Low Molecular Weight Fragments Research Articles

Surface Modification of Polymers by Plasma Treatment for Appropriate Adhesion of Coatings.

In this study, recent advances in tailoring the surface properties of polymers for the optimization of the adhesion of various coatings by non-equilibrium gaseous plasma are reviewed, and important findings are stressed. Different authors have used various experimental setups and reported results that scatter significantly and are sometimes contradictory. The correlations between the processing parameters and the adhesion are drawn, and discrepancies are explained. Many authors have explained improved adhesion with the adjustment of the surface free energy or wettability of the polymer substrate and the surface tension of liquids used for the deposition of thin films. The adhesion force between the polymer substrate and the coating does not always follow the evolution of the surface wettability, which is explained by several effects, including the aging effects due to the hydrophobic recovery and the formation of an interlayer rich in loosely bonded low molecular weight fragments.

Speeding-up the Determination of Protein-Ligand Affinities by STD NMR: The Reduced Data Set STD NMR Approach (rd-STD NMR).

STD NMR spectroscopy is a powerful ligand-observed NMR tool for screening and characterizing the interactions of small molecules and low molecular weight fragments with a given macromolecule, identifying the main intermolecular contacts in the bound state. It is also a powerful analytical technique for the accurate determination of protein-ligand dissociation constants (KD) of medium-to-weak affinity, of interest in the pharmaceutical industry. However, accurate KD determination and epitope mapping requires a long series of experiments at increasing saturation times to carry out a full analysis using the so-called STD NMR build-up curve approach and apply the "initial slopes approximation". Here, we have developed a new protocol to bypass this important limitation, which allows us to obtain initial slopes by using just two saturation times and, hence, to very quickly determine precise protein-ligand dissociation constants by STD NMR.

Radio-lytic degradation of reactive dyes in aqueous solution: comparative analysis using gamma/H2O2 and UV/H2O2 processes

Abstract In this study, gamma/H2O2 and UV/H2O2 treatment procedures were used for the degradation of five dyes including reactive red PB (R-24), reactive orange P3LN (O-13), reactive turquoise blue PG (B-21), reactive golden yellow H2R (O-12) and reactive lemon yellow C4G L (Y-15). The dye samples of 50 or 100 ppm concentration were treated with either gamma (0–10 kGy) or UV radiations in the presence/absence of H2O2. This treatment resulted in the elimination of chromophoric groups and degradation of dye molecule into low molecular weight fragments. The H2O2 treatment caused the generation of hydroxyl radicals which degraded the pollutants non-selectively by means of chain oxidation process. The treatment effectiveness was increased when H2O2, which was used in conjunction with UV or gamma radiation and the treated water quality, improved significantly. However, the gamma/H2O2 treatment was found to be the more effective and efficient method as compared to the UV/H2O2 treatment for the removal of dyes from the water.

Effects of HSP70 chaperones Ssa1 and Ssa2 on Ste5 scaffold and the mating mitogen-activated protein kinase (MAPK) pathway in Saccharomyces cerevisiae.

Ste5 is a prototype of scaffold proteins that regulate activation of mitogen-activated protein kinase (MAPK) cascades in all eukaryotes. Ste5 associates with many proteins including Gβγ (Ste4), Ste11 MAPKKK, Ste7 MAPKK, Fus3 and Kss1 MAPKs, Bem1, Cdc24. Here we show that Ste5 also associates with heat shock protein 70 chaperone (Hsp70) Ssa1 and that Ssa1 and its ortholog Ssa2 are together important for Ste5 function and efficient mating responses. The majority of purified overexpressed Ste5 associates with Ssa1. Loss of Ssa1 and Ssa2 has deleterious effects on Ste5 abundance, integrity, and localization particularly when Ste5 is expressed at native levels. The status of Ssa1 and Ssa2 influences Ste5 electrophoresis mobility and formation of high molecular weight species thought to be phosphorylated, ubiquitinylated and aggregated and lower molecular weight fragments. A Ste5 VWA domain mutant with greater propensity to form punctate foci has reduced predicted propensity to bind Ssa1 near the mutation sites and forms more punctate foci when Ssa1 Is overexpressed, supporting a dynamic protein quality control relationship between Ste5 and Ssa1. Loss of Ssa1 and Ssa2 reduces activation of Fus3 and Kss1 MAPKs and FUS1 gene expression and impairs mating shmoo morphogenesis. Surprisingly, ssa1, ssa2, ssa3 and ssa4 single, double and triple mutants can still mate, suggesting compensatory mechanisms exist for folding. Additional analysis suggests Ssa1 is the major Hsp70 chaperone for the mating and invasive growth pathways and reveals several Hsp70-Hsp90 chaperone-network proteins required for mating morphogenesis.

