A reappraisal of the role of cerium in burn wound management

A Bionic Self-Assembly Hydrogel Constructed by Peptides With Favorable Biosecurity, Rapid Hemostasis and Antibacterial Property for Wound Healing

Bionic self-assembly hydrogel derived by peptide as an effective biomedical hemostatic agent has always gained great attention. However, developing hydrogels with eminent-biosecurity, rapidly hemostatic and bactericidal function remains a critical challenge. Hence, we designed an injectable hydrogel with hemostatic and bactericidal function based on Bionic Self-Assembling Peptide (BSAP) in this study. BSAP was formed with two functionalized peptides containing (RADA)₄ motif and possessed the ability to self-assemble into nanofibers. As expected, BSAP could rapidly co-assemble into hydrogel network structure in situ driven by Ca²⁺. The hydrogel with a concentration of 5% showed a superior microporous structure and excellent shear thinning characteristics, as well as injectability. Moreover, in the foot trauma model and tail amputation model, the fabricated hydrogel exhibited a lower blood clotting index and dramatically reduced blood clotting time and bleeding volume. Remarkably, the hydrogel reduced inflammatory responses by blocking bacterial infection, promoting wound healing. Finally, the hydrogel is highly hemocompatible and has no cytotoxicity. Overall, this work provides a strategy for developing a high-biosecurity hydrogel with hemostatic and antibacterial properties, which will allow for the clinical application of BSAP.

Compounded Cerium Nitrate-Silver Sulfadiazine Cream is Safe and Effective for the Treatment of Burn Wounds: A Burn Center's Four-Year Experience

Wound infections and sepsis are significant causes of morbidity after burn injury and can be alleviated by early excision and grafting. In situations that preclude early surgery, topical agents allow for a safer delay. Cerium nitrate compounded with silver sulfadiazine (Ce-SSD) is a burn cream that provides broad antibacterial activity, forms a temporary barrier, and promotes re-epithelialization. Methemoglobinemia is a rare, but oft-cited, systemic complication of Ce-SSD. In this retrospective review, 157 patients treated with Ce-SSD between July 2014 - July 2018 were identified and the monitoring protocol for methemoglobinemia during Ce-SSD treatment was evaluated. Median age was 59 years (IQR, 47-70.5 years), with total body surface area burn (TBSA) of 8.5% (IQR, 3-27), adjusted Baux score of 76 (IQR, 59-94), and inhalation injury present in 9.9% of patients. Primary endpoints included incidence of symptomatic and asymptomatic methemoglobinemia. Of the 9.6% (n = 15) of patients with methemoglobinemia, 73.3% (n=11) had maximum methemoglobin levels ≥ 72 hours from time of first application. One patient developed clinically significant methemoglobinemia. Patients with TBSA ≥ 20% were more likely to develop methemoglobinemia (OR 9.318, 95% CI 2.078 to 65.73, p = 0.0078), however neither Ce-SSD doses nor days of exposure were significant predictors. Ce-SSD application to temporize burn wounds until excision and grafting is safe, effective, and, in asymptomatic patients with TBSA < 20%, can be used without serial blood gas monitoring. Vigilant monitoring for symptoms should be performed in patients with TBSA ≥ 20%, but routine blood gases are not necessary.

Interactions Between Hydrated Cerium(III) Cations and Carboxylates in an Aqueous Solution: Anomalously Strong Complex Formation with Diglycolate, Suggesting a Chelate Effect

Interactions between hydrated Ce3+ and various carboxylates are of fundamental interest. Anomalously strong interactions with Ce3+ occur when diglycolic acid (DGA) is added into a Ce3+ aqueous solution, unlike various other carboxylic acids. Herein, the complex-formation constants of Ce3+ with these acids are evaluated via absorption and emission spectra. Hydrated Ce3+ emits fluorescence with unity quantum yield; however, addition of various carboxylates statically quenches the fluorescence when Ce3+-carboxylate complexes form because the fluorescence lifetime is constant irrespective of the carboxylate concentration. In the observed static quenching, the complex-formation constants obtained from the absorption and emission spectra (K abs and K em) agree well. The binding of Ce3+ by the conjugate Lewis bases, i.e., carboxylates, is approximately inversely proportional to the pH. Adding DGA into the system also statically quenches the fluorescence, but far more efficiently, even in a much weaker solution. We rigorously deduce K abs and K em of Ce3+ with DGA without any approximation using comparable concentrations. Careful fittings provide equivalent K em and K abs values, and by varying the pH and ionic strength, we confirm that this equivalence is an inherent property of the Ce3+-DGA system. The Lewis acid-base theory cannot explain why DGA binds to Ce3+ ∼1000 times more strongly than the other carboxylates. This anomalously strong binding may be due to a chelate effect caused by the DGA's central oxygen atom, which forms a five-membered ring with the conjugate Lewis bases of DGA; double chelate rings can also form, while bis-deprotonated DGA binds to Ce3+, facilitated by the central oxygen. Therefore, DGA enables efficient quenching through the chelate effect when it binds to Ce3+.

