Biosensitive and antibacterial coatings on metallic material for medical applications.

Metallic materials are commonly used for load-bearing implants and as internal fixation devices. It is customary to use austenitic stainless steel, especially surgical grade type 316L SS as temporary and Ti alloys as permanent implants. However, long-term, poor bonding with bone, corrosion, and release of metal ions, such as chromium and nickel occur. These ions are powerful allergens and carcinogens and their uncontrolled leaching may be avoided by surface coatings. Therefore, bioactive glasses (BGs) became a vital biomedical material, which can form a biologically active phase of hydroxycarbonate apatite on their surface when in contact with physiological fluids. To reduce the high coefficient of friction and the brittle nature of BGs, polymers are normally incorporated to avoid the high-temperature sintering/densification of ceramic-only coatings. For medical application, electrophoretic deposition (EPD) is now used for polymer (organic) and ceramic (inorganic) components at room temperature due to its simplicity, control of coating thickness and uniformity, low cost of equipment, ability to coat substrates of intricate shape and to supply thick films in composite form, high purity of deposits as well as no phase transformation during coating. Although extensive research has been conducted on polymer/inorganic composite coatings, only some studies have reported multifunctional properties, such as biological antibacterial activity, enhanced cell adhesion, controlled drug release ability, and mechanical properties. This review will focus on biodegradable coatings, including zien, chitosan, gelatin, cellulose loaded with antibacterial drugs/metallic ions/natural herbs on biostable substrates (PEEK/PMMA/PCL/PLLA layers), which have the potential of multifunctional coating for metallic implants.

Injectable and Radiopaque Liquid Metal/Calcium Alginate Hydrogels for Endovascular Embolization and Tumor Embolotherapy.

Improved endovascular embolization can contribute to assistant treatment for patients. However, many traditional embolic materials, such as metal microcoils or liquid embolic agents, are associated with limitations of coil migration or recanalization. Herein, as the first trial, an injectable and radiopaque liquid metal/calcium alginate (LM/CA) hydrogel is introduced and fabricated as a candidate for endovascular embolization and tumor embolotherapy through developing LM droplets as radiopaque units into biocompatible calcium alginate cross-linked network. The adoption of LM droplets makes hydrogels radiopaque under X-ray and CT scan, which significantly facilitates the tracking of material location during surgical vascular operation. In addition, in vitro and in vivo experiments prove that such smart hydrogel could convert from liquid to solid rapidly via cross-linking, showing pretty flexible and controllable functions. Benefiting from these properties, the hydrogel can be performed in blood vessels through injection via syringes and then served as an embolic material for endovascular embolization procedures. In vivo experiments demonstrate that such hydrogels can occlude arteries and block blood flow until they ultimately lead to ischemic necrosis of tumors and partial healthy tissues. Overall, the present LM/CA hydrogels are promising to be developed as new generation embolic materials for future tumor embolotherapy.

Revision total knee arthroplasty due to bone cement and metal hypersensitivity.

INTRODUCTION: Hypersensitivity to implants is a rare complication of total knee arthroplasty (TKA). Metal and, less frequently, bone cement can produce allergic symptomatology that if unresponsive to conservative treatment could lead to revision. MATERIALS AND METHODS: We present the case of a patient with generalized pruritus and metal taste starting during the first postoperative month after TKA. Dermal allergy exams revealed that the patient had hypersensitivity to nickel sulphate and cobalt chloride and bone cement. Conservative treatment with antihistamine medication and corticosteroids failed to control the symptoms. The patient underwent revision TKA with a hypoallergic prosthesis 8 months after the primary procedure. RESULTS: Full disappearance of the symptoms occurred 3 months after revision. The latest follow-up evaluation (3 years post-revision) was unremarkable. CONCLUSIONS: In our opinion, an exhaustive medical history should be obtained from every candidate for total joint replacement and in cases of prior severe allergic reactions to metals, plastics or glues, patch testing of the components of the future prosthesis should be done. When an already implanted prosthesis causes symptoms like pain, edema, pruritus, erythema, limited range of motion and increase in joint's temperature, the possibility of allergy to metals and/or bone cement (in case of cemented prosthesis) should be checked after the exclusion of other reasons like infection. If symptoms cannot be controlled by conservative measures, revision should be decided and carried out with hypoallergic prosthesis.