Low, medium, and high molecular weight hyaluronic acid effects on human dental pulp stem cells in vitro

Hyaluronic acid (HA), an extracellular biopolymer found throughout the human body, holds promise as a biocompatible and biodegradable scaffold material. High molecular weight (HMW) HA degrades, generating low molecular weight (LMW) fragments with distinct properties. These fragments can influence the behaviour of cells, including human dental pulp stem cells (hDPSCs) incorporated into HA-containing hydrogels or scaffolds. Therefore, a comprehensive examination of the impact of a range of HA molecular weights on hDPSCs is essential before designing HA-based scaffolds for these cells. hDPSC lines were cultured with LMW HA (800 Da, 1600 Da, 15 kDa), medium molecular weight HA (237 kDa), or HMW HA (1500 kDa) over six passages. The various molecular weights had negligible effects on hDPSCs viability, morphology, adhesion, or relative telomere length. Furthermore, the expression of key surface stemness markers (CD29, CD44, CD73, CD90) remained unaltered. HA did not induce osteogenic, chondrogenic, or adipogenic differentiation. Moreover, the potential for chondrogenic and osteogenic differentiation was not adversely affected by LMW or HMW HA. Various molecular weights of HA seem safe, biocompatible and therefore suitable components for hDPSCs-containing scaffolds. These findings affirm that the hDPCSs will not be negatively affected by HA fragments resulting from scaffold degradation.

In-depth size and charge variants characterization of monoclonal antibody with native mass spectrometry

Although the reversed-phase liquid chromatography (RPLC) is the most used separation front for mass spectrometry, many other separation modes are critical for enabling characterization of the protein therapeutics. Specifically, chromatographic separations under native conditions, such as those based on size exclusion chromatography (SEC) and ion-exchange chromatography (IEX), are used for characterizing important biophysical properties of protein variants in drug substance and drug product. Because most native state separation modes use non-volatile buffers with high salt concentration, optical detection has been traditionally used. However, there is an increasing need to understand and identify the optical underlying peaks by mass spectrometry for structure elucidation. For size variant separation by SEC, the native MS helps to understand the nature of the high molecular weight species, as well as clipping sites for low molecular weight fragments. For charge variant separation by IEX, native MS can reveal the post-translational modifications or other important factors contributing to charge heterogeneity at the intact level. Here, we demonstrate the power of native MS by direct coupling of SEC and IEX eluent to a time-of-flight mass spectrometer to characterize bevacizumab and NISTmAb. Our studies exemplify the effectiveness of native SEC-MS for characterizing bevacizumab's high molecular weight species at less than 0.3% (based on SEC/UV peak area%) and analyzing the fragment pathway with single amino acid difference for its low molecular weight species at less than 0.05%. Good IEX charge variant separation was obtained with consistent UV and MS profiles. The identity of separated acidic and basic variants were elucidated by native MS at intact level. We successfully differentiated several charge variants including glycoform variants that have not been reported before. In addition, native MS allowed identification of higher molecular weight species as late eluted variants. Overall, the SEC and IEX separation combined with high resolution and high sensitivity native MS, which is significantly different from the traditional RPLC-MS workflows, can be an effective tool that offers valuable insights for us to understand protein therapeutics at native state.

Hyaluronan and Reactive Oxygen Species Signaling-Novel Cues from the Matrix?

