Antimicrobial properties of fibrous cellulose and other polymeric materials modified with chlorhexidine]

Since fibrous cellulose and other polymeric materials are widely used as dressings, it was of interest to study the mechanism of the antimicrobial action of the products from such materials physically and chemically modified by chlorhexidine, a broad spectrum antiseptic. As vehicles and prolongation agents the following products were used: dressing gauze and cation exchange derivatives of cellulose and starch i.e. monocarboxycellulose (MCC), phosphate cellulose (PC), carboxymethyl cellulose (CMC), monocarboxyl starch (MCS) and alginic acid (AA), a natural compound. It was shown that chemical attachment of chlorhexidine provided a 2-4-fold increase in the antimicrobial effect of the preparations as compared to the use of physical sorption. The antimicrobial effect of the polymeric form of chlorhexidine based on MCC and PC was much higher than that based on MCC, MCS and AA.     

Studies on the blood-anticoagulant activity of sulphated polysaccharides with different uronic acid content

The anticoagulant activities of sulphated alginic acids, amylose, cellulose, chitosan, curdlan, dextran, guaran, laminaran and locust bean gum have been studied. The alginic acids have been partially reduced and some of the neutral polysaccharides have been partially oxidised at C-6 of the glycopyranosyl residues. The activities of sulphated polymers containing different proportions of uronic acid and neutral sugar residues have been compared.The results suggest that polysaccharides with an average of at least one sulphate group on each monomeric unit, a molecular weight higher than 10 000 and a high proportion of sulphated primary hydroxyl functions will display activity in the activated, partial thromboplastin time assay (APTT). Sulphated guaran and locust bean gum had the highest activities of the polymers investigated (70 IU/mg, heparin has 130-50 IU/mg). In the concentration range investigated, none of the sulphated polymers showed any significant activity in an anti-factor X_a assay.     

Morphology, molecular dynamics and electric conductivity of carbohydrate polymer films based on alginic acid and benzimidazole

The present paper describes a preparation method and molecular investigations of new biodegradable proton-conducting carbohydrate polymer films based on alginic acid and benzimidazole. Electric conductivity was studied in a wide temperature range in order to check the potential application of these compounds as membranes for electrochemical devices. Compared to pure alginic acid powder or its film, the biodegradable film of alginic acid with an addition of benzimidazole exhibits considerably higher conductivity in the range above water boiling temperature (up to approximately 10⁻³ S/cm at 473 K). Due to this important feature the obtained films can be considered as candidates for application in high-temperature electrochemical devices. The microscopic nature and mechanism of the conduction in alginate based materials were studied by proton nuclear magnetic resonance (NMR). The results show specific changes in morphology and molecular dynamics between pure alginate powders and the films obtained without and with the addition of benzimidazole molecules.     

Local antibiotic delivery with demineralized bone matrix

A method of care for these infected nonunions is prolonged intravenous systemic antibiotic treatment and implantation of methyl methacrylate antibiotic carrier beads to delivery high local doses of antibiotics. This method requires a second surgery to remove the beads once the infection has cleared. Recent studies have investigated the use of biodegradable materials that have been impregnated with antibiotics as tools to treat bone infections. In the present study, human demineralized bone matrix (DBM) was investigated for its ability to be loaded with an antibiotic. The data presented herein demonstrates that this osteoinductive and biodegradable material can be loaded with gentamicin and release clinically relevant levels of the drug for at least 13 days in vitro. This study also demonstrates that the antibiotic loaded onto the graft has no adverse effects on the osteoinductive nature of the DBM as measured in vitro and in vivo. This bone void filler may represent a promising option for local antibiotic delivery in orthopedic applications.     

Preparation and characterization of a thermostable and biodegradable biopolymers using natural cross-linker

The present study describes preparation and characterization of a thermally stable and biodegradable biopolymer using collagen and a natural polymer, alginic acid (AA). Required concentration of alginic acid and collagen was optimized and the resulting biopolymer was characterized for, degree of cross-linking, mechanical strength, thermal stability, biocompatibility (toxicity) and biodegradability. Results reveal, the degree of cross-linking of alginic acid (at 1.5% concentration) with collagen was calculated as 75%, whereas it was 83% with standard cross-linking agent, glutaraldehyde (at 1.5% concentration). The AA cross-linked biopolymer was stable up to 245°C and Exhibits 5-6-fold increase in mechanical (tensile) strength compared to plain collagen (native) materials. However, glutaraldehyde cross-linked material exhibits comparatively less thermal stability and brittle in nature (low tensile strength). With regard to cell toxicity, no cytotoxicity was observed for AA cross-linked material when tested with mesenchymal cells and found degradable when treated with collagenase enzyme. The nature of bonding pattern and the reason for thermal stability of AA cross-linked collagen biopolymer was discussed in detail with the help of bioinformatics. A supplementary file on efficacy of AACC as a wound dressing material is demonstrated in detail with animal model studies.     

