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Exploring the frostbite healing potential of Hyaluronic acid based hydrogel of Manuka Honey through in-silico Antithrombotic and Anti-platelet studies of Major Phytoconstituents and in-vivo Evaluation in Wistar Rat Model
Abstract
Objective:
Development of Frostbite healing hydrogel of manuka honey and hyaluronic acid.
Significance:
Frostbite is a cold-induced ischemic vascular injury non-responsive to most of the wound healing products. Thrombus induced ischemia is main cause of frostbite related necrosis. Hyaluronic acid is known to possess significant antithrombotic and wound healing activity. Moreover Manuka Honey is also rich in flavonoids and polyphenols with potential antithrombotic activity. These two agents were together utilized to develop a frostbite healing formulation.
Methods:
In Silico antithrombotic efficacy of major phytoconstituents of manuka honey was evaluated using in silico- docking studies against Tissue plasminogen activator and Cyclooxigenase-1 protein. Further in-vivo frostbite healing evaluation was carried out in wistar rat, by inducing frostbite with super cooled rod.
Results:
The results indicate that major leptosin and other major phytoconstituent of manuka honey has significant antithrombotic property. The hydrogel formulation of HA and MH possess significant antimicrobial efficacy. The wound contraction studies and histopathological evaluation reveals that the hydrogel also has a good frostbite healing activity showing complete wound healing within 18 day period. The findings of the western blotting studies suggest that the hydrogel acts by VEGF- NRF-2 pathway.
Conclusion:
This result implies that the prepared hydrogel can serve as an effective frostbite healing formulation.
... Treatment with HA activates Nrf2 and induces Nrf2-target genes in bovine chondrocytes and human breast cancer cells, with increased phosphorylation of AKT or higher levels of p62, which competes with Nrf2 for binding to Keap1 (Komatsu et al., 2010), correlating with Nrf2 activation (Choi et al., 2022;Onodera et al., 2015;Ryoo et al., 2018). In addition, a hydrogel formulation of HA increased the levels of Nrf2 in frostbite-wounded skin tissues of Wistar rats (Joshi et al., 2021). To our knowledge, the possibility that Nrf2 activation may also occur in macrophages exposed to HA has not been explored. ...
Nuclear factor erythroid 2-related factor 2 (Nrf2) mediates the cellular antioxidant response, allowing adaptation and survival under conditions of oxidative, electrophilic and inflammatory stress, and has a role in metabolism, inflammation and immunity. Activation of Nrf2 provides broad and long-lasting cytoprotection, and is often hijacked by cancer cells, allowing their survival under unfavorable conditions. Moreover, Nrf2 activation in established human tumors is associated with resistance to chemo-, radio-, and immunotherapies. In addition to cancer cells, Nrf2 activation can also occur in tumor-associated macrophages (TAMs) and facilitate an anti-inflammatory, immunosuppressive tumor immune microenvironment (TIME). Several cancer cell-derived metabolites, such as itaconate, L-kynurenine, lactic acid and hyaluronic acid, play an important role in modulating the TIME and tumor-TAMs crosstalk, and have been shown to activate Nrf2. The effects of Nrf2 in TIME are context-depended, and involve multiple mechanisms, including suppression of pro-inflammatory cytokines, increased expression of programmed cell death ligand 1 (PD-L1), macrophage colony-stimulating factor (M-CSF) and kynureninase, accelerated catabolism of cytotoxic labile heme, and facilitating the metabolic adaptation of TAMs. This understanding presents both challenges and opportunities for strategic targeting of Nrf2 in cancer.
... Its action in tissue healing and renewal is based on reducing inflammatory cell response and, concurrently, activating cytokine production in the wound area, resulting in the proliferation of epithelial cells. On this basis, various formulations based on honey, and in combination with other substances such as hyaluronic acid and zein coatings, have been tested [90][91][92][93]. ...
