Hemostatic dressings based on poly(vinyl formal) sponges.

The development of novel hemostatic agents is related to the fact that severe blood loss due to hemorrhage continues to be the leading cause of preventable death of patients with military trauma and the second leading cause of death of civilian patients with injuries. Herein we assessed the hemostatic properties of porous sponges based on biocompatible hydrophilic polymer, poly(vinyl formal) (PVF), which meets the main requirements for the development of hemostatic materials. A series of composite hemostatic materials based on PVF sponges with different porosities and fillers were synthesized by acetalization of poly(vinyl alcohol) with formaldehyde. Nano-sized aminopropyl silica, micro-sized calcium carbonate, and chitosan hydrogel were used to modify PVF matrixes. The physicochemical properties (pore size, elemental composition, functional groups, hydrophilicity, and acetalization degree) of the synthesized composite sponges were studied by gravimetrical analysis, optical microscopy, scanning electron microscopy combined with energy dispersive x-ray spectroscopy, infrared spectroscopy, and nuclear magnetic resonance. Hemostatic properties of the materials were assessed using a model of parenchymal bleeding from the liver of white male Wistar rat with a gauze bandage as a control. All investigated PVF-based porous sponges showed high hemostatic activity: upon the application of PVF-samples the bleeding decreased within 3 min by 68.4-94.4% (р < 0.001). The bleeding time upon the application of PVF-based composites decreased by 78.3-90.4% (p < 0.001) compared to the application of well-known commercial product Celox™.

CORRELATION BETWEEN THE LEVELS OF ADIPOSE-DERIVED HORMONE AND CARDIOMETABOLIC MARKERS IN PATIENTS WITH HYPERTENSION AND OBESITY.

The aim - to analyze the relationship between leptin levels and morphometric, anthropometric, biochemical parameters in patients with hypertension and obesity and in healthy individuals. The study included 64 patients with obesity and hypertension and 21 healthy individuals. The groups were comparable in age and gender. Leptin was determined by enzyme immunoassay method. Data are presented as mean values and the error of the mean (M±m). Differences were considered statistically significant at p<0,05. It was found out a strong positive correlation in the group with hypertension and obesity between plasma leptin levels and total cholesterol (r=0.40, p=0.00004), strong negative correlation between leptin and HDL (r=-0 , 43, p=0.0005), uric acid (r=0.32 p=0.00092) and ionized calcium levels (r=-0.35 p=0.00027). Leptin levels in the group of healthy individuals correlated with a waist circumference (r=0.78, p=0.005), BFM, BMI and age (r=0.92, r=0.94, r=0.81, p<0 , 05), uric acid levels (r=0.94) and ionized calcium (r=0.91) at p<0.05. The present study provides evidence that BFM, TG, HDL, VLDL, atherogenic index, ionized calcium levels and uric acid have a significant impact on serum leptin in patients with hypertension and obesity.

QUANTITATIVE HISTOLOGICAL ASSESSMENT OF SKELETAL MUSCLE HYPOTROPHY AFTER NEUROTOMY AND SCIATIC NERVE REPAIR IN RATS.

Reinnervation of skeletal muscles, wich occurs in time, is considered a factor in preventing muscle atrophy and potentially successful functional recovery. Morphometry of denervated muscles makes it possible to assess the dynamics of muscle atrophy after various methods of repairing of a damaged peripheral nerve. The aim - evaluate histological changes and morphometry of m. gastrocnemius in rats after complete neurotomy and nerve repair techniques. In rats the sciatic nerve was crossed and sutured with 4 epineural sutures, 2 sutures with DuraSeal, and 2 sutures with Tisseel. On the 14th, 30th, and 60th day histological changes of m.gastrocnemius were examined and morphometry was performed based on two parameters: muscle fiber diameter and collagen density. Skeletal muscles morphometry was performed after sciatic nerve neurotomy and subsequent microsurgical repair. Muscle fiber wasting was already detected on the 14th day after epineural suture with DuraSeal, and in the Tisseel group - on the 30th day after sciatic nerve damage. The average diameter of muscle fibers in the DuraSeal group increased significantly by the day 60 due to the appearance of hypertrophied fibers. In areas of wasting, connective tissue density increased, which did not change quantitatively during the experiment, while the use of DuraSeal and Tisseel delayed the development of fibrosis for up to the 30th day. Application of DuraSeal and Tisseel with epineural suture delays the development of fibrosis and wasting in denervated muscles during the reinnervation period.

EPINEURIAL SUTURES, POLYETHYLENE GLYCOL HYDROGEL AND FIBRIN GLUE IN THE SCIATIC NERVE REPAIR IN RATS: FUNCTIONAL AND MORPHOLOGICAL ASSESSMENTS IN EXPERIMENT.