Biodegradable microfluidic scaffolds for tissue engineering from amino alcohol-based poly(ester amide) elastomers

Biodegradable polymers with high mechanical strength, flexibility and optical transparency, optimal degradation properties and biocompatibility are critical to the success of tissue engineered devices and drug delivery systems. Most biodegradable polymers suffer from a short half-life due to rapid degradation upon implantation, exceedingly high stiffness, and limited ability to functionalize the surface with chemical moieties. This work describes the fabrication of microfluidic networks from poly(ester amide), poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS), a recently developed biodegradable elastomeric polymer. Microfluidic scaffolds constructed from APS exhibit a much lower Young''s modulus and a significantly longer degradation half-life than those of previously reported systems. The device is fabricated using a modified replica-molding technique, which is rapid, inexpensive, reproducible and scalable, making the approach ideal for both rapid prototyping and manufacturing of tissue engineering scaffolds.Key words: biodegradable, microfluidics, tissue engineering, elastomer, scaffold, polymer     

Biodegradable microfluidic scaffolds for tissue engineering from amino alcohol-based poly(ester amide) elastomers

Biodegradable polymers with high mechanical strength, flexibility and optical transparency, optimal degradation properties and biocompatibility are critical to the success of tissue engineered devices and drug delivery systems. Most biodegradable polymers suffer from a short half life due to rapid degradation upon implantation, exceedingly high stiffness, and limited ability to functionalize the surface with chemical moieties. This work describes the fabrication of microfluidic networks from poly(ester amide), poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS), a recently developed biodegradable elastomeric poly(ester amide). Microfluidic scaffolds constructed from APS exhibit a much lower Young’s Modulus and a significantly longer degradation half-life than those of previously reported systems. The device is fabricated using a modified replica-molding technique, which is rapid, inexpensive, reproducible, and scalable, making the approach ideal for both rapid prototyping and manufacturing of tissue engineering scaffolds.     

Effects of 60Co gamma-irradiation of mice on the temporal changes of acid phosphatase activity in spleen and liver.

Acid phosphatase activity and protein content of spleen and liver, and organ weight of whole-body 10 Gy 60Co gamma-irradiated mice were measured every four hours during a 24-hour period. In irradiated mice, in comparison with those non-irradiated, increased acid phosphatase activity in spleen related to both 1 mg of protein at 20.00I, 04.00, 08.00, 12.00, 16.00 and 20.00II and 1 g of fresh tissue at 20.00I, 08.00, 12.00, 16.00 and 20.00II; decreased weight of spleen and protein amount in spleen during the whole 24-hour period, as well as fluctuations in all the parameters measured in spleen, except the level of protein related to 1 g of fresh tissue, were observed. In irradiated mice, compared with the controls, the increased acid phosphatase activity in liver calculated per both 1 mg of protein at 24.00, 08.00 and 16.00 and 1 g of fresh tissue at 08.00 and 16.00; the decreased protein concentration in liver related to 1 g of fresh tissue and the whole organ weight at 12.00, as well as temporal changes in the protein level in liver expressed per 1 g of fresh tissue, were found. 60Co irradiation of mice influenced the acid phosphatase activity and protein concentration in liver are less than in spleen.     

Pharmacokinetics of protegentin, a combined preparation

Protegentin is a combined preparation in the form of ointment containing 0.1 per cent of gentamicin, 0.25 per cent of erythromycin and 0.1 per cent of protease C. Pharmacokinetic studies on the preparation were conducted. Protegentin and gentamicin ointment, currently manufactured in this country, were applied to the surface of experimental pure cutaneous wounds in guinea pigs in a dose of 1 g. It was shown that inspite of the same contents of gentamicin in the ointments, the mean maximum concentration of the antibiotic in the underlying muscular tissue after the protegentin application was somewhat higher than that after the use of the gentamicin ointment. The differences in the drug concentration maintained during the whole observation period of 24 hours. However, they were not statistically significant. The gentamicin concentrations in serum after the use of protegentin were also somewhat higher than those after application of the gentamicin ointment (the differences were not statistically significant). Still, in no case the concentrations reached the potentially toxic ones. The erythromycin concentrations in the muscular tissue were much higher than those in the blood.     