Hyaluronan (HA) is a naturally occurring non-sulfated glycosaminoglycan (GAG) localized to the cell surface and the tissue extracellular matrix (ECM). It is composed of disaccharides containing glucuronic acid and N-acetylglucosamine, is synthesized by the HA synthase (HAS) enzymes and is degraded by hyaluronidase (HYAL) or reactive oxygen and nitrogen species (ROS/RNS) actions. HA is deposited as a high molecular weight (HMW) polymer and degraded to low molecular weight (LMW) fragments and oligosaccharides. HA affects biological functions by interacting with HA-binding proteins (hyaladherins). HMW HA is anti-inflammatory, immunosuppressive, and antiangiogenic, whereas LMW HA has pro-inflammatory, pro-angiogenetic, and oncogenic effects. ROS/RNS naturally degrade HMW HA, albeit at enhanced levels during tissue injury and inflammatory processes. Thus, the degradation of endothelial glycocalyx HA by increased ROS challenges vascular integrity and can initiate several disease progressions. Conversely, HA exerts a vital role in wound healing through ROS-mediated HA modifications, which affect the innate immune system. The normal turnover of HA protects against matrix rigidification. Insufficient turnover leads to increased tissue rigidity, leading to tissue dysfunction. Both endogenous and exogenous HMW HA have a scavenging capacity against ROS. The interactions of ROS/RNS with HA are more complex than presently perceived and present an important research topic.

Characterization of a highly conserved MUC5B-degrading protease, MdpL, from Limosilactobacillus fermentum.

MUC5B is the predominant glycoprotein in saliva and is instrumental in the establishment and maintenance of multi-species eubiotic biofilms in the oral cavity. Investigations of the aciduric Lactobacillaceae family, and its role in biofilms emphasizes the diversity across different genera of the proteolytic systems involved in the nutritional utilization of mucins. We have characterized a protease from Limosilactobacillus fermentum, MdpL (Mucin degrading protease from Limosilactobacillus) with a high protein backbone similarity with commensals that exploit mucins for attachment and nutrition. MdpL was shown to be associated with the bacterial cell surface, in close proximity to MUC5B, which was sequentially degraded into low molecular weight fragments. Mapping the substrate preference revealed multiple hydrolytic sites of proteins with a high O-glycan occurrence, although hydrolysis was not dependent on the presence of O-glycans. However, since proteolysis of immunoglobulins was absent, and general protease activity was low, a preference for glycoproteins similar to MUC5B in terms of glycosylation and structure is suggested. MdpL preferentially hydrolyzed C-terminally located hydrophobic residues in peptides larger than 20 amino acids, which hinted at a limited sequence preference. To secure proper enzyme folding and optimal conditions for activity, L. fermentum incorporates a complex system that establishes a reducing environment. The importance of overall reducing conditions was confirmed by the activity boosting effect of the added reducing agents L-cysteine and DTT. High activity was retained in low to neutral pH 5.5-7.0, but the enzyme was completely inhibited in the presence of Zn2+. Here we have characterized a highly conserved mucin degrading protease from L. fermentum. MdpL, that together with the recently discovered O-glycanase and O-glycoprotease enzyme groups, increases our understanding of mucin degradation and complex biofilm dynamics.

A Review on the Role of Microbes in Polyethene Degradation

Polyethene is a polyolefin produced from polymerization of the olefin ethylene (C2H4). It is one of the most commonly used plastic and one of the most resistant to degradation. Its accumulation in the surrounding has caught the attention of many governments and researchers with attempts to come up with better disposal methods. This review focused on the role played by microorganisms in the degradation of polyethene. The references reviewed were obtained from journals and databases including PubMed, Google Scholar (http: //scholar. google.com) and Science Direct (http://www.science direct.com). We focused on data published from 2010 up to 2021. The findings obtained indicated that 19 genera of bacteria and actinomycetes and 5 fungal genera have the ability to degrade polyethene through secretion of extracellular depolymerases. The enzymes cleave polymer chains into low molecular weight fragments, which are then assimilated through the microbial cell membrane and mineralized. Microbial degradation is a sustainable and promising idea. However, there is need for more research to clearly determine the mechanism of enzymatic degradation, which will be useful in the development of novel biotechnological tools for degradation of a variety of plastic materials by microorganisms.

Cathepsin K degrades osteoprotegerin to promote osteoclastogenesis in vitro

Osteoblasts produce the receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin, the inducer and the suppressor of osteoclast differentiation and activation. We previously proposed that the degradation of osteoprotegerin by lysine-specific gingipain of Porphyromonas gingivalis and neutrophil elastase is one of the mechanisms of bone resorption associated with infection and inflammation. In the present study, we found that cathepsin K (CTSK) also degraded osteoprotegerin in an acidic milieu and the buffer with a pH of 7.4. The 37k fragment of osteoprotegerin produced by the reaction with CTSK was further degraded into low molecular weight fragments, including a 13k fragment, depending on the reaction time. The N-terminal amino acid sequence of the 37k fragment matched that of the intact osteoprotegerin, indicating that CTSK preferentially hydrolyzes the death domain-like region of osteoprotegerin, not its RANKL-binding region. The 13k fragment of osteoprotegerin was the C-terminal 13k portion within the RANKL-binding region of the 37k fragment. Finally, CTSK restored RANKL-dependent osteoclast differentiation that was suppressed by the addition of osteoprotegerin. Collectively, CTSK is a possible positive regulator of osteoclastogenesis.