Research attention has been drawn to honey’s nutritional status and beneficial properties for human health. This study aimed to provide a bibliometric analysis of honey’s antioxidant and antimicrobial properties. The research advancements within this field from 2001 to 2022 were addressed using the Scopus database, R, and VOSviewer. Of the 383 results, articles (273) and reviews (81) were the most common document types, while the annual growth rate of published manuscripts reached 17.5%. The most relevant topics about honey’s antimicrobial and antioxidant properties were related to the agricultural and biological sciences, biochemistry, and pharmacology. According to a keyword analysis, the most frequent terms in titles, abstracts, and keywords were honey, antimicrobial, antioxidant, bee, propolis, phenolic compounds, wound, antibacterial, anti-inflammatory, and polyphenols. A trend topic analysis showed that the research agenda mainly encompassed antioxidants, pathogens, and anti-infection and chemical agents. In a co-occurrence analysis, antioxidants, anti-infection agents, and chemistry were connected to honey research. The initial research focus of this domain was primarily on honey’s anti-inflammatory and antineoplastic activity, wound healing, and antibacterial agents. The research agenda was enriched in the subsequent years by pathogens, propolis, oxidative stress, and flavonoids. It was possible to pinpoint past trends and ongoing developments and provide a valuable insight into the field of honey research.
Frostbite is a cold induced injury which occurs due to exposure of a particular site of body to sub-zero temperature. One of the primary reasons for lack of proper studies about the underlying mechanism of frostbite injury is due to non-availability of any reliable animal model and method for inflicting frostbite. In our current research, a device was designed and standardised to inflict frostbite wound in wistar rat. A formulation comprising different combination of essential oils was also developed and its activity was assessed and found effective in the treatment of frostbite wound.
Honey exhibits antimicrobial activities against a wide range of bacteria in different milieu. This study aims to compare the effects of five types of honey (both imported and local Saudi honey) against Staphylococcus aureus. The five types of honey (Manuka Honey UMF +20, Manuka Honey UMF +16, Active +10 Manuka Honey, Sidr honey and Nigella sativa honey) were evaluated for their bactericidal/bacteriostatic activities against both methicillin resistant and sensitive Staphylococcus aureus. The inhibitory effect of honey on bacterial growth was evident at concentrations of 20% and 10% (v/v). Manuka honey showed the best results .Manuka Honey UMF +20 had a bactericidal effect on both methicillin resistant and sensitive S. aureus. However, Sidr and N. sativa honey exerted only a bacteriostatic effect. The efficacy of different types of honey against S. aureus was dependent on the type of honey and the concentration at which it was administered. Manuka honey had the best bactericidal activity. Future experiments should be conducted to evaluate the effects of honey on bacterial resistance.
Amputations are common after severe frostbite injuries, often mediated by postinjury arterial thrombosis. Since 1994, the authors have performed angiography to identify perfusion deficits in severely frostbitten digits and treated these lesions with intraarterial infusion of thrombolytic agents, usually combined with papaverine to reduce vasospasm. A retrospective review was performed of patients admitted to the regional burn center with frostbite injury from 1994 to 2007. Patients with severe frostbite, without contraindications to thrombolytic therapy, underwent diagnostic angiography of the affected extremities. Limbs with perfusion defects received intraarterial thrombolytic therapy according to protocol and the response was documented. Delayed amputation was performed for mummified digits. Angiogram results and amputation rates were tabulated. In this 14-year review, 114 patients were admitted for frostbite injuries. There was a male predominance (84%) and the mean age was 40.4 years. Of this group, 69 patients with severe frostbite underwent angiography; 66 were treated with intraarterial thrombolytic therapy. Four treated were excluded due to incomplete data. In the remaining 62 patients, angiography identified 472 digits with frostbite injury and impaired arterial perfusion. At the termination of thrombolytic infusion, a completion angiogram was performed. Partial or complete amputations were performed on only four of 198 digits (2.0%) with distal vascular blush, and in 71 of 75 digits (94.7%) with no improvement. Amputations occurred in 73 of 199 digits (36.7%) with partially restored flow. Overall complete digit salvage rate was 68.6%. Angiography after severe frostbite is a sensitive method to detect impaired arterial blood flow and permits catheter-directed treatment with thrombolytic agents. Improved perfusion after such treatment decreases late amputations following frostbite injury.
We developed an experimental model of ethanol-induced dermatotoxicity and hepatocytoxicity using normal human keratinocytes and normal human hepatocytes that preserve inducible cytochrome p450 activities. The original work was described in several articles. The objective of this study was to determine whether hyaluronic acid attenuates skin necrosis, and to further clarify its uses in wound repair in humans, animal models and in vitro studies.
We performed a systematic review of the literature using the terms "hyaluronic acid" and "wound healing". PubMed was searched for studies published during the period 2010-2014.
Hyaluronic acid is used in tissue regeneration alone or in combination with herbal or Western medicine. Scaffolds made up of hyaluronic acid were used to embed basic fibroblast growth factor.
Hyaluronic acid extracts are safe and efficacious products to be used in skin repair. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.