Mechanical damage to the peripheral nerve is a fairly common type of injury, which is characterized by a complex of long-term neurological disorders and require significant financial costs. The aim of this work is to evaluate the efficiency of sciatic nerve (SN) regeneration after neuroraphy using epineural suture (ES), polyethylene glycol hydrogel (PEG), and fibrin glue (FG). The studies were carried out on 30 white outbred male rats, which were divided into six experimental groups: Group №1: intact rats; Group №2: Sham operated; Group №3: complete transection of the SN; Group №4: nerve repair with ES; Group №5: nerve repair with PEG; Group №6: nerve repair with FG. Functional recovery was assessed at 1, 2, 3, 4 postoperative weeks using a walking-track analysis with subsequent determination of the sciatic nerve functional index (SFI). At 4 weeks, electroneuromyography, histological and morphometric analyzes were performed. The combined analysis indicated that PEG significantly improved functional recovery, both in the SFI index and in the skeletal muscle M-response. Compared to ES and PEG, the use of FG was reflected in a lower significance of the indicators compared to PEG. Statistical analysis indicates a positive effect of PEG and FG on nerve regeneration, although significantly greater remyelination (analysis based on fiber diameter) was confirmed only in the PEG group, which explains the faster functional recovery of the limb. PEG in the form of a hydrogel is a more promising agent in microsurgical restoration of damaged nerves as an adhesive, it promotes rapid nerve regeneration, denervated muscle re-innervation and functional limb recovery.

Nanosilica modified by polydimethylsiloxane depolymerized and chemically bound to nanoparticles or physically bound to unmodified or modified surfaces: Structure and interfacial phenomena.

Three polydimethylsiloxanes (PDMS200, PDMS1000, and PDMS12500 with numbers showing the viscosity values dependent on the molecular weight) were used for adsorption (14-95 wt% PDMS) onto unmodified and PDMS-modified (16.7 wt% PDMS using dimethyl carbonate (DMC) as a siloxane bond breaking reagent) nanosilica A-300. The materials were studied using microscopy, infrared spectroscopy, thermodesorption, calorimetry, ethanol and water/ethanol evaporation, nitrogen adsorption-desorption, and quantum chemical methods. The interfacial and temperature behaviors of a PDMS layer at a silica surface depend strongly on the type of bonding to silica particles, molecular weight and content of PDMS. Upon chemical bonding, shorter PDMS200 forms a denser coverage of the silica surface since SBET diminution is larger and residual free silanols are practically absent (the degree of free silanol substitution Θ > 0.95) in contrast to the reactions with PDMS1000/DMC or PDMS12500/DMC providing Θ = 0.60-0.63 at larger SBET values. Upon thermal decomposition of the PDMS layer, oxidation/depolymerization desorption gives a greater contribution than pure depolymerization destruction. An increase in the PDMS adsorption layer thickness leads to enhancement of the depolymerization contribution because the oxidation mainly occurs at the top of the layer, but the depolymerization can occur in the total PDMS layer. The adsorption, desorption, and evaporation processes of low-molecular weight probes at a surface of PDMS-modified nanosilica depend strongly on the type of bonding and content of PDMS. Thus, the most effective hydrophobization of nanosilica by PDMS/DMC could be carried out using the shortest polymer giving the shortest PDMS fragments upon the interaction with DMC that is of interest from a practical point of view.

Titania-Coated Silica Alone and Modified by Sodium Alginate as Sorbents for Heavy Metal Ions.

The novel organic-inorganic biohybrid composite adsorbent was synthesized based on nanosized silica-titania modified with alginate within the development of effective adsorbent for heavy metal ions. Effects of metal species Cu(II), Zn(II), Cd(II), and Pb(II); concentrations; pH; temperature; and adsorption onto titania-coated silica (ST20) initial or modified by sodium alginate (ST20-ALG) were studied. The equilibrium and kinetic data of metal ions adsorption were analyzed using Langmuir and Freundlich adsorption models and kinetic models: pseudo first order, pseudo second order, intraparticle kinetic model, and Elovich. The maximum sorption capacities observed were higher for the ST20-ALG composite compared to the initial ST20 oxide for all studied metal ions, namely their values for ST20-ALG were 22.44 mg g- 1 for Cu(II) adsorption, 19.95 mg g- 1 for Zn(II), 18.85 mg g- 1 for Cd(II), and 32.49 mg g- 1 for Pb(II). Structure and properties of initial silica-titania ST20 and modified by sodium alginate ST20-ALG adsorbents were analyzed using nitrogen adsorption/desorption isotherms, ATR-FTIR, SEM-EDS, and pHpzc techniques.

Nanostructure of Poly(Acrylic Acid) Adsorption Layer on the Surface of Activated Carbon Obtained from Residue After Supercritical Extraction of Hops.