Technology for the production of bionutrients based on a combination of activated coprolites and silatranes and evaluation of their effectiveness in the field

The article presents the results of the development of technology and technological line for the production of bionutrients based on the processing of animal waste into coprolites and the use of cavitation to increase their biological efficiency. Cavitation makes it possible by physical action on long molecules of humic substances simultaneously with ultrasonic vibrations and pulsating ultrahigh pressure to ensure the crushing of humic substances into low molecular weight fragments, which increases their biological activity. The resulting product has been tested for effectiveness on sugar beet. A noticeable increase in resistance to climatic factors and an increase in yield while maintaining high food qualities is shown.

Biodegradability of polyethylene mulch film by Bacillus paramycoides

Discarded polyethylene (PE) mulch film has led to persistent agricultural pollution. Biodegradation of plastic waste is considered as a promising solution that can potentially overcome environmental and economic problems. In this study, a novel bacterium (Bacillus paramycoides) was isolated from a waste mulch recycling plant and showed an extraordinary ability to customize polyethylene film. It was observed by scanning electron microscopy that a large number of pits and wrinkle cracks existed on the polyethylene, indicating that the strain used PE film as the sole carbon source. Meanwhile, the loss of weight of the film was tested continuously, and approximately 12% of the initial weight of the film was found to be lost within 45 days after coincubation with TW-2. The surface hydrophobicity of the polyethylene film decreased while the surface tension increased from 9.755 to 31.013. Fourier transform infrared (FTIR) analysis indicated that absorption peaks near 1740 cm−1 and 2760 cm−1 were attributed to the stretching vibrations of aldehyde and carboxyl groups, respectively, suggesting that hydrophilic groups were produced. This was also confirmed by XPS spectroscopy analysis. X-ray diffraction (XRD) analysis also showed that the relative crystallinity decreased from 33% to 11.51%. In addition, GPC analysis showed that the molecular weight decreased, while the proportion of low molecular weight fragments increased. These results strongly indicated that the PE film was able to be degraded to some extent by the strain. Finally, a new biodegradable mechanism for polyethylene was proposed.

Small fragments of hyaluronan are increased in individuals with obesity and contribute to low-grade inflammation through TLR-mediated activation of innate immune cells

Background and aimExtracellular matrix (ECM) components released during excessive fat mass expansion are considered potential endogenous danger/alarm signals contributing to innate immune system activation. The aim of the current study was to specifically measure plasma levels of low molecular weight (LMW) hyaluronan (HA) and to evaluate its role as pro-inflammatory damage-associated molecular pattern (DAMP) on leukocyte response in the context of human obesity.Subjects and methodsParticipants were selected according to their body mass index (BMI, kg/m2) as non-obese (BMI < 29.9, n = 18) and obese (BMI > 29.9, n = 33). Plasma samples were size-dependent fractionated using ion-exchange chromatography to specifically obtain LMW HA fractions that were subsequently quantified by ELISA. Cell incubation experiments with synthetic HA molecules were performed on freshly Ficoll-isolated neutrophils (PMN) and peripheral blood monocytes (PBMC). Leukocyte and adipose tissue gene expression was assessed by real-time PCR and NF-κB activation by western blot. Plasma cytokine levels were measured by fluorescent bead-based (Luminex) immunoassay.ResultsWe observed a statistically significant increase in the circulating levels of HA fragments of LMW in individuals with obesity which were consistent with significant up-regulated expression of the LMW HA synthesizing enzyme hyaluronan synthase-1 (HAS-1) in obese adipose tissue. Gene expression assessment of HA receptors revealed up-regulated levels for TLR2 in both obese PMN and PBMC. Synthetic HA molecules of different sizes were tested on leukocytes from healthy donors. LMW HA fragments (15–40 kDa) and not those from intermediate molecular sizes (75–350 kDa) induced a significant up-regulation of the expression of major pro-inflammatory cytokines such as IL-1β, MCP-1 and IL-8 in PBMC. Importantly, LMW HA was able to induce the phosphorylation of IKK α/β complex supporting its pro-inflammatory role through NF-κB activation.ConclusionCirculating LMW HA molecules are elevated in obesity and may play an important role in triggering low-grade inflammation and the development of metabolic complications.