[Contact allergic gastritis : Rare manifestation of a metal allergy]. / Kontaktallergische Gastritis : Seltene Manifestation einer Metallallergie.

Only a few cases of contact allergic gastritis in patients with nickel allergy have been reported in the literature. We report a case of probable contact-allergic gastritis in a 46-year-old woman. Clinical examination revealed lichenoid mucosal lesions of the gums adjacent to a bridge and crowns that had been implanted several weeks previously. Since implantation, the patient suffered from gastrointestinal complaints including stomach pain. Gastroscopy and histological investigation of stomach biopsies showed eosinophilic gastritis. Patch testing done under the diagnosis of contact allergic stomatitis showed positive reactions to gold sodium thiosulphate, manganese (II) chloride, nickel (II) sulphate, palladium chloride, vanadium (III) chloride, zirconium (IV) chloride, and fragrances. The crowns and the bridge contained gold, palladium, and zirconium, hence they were replaced by titan-based dentition. Shortly after replacing the artificial dentition, all gastrointestinal symptoms resolved spontaneously without further treatment. Delayed-type allergy to components in the artificial dentition seem to have caused the gastritis.

The new nitinol conformable self-expandable metal stents for malignant colonic obstruction: a pilot experience as bridge to surgery treatment.

INTRODUCTION: Self-expandable metal stents (SEMS) are a nonsurgical option for treatment of malignant colorectal obstruction also as a bridge to surgery approach. The new nitinol conformable stent has improved clinical outcomes in these kinds of patients. We report a pilot experience with nitinol conformable SEMS placement as bridge to surgery treatment in patients with colorectal obstruction. MATERIALS AND METHODS: Between April and August 2012, we collected data on colonic nitinol conformable SEMS placement in a cohort of consecutive symptomatic patients, with malignant colorectal obstruction, who were treated as a bridge to surgery. Technical success, clinical success, and adverse events were recorded. RESULTS: Ten patients (7 male (70%)), with a mean age of 69.2±10.1, were evaluated. The mean length of the stenosis was 3.6±0.6 cm. Five patients (50%) were treated on an emergency basis. The median time from stent placement to surgery was 16 days (interquartile range 7-21). Technical and clinical success was achieved in all patients with a significant early improvement of symptoms. No adverse events due to the SEMS placement were observed. CONCLUSION: This pilot study confirmed the important role of nitinol conformable SEMS as a bridge to surgery option in the treatment of symptomatic malignant colorectal obstruction.

Exposure to metals premixed with microplastics increases toxicity through bioconcentration and impairs antioxidant defense and cholinergic response in a marine mysid.

Coexistence of metals and microplastics (MPs) in aquatic environments represents a growing concern; however, little is known regarding the risks associated with their combined effects. Here, the effects of five metals (As, Cd, Cu, Pb, and Zn), alone or combined with MPs for various premixing durations (30 and 60 days), on the juvenile and adult stages of the marine mysid Neomysis awatschensis were evaluated. The toxicity (50% lethal concentration for 96 h) and bioconcentration of metals premixed with MPs were measured, and their effects on the antioxidant defense and cholinergic systems were examined. Metal toxicity increased with increasing premixing period with MPs, and juveniles were more sensitive to exposure to metals premixed with MPs than adults. Metal bioconcentration in the mysid body increased following co-exposure with MPs. Metals premixed with MPs significantly increased intracellular malondialdehyde content at both stages but decreased glutathione content in juveniles. At both stages, catalase and superoxide dismutase activity was suppressed following co-exposure to metals and MPs, except under the Cu treatment. Moreover, co-exposure inhibited acetylcholinesterase activity at both stages, suggesting cholinergic impairment. Taken together, metals and MPs produce synergistic detrimental effects on marine mysids in a stage-specific manner. Further studies are warranted to elucidate the role of MPs as a vector for contaminants and stimulator of toxicity in aquatic organisms.