Cerium Chloride Application Promotes Wound Healing and Cell Proliferation in Human Foreskin Fibroblasts

This study investigated the effect of cerium chloride (CeCl₃) on cell migration and gene expression of human foreskin fibroblasts (HFF). HFF were exposed to three different CeCl₃ solutions (1%, 5% and 10%, w/v %) for three different time durations (1, 5 and 10 min). 72 h after exposure to CeCl₃, cell viability was assessed by MTT test. A scratch-wounded assay determined the cell migration and the width of the wound, measured at 24 h. Gene expression patterns for cyclins B1, D1 and E1 were analyzed by RT-PCR (p < 0.05, t-test). The viability proliferation increased at 1- and 5-min exposures for all CeCl₃ concentrations, in contrast to no treatment (p < 0.05 at 24 h). No influence of CeCl₃ was found after 10 min. The scratch assay showed increased cell migration up to 60% at 1 and 5 min after 24 h at 5% and 10%. Cyclin B1, D1 and E1 all showed upregulation, confirming an increase in cell proliferation. This study demonstrates that exposure time and concentration of CeCl₃ may have a positive effect on fibroblast viability and migration. Application of CeCl₃ may be beneficial as a cell-stimulating agent leading to therapeutic tissue fibrosis or more resistant tissue around teeth, when warranted, during different periodontal therapies.

Silver in medicine: a brief history BC 335 to present

Silver is a naturally occurring element. Similar to other metals, the ionized form of silver (Ag(+1)) has known antimicrobial properties. A number of wound dressings incorporating silver ion or silver compounds have recently been developed and marketed. In addition, the antimicrobial effects of silver are currently being promoted in consumer products such as clothing and household appliances. The present use of silver in medical and consumer products has prompted concerns for potential toxicity and ecological effects, including induction of microbial resistance to antibiotics. These concerns ignore the fact that silver has been used for medicinal purposes for several thousand years. A historical review of the uses of silver in medicine is presented.

Effect of nanosilver on blood parameters in chickens having aflatoxicosis

This experiment is designed to investigate the positive effects of commercial nanosilver compound on blood parameters in experimental aflatoxicosis in broiler chickens. For this, 270 one-day-old broiler chickens were randomly divided into six treatment groups with three replicates. The experimental groups were group A: chickens fed with basal diet; group B: chickens fed with 3 ppm productive aflatoxin in basal diet; groups of C, D, E and F received Mycoad (2.5 g/kg diet), Mycoad (2.5 g/kg diet) + productive aflatoxin (3 ppm), Nanocid (2500 ppm), and Nanocid (2500 ppm) + productive aflatoxin (3 ppm) in basal diet, respectively. Results revealed that some of the blood parameters such as mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration lymphocytes, neutrophils, basophils, monocytes, and eosinophils percentage were not affected in this experiment; whereas, hemoglobin percentage and white blood cell (WBC) count in all the groups fed with 3 ppm aflatoxin except nanocid + aflatoxin decreased significantly ( p < 0.05). There are no significant differences between the groups that received nanocid + aflatoxin and mycoad + aflatoxin in hemoglobin percentage and WBC count parameters. The red blood cell count and hematocrit in chickens received aflatoxin were significantly lower than other groups ( p < 0.05). Therefore, this study suggests that nanocid similar as mycoad can be useful in reducing the adverse effects of aflatoxin on blood parameters in chickens affected with aflatoxicosis.

Computational study of the cerium(III) ion in aqueous environment

This work comprises the first quantum chemical simulation study of the Ce3+ ion in aqueous environment. The structural and dynamical properties have been investigated by means of the quantum mechanical charge field (QMCF) molecular dynamics (MD) approach and the results, where applicable, have been compared to experimental data. Besides conventional analytical tools, angular radial distribution functions have been employed to gain deeper insight into the structure of the hydrate. The ion-oxygen stretching motion's wavenumber, further characterising the Ce-O bond, is in excellent agreement with experimental results, same as the structural values obtained from the simulation.