Analysis of chitosan molecular weight profile by electrophoresis in a porosity step gradient polyacrylamide gel

Chitosan is biocompatible and biodegradable natural biopolymer widely applied in various fields of biology, medicine, and pharmacy, however, its effects significantly depend on the degree of polymerization (DP) and the degree of deacetylation (DDA) of polymer chains. Evaluation of the chitosan chain diversity by DP requires the use of a highly expensive method of high-performance size exclusion chromatography. The aim of our study was to determine the molecular weight profile of chitosan specimens by the use of electrophoresis in a porosity step gradient polyacrylamide gel and to evaluate the efficacy of this method in monitoring the purification of chitosan fragments and its derivatives. Two types of step gradient porosity gels were used: 1) gels of layers with acrylamide concentration 2.5, 3.5, 5.0, 10.0, 15.0, 20.0 % w/v for native chitosan or its high molecular fragments; 2) gels of layers with acrylamide concentration 2.5, 5.0, 10.0, 15.0, 20.0, 25.0 % w/v for low molecular chitosan fragments. The main amount of molecules from the chitosan pool was localized in the type 1 gel in the region of 550-40 kDa and distributed among three bands, which in different samples differed significantly in percentage. Electrophoresis of chitosan fragments fractionated by gel permeation chromatography provided a clear separation of medium molecular weight fragments (50–400 kDa) in type 1 gel and of low molecular weight fragments (3–40 kDa) in type 2 gel. Thus the method of chitosan electrophoresis in a step-gradient porosity of polyacrylamide gel was developed which permits to characterize the molecular weight profile of chitosan specimens polymer chains and is effective in monitoring the isolation of chitosan fragments by gel penetration chromatography of molecular weights from 3 to 400 kDa.

REVIEW OF EVALUATION METHODS FOR BIODEGRADABILITY OF POLYMERIC MATERIALS

Development and further use of biodegradable polymeric materials requires prior assessment the degree of their biodegradation. There are a large number of methods developed taking into account the specifics of the destruction of polymeric materials. The purpose of this review is to systematize scientific and technical information regarding methods for assessing the biodegradation of polymeric materials. Laboratory methods of researches, including the following: influence of abiotic factors (temperature, moisture, UV irradiation), impact of microorganisms (fungi, bacteria, yeast), respiratory methods (Sturm, Zahn-Wellness, etc.), conditions of composting, enzyme analysis methods, ecotoxicity tests are given. Test methods in both aqueous and solid media are also presented. The parameters of biodegradability, which determine the degree of destruction (mass, strain strength, molecular weight distribution, temperature characteristics, macro-and microstructure of samples, etc.) or the composition and properties of the biological system in which biodegradation takes place (acidity, respiratory activity, chemical and microbiological composition of soil or other biological environment, etc.) are considered as well. Advantages of laboratory methods for studying the biodegradation of polymeric materials could be realized in the given directions: varying of the experimental conditions (temperature, humidity, UV and IR radiation, the presence of aggressive media, etc.), biochemical compositions of the environment; study of the ability of individual strains of microorganisms to dispose of polymer composites and targeted selection of the most active microbial associations (in particular, for the manufacture of special biocomposts); utilize of simple and fast methodical approaches and modern devices for evaluation experiments. However, laboratory methods do not always allow modeling a set of endogenous and exogenous factors that define the process of biodegradation in the natural environment. Therefore, this review also considers methods for assessing biodegradation in the environment. So, the essence of the test regarding the samples’ burial in the ground is given. International standards governing methods for assessing the biodegradability of organic substances and polymeric materials are summarized. Applying different test methods, one can evaluate the whole process of biodegradation of polymeric materials, consisting of several stages, which occur regardless the type of microorganisms and accompanying abiotic factors, and can be represented as follows: adhesion → colonization → biodeterioration → biofragmentation → assimilation → mineralization. Thus, the adhesion and colonization of microorganisms can be estimated by visual, bioindicator and spectral methods. Abiotic degradation and biodeterioration are associated with physical tests (e.g., thermal and physico-mechanical). Biofragmentation is detected by identifying fragments of lower molecular weight (i.e. by chromatographic methods). In turn, assimilation is assessed by the amount of metabolites produced using, for example, respirometric methods or involving analysis of microbial biomass (e.g., macroscopic and microscopic observations). The most productive should be considered a comprehensive approach to the study of biodegradation of polymers. To determine the reliable kinetic parameters and link the mechanism of this process, it is necessary to carry out a comparative analysis of the results of physical, chemical, microbiological experiments, which are carried out in both laboratory and natural conditions.