小鼠胚泡着床过程中子宫6—酮—PGF1α（6—KF）及TXB2含量的变化

本实验利用前列环素(Prostacyclin,简称PGI_2)及血栓素(Thromboxane A_2,简称TXA_2)的代谢产物6-KF及TXB_2的RIA技术,探讨了小鼠子宫在胚泡着床点及非着床部位上述二类PG_s的含量变化。实验表明,妊娠D_5胚泡着床部位及着床间区,6-KF的水平较高;而TXB_2含量较低变化也小。表明胚泡着床时,血管通透性增强与PGI_2升高密切相关。PGI_2与TXA_2比值的增高,使血管舒张,增强抗凝,有利于胚泡着床及营养供应。     

Small-angle X-ray scattering and rheological characterization of alginate gels. 3. Alginic acid gels

Alginic acid gels were studied by small-angle X-ray scattering and rheology to elucidate the influence of alginate chemical composition and molecular weight on the gel elasticity and molecular structure. The alginic acid gels were prepared by homogeneous pH reduction throughout the sample. Three alginates with different chemical composition and sequence, and two to three different molecular weights of each sample were examined. Three alginate samples with fractions of guluronic acid residues of 0.39 (LoG), 0.50 (InG), and 0.68 (HiG), covering the range of commercially available alginates, were employed. The excess scattering intensity I of the alginic acid gels was about 1 order of magnitude larger and exhibited a stronger curvature toward low q compared to ionically cross-linked alginate. The I(q) were decomposed into two components by assuming that the alginic acid gel is composed of aggregated multiple junctions and single chains. Time-resolved experiments showed a large increase in the average size of aggregates and their weight fraction within the first 2 h after onset of gelling, which also coincides with the most pronounced rheological changes. At equilibrium, little or no effect of molecular weight was observed, whereas at comparable molecular weights, an increased scattering intensity with increasing content of guluronic acid residues was recorded, probably because of a larger apparent molecular mass of domains. The results suggest a quasi-ordered junction zone is formed in the initial stage, followed by subsequent assembling of such zones, forming domains in the order of 50 A. The average length of the initial junction zones, being governed by the relative fraction of stabilizing G-blocks and destabilizing alternating (MG) blocks, determines the density of the final random aggregates. Hence, high-G alginates give alginic acid gels of a higher aggregate density compared to domains composed of loosely packed shorter junction zones in InG or LoG system.     

Structural determination of alginic acid and the effects of calcium binding as determined by high-field n.m.r.

The nature of the solution conformations of the alginic acid components D-mannuronan (poly-ManA) and L-guluronan (poly-GulA) from Azotobacter vinelandii were investigated by both one- and two-dimensional n.m.r. methods. Unequivocal proton assignments for both polymers as well as their constituent monomer units were made based on chemical-shift theory, coupling constant analysis, and nuclear Overhauser enhancement measurements. These data were used to investigate the interactions of poly-GulA and poly-ManA with Ca2+ ion in aqueous medium. Based on relative crosspeak integrals measured in two-dimensional phase-sensitive NOESY spectra of free and calcium-bound polymer, a model for calcium binding is proposed.     

Gentamicin level in the prostate and its pharmacokinetics in patients with benign prostatic hypertrophy]

The study involved 15 male patients with periurethral prostatic adenoma without complete anuresis. The patients were given 80 mg of gentamicin intramuscularly one day before surgery and 80 mg in a one-hour infusion immediately before an operation. Gentamicin blood concentrations were measured. Pharmacokinetic parameters were calculated and dosage schemes for each patient basing on the antibiotic blood levels. Gentamicin levels in removed adenomas were also determined. Adenomas weighed between 18.0 and 45.8 grams while gentamicin concentration ranged from 1.31 to 3.8 micrograms/mL. It was found that gentamicin concentration in adenomas depend upon their weight. Moreover, pharmacokinetic parameters of this antibiotic exert negligible effect on its levels in adenoma.     

Cell wall assembly in fucus zygotes: I. Characterization of the polysaccharide components

