Statistical Product and Service Solutions (SPSS) software was used to analyze the OED results, and the importance of the deacetylation parameters was sorted as Solution > Swelling time > Reaction time > Concentration. The optimal deacetylation condition of 96 vol.% ethanol solution, swelling time 24 h, the concentration of NaOH (0.075 M), and the reaction time (2 h) were identified. The regenerated cellulose hollow fibers under the optimal deacetylation condition can be further used as precursors for preparation of hollow fiber carbon membranes.

Abstract 4210: Non-invasive molecular imaging of SIRT1-mediated epigenetic regulation in cancer using PET/CT with a novel substrate-type radiotracer 2-[18F]PhAHA

Abstract SIRT1 is involved in a wide variety of cellular processes and functions and is known to mediate cleavage of the acetyl moiety from the acetylated lysine residues of several proteins, including p53, PPARγ, members of the FOXO family and NF-KB. Therefore, SIRT1 has emerged as an important target for therapy of cancer. However, currently there are no methods for non-invasive monitoring of pharmacodynamics of novel SIRT1 isoform-selective inhibitors in norm and disease. Therefore, there is a need for development of agents for non-invasive imaging of expression and activity of various SIRT1 in vivo. Previous studies demonstrated that SIRT1 can dephenylacetylate a lysine residue at a rate of ∼56% of its natural deacetylation rate, while other SIRT isoforms cannot cleave an aromatic leaving group. This provided an opportunity to develop a SIRT1-selective imaging agent for PET imaging, which would allow for quantitative measurement of the SIRT1 expression-activity product in vivo. We developed a focused library of compounds to elucidate the structure-activity relationship of SIRT1 and to identify the most selective and efficient imaging substrate for SIRT1. This preliminary screening utilized high-throughput fluorogenic assay with the Carbazol-L-Lysine-Aminomethylcoumarin as a backbone [1]. Subsequently, this backbone was exchanged for 6-aminohexanoicanilide, AHA [2] to develop PET radiotracer. The lead compound, 2-fluorophenylaminohexanoicanilide, was developed in both F-19 (2-FPhAHA) and F-18 (2-[18F]PhAHA) versions. 2-[18F]PhAHA was injected i.v. into Sprague-Dawley (SD) rats followed by dynamic imaging using MicroPET R4 (Siemens, TN), followed by CT imaging on INVEON microCT (Siemens, TN). The kinetics of radiotracer uptake was quantified using Logan graphical analysis [3], which demonstrated differential accumulation of 2-[18F]PhAHA-derived radioactivity in specific areas of the rat brain with high expression of SIRT1 (i.e., the dentate gyrus, CA1, nucleus accumbens, and caudate putamen). Following characterization of 2-[18F]PhAHA-derived radioactivity in the normal rat brain, 2-[18F]PhAHA was administered to SD rats bearing intracerebral 9L gliomas. PET/CT demonstrated significantly increased uptake of 2-[18F]PhAHA-derived radioactivity in the 9L tumors vs. normal brain tissue (P<0.01) and matched with tumor localization as observed with MRI and histological staining. In summary, SIRT1 activity is upregulated in intracerebral 9L gliomas, as evidenced by increased accumulation of 2-[18F]PhAHA on PET/CT images, which demonstrates the feasibility of this method for visualization and quantification of SIRT1 activity in brain tumors. Also, 2-[18F]PhAHA on PET/CT should allow for future monitoring of pharmacodynamics of SIRT1 inhibitors during anti-cancer therapy. Citation Format: Robin E. Bonomi, Maxwell Laws, Aleksandr Shavrin, Thomas Mangner, Juri G. Gelovani. Non-invasive molecular imaging of SIRT1-mediated epigenetic regulation in cancer using PET/CT with a novel substrate-type radiotracer 2-[18F]PhAHA. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4210.

Haemostatic chitosan coated gauze: in vitro interaction with human blood and in-vivo effectiveness.

BackgroundChitosan and its derivates are widely used for biomedical application due to antioxidative, anti-inflammatory, antimicrobial and tissue repair induced properties. Chitosan-based materials also used as a haemostatic agent but influence of different molecular weight and concentration of chitosan on biological response of blood cells is still not clear.The aim of this research was to evaluate interaction between human blood cells and various forms of chitosan-based materials with different molecular weight and chitosan concentration and prove their effectiveness on in-vivo model.MethodsWe used chitosan with molecular weight 200, 500 and 700 kDa and deacetylation rate 80-82 %. For chitosan impregnation of gauze chitosan solutions in 1 % acetic acid with different concentrations (1, 2, 3, 5 %) were used. We used scanning electron microscopy to obtain information about chitosan distribution on cotton surface; Erythrocyte agglutination test and Complete blood count test – for evaluation of interaction between blood cells and chitosan-based materials with different compound. In-vivo studies was performed in 20 Wistar rats to evaluate effectiveness of new dressing.ResultsOur data shown that chitosan can bind erythrocytes in concentration-depend manner that does not depend on its molecular weight. In addition, chitosan-based materials affect selectively human blood cells. Composition of chitosan with cotton materials does not change erythrocyte shape and does not cause agglutination.ConclusionsСotton-chitosan materials have higher adhesive properties to platelets that depend on molecular weight and concentration of chitosan. These materials also change platelets’ shape that probable is one of the most important mechanisms of haemostatic effect. In-vivo studies have shown high effectiveness of 2 % 200 kDa chitosan for stop bleeding from arteries of large diameter.

Positional preferences of acetyl esterases from different CE families towards acetylated 4-O-methyl glucuronic acid-substituted xylo-oligosaccharides

BackgroundAcetylation of the xylan backbone restricts the hydrolysis of plant poly- and oligosaccharides by hemicellulolytic enzyme preparations to constituent monosaccharides. The positional preferences and deacetylation efficiencies of acetyl esterases from seven different carbohydrate esterase (CE) families towards different acetylated xylopyranosyl units (Xylp) - as present in 4-O-methyl-glucuronic acid (MeGlcA)-substituted xylo-oligosaccharides (AcUXOS) derived from Eucalyptus globulus - were monitored by 1H NMR, using common conditions for biofuel production (pH 5.0, 50°C).ResultsDifferences were observed regarding the hydrolysis of 2-O, 3-O, and 2,3-di-O acetylated Xylp and 3-O acetylated Xylp 2-O substituted with MeGlcA. The acetyl esterases tested could be categorized in three groups having activities towards (i) 2-O and 3-O acetylated Xylp, (ii) 2-O, 3-O, and 2,3-di-O acetylated Xylp, and (iii) 2-O, 3-O, and 2,3-di-O acetylated Xylp, as well as 3-O acetylated Xylp 2-O substituted with MeGlcA at the non-reducing end. A high deacetylation efficiency of up to 83% was observed for CE5 and CE1 acetyl esterases. Positional preferences were observed towards 2,3-di-O acetylated Xylp (TeCE1, AnCE5, and OsCE6) or 3-O acetylated Xylp (CtCE4).ConclusionsDifferent positional preferences, deacetylation efficiencies, and initial deacetylation rates towards 2-O, 3-O, and 2,3-di-O acetylated Xylp and 3-O acetylated Xylp 2-O substituted with MeGlcA were demonstrated for acetyl esterases from different CE families at pH 5.0 and 50°C. The data allow the design of optimal, deacetylating hemicellulolytic enzyme mixtures for the hydrolysis of non-alkaline-pretreated bioenergy feedstocks.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-014-0187-6) contains supplementary material, which is available to authorized users.