Diversity analysis of BmNPV Isolates Infecting Mulberry Silkworm (Bombyx mori) using Restriction Endonuclease Digestion Profiling

Understanding the genetic diversity of BmNPV isolates causing grasserie viral disease of mulberry silkworm Bombyx mori L. is essential for adoption of management strategies including biotechnological tools. The present study was aimed at the use of restriction fragment length polymorphism (RFLP) profiling for studying the molecular diversity analysis of six BmNPV isolates collected from Devanahalli, Kolar, Shidlaghatta, Hosakote, Tumakuru, and Ramanagara areas in Karnataka, India (BmNPV-Ko, BmNPV-Ho, BmNPV-SG, BmNPV-DH, BmNPV-TM, BmNPV-Ram respectively). DNA was extracted from each of these isolates and subjected to digestion with different restriction enzymes EcoR1, BamH1, Sma1, Nco1, and a combination of BamH1+Nco1 and electrophoresed in 0.8% w/v agarose gel to visualize restriction enzyme profile. The analysis revealed that all the six BmNPV isolates had similar Nco1 and Sma1 restriction patterns, although there was variation in low molecular weight fragments. The EcoR1 and BamH1 restriction patterns were nearly the same for all the isolates except for the presence of an approximately 4kb and an additional 1.5kb polymorphic band only in BmNPV-TM and BmNPV-Ram isolates. BamH1+Nco1 digestion of the DNA from each isolate yielded numerous fragments, which was different in BmNPV-Ram isolate. Molecular diversity analysis can helps in understanding the evolution and phylogeny of the virus, enhance the knowledge on its pathogenicity and can help to develop and adopt suitable measures to combat and diagnose the disease to reduce crop loss and increase income generating ability of the farmer.

Chemical and enzymatic destruction of chondroitin sulfate from Arctic skate

Due to its biocompatibility with human and animal tissues, low toxicity, and biodegradability, chondroitin sulfate (CS) is of great interest for medicine. Since CS is used as a pharmaceutical preparation, its molecular weight and solubility determine the possibilities of its use. This work presents the results of studying the chemical and enzymatic destruction of CS macromolecules and its effect on the molecular weight, solubility and crystallinity degree of the polysaccharide. CS was obtained from the cartilaginous tissue of the Arctic skate ( Amblyraja hyperborea ). At the stage of cartilage tissue fermentolysis, the enzymes pancreatin, hepatopancreatin and protosubtil were used. The obtained CS samples were identified by IR spectroscopy. Enzymatic destruction of glycosidic bonds in cholesterol macromolecules was carried out with a 1 % solution of the enzyme hepatopancreatin, chemical destruction with hydrogen peroxide and hydrochloric acid. The CS content in the samples was determined by the Dische method. The chemical composition of CS samples was evaluated by standard methods. The average molecular weight (MW) was determined using high performance liquid chromatography and the nephelometric method. The crystallinity degree (CD) was determined by graphical processing of diffraction patterns obtained by X-ray phase analysis of CS samples. It was found that under the action of hepatopancreatin and hydrogen peroxide, deep destruction of chondroitin sulfate occurs, to the formation of low molecular weight and oligomeric fragments. Under conditions of acid destruction in 0.5 N HCl for 20 min the MW of chondroitin sulfate is reduced by 10 % compared to the initial one. Acid destruction causes a significant decrease in the CD of the CS samples. For CS samples not degraded in acid, the solubility in distilled water increases with decreasing MW and CD. The solubility of CS after acid destruction in the range of pH = 5-9 units is 99.0 ± 0.5 %. This high solubility is most likely explained by the significant content of the amorphous phase in the samples.