Nanosilver effects on growth parameters in experimental aflatoxicosis in broiler chickens

Aflatoxicosis is a cause of economic losses in broiler production. In this study, the effect of one commercial nanocompound, Nanocid (Nano Nasb Pars Co., Iran) was evaluated in reduction of aflatoxin effects on the growth and performance indices in broiler chickens suffering from experimental aflatoxicosis. For this, a total of 300 one-day-old broiler chicks (Ross strain) were randomly divided into 4 groups with 3 replicates of 15 chicks in each separated pen during the 28-day experiment. Treatment groups including group A: chickens fed basal diet, group B: chickens fed 3 ppm productive aflatoxin in basal diet, group C: chickens fed basal diet plus 2500 ppm Nanocid, and group D: chickens fed 3 ppm productive aflatoxin and 2500 ppm Nanocid, in basal diet. Data on body weight, body weight gain (BWG), feed intake, and feed conversion ratio (FCR) were recorded at weekly intervals. Also cumulative data were assessed. Results showed, although supplement of Nanocid to conventional diet had no effect on performance but addition of Nanocid to diet containing 3 ppm aflatoxin increased significantly the cumulative BWG, cumulative feed consumption and decreased FCR in the last 2 weeks of experimental period. The improvement in these performance indices by supplement of Nanocid to diet containing aflatoxin showed the ability of Nanocid to diminish the inhibitory effects of aflatoxin.

Critical Observations on the Neurotoxicity of Silver

Silver is a xenobiotic element with no recognized trace metal value in the human body. It is absorbed into the body through the lungs, gastrointestinal tract, mucus membranes of the urinogenital tract, and through the skin, mainly in the form of silver protein complexes. Although silver is metabolized throughout the soft tissues, available evidence from experimental animal studies and human clinical reports has failed to unequivocally establish that it enters tissues of the central nervous system or is a cause of neurotoxic damage. Argyria characterized by deposition of particles of silver sulfide or silver selenide is the principle contraindication for using silver in medical devices or occupationally. This presents discoloration of the skin but is not regarded as a health risk or manifestation of toxicity. No evidence is available to demonstrate the toxic risk of silver to the peripheral nervous system, although silver sulfide deposits have been identified in the region of cutaneous nerves. Transitory silver sulfide deposits seen in the tissues of the blood-brain and blood-CSF barriers are mostly lysosomally bound or deposited on basement membranes or collagen without toxic effect. Silver is mostly excreted from the body in the urine and feces. Further research is indicated to evaluate the role of metal binding proteins including metallothioneins as cytoprotectants for neurological tissue.

Inhibitory effects of lanthanum chloride on extracellular matrix in injury tissues of rats

The propose of the present study is to investigate the effects of lanthanum chloride (LaCl(3)), a rare earth compound, on extracellular matrix molecules in rat wound tissues, hoping to provide a clue for further study in reducing excessive extracellular matrix formation in trauma and burn, as well as in fibrous disorders. In order to elucidate its action mechanism, we investigated its effects on fibroblast apoptosis, intracellular calcium, collagen synthesis and expression, and fibronectin mRNA expression. We found that treatment with 0.25 ml of 50 mM (1.5mg/injection) LaCl(3) for three consecutive days induced fibroblast apoptosis and inhibited collagen synthesis and expression. Comparing to control, at day 14 after wounding, apoptosis and the level of intracellular calcium in wound tissues were significantly increased, but at day 28 after wounding, apoptosis was not continually increased and gradually became normal. In contrast, the amount of (3)H-proline incorporation and the expression of type I and III collagen decreased at days 14 and 28 after wounding by LaCl(3)-treatment. The expression of fibronectin mRNA was not significant changed at days 14 and 28 after-wounding by LaCl(3)-treatment as compared to the control. The results suggest that LaCl(3) may reduce the extracellular matrix formation at certain concentrations during wound healing and be worth further study as an anti-fibrous agent. Because lanthanides have been used to clinical treatment with antibacterial agents in burn, it may be more suitable for the treatment of severe burn.

Pharmacological properties of cerium compunds

Cerium is a member of the lanthanide series or rare earth elements which exert diverse biological effects mainly by their resemblance to calcium. This similarity, which is particularly characteristic for the lighter members of the lanthanide series, enables these elements to replace calcium in biomolecules without necessarily substituting for it functionally. While the inhibitory effects on calcium-dependent physiological processes (such as those involved in the blood clotting cascade as well as in neuronal and muscular functions) are well-known, their relevance for the pharmacological properties of cerium are less clear. Historically, cerium oxalate was used as an antiemetic, especially in vomiting of pregnancy and kinetoses, although its mechanism of action has never been clarified. At present, cerium nitrate is available as an adjunct to silver sulfadiazine cream for the topical treatment of extensive burns not amenable to early wound excision. Apart from direct antiseptic effects, cerium helps to prevent postburn sepsis and systemic inflammatory response by fixing burn toxins. The antineoplastic potential of cerium compounds, which had fallen into oblivion, is currently being re-explored in experimental settings, though the mechanistic basis remains to be elucidated.

Plastic Surgery

The range of casualties treated by the Defence Medical Services in the recent Gulf conflict has reaffirmed the important role of plastic surgery within the military. This review seeks to highlight some areas of recent innovation and improvement within the realms of plastic surgery generally, of which some, such as the introduction of Flammacerium and the availability of skin substitutes, have direct military relevance.