Honey has been used as a food and medical product since the earliest times. It has been used in many cultures for its medicinal properties, as a remedy for burns, cataracts, ulcers and wound healing, because it exerts a soothing effect when initially applied to open wounds. Depending on its origin, honey can be classified in different categories among which, monofloral honey seems to be the most promising and interesting as a natural remedy. Manuka honey, a monofloral honey derived from the manuka tree (Leptospermum scoparium), has greatly attracted the attention of researchers for its biological properties, especially its antimicrobial and antioxidant capacities. Our manuscript reviews the chemical composition and the variety of beneficial nutritional and health effects of manuka honey. Firstly, the chemical composition of manuka honey is described, with special attention given to its polyphenolic composition and other bioactive compounds, such as glyoxal and methylglyoxal. Then, the effect of manuka honey in wound treatment is described, as well as its antioxidant activity and other important biological effects.
Background. Ixora coccinea L. (Rubiaceae) has been documented for traditional use in hypertension, menstrual irregularities, sprain, chronic ulcer, and skin diseases. In the present study, I. coccinea was subjected to in vitro and in vivo wound healing investigation. Methods. Petroleum ether, chloroform, methanol, and water sequential I. coccinea leaves extracts were evaluated for in vitro antioxidant, antimicrobial, and fibroblast proliferation activities. The promising I. coccinea methanol extract (IxME) was screened for in vivo wound healing activity in Wistar rat using circular excision model. Wound contraction measurement, hydroxyproline quantification, and western blot for collagen type III (COL3A1), basic fibroblast growth factor (bFGF), and Smad-2, -3, -4, and -7 was performed with 7-day postoperative wound granulation tissue. Gentamicin sulfate (0.01% w/w) hydrogel was used as reference standard. Results. IxME showed the potent antimicrobial, antioxidant activities, with significant fibroblast proliferation inducing activity, as compared to all other extracts. In vivo study confirmed the wound healing accelerating potential of IxME, as evidenced by faster wound contraction, higher hydroxyproline content, and improved histopathology of granulation tissue. Western blot analysis revealed that the topical application of I. coccinea methanol extract stimulates the fibroblast growth factor and Smad mediated collagen production in wound tissue.
The antioxidant activity of extracts and fractions of six vegetal species from the Brazilian Atlantic Forest were determined. The total antioxidant activity was assessed based on the scavenging activity of the stable DPPH free radical. Eight extracts or fractions of plants showed significant DPPH scavenging activity (IC50 ≤ 10.0 µg/mL) compared with the values obtained for ascorbic acid (IC50 = 8.4 µg/mL) and gallic acid (IC50 = 2.6 µg/mL). The extracts or fractions were as follows: ethanol extracts of leaves, flowers, and stems of Baccharis illinita. DC., ethanol extracts of leaves and stems of B. platypoda. DC., hydroalcoholic extract and ethyl acetate fraction of leaves of Cyathea phalerata. Mart. and hydroalcoholic extract of bark of Trichilia catigua. A. Juss. Seven flavonoids present in the plant extracts were also investigated. The most active compounds were taxifolin, quercetin, and luteolin, which possess the catechol group 3′,4′-diOH. In addition, the total phenolic or flavonoid contents of these extracts and fractions were evaluated. The phenolic content of the sample was determined using Folin-Ciocalteu reagent and varied from 489.07 to 11.29 mg/g dry weight expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 61.82 to 5.6 mg quercetin equivalents (QE)/g dry weight. These results suggest that the level of antioxidant activity in these plants varies by a great extent. They also suggest that the phenolic content in these plants provides substantial antioxidant activity. The flora of Brazil appears to be a rich and interesting source for supplementary ethnomedical and phytochemical studies.
Background:
Frostbite is a thermal injury caused when tissue is exposed to sub-zero temperatures (in degrees Celsius) long enough for ice crystals to form in the affected tissue. Depending on the degree of tissue damage, thrombosis, ischaemia, necrosis (tissue death), gangrene and ultimately amputation may occur. Several interventions for frostbite injuries have been proposed, such as hyperbaric oxygen therapy, sympathectomy (nerve block), thrombolytic (blood-thinning) therapy and vasodilating agents such as iloprost, reserpine, pentoxifylline and buflomedil, but the benefits and harms of these interventions are unclear.
Objectives:
To assess the benefits and harms of the different management options for frostbite injuries.