The Relationship Between Indecisiveness and Network Integration in Scalp Resting-State EEG

Fragment-based drug design (FBDD) is a structure-based approach of ligand designing used in drug discovery. It involves the identification of low molecular weight fragments as hit and then their binding mode is determined using X-ray crystallography and NMR spectroscopy. The binding information retrieved facilitates the optimization of fragments as hits which are later on converted into drug-like molecules. The identified fragments bind efficiently and form high-quality binding interactions. X-ray protein crystallography is considered as one of the most reliable and sensitive biophysical methods used for screening that reduce the chances to come up with false positive hits. It also provides insight into the structural details of the protein–fragment complex at the atomic level. Therefore, the fragment-based screening by using X-ray crystallography can be considered as an efficient method to identify the binding hotspots on proteins that can be further explored by chemists and biologists for the discovery of new drugs.

From theory to practice: immunotherapy of purulent-inflammatory diseases and purulent-septic complications

Lack of anti-infective protection is one of the reasons for the occurrence of purulent-inflammatory diseases of the skin, soft tissues and purulent-septic complications in the postoperative period. Immunocorrective therapy is extremely relevant in surgical practice, and it can be used both for the prevention and treatment of postoperative complications. In this regard, special attention should be paid to low molecular weight fragments of peptidoglycan of cellular bacteria muramyl peptides.&#x0D; The study included 65 patients with purulent inflammatory diseases, of which 35 men aged 2355 years with chronic recurrent pyoderma (ostiofolliculitis, folliculitis, sycosis, furunculosis), and 30 patients aged 18 to 65 years with purulent inflammatory diseases of soft tissues, mainly abscesses and phlegmons of various localization without pronounced concomitant pathology. The examination included 26 patients with purulent-septic complications in the postoperative period. The patients included in the study were divided into 2 equal groups: 1 is the main group, in which patients received intramuscularly Polimuramil 200 mg daily for 5 days in addition to treatment; Comparison group 2, in which patients received only standard treatment. The clinical symptoms of pyoderma were assessed from day 0 to day 7, then on day 14, after 1 and 6 months of the study. Blood samples were taken from all patients for hematological and immunological studies. The timing of the appearance of granulations was monitored daily.&#x0D; The inclusion of Polimuramil in the complex treatment of pyoderma accelerated the regression of the main clinical manifestations of the disease and promoted the induction of stable remission. In patients with soft tissue infections, Polimuramil increased the degree of regression of the depth and area of the wound and accelerated the appearance of granulations. The clinical efficacy of Polimuramil in patients with purulent-septic complications in the postoperative period correlated with a decrease in CRP and procalcitonin levels. The study confirms the effectiveness of Polimuramil in the treatment of purulent-inflammatory diseases and purulent-septic complications in the postoperative period and its high immunomodulatory potential (8 figs, 2 tables, bibliography: 5 refs).

Stimuli‐Responsive Depolymerization of Poly(Phthalaldehyde) Copolymers and Networks

AbstractThis article describes a stimuli‐responsive cross‐linked network based on a poly(phthalaldehyde) (PPA) self‐immolating polymer backbone which, upon removal of polymer end‐caps, becomes degradable under ambient conditions. Self‐immolating polymers (SIPs) are of particular interest due to their ability to undergo controlled depolymerization resulting in the elimination of the polymer structure and potential recovery and reuse of the original monomers. Linear copolymers of phthalaldehyde and unsymmetrical allylated‐phthalaldehyde monomers are obtained via anionic polymerization with appreciable incorporation of the allyl‐functional monomeric units. This approach enables crosslinking of the otherwise linear polymers via thiol–ene reactions with the allyl functional phthalaldehyde polymers. The polymer network thus formed unzips along the phthalaldehyde backbone to yield monomers and low molecular weight fragments in response to chemical (F−, H+) or physical (light, sonication) stimuli that remove the stabilizing functional endcaps on the phthalaldehyde polymers. Rheology is used to demonstrate gelation within 5 s of light exposure of the allylated‐phthalaldehyde polymers reacted with pentaerythritol tetrakis(3‐mercaptopropionate) and photoinitiator (3 wt%). Triggerable degelation makes this material well suited for photolithography and additive manufacturing as well as other applications that necessitate polymer network degradation or elimination. Further, a method is described for determining the degelation temperature of a self‐immolative cross‐linked network.