Mathematical modelling and kinetic study for CD production catalysed by Toruzyme® and CGTase from Bacillus firmus strain 37

A new mathematical model was developed for the kinetics of α-, β- and γ-cyclodextrin production, expanding an existing model that only included the production of β- and γ-cyclodextrins, because a detailed kinetic modelling of the reactions involved allows the manipulation of the process yields. The kinetic behaviour of the commercial enzyme Toruzyme^® was studied with maltodextrin as substrate at different concentrations and for CGTase from Bacillus firmus strain 37 at a concentration of 100 g L⁻¹. The mathematical model showed a proper fit to the experimental data, within the 24-h period studied, confirming that the considered hypotheses represent the kinetic behaviour of the enzymes in the reaction medium. The kinetic parameters generated by the model allowed reproducing previous observed qualitative tendencies as it can be seen that changing experimental conditions in the reaction process such as enzyme and substrate concentrations results in large changes in the enzyme kinetics and using high substrate concentrations does not guarantee the highest conversion rates due to enzyme inhibition and reverse reactions. In addition, this new mathematical model complements previous qualitative observations enabling the manipulation of the direct and reverse reactions catalysed by the enzyme by adjusting the reaction conditions, to target quantitative results of increased productivity and better efficiency in the production of a desired cyclodextrin.

     

Assessment of micronucleus frequency in normal oral mucosa of patients exposed to carcinogens

OBJECTIVE: To assess the presence of micronuclei in exfoliated oral mucosal cells collected from 3 anatomic sites in patients exposed to tobacco and alcohol. STUDY DESIGN: Smears were prepared with normal oral mucosal cells obtained from the lower lip, tongue border and floor of the mouth of 21 controls, 28 tobacco users and 19 tobacco/alcohol users. Slides were stained with Feulgen stain for quantification of micronucleated cells, karyorrhexis and "broken eggs." RESULTS: The groups were similar in terms of the mean number of micronucleated cells and cells undergoing karyorrhexis. In the comparison of anatomic sites, the mean number of cells undergoing karyorrhexis was higher on the lower lip than on the tongue border or floor of the mouth (all groups). A significantly higher number of broken eggs was observed in the control group when compared to the tobacco and tobacco/alcohol groups at all anatomic sites. CONCLUSION: The higher number of broken eggs in patients not exposed to tobacco and/or alcohol suggests that this nuclear alteration may be associated with DNA repair or a healthy mucosa. A trend toward an increased number of micronucleated cells was observed for tobacco and/or alcohol users at all anatomic sites.     

The interaction of Trichomonas vaginalis and Tritrichomonas foetus with epithelial cells in vitro

The Madin-Darby canine kidney epithelial cell line (MDCK) was used as a model for trichomonad-host cell interaction. Two laboratory strains of the human parasite Trichomonas vaginalis and the cattle's parasite Tritrichomonas foetus or their supernatants from axenic cultures were allowed to interact with confluent epithelial cultures. The interaction process studied by transmission and scanning electron microscopy revealed that both parasites adhere to monolayers through flagella, cell body and particularly for T. foetus, through the posterior projection of the axostyle. A close contact region between the trichomonad's surface and MDCK cells was observed. A study of the involvement of trichomonad surface component in the interaction process indicated that cytochalasin B treated-parasites adhere much less to epithelial monolayers than untreated parasites. Colchicine treatment did not affect such adhesion. Treatment of the parasites with trypsin reduced the adhesion of trichomonads to monolayers but did not interfere with the cytopathic effect. In contrast, treatment of the parasites with neuraminidase did not interfere with their adhesion to epithelial cells and the monolayer destruction was further increased.     

The finding of Enterobius vermicularis eggs in pre-Columbian human coprolites

Enterobius vermicularis eggs were found in human coprolites collected in the archaeological site of Caserones, Tarapaca Valley, Chile, dating from 400 BC to 800 AD. The human pinworm had already been found in other pre-historic archaeological sites in America, and its introduction in this continent is discussed.     

DNA barcode reveals candidate species of Scinax and Ololygon (Anura: Hylidae) in Atlantic Forest

Molecular species delimitation methods are efficient tools to identify species, including the discovery of new taxa and cryptic organisms, thus being useful to biodiversity studies. In the present work, 16S mitochondrial sequences and cytochrome oxidase I (COI) were used to evaluate the richness of species in the genus Scinax and Ololygon from a biodiversity hotspot in Atlantic Forest. A total of 109 specimens formally belonging to eight species of Scinax and three species of Ololygon were collected in 13 localities along the state of Bahia (northeastern Brazil) and one site in Espírito Santo (southeastern Brazil). Of the Scinax species collected in this study, three were morphologically differentiated from other described species and identified as putative new species (Scinax sp.1, Scinax sp.2 and Scinax sp.3). The species delimitations were inferred using three different methods: ABGD, PTP and mPTP which allowed recognizing 11 Scinax species and five Ololygon species. Scinax sp. 1, Scinax sp. 2 and Scinax sp. 3, have been confirmed as new putative species and Ololygon argyreornata possibly contains cryptic species. We suggest additional studies, including morphological and bioacoustic data to validate these new putative species.     

Control of the growth of Alicyclobacillus acidoterrestris in industrialized orange juice using rosemary essential oil and nisin

The use of rosemary essential oil (RO) and its combination with nisin (RO+N) in preventing the multiplication of Alicyclobacillus acidoterrestris in orange juice was evaluated. The minimum inhibitory and bactericidal concentrations (MIC and MBC) for RO were both 125 μg ml⁻¹ while RO+N displayed a synergistic effect. The use of RO and RO+N at concentrations of 1, 4 and 8× MIC in orange juice for 96 h was evaluated in terms of their sporicidal effectiveness. With regard to the action against A. acidoterrestris spores, RO at 8× MIC was sporostatic, whereas RO+N at 1× MIC was sporicidal. Morphological changes in the structure of the micro-organism after treatment were also observed by microscopy. Furthermore, flow cytometric analysis showed that most cells were damaged or killed after treatment. In general, the antioxidant activity after addition of RO+N decreased with time. The results demonstrate that using the combination of RO and nisin can prevent the A. acidoterrestris growth in orange juice.     

Abrolhos bank reef health evaluated by means of water quality, microbial diversity, benthic cover, and fish biomass data

The health of the coral reefs of the Abrolhos Bank (Southwestern Atlantic) was characterized with a holistic approach using measurements of four ecosystem components: (i) inorganic and organic nutrient concentrations, [1] fish biomass, [1] macroalgal and coral cover and (iv) microbial community composition and abundance. The possible benefits of protection from fishing were particularly evaluated by comparing sites with varying levels of protection. Two reefs within the well-enforced no-take area of the National Marine Park of Abrolhos (Parcel dos Abrolhos and California) were compared with two unprotected coastal reefs (Sebasti?o Gomes and Pedra de Leste) and one legally protected but poorly enforced coastal reef (the "paper park" of Timbebas Reef). The fish biomass was lower and the fleshy macroalgal cover was higher in the unprotected reefs compared with the protected areas. The unprotected and protected reefs had similar seawater chemistry. Lower vibrio CFU counts were observed in the fully protected area of California Reef. Metagenome analysis showed that the unprotected reefs had a higher abundance of archaeal and viral sequences and more bacterial pathogens, while the protected reefs had a higher abundance of genes related to photosynthesis. Similar to other reef systems in the world, there was evidence that reductions in the biomass of herbivorous fishes and the consequent increase in macroalgal cover in the Abrolhos Bank may be affecting microbial diversity and abundance. Through the integration of different types of ecological data, the present study showed that protection from fishing may lead to greater reef health. The data presented herein suggest that protected coral reefs have higher microbial diversity, with the most degraded reef (Sebasti?o Gomes) showing a marked reduction in microbial species richness. It is concluded that ecological conditions in unprotected reefs may promote the growth and rapid evolution of opportunistic microbial pathogens.     

The surface free energy of Leishmania mexicana amazonensis.

Surface charge of Leishmania mexicana amazonensis was investigated by direct zeta-potential determination and ultrastructural cytochemistry, and its surface tension was studied by measurements of the advancing contact angle formed by the parasite monolayers with drops of liquids of different polarities. Both virulent and avirulent promastigotes exhibited negatively charged surfaces with a zeta-potential of about -15 mV. Treatment of these cells with trypsin, alkaline phosphatase, or phospholipase C rendered their surfaces less negatively charged, whereas neuraminidase did not alter the parasite negativeness. Cytochemically, we could observe a reduction in the cationized ferritin binding after the parasite treatment with each of the former enzymes, but not with neuraminidase. The surface free energy of parasites was calculated by taken to account the London dispersion, the Keeson dipole-dipole, and the Debye dipole-induced forces, as well as the surface polarity of the parasites and their zeta-potentials, by considering their adhesion to polystyrene surfaces. The delta G values of -6.4 and -18.1 mJ.m-2 were obtained for avirulent and virulent promstigotes, respectively.     

Assessment of the efficacy of the utilisation of conventional and electric toothbrushes by the older adults

Objective: To evaluate the efficacy of electric and conventional toothbrushes for a group of elderly individuals. Background: Although the electric toothbrush has been recommended for elderly individuals, there had previously never been a study regarding its efficacy. Material and methods: Sixty independent elders of both genders with different oral conditions from the Center Adult Day Vitória, Espírito Santo, Brazil, were randomly divided into two groups of 30 individuals. One group received the Oral B CrossAction Power electric toothbrush, whereas the other received a conventional Bitufo Class 32 soft toothbrush to perform oral hygiene. The bacterial plaque index (O’Leary Plaque Index) and DMFT index were assessed as a measure of oral hygiene and oral health. The data were analysed using the Shapiro–Wilk, Mann–Whitney and Wilcoxon tests. Results: The results of the efficacy of the Oral B Cross Action Power electric toothbrush demonstrated that on the 7th and 15th days, the bacterial plaque indexes were 24.91 ± 12.81 and 22.11 ± 14.46, respectively, which corresponds to a 50.24% removal of bacterial plaque on the 7th and 55.83% on the 15th days. Although the electric toothbrush removed more bacterial plaque than the conventional toothbrush, the difference was not statistically significant. Conclusion: Both the conventional and the electric toothbrushes were effective in removing bacterial plaque within the elderly group