Fertilization triggers the assembly of a cell wall around the egg cell of three brown algae, Fucus vesiculosus, F. distichus, and F. inflatus. New polysaccharide polymers are continually being added to the cell wall during the first 24 hours of synchronous embryo development. This wall assembly involves the extracellular deposition of fibrillar material by cytoplasmic vesicles fusing with the plasma membrane. One hour after fertilization a fragmented wall can be isolated free of cytoplasm and contains equal amounts of cellulose and alginic acid with no fucose-containing polymers (fucans) present. Birefringence of the wall caused by oriented cellulose microfibrils is not detected in all zygotes until 4 hours, at which time intact cell walls can be isolated that retain the shape of the zygote. These walls have a relatively low ratio of fucose to xylose and little sulfate when compared to walls from older embryos. When extracts of walls from 4-hour zygotes are subjected to cellulose acetate electrophoresis at pH 7, a single fucan (F₁) can be detected. By 12 hours, purified cell walls are composed of fucans containing a relatively high ratio of fucose to xylose and high levels of sulfate, and contain a second fucan (F₂) which is electrophoretically distinct from F₁. F₂ appears to be deposited in only a localized region of the wall, that which elongates to form the rhizoid cell. Throughout wall assembly, the polyuronide block co-polymer alginic acid did not significantly vary its mannuronic (M) to guluronic (G) acid ratio (0.33-0.55) or its block distribution (MG, 54%; GG, 30%; MM, 16%). From 6 to 24 hours of embryo development, the proportion of the major polysaccharide components found in purified walls is stable. Alginic acid is the major polymer and comprises about 60% of the total wall, while cellulose and the fucans each make-up about 20% of the remainder. During the extracellular assembly of this wall, the intracellular levels of the storage glucan laminaran decreases. A membrane-bound β-1, 3-exoglucanase is found in young zygotes which degrades laminaran to glucose. It is postulated that hydrolysis of laminaran by this glucanase accounts, at least in part, for glucose availability for wall biosynthesis and the increase in respiration triggered by fertilization. The properties and function of alginic acid, the fucans, and cellulose are discussed in relation to changes in wall structure and function during development.     

Effect of dietary alginic acid on juvenile tilapia (Oreochromis niloticus) intestinal microbial balance, intestinal histology and growth performance

The aim of the present study was to assess the effect of a commercial alginic acid source (Ergosan) on tilapia Oreochromis niloticus intestinal microbial balance, intestinal morphology, and growth parameters. Fish were fed a basal control diet or the basal diet plus a source of alginic acid (5?g?kg(-1) Ergosan; Schering-Plough Aquaculture, UK) for 9?weeks. At the end of the trial, light and electron microscopy demonstrated that the morphology of the intestinal tract at the gross and ultra-structural level was not affected by dietary alginic acid inclusion. Both groups of fish displayed healthy, normal morphology with no signs of disease, cell or tissue damage. Intestinal epithelial leucocyte infiltration was not affected by dietary alginic acid. Molecular bacterial profiles derived from PCR-DGGE illustrated highly similar microbial communities (both within the lumen and associated with the intestinal mucosa) in the respective treatment groups. Microbial ecological parameters (e.g. species diversity and richness) also remained unaffected. Although not significant, trends towards elevated survival and body protein content were observed in the alginic acid-fed fish. These results are suggestive that alginic acid does not adversely impact the indigenous gastrointestinal microbial balance and subsequently does not impact upon the epithelial brush border integrity. Validation of non-detrimental impacts of immunostimulatory products on gastric microbiota and epithelial integrity should be pursued in future studies as maintaining microbial balance and epithelial integrity is essential for proper gut functionality.     

Application of the spiral plating method to study antimicrobial action

The spiral gradient endpoint (SGE), a developement method for determination of minimum inhibitory concentration (MIC), was compared to a standard agar dilution method (SAD). Three antimicrobials, benzyl-penicillin, ampicillin and gentamicin, were tested against a laboratory collection of 14 streptococci and r_s values were, depending on inoculum tested, 0.93−0.84, 0.97−0.89 and 0.86−0.73, respectively, for each antibiotic. Using a membrane transfer technique, the spiral plater was further evaluated as a method for determination of interaction between an aminoglycoside and 2 β-lactams. The effect of gentamicin at fixed concentrations of 2 and 8 mg.l⁻¹ on determination of MIC and minimum bactericidal concentration (MBC) for benzylpenicillin and ampicilin was determined. Synergy between gentamicin and the 2 β-lactams corresponded to previously published data in that, marked synergy required a degree of susceptibility by the streptococci to gentamicin (MIC<3 mg·l⁻¹) and a degree of insuscpetibility to the β-lactams.     