Search methods:
On 25 February 2020, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R), Embase (OvidSP), ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED), Conference Proceedings Citation Index-Science (CPCI-S), as well as trials registers. Shortly before publication, we searched Clinicaltrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform, OpenGrey and GreyLit (9 November 2020) again. We investigated references from relevant articles, and corresponded with a trial author.
Selection criteria:
We included randomised controlled trials (RCTs) that compared any medical intervention, e.g. pharmacological therapy, topical treatments or rewarming techniques, for frostbite injuries to another treatment, placebo or no treatment.
Data collection and analysis:
Two authors independently extracted data. We used Review Manager 5 for statistical analysis of dichotomous data with risk ratio (RR) with 95% confidence intervals (CIs). We used the Cochrane 'Risk of bias' tool to assess bias in the included trial. We assessed incidence of amputations, rates of serious and non-serious adverse events, acute pain, chronic pain, ability to perform activities of daily living, quality of life, withdrawal rate from medical therapy due to adverse events, occupational effects and mortality. We used GRADE to assess the quality of the evidence.
Main results:
We included one, open-label randomised trial involving 47 participants with severe frostbite injuries. We judged this trial to be at high risk of bias for performance bias, and uncertain risk for attrition bias; all other risk of bias domains we judged as low. All participants underwent rapid rewarming, received 250 mg of aspirin and 400 mg intravascular (IV) buflomedil (since withdrawn from practice), and were then randomised to one of three treatment groups for the following eight days. Group 1 received additional IV buflomedil 400 mg for one hour per day. Group 2 received the prostacyclin, iloprost, 0.5 ng to 2 ng/kg/min IV for six hours per day. Group 3 received IV iloprost 2 ng/kg/min for six hours per day plus fibrinolysis with 100 mg recombinant tissue plasminogen activator (rtPA) for the first day only. The results suggest that iloprost and iloprost plus rtPA may reduce the rate of amputations in people with severe frostbite compared to buflomedil alone, RR 0.05 (95% CI 0.00 to 0.78; P = 0.03; very low-quality evidence) and RR 0.31 (95% CI 0.10 to 0.94; P = 0.04; very low-quality evidence), respectively. Iloprost may be as effective as iloprost plus rtPA at reducing the amputation rate, RR 0.14 (95% CI 0.01 to 2.56; P = 0.19; very low-quality evidence). There were no reported deaths or withdrawals due to adverse events in any of the groups; we assessed evidence for both outcomes as being of very low quality. Adverse events (including flushing, nausea, palpitations and vomiting) were common, but not reported separately by comparator arm (very low-quality evidence). The included study did not measure the outcomes of acute pain, chronic pain, ability to perform activities of daily living, quality of life or occupational effects.
Authors' conclusions:
There is a paucity of evidence regarding interventions for frostbite injuries. Very low-quality evidence from a single small trial indicates that iloprost, and iloprost plus rtPA, in combination with buflomedil may reduce the need for amputation in people with severe frostbite compared to buflomedil alone. However, buflomedil has been withdrawn from use. High quality randomised trials are needed to establish firm evidence for the treatment of frostbite injuries.
Ethnopharmacological relevance
The history of medical application of propolis (also known as bee glue) dates back to the times of ancient Greeks, Romans, Persians and Egyptians. Honey and other bee products, including propolis, occupy an important place in Polish folk medicine. Scientific research on propolis in Poland began in the early 1960s in Zabrze and continues until now.
Aim of the review
The aim of this review is to provide an overview of information on Polish research on propolis and its medical application with particular emphasis on studies concerning wound healing. Consequently, our goal is also to shed a new light on therapeutic potential of Polish propolis in order to support future research in the field.
Materials and Methods
A systematic review of scientific literature on propolis and its medical application was performed by using the literature databases (PubMed, Web of Science, Google Scholar). We paid special attention to papers describing the effect of propolis on skin wound healing as well as to Polish contribution to research on propolis.
Results
Professor Stan Scheller was the first Polish scientist dealing with propolis and its medical potential. His legacy was continued by several research teams that studied the topic in various aspects. They analysed propolis composition, its antioxidant, anti-inflammatory, antimicrobial, antiapoptotic and anticancer properties as well as its application in dentistry and wound treatment. Burn wound healing physiology after propolis administration was thoroughly studied on pig model, whereas research on patients proved the efficacy of propolis in chronic venous leg ulcer treatment.
Conclusion
Polish scientists have made a significant contribution to the research on propolis, its biological properties and influence on wound healing. Propolis ointments can effectively accelerate the healing process and improve healing physiology, so they can be recommended as a promising topical medication for wound treatment in the future clinical and preclinical trials.