The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.

Interfacial phenomena at a surface of individual and complex fumed nanooxides.

Investigations of interfacial and temperature behaviors of nonpolar and polar adsorbates interacting with individual and complex fumed metal or metalloid oxides (FMO), initial and subjected to various treatments or chemical functionalization and compared to such porous adsorbents as silica gels, precipitated silica, mesoporous ordered silicas, filled polymeric composites, were analyzed. Complex nanooxides include core-shell nanoparticles, CSNP (50-200nm in size) with titania or alumina cores and silica or alumina shells in contrast to simple and smaller nanoparticles of individual FMO. CSNP could be destroyed under high-pressure cryogelation (HPCG) or mechanochemical activation (MCA). These treatments affect the structure of aggregates of nanoparticles and agglomerates of aggregates, resulting in their becoming more compacted. The analysis shows that complex FMO could be more sensitive to external actions than simple nanooxides such as fumed silica. Any treatment of 'soft' FMO affects the interfacial and temperature behaviors of polar and nonpolar adsorbates. Rearrangement of secondary particles and surface functionalization affects the freezing-melting point depression of adsorbates. For some adsorbates, open hysteresis loops became readily apparent in adsorption-desorption isotherms. Clustering of adsorbates bound in textural pores in aggregates of nanoparticles (i.e., voids between nanoparticles in secondary structures) causes reduced changes in enthalpy during phase transitions (freezing, fusion, evaporation). Freezing point depression and melting point elevation cause significant hysteresis freezing-melting effects for adsorbates bound to FMO in the textural pores. Relaxation phenomena for both low- and high-molecular weight adsorbates or filled polymeric composites are affected by the morphology of primary particles, structural organization of secondary particles of differently treated or functionalized FMO, content of adsorbates, co-adsorption order, and temperature.

Interfacial phenomena at a surface of partially silylated nanosilica.

Unmodified pyrogenic silica PS300 and partially silylated nanosilica samples at a degree of substitution of surface silanols by trimethylsilyl (TMS) groups Θ(TMS)=27.2% and 37.2% were studied to elucidate features of the interfacial behavior of water adsorbed alone, or co-adsorbed with methane, hydrogen, or trifluoroacetic acid (TFAA). In the aqueous suspension modified PS300 at Θ(TMS)=37.2% forms aggregates of 50-200 nm in size and can bind significant amounts of water (up to ∼5 g/g). Only 0.5 g/g of this water is strongly bound, while the major fraction of water is weakly bound. The presence of surface TMS groups causes the appearance of weakly associated water (WAW) at the interfaces. The adsorption of methane and hydrogen onto TMS-nanosilica with pre-adsorbed water (hydration degree h=0.05 or 0.005 g/g) increases with increasing temperature. In weakly polar CDCl3 medium, interfacial water exists in strongly (SAW, chemical shift δ(H)=4-5 ppm) and weakly (δ(H)=1-2 ppm) associated states, as well as strongly (changes in the Gibbs free energy -ΔG>0.5-0.8 kJ/mol) and weakly (-ΔG<0.5-0.8 kJ/mol) bound states. WAW does not dissolve TFAA but some fraction of SAW bound to TMS-nanosilica surface can dissolve TFAA.

Interfacial behavior of polar, weakly polar, and nonpolar compounds bound to activated carbons.

Detailed analysis of the interfacial behavior of water and weakly polar or nonpolar organics adsorbed alone or co-adsorbed onto activated carbons (AC) at different temperatures is a complex problem important for practical applications of adsorbents. Interaction of water, 1-decanol, and n-decane with AC possessing highly developed porosity (pore volume Vp≈1.4-2.3 cm(3)/g, specific surface area S(BET)≈1500-3500 m(2)/g) was studied over a broad temperature range using differential scanning calorimetry (DSC), thermoporometry, (1)H NMR spectroscopy, cryoporometry, and temperature-programmed desorption with mass-spectrometry control methods. Comparison of the pore size distributions (PSD) calculated using the DSC thermoporometry, NMR cryoporometry, and nitrogen adsorption isotherms allows us to determine localization of adsorbates in different pores, as well as changes in the PSD of AC due to freezing of adsorbates in pores. Theoretical calculations (using ab initio HF/6-31G(d,p), DFT B3LYP/6-31G(d,p), and PM7 methods) explain certain aspects of the interfacial behavior of water, decane, and decanol adsorbed onto AC that appear in the experimental data. Obtained results show strong temperature dependence (above and below the freezing point, Tf, of bulk liquids) of the interfacial behavior of adsorbates on the textural characteristics and hydrophilic/hydrophobic properties of AC and the adsorbate amounts that affect the distributions of adsorbates unfrozen at T