Titanates deliver metal ions to human monocytes.

Amorphous peroxotitantes (APT) are insoluble titanium-based particles that bind a variety of metal compounds with high affinity; these particles could be sequestered locally in a solid phase to deliver metal-based drugs. Previous studies have confirmed the 'biodelivery' of metals from metal-APT complexes to fibroblasts, but not monocytes. Our goal in the current study was to use monocytic cytokine secretion to assess delivery of gold or platinum-based compounds from APT to human THP1 monocytes. Cytokine secretion was not triggered by APT alone or metal-APT complexes. In monocytes activated by lipopolysaccharide (LPS), APT alone enhanced or suppressed IL1beta or IL6 secretion, yet TNFalpha secretion was unaffected. Complexes of APT and Au(III) or cis-platin altered LPS-activated IL6 or IL1beta secretion most, TNFalpha least. Our results suggest that the APT deliver metals to monocytes.

Nano-engineered delivery systems for cancer imaging and therapy: Recent advances, future direction and patent evaluation.

Cancer is the second highest cause of death worldwide. Several therapeutic approaches, such as conventional chemotherapy, antibodies and small molecule inhibitors and nanotherapeutics have been employed in battling cancer. Amongst them, nanotheranostics is an example of successful personalized medicine bearing dual role of early diagnosis and therapy to cancer patients. In this review, we have focused on various types of theranostic polymer and metal nanoparticles for their role in cancer therapy and imaging concerning their limitation, future application such as dendritic cell cancer vaccination, gene delivery, T-cell activation and immune modulation. Also, some of the recorded patent applications and clinical trials have been illustrated. The impact of the biological microenvironment on the biodistribution and accumulation of nanoparticles have been discussed.

Review of recent research on biomedical applications of electrospun polymer nanofibers for improved wound healing.

Wound dressings play an important role in a patient's recovery from health problems, as unattended wounds could lead to serious complications such as infections or, ultimately, even death. Therefore, wound dressings since ancient times have been continuously developed, starting from simple dressings from natural materials for covering wounds to modern dressings with functionalized materials to aid in the wound healing process and enhance tissue repair. However, understanding the nature of a wound and the subsequent healing process is vital information upon which dressings can be tailored to ensure a patient's recovery. To date, much progress has been made through the use of nanomedicine in wound healing due to the ability of such materials to mimic the natural dimensions of tissue. This review provides an overview of recent studies on the physiology of wound healing and various wound dressing materials made of nanofibers fabricated using the electrospinning technique.

Shear Bond Strength of Three Orthodontic Bonding Systems on Enamel and Restorative Materials.

Objective. The aim of this in vitro study was to determine the shear bond strength (SBS) and adhesive remnant index (ARI) score of two self-etching no-mix adhesives (iBond™ and Scotchbond™) on different prosthetic surfaces and enamel, in comparison with the commonly used total etch system Transbond XT™. Materials and Methods. A total of 270 surfaces (1 enamel and 8 restorative surfaces, n = 30) were randomly divided into three adhesive groups. In group 1 (control) brackets were bonded with Transbond XT primer. In the experimental groups iBond adhesive (group 2) and Scotchbond Universal adhesive (group 3) were used. The SBS was measured using a Zwicki 1120™ testing machine. The ARI and SBS were compared statistically using the Kruskal-Wallis test (P ≤ 0.05). Results. Significant differences in SBS and ARI were found between the control group and experimental groups. Conclusions. Transbond XT showed the highest SBS on human enamel. Scotchbond Universal on average provides the best bonding on all other types of surface (metal, composite, and porcelain), with no need for additional primers. It might therefore be helpful for simplifying bonding in orthodontic procedures on restorative materials in patients. If metal brackets have to be bonded to a metal surface, the use of a dual-curing resin is recommended.

The relationship between microbial metabolic activity and biocorrosion of carbon steel.

