Bioactive glasses as delivery systems for antimicrobial agents.

Most biomaterial-associated infections are caused by opportunistic pathogens and bacteria that are regularly found within the microflora of the implant site. In addition, a biomaterial implant or device remains at risk of infection by hematogenous spread of bacteria disseminated from infections elsewhere in the body or from infected peri-implant tissue in revision surgery. The resulting infections are frequently accompanied by patient morbidity and discomfort and can lead to surgical replacement of the implant after lengthy, unsuccessful attempts to mitigate infections with antibiotic treatments. Therefore, extensive study is aiming to find new infection-resistant antimicrobial biomaterials and coatings for implants and devices to effectively reduce the incidence of biomaterial-associated infections. An overview of the in vitro and in vivo antimicrobial efficacies of the numerous biomaterials currently available is beyond the scope of this review. Herein, we provide a comprehensive review of bioactive glasses as biomaterial delivery systems for antimicrobial agents.

Evaluation of antibacterial and cytotoxic effects of nano-sized bioactive glass/collagen composites releasing tetracycline hydrochloride.

AIMS: To evaluate the antibacterial efficacy of silicate bioactive glass nanoparticles/collagen composites functionalized with tetracycline hydrochloride (TCH). METHODS AND RESULTS: Different concentrations of tetracycline hydrochloride (TCH) were incorporated on silicate bioactive glass nanoparticles/collagen composites by dipping these biomaterials for 48 h at 37°C in a solution of simulated body fluid (SBF) plus 0·05, 0·20 or 0·35 mg ml(-1) of the antibiotic. TCH release was assessed in double-distilled water at 37°C up to 72 h. The antibacterial activity of the samples has been evaluated in two ways: inhibition zone test and plate count method. The experiments were performed in vitro up to 48 h on four staphylococci strains (Staphylococcus aureus ATCC29213, ATCC25923, ATCC6538P and Staphylococcus epidermidis ATCC12228). The new composites were also tested for cytotoxicity on MG-63 human osteosarcoma cells. The results showed that the incorporation and release of TCH was dependent on the initial concentration of TCH in SBF. The biomaterials also inhibited the Staph. aureus cell growth even though the efficacy was similar for all concentration. On the other hand, no cytotoxic effects were found on osteoblast-like cells, even at the highest concentration. CONCLUSIONS: Considering all results, it can be concluded that the new composite acts as a suitable bioactive carrier of TCH and could have potential in the prevention of biomaterial related infections. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest a potential application as wound dressing.

In vitro antistaphylococcal effects of a novel 45S5 bioglass/agar-gelatin biocomposite films.

AIMS: To assess the antibacterial efficacy of new composite materials developed from microparticles of 45S5 bioactive glass (BG) and agar-gelatin films. METHODS AND RESULTS: In vitro antibacterial activity was evaluated against Staphylococcus spp. because of the importance of this pathogen in damaged tissues and in failures associated with biomaterial implants. To our knowledge, this is the first paper reporting on the suitable combination of BG and agar-gelatin for bioactive and antibacterial films. Bacterial suspensions up or below 10(5) CFU ml(-1) reflecting situations of wound infection and of noninfection, respectively, were prepared and then put in contact with the biomaterials at 37°C. After 24 and 48 h of incubation, the pH value was measured and the staphylococci strains viability was determined by counting in Mueller-Hinton agar plates. Moreover, the biomaterials were prepared for observation under scanning electron microscopy (SEM). Biocomposites (BCs) showed a strong antibacterial effect against all staphylococci strains tested. Some differences were found depending on the strain, the inoculum size and the contact time. This effect was correlated with an alkalinization of the media. By SEM analyses, no bacterial presence was observed on the surface of BCs in any of the cell concentrations tested at any time. CONCLUSIONS: Overall, the coating of 45S5 BG on agar-gelatin films promoted BCs with strong antistaphylococcal activity. The effect was efficient under bacterial concentration up or below 10(5) CFU ml(-1). Additionally, none of the strains were found on BCs surfaces. SIGNIFICANCE AND IMPACT OF STUDY: 45S5 bioglass/agar-gelatin biocomposite films are reported for the first time. The results suggest a potential application as wound dressing.

Spectroscopic characterization of a VO2+ complex of oxodiacetic acid and its bioactivity on osteoblast-like cells in culture.

The oxovanadium(IV) complex of oxodiacetic acid (H2oda) of stoichiometry [VO(oda)(H2O)2], which presents an unprecedented tridentate OOO coordination, was thoroughly characterized by infrared, Raman, electronic, and electron paramagnetic resonance spectroscopies. The biological activity of the complex on the cell proliferation and differentiation was tested on osteoblast-like cells (MC3T3E1 osteoblastic mouse calvaria-derived cells and UMR106 rat osteosarcoma-derived cells) in culture. The complex caused inhibition of cellular proliferation in both osteoblast-like cells in culture, but the cytotoxicity was stronger in the normal (MC3T3E1) than in the tumoral (UMR106) osteoblasts. The effect of the complex in cell differentiation was tested through the specific activity of alkaline phosphatase of the UMR106 cells because they expressed a high activity of this enzyme. What occurs with other vanadium compounds [VO(oda)(H2O)2] is an inhibitory agent of osteoblast differentiation.

Cytotoxicity of a vanadyl(IV) complex with a multidentate oxygen donor in osteoblast cell lines in culture.

Strong chelating ligands as oxodiacetate (oda) are model systems to study the process of metal trapping by living organisms. Vanadium compounds display interesting biological and pharmacological actions. In vertebrates, vanadium is stored mainly in bones. In the present study we report the effects of the complex of oda with vanadyl(IV) cation, VO(oda), on two osteoblast cell lines, one normal (MC3T3E1) and the other tumoral (UMR106). VO(oda) exerted cytotoxic actions in osteoblasts as it was determined through a dose-dependent decrease in cell proliferation, and morphological and actin alterations. The putative mechanisms underlying VO(oda) deleterious effects were also investigated. The complex increased the level of ROS which correlated with a decreased in GSH/GSSG ratio. Besides, VO(oda) induced a dissipation of the mitochondria membrane potential (MMP) and promoted an increase in ERK cascade phosphorylation, which is involved in the regulation of cellular death and survival. All the effects were more pronounced in MC3T3-E1 than in UMR106 cells. ERK activation was inhibited by PD98059, Wortmanin and the ROS scavenger NAC (N-acetyl cysteine). These results suggest that VO(oda) stimulated ERKs phosphorilation by induction of free radicals involving kinases upstream of ERK pathway. The inhibitory effect of the complex on cell proliferation was partially reversed in both cell lines by NAC. Moreover, PD98059 and Wortmanin also partially reversed the inhibition of cell proliferation in the tumoral osteoblasts. The use of specific inhibitors and ROS scavengers suggested the involvement of oxidative stress, MMP alterations and ERK pathway in the apoptotic actions of this complex.

Spectroscopic behavior and biological activity of K3[VO(O2)2CO3]∙H2O.

The potassium salt of the carbonato oxodiperoxovanadate(V) complex, obtained by a known synthetic procedure, was thoroughly characterized by infrared, Raman, and electronic spectroscopy. The bioactivity of the complex on the cell proliferation was tested on osteoblast-like cells (MC3T3E1 osteoblastic mouse calvaria-derived cells and UMR106 rat osteosarcoma-derived cells) in culture. At low doses, the complex is more toxic for the nontransformed osteoblasts than for the tumoral ones, whereas at higher doses the deleterious effects are similar for both cell lines. This peroxo complex seems to be the most toxic compound that has so far been tested on osteoblast-like cells in culture.

[Distribution of hepatitis B antigen in Cordoba, Argentina]. / Distribución del antígeno de la hepatitis B en Córdoba, Argentina

This article presents the results obtained in the search for the hepatitis B antigen by the counter-immunoelectrophoresis technique in sera of more than 50.000 persons from Córdoba, Argentina. Groups of voluntary blood donors, general population, 20 years old army recruits, patients, with acute hepatitis and patients admitted to a hospital due to other diseases were included in this study. In the apparenly healthy population the positivity of the test ranged between 0.33 to 0.53 percent; the highest rate was found among the recruits. In the group of patients with acute hepatitis, 38.53% of the sera were positive. No statistically significant differences were observed in the monthly distribution of the hepatitis B antigen during the period of study. These results are compared with those found by other workers in different countries. This study shows the importance of the early detection of the hepatitis B antigen in blood donors, to reduce the incidence of hepatitis transmitted by transfusions. The importance of establishing centers for the standardization and control of reagents, as well as for the training of laboratory personnel is emphasized.

Distribución del antígeno de la hepatitis B en Córdoba, Argentina / [Distribution of hepatitis B antigen in Cordoba, Argentina]

This article presents the results obtained in the search for the hepatitis B antigen by the counter-immunoelectrophoresis technique in sera of more than 50.000 persons from Córdoba, Argentina. Groups of voluntary blood donors, general population, 20 years old army recruits, patients, with acute hepatitis and patients admitted to a hospital due to other diseases were included in this study. In the apparenly healthy population the positivity of the test ranged between 0.33 to 0.53 percent; the highest rate was found among the recruits. In the group of patients with acute hepatitis, 38.53

of the sera were positive. No statistically significant differences were observed in the monthly distribution of the hepatitis B antigen during the period of study. These results are compared with those found by other workers in different countries. This study shows the importance of the early detection of the hepatitis B antigen in blood donors, to reduce the incidence of hepatitis transmitted by transfusions. The importance of establishing centers for the standardization and control of reagents, as well as for the training of laboratory personnel is emphasized.

Distribución del antígeno de la hepatitis B en Córdoba, Argentina / [Distribution of hepatitis B antigen in Cordoba, Argentina]

This article presents the results obtained in the search for the hepatitis B antigen by the counter-immunoelectrophoresis technique in sera of more than 50.000 persons from Córdoba, Argentina. Groups of voluntary blood donors, general population, 20 years old army recruits, patients, with acute hepatitis and patients admitted to a hospital due to other diseases were included in this study. In the apparenly healthy population the positivity of the test ranged between 0.33 to 0.53 percent; the highest rate was found among the recruits. In the group of patients with acute hepatitis, 38.53

of the sera were positive. No statistically significant differences were observed in the monthly distribution of the hepatitis B antigen during the period of study. These results are compared with those found by other workers in different countries. This study shows the importance of the early detection of the hepatitis B antigen in blood donors, to reduce the incidence of hepatitis transmitted by transfusions. The importance of establishing centers for the standardization and control of reagents, as well as for the training of laboratory personnel is emphasized.