Vanessa J. S. V. Santos

Assessment of the genetic risks of a metallic alloy used in medical implants

The use of artificial implants provides a palliative or permanent solution for individuals who have lost some bodily function through disease, an accident or natural wear. This functional loss can be compensated for by the use of medical devices produced from special biomaterials. Titanium alloy (Ti-6Al-4V) is a well-established primary metallic biomaterial for orthopedic implants, but the toxicity of the chemical components of this alloy has become an issue of concern. In this work, we used the MTT assay and micronucleus assay to examine the cytotoxicity and genotoxicity, respectively, of an extract obtained from this alloy. The MTT assay indicated that the mitochondrial activity and cell viability of CHO-K1 cells were unaffected by exposure to the extract. However, the micronucleus assay revealed DNA damage and an increase in micronucleus frequency at all of the concentrations tested. These results show that ions released from Ti-6Al-4V alloy can cause DNA and nuclear damage and reinforce the importance of assessing the safety of metallic medical devices constructed from biomaterials.

Digoxin reduces the mutagenic effects of Mitomycin C in human and rodent cell lines

Abstract Digoxin is a drug widely used to treat heart failure and studies have demonstrated its potential as anticancer agent. In addition, digoxin presents the potential to interact with a series of other compounds used in medicine. The aim of the present study was to evaluate in vitro the cytotoxicity, genotoxicity and mutagenicity of digoxin and its potential to interact with the mutagen Mitomycin C (MMC). The cytotoxicity of digoxin was assessed by employing the MTT method and the comet assay was performed to assess the genotoxicity of this medicine in CHO-K1 and HeLa cell lines. Besides, the cytokinesis-block micronucleus assay was performed to assess the mutagenicity and the antimutagenicity of this drug. The Ames assay was also performed with TA98 and TA100 strains of S. typhimurium. Results showed that digoxin was cytotoxic, genotoxic and mutagenic for HeLa and CHO-K1 cell lines at concentrations many times higher than those observed in human therapeutic conditions. Nevertheless, an antimutagenic effect against the mutagen MMC was observed on both cell lines in concentrations near those used therapeutically in humans. This chemoprotective effect observed is an interesting finding that should be better explored regarding its impact in anticancer chemotherapy.

CHAPTER 9:Sucrose Chemistry

Sucrose, which is usually known as “table sugar”, is a carbohydrate that is the most abundant organic molecule produced at the industrial scale from renewable sources, and it is widely employed in the world of nutrition. Sucrose is a disaccharide formed by glycosidic ligation between two monosaccharides: glucose and fructose molecules with the molecular formula C12H22O11. Carbohydrates constitute the main source of energy for life, and sucrose is a fundamental food for human nutrition. Indeed, sucrose is one of the most important components in the food industry. In this context, it is important to note the relevant role of inverted sugar, a mixture of glucose and fructose that is obtained by splitting the glycosidic bond of sucrose. Sugestao para remocao Sucrose is an extraordinarily nutritious constituent of a great number of foods. However, its ingestion is a public health problem associated with diabetes, obesity and other chronic healthy difficulties that has motivated studies on this highly relevant carbohydrate. Furthermore, there are several aspects related to the structure-function relationship of carbohydrates with a special emphasis on the sucrose structure, which remains unresolved. In fact, the tendency of carbohydrates to form isomers is an interesting structural property that significantly affects their activities. Thus, research studies focused on sucrose chemistry and the employment of “sugar substitutes” in the food industry are necessary for the improvement of general health conditions for the worlds population.

Evaluation of the Structure-Activity Relationship of Hemoproteins through Physicochemical Studies: Hemoglobins as a Prototype of Biosensor

In the present work, we have studied a group of prerequisites in terms of “structurefunction relationship” of hemoproteins, especially hemoglobins, emphasizing the role of the heme and its chemical environment in the biochemical and physicochemical properties of the biomolecule. We have discussed the ferrous center and its properties as coordination center; the macrocyclic ligands, especially the porphyrins; the esterochemical and electronic properties of the iron-porphyrins (heme groups); and the interaction between heme groups and globins, which is related to several redox and oligomeric properties of hemoprotein systems and its potential applications with respect to novel materials. One of the main uses of hemoglobins in new materials is also discussed, which is its employment as a biosensor. Therefore, we have discussed the development of novel biosensors based on hemoglobins and their physicochemical properties as well as on the main molecules of biological relevance that have been detected by these biosensors, such as hydrogen peroxide (H2O2), nitric oxide (NO), and cholesterol, among others. Indeed, several important biomolecules and biological processes can be detected and/or evaluated by devices that present hemoglobins as leading chemical components. Different apparatus are covered with respect to distinct characteristics, such as chemical stability, sensitivity, selectivity, reproducibility, durability, optimum conditions of measurements, etc. and their respective characteristics are analyzed.

CHAPTER 2:The Biological Roles of Calcium: Nutrition, Diseases and Analysis

Calcium is an alkaline-earth metal with atomic number 20 and the fifth most abundant element by mass in the Earths crust, being one component of several common mineral salts. This mineral is important in plant physiology as well as to several metabolic and cellular functions of the human organism, as well as to the formation of bone tissues. Insufficient calcium intake may lead to the development of osteoporosis. On the other hand, the excessive ingestion of calcium increases the risk for renal calculus and intestinal constipation. The presence of calcium in the blood is regulated by vitamin D and by the hormones calcitonin and parathormone.

CHAPTER 29:Sucrose Determination by Raman Spectroscopy

Raman spectroscopy is one of the most versatile instrumental techniques currently used for structural characterisation. Although Raman spectroscopy is well-known as a powerful technique for the structural characterisation of several chemical compounds, its applications in the biomedical engineering field have increased significantly in recent years. Indeed, because of the identification of various fingerprint peaks, this technique can be employed for the biochemical analysis of several biological compounds and is commonly applied to diagnosis. In this context, Raman spectroscopy has been successfully used as an important tool for the determination of food contents. Spectral profiles of sucrose in different commercial forms are discussed in the present chapter as well as the employment of vibrational techniques to quantitative and physico-chemical analyses to obtain a well-defined characterisation of sucrose.

CHAPTER 6:Galactose Chemistry

Galactose is an important monosaccharide containing six carbons. It possesses a carbonyl group at its extremity, which characterises the molecule as an aldose. This sugar can be found linked to a glucose residue by a β(1-4) glycosidic bond in the structure of the disaccharide lactose, a sugar that is naturally present in milk. D-galactose is an epimer of D-glucose, and these monosaccharides only differ stereochemically because of the configuration of their hydroxyl groups at C-4. Monosaccharides in aqueous solutions are generally observed in the ring structure, and D-galactose, like other aldohexoses, can be present in the anomeric form α or β, which is based on the position of the OH group in the anomeric carbon (C-1). In equilibrated aqueous solutions, α-D-galactopyranose and β-D-galactopyranose are prevalent, which indicates that the pyran ring is more common in this sugar. Different chemical reactions can be performed with D-galactose. The oxidation of this monosaccharide in different manners can produce several products, such as D-galactonic acid, D-galactaric acid and D-galacturonic acid. Reduction of D-galactose produces D-galactitol, and this process can, for instance, occur in individuals with galactosaemia and cause eye cataracts.