Human skin possesses an essential function in the maintenance of individuals' health. However, it may undergo a variety of lesions that produce wounds of distinct severity. In this respect, instantly after any skin wound, the process of tissue regeneration and repair initiates. Nevertheless, diverse factors can delay this process, including bacterial infections, nutritional status, age, hypoxia, chronic diseases, necrosis, and vascular and arterial diseases. Thus, wound dressings are frequently used to improve wound healing. Those wound dressings are fabricated with diverse materials, which confer them different properties. In this regard, hyaluronic acid is a natural polysaccharide widely distributed in extracellular matrices of mammal tissues, which possesses remarkable attributes in terms of biocompatibility, biodegradability, and low cost. Moreover, hyaluronic acid exhibits several beneficial effects on wound healing, such as the decrease of inflammatory processes, regulation of tissue remodeling, and enhancement of angiogenesis. Therefore, in recent years, there is growing attention in this polysaccharide for the design and manufacture of novel wound dressings, which have shown encouraging properties. Here, we describe the different approaches of hyaluronic acid for the production of wound dressings, encompassing hydrogels, films, scaffolds, foams, topical formulations, and nanoformulations, as well as its beneficial effects on wound healing. Finally, we discuss perspectives about the use of hyaluronic acid in wound dressings.
AutoDock Vina, a new program for molecular docking and virtual screening, is presented. AutoDock Vina achieves an approximately two orders of magnitude speed-up compared with the molecular docking software previously developed in our lab (AutoDock 4), while also significantly improving the accuracy of the binding mode predictions, judging by our tests on the training set used in AutoDock 4 development. Further speed-up is achieved from parallelism, by using multithreading on multicore machines. AutoDock Vina automatically calculates the grid maps and clusters the results in a way transparent to the user.
We introduce two new computer models in which the influence of the finite potential mesh is, for most practical purposes, eliminated. The Quiet Particle-Mesh model (QPM) uses a Gaussian-shaped charge cloud and careful shaping of the potential solution in either real or transform space. The QPM model is measured to be 150 times less noisy than the conventional CIC model and is suitable for large collisionless plasma simulations with 105 or more particles. This is achieved at little or no cost in computing time. The hybrid Particle-Particle/Particle-Mesh model (PPPM), on the other hand, adds to the above mesh calculation contributions from nearby particles by direct summation. This model has a spatial resolution which is independent of the mesh spacing and may be a small fraction of a mesh cell. It is more time-consuming and is suitable for high-resolution sub-Debye length investigations with a smaller number of particles (∼104). Applied to molecular dynamics, the PPPM model can simulate systems with approximately 100 times the number of particles than conventional methods.
We describe the testing and release of AutoDock4 and the accompanying graphical user interface AutoDockTools. AutoDock4 incorporates limited flexibility in the receptor. Several tests are reported here, including a redocking experiment with 188 diverse ligand-protein complexes and a cross-docking experiment using flexible sidechains in 87 HIV protease complexes. We also report its utility in analysis of covalently bound ligands, using both a grid-based docking method and a modification of the flexible sidechain technique.
Cold exposure injuries comprise nonfreezing injuries that include chilblain (aka pernio) and trench, or immersion, foot, as well as freezing injuries that affect core body tissues resulting in hypothermia of peripheral tissues, causing frostnip or frostbite. Frostbite, the most serious peripheral injury, results in tissue necrosis from direct cellular damage and indirect damage secondary to vasospasm and arterial thromboses. The risk of frostbite is influenced by host factors, particularly alcohol use and smoking, and environmental factors, including ambient temperature, duration of exposure, altitude, and wind speed. Rewarming for frostbite should not begin until definitive medical care can be provided to avoid repeated freeze-thaw cycles, as these cause additional tissue necrosis. Rewarming should be rapid and for an affected limb should be performed by submersion in warm water at 104 degrees to 107.6 degrees F (40 degrees to 42 degrees C) for 15 to 30 minutes. Débridement of necrotic tissues is generally delayed until there is a clear demarcation from viable tissues, a process that usually takes from 1 to 3 months from the time of initial exposure. Immediate escharotomy and/or fasciotomy is necessary when circulation is compromised. In addition to the acute injury, frostbite is associated with late sequelae that include altered vasomotor function, neuropathies, joint articular cartilage changes, and, in children, growth defects caused by epiphyseal plate damage.
A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
Biocompatible stent coatings may alleviate problems of increased (sub)acute thrombosis after stent implantation. Hyaluronic acid (HA), a ubiquitous, nonsulfated glycosaminoglycan, inhibits platelet adhesion and aggregation and prolongs bleeding when administered systemically. However, the effects of immobilized HA for reducing stent platelet deposition in vivo are unknown. We therefore quantified the antithrombotic effects of coating stainless steel stents and tubes with HA using an established baboon thrombosis model under physiologically relevant blood flow conditions. HA-coated and uncoated (control) stents (3.5 mm in diameter, n=32) and stainless steel tubes (4.0 mm in diameter, n=18) were deployed into exteriorized arteriovenous shunts of conscious, nonanticoagulated baboons. Accumulation of (111)In-radiolabeled platelets was quantified by continuous gamma-camera imaging during a 2-hour blood exposure period. HA coating resulted in a significant reduction in platelet deposition in long (4 cm) tubes (0.24+/-0.15 x 10(9) versus 6.12+/-0.49 x 10(9) platelets; P<0.03), short (2 cm) stainless steel tubes (0.18+/-0.06 x 10(9) versus 3.03+/-0.56 x 10(9) platelets; P<0.008), and stents (0.82+/-0.20 x 10(9) versus 1.83+/-0. 23 x 10(9) platelets; P<0.02) compared with uncoated control devices. Thus, HA coating reduces platelet thrombus formation on stainless steel stents and tubes in primate thrombosis models. These results indicate that immobilized HA may represent an attractive strategy for improving the thromboresistance of endovascular devices.
HemCon bandage is an engineered chitosan acetate preparation used as a hemostatic control dressing, and its chemical structure suggests that it should also be antimicrobial. We tested its ability to rapidly kill bacteria in vitro and in mouse models of infected wounds. We used the Gram-negative species Pseudomonas aeruginosa and Proteus mirabilis and the Gram-positive Staphylococcus aureus that had all been stably transduced with the entire bacterial lux operon to allow in vivo bioluminescence imaging. An excisional wound in Balb/c mice was inoculated with 50-250 million cells followed after 30 min by application of HemCon bandage, alginate sponge bandage, silver sulfadiazine cream or no treatment. HemCon was more adhesive to the wound and conformed well to the injury compared to alginate. Animal survival was followed over 15 days with observations of bioluminescence emission and animal activity daily. Chitosan acetate treated mice infected with P. aeruginosa and P. mirabilis all survived while those receiving no treatment, alginate and silver sulfadiazine demonstrated 25-100% mortality. Chitosan acetate was much more effective than other treatments in rapidly reducing bioluminescence in the wound consistent with its rapid bactericidal activity in vitro as well as its light-scattering properties. S. aureus formed only non-lethal localized infections after temporary immunosuppression of the mice but HemCon was again more effective in reducing bioluminescence. The data suggest that chitosan acetate rapidly kills bacteria in the wound before systemic invasion can take place, and is superior to alginate bandage and silver sulfadiazine that may both encourage bacterial growth in the short term.
Complex polysaccharides, hyaluronic acid or hyaluronan (HA), keratan sulfate (KS), chondroitin sulfates (CSs) and heparin (Hep)/heparan sulfate (HS), are a class of ubiquitous molecules exhibiting a wide range of biological functions. They are widely distributed as glycosaminoglycans (GAGs) sidechains of proteoglycans (PGs) in the extracellular matrix and at cellular level. The recent emergence of improved enzymatic and analytical tools for the study of these complex sugars has produced a virtual explosion in the field of glycomics. In particular, the study of the GAG family of polysaccharides has shed considerable light on the way in which specific carbohydrate structures modulate cellular phenotypes. In addition to the well-known therapeutic applications of some of these macromolecules, such as HA and derivatives as structure modifying molecules and possessing gel-like properties able to provide functional support for tissues, Hep as an anticoagulant and antithrombotic drug and CS in the treatment of osteoarthritis (OA), this increased understanding of GAG structure-function relationship has led to the discovery of novel pharmaceuticals for the possible treatment of serious diseases, such as cancer. In this paper, the structure and the therapeutic applications of several complex natural polysaccharides, including HA, CS/DS, Hep and their derivatives, are presented and discussed also in the light of the many questions still left unanswered, such as improved preparation and GAG-based drugs with improved properties and new possible therapeutic applications.
Determination of minimum inhibitory concentrations
- J M Andrews
AutoDock vina: improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading
- O Trott
- A J Olson