The effect of metabolic activity (expressed by generation time, rate of H2S production and the activity of hydrogenase and adenosine phosphosulphate (APS)-reductase enzymes) of the 8 wild strains of Desulfovibrio desulfuricans and of their resistance to metal ions (Hg2+, Cu2+, Mn2+, Zn2+, Ni2+, Cr3+) on the rate of corrosion of carbon steel was studied. The medium containing lactate as the carbon source and sulphate as the electron acceptor was used for bacterial metabolic activity examination and in corrosive assays. Bacterial growth inhibition by metal ions was investigated in the sulphate-free medium. The rate of H2S production was approximately directly proportional to the specific activities of the investigated enzymes. These activities were inversely proportional to the generation time. The rate of microbiologically induced corrosion (MIC) of carbon steel was directly proportional to bacterial resistance to metal ions (correlation coefficient r = 0.95). The correlation between the MIC rate and the activity of enzymes tested, although weaker, was also observed (r = 0.41 for APS-reductase; r = 0.69 for hydrogenase; critical value rc = 0.30, p = 0.05, n = 40).

The effect of some metal ions on the intradental sensory nerves of the cat.

Intradental nerve activity from canine teeth of anesthetized cats was recorded during the application of different metal ion solutions in a dentinal cavity. The application of Ag2+, Ca2+, Cd2+, Cr3+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+, Sn2+, and Zn2+ reduced the nerve activity induced by NaCl 0.76 M and compound 48/80. The application of Cu2+ and Co2+ excited the intradental sensory nerves.

Microprobe and SEM analysis of surface coatings on caries-like lesions in enamel after metal ion mordanting and APF application.

The production of tenacious surface coatings on enamel after metal ion mordanting followed by APF has been reported to prevent caries-like lesion initiation in vitro. In this study, similar surface coatings, which may be responsible for the inhibition of lesion progression, were examined using SEM and microprobe analysis. Relatively thick, even surface coatings which were in intimate contact with the enamel surface of caries-like lesions were seen after zirconium and iron (ferric) pre-treatment, but a thinner and unevenly distributed coating was seen after titanium pre-treatment. This latter coating was similar to that seen after APF treatment alone. Fluoride concentrations on the surface and in the subsurface of caries-like lesions were similar for all treatment groups. The surface coatings after zirconium and iron mordanting may be responsible for the greater inhibition of lesion progression than that seen after both titanium pre-treatment and APF treatment alone.

Response of L-929 fibroblasts, human gingival fibroblasts, and human tissue mast cells to various metal cations.

Recent data suggest that under certain conditions, various metal cations are released from dental alloys. These ions may produce adverse effects in various cell types in vivo. In this study, the cytopathogenic effects of 13 metal cations on murine L-929 fibroblasts, human gingival fibroblasts, and human tissue mast cells were analyzed in vitro. Several metal cations (dose range, from 0.0033 to 1.0 mmol/L) were found to induce dose-dependent inhibition of 3H-thymidine incorporation into cultured fibroblasts. The rank order of potency (lowest observed effect level, LOEL) for L-929 fibroblasts was: Ag+ > Pt4+ > Co2+ > In3+ > Ga3+ > Au3+ > Cu2+ > Ni2+ > Zn2+ > Pd2+ > Mo5+ > Sn2+ > Cr2+. A similar rank order of potency was obtained for primary human gingival fibroblasts: Pt4+ > Ag+ > Au3+ > In3+ > Ga3+ > Ni2+ > Co2+ > Zn2+ > Cu2+ > Cr2+ > Pd2+ > Mo5+ > Sn2+. In primary human mast cells, Ag+ and Au3+ caused dose-dependent toxic histamine release, whereas the other metal cations were ineffective over the dose range tested. To investigate the mechanism of metal cation-induced effects, we performed DNA as well as electron microscopic analyses on cultured fibroblasts. Both the DNA pattern and the ultrastructure of L-929 cells and gingival fibroblasts after exposure to cytopathogenic metal cations revealed signs of necrosis but no signs of apoptosis. Together, our data provide evidence that various metal cations produce dose-dependent cytopathogenic effects in distinct cell types, including human gingival fibroblasts and human tissue mast cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Potential efficacy of low metal diets and dental metal elimination in the management of atopic dermatitis: an open clinical study.

We performed an open clinical study on the effects of low metal diets and/or dental metal elimination on 27 patients with moderate to severe atopic dermatitis (AD), who showed positive patch tests for metal allergens and/or clinical exacerbation by oral provocation tests with metal salts. All the patients were recommended to ingest low metal diets for 3 months and/or undergo dental metal elimination. Marked or moderate improvement was noted in 18 patients (67%); 7 patients (26%) showed marked improvement and 11 patients (41%), moderate improvement. Nine patients (33%) showed minimal improvement or no change. In the patients who showed marked or moderate improvement, we observed statistically significant decreases (p < 0.05) in both peripheral blood eosinophil counts and serum LDH levels after 3 months of treatment. The present study suggests that restriction of ingested metal allergens to which patients have positive patch tests and/or oral challenge tests may be useful in the management of some patients with AD who have metal sensitivity.

Models for oral uptake of nanoparticles in consumer products.

Presently, many consumer products contain nano-sized materials (NMs) to improve material properties, product quality and ease of use. NMs in food additives and in cosmetic articles (e.g., tooth paste) may be taken up by the oral route. As adverse effects of environmental nanoparticles, like ultrafine particles, have been reported, consumers worry about potential risks when using products containing NMs. The review focuses on metal and metal oxide NMs as common additives in tooth paste and in food industry and exposure by the oral route. Testing of NMs for oral exposure is very complex because differences in the diet, in mucus secretion and composition, in pH, in gastrointestinal transit time and in gastrointestinal flora influence NM uptake. Acellular (mucus, saliva) and epithelial layer of the orogastrointestinal barrier are described. Expected exposure doses, interaction of the NMs with mucus and permeation through the epithelium as well as in vivo data are mentioned. The role of in vitro models for the study of parameters relevant for ingested NMs is discussed.

Fortnightly fluoride rinsing combined with topical painting of fluoride solutions containing Al-, Fe-, and Mn-ions.

The possibility of achieving a caries-reducing effect by a combination of fortnightly mouthrinsings with 0.2% NaF-solutions and topical painting with solutions containing Al-, Fe-, and Mn-ions was examined in a 4-year clinical study. In addition to the fluoride rinses one of two randomized groups was given three paintings per year with a 0.2% NaF-solution. The other group was painted three times per year with a potassium fluoride solution containing Al-, Fe-, and Mn-ions. This group developed significantly less caries during the study than the NaF-group. The results indicate that certain metal ions can enhance the caries-prophylactic action of the fluoride ions.

[Biotechnological and biomedical aspects of production and study of metal cation-phospholipid complexes]. / Biotekhnologicheskie i biomeditsinskie aspekty polucheniia i isslodovaniia kompleksov kation metalla-fosfolipid.

Problems relating to the technology of a phospholipid preparation from natural materials, liposome production, and studies into the mechanisms of interaction between metal (trace elements) cations and model bilayer lipid membranes are discussed. The proposed technology of extraction allows for preparation of phospholipids utilizable for liposome formation. The cation specificity of lipid bilayers is found to be determined by the presence of anionic phosphate adsorption sites on their surface.

Contrast enhancement of malignant tumors after intravenous polyvinylpyrrolidone with metallic salts as determined by computed tomography.

Rabbits with V2 carcinoma thigh implants received intravenous injections of solutions of polyvinylpyrrolidone (PVP) and metallic salts. This resulted in dense contrast enhancement of the carcinomas in some of the studies, as determined both by computed tomography (CT) and conventional radiography. The contrast enhancement lasted for several weeks, greatly facilitating tumor detection. The magnitude and duration of this contrast enhancement would be expected to improve CT detection of small lesions and to be useful in evaluating the efficacy of therapy.