Intralymphatic administration of antibiotics in the complex treatment of suppurative complications in patients with neurosurgical pathology

The efficacy of endolymphatic route of gentamicin and ceporin administration was studied in 89 patients with neurosurgical pathological processes complicated by acute pneumonia (80 patients) and meningoencephalitis (9 patients) usually after ineffective antibiotic therapy according to the routine methods. The antibiotics were used in accordance with the antibiograms of the causative agents isolated from the bronchial tree or CSF. The endolymphatic use of gentamicin or ceporin once a day in doses of 80 mg or 1 g respectively provided rapid sanation and arresting of the inflammatory foci, lowering of the intoxication level, more rapid promotion of the positive time course of the clinico-roentgenological and laboratory indices and decreasing of the recovery periods by 1.5-2 times in 86 per cent of the patients with pneumonia. The endolymphatic administration of gentamicin in a dose of 80 mg twice a day or ceporin in a dose of 1 g twice a day allowed one to maintain the antibiotic therapeutic levels in the cerebrospinal fluid and to obtain satisfactory clinical results in the combined treatment of meningoencephalitis. The endolymphatic administration of the drugs was well tolerated by the patients and no adverse reactions were observed. This route of administration of antibiotics and in particular broad spectrum antibiotics may be recommended for urgent antibacterial therapy of especially severe neurosurgical patients with pyo-inflammatory complications and patients who did not respond to the routine antibiotic therapy.     

A gas chromatographic method for the quantitative detemination of hexuronic acids in alginic acid

A method has been developed for the quantitative determination of the relative proportions of d-mannuronic and l-guluronic acids in alginic acid. To obtain homogeneous reaction conditions the viscosity of the alginic acid sample was first decreased by limited hydrolysis with mineral acid. The carboxyl groups were then esterified by reaction with 1-ethyl-3-[3-(dimethylamino)propyl]-carbodiimide, and reduced with sodium borohydride. The resulting hexosans were converted by acid hydrolysis to d-mannose and an equilibrium mixture of l-gulose and 1,6-anhydro-l-gulose. These were treated with sodium borohydride; the 1,6-anhydro-l-gulose was not reduced whereas d-mannose and l-gulose were converted to d-mannitol and d-glucitol. The hexitols were estimated by gas-liquid chromatography as the n-butane boronic acid esters, and the relative proportions of the uronic acids in the alginic acid were calculated by taking into account the equilibrium ratio of l-gulose and 1,6-anhydro-l-gulose. The method can be used to analyze as little as 2 mg of alginic acid.     

Reduction of antibiotic-induced biofilm accumulation of Pseudomonas aeruginosa by quaternized phytoglycogen

Biofilms are oft cited as a factor in the unwanted persistence and recalcitrance of microbial life and a strong research initiative exists to identify, understand, and target vulnerabilities. Phytoglycogen is a biodegradable nanoparticulate biomaterial that is purified from crop plants. Importantly, the highly branched glucan structure provides a scaffold on which to construct novel polymers. Functionalized phytoglycogen (FP) was synthesized using green chemistry principles. Screening of several molecules identified a form of quaternized phytoglycogen which reduced biofilm formation and accretion by Pseudomonas aeruginosa. Exposing P. aeruginosa to modified phytoglycogen and antibiotic in combination not only substantively reduced biofilms, but also prevented increased biofilm formation, a biological response to suboptimal antibiotic concentrations. Treatment of pregrown biofilms with sub-minimum inhibitory concentration antibiotic alone also led to increased proliferation, whereas FP-antibiotic combinations prevented or reduced the extent of this. Swimming, swarming and twitching motility, all critical for biofilm development, were negatively affected by FP. This work supports phytoglycogen as a promising foundational molecule for novel polymers, including those with anti-biofilm function. Critically, in addition to published reports on how suboptimal antibiotic concentrations promote biofilm formation, we demonstrated a similar effect upon pre-existing biofilms, indicating a further route for the failure of antibiotic therapies.     

Modification of biochemical parameters of gentamicin nephrotoxicity by coenzyme Q10 and green tea in rats

The present study was designed to investigate the possible potential protective role of coenzymeQ10 (CoQ10; 10 mg/kg/day, ip) and/or green tea (GT; 25mg/kg/day, po) against gentamicin (GM) nephrotoxicity. Marked increase in the level of serum urea. creatinine and lipid peroxidation (LPO) content was found after administration of gentamicin (80 mg/kg/day, ip) for eight days along with significant decrease in the antioxidant enzymes, superoxide dismutase (SOD), reduced glutathione (GSH), catalase (CAT) as well as brush border enzymes (Na+/K+ ATPase, Mg(+2)ATPase and Ca2+ ATPase).Treatment with CoQ10 or green tea alone with GM showed significant decrease in serum urea, creatinine and tissue LPO content and significant increase in antioxidant and membrane bound enzymes. Combined treatment with CoQ10 and green tea was more effective in mitigating adverse effect of GM nephrotoxicity. The present work indicated that CoQ10 and green tea due to their antioxidant activity modified the biochemical changes occurred during gentamicin nephrotoxicity and thus had a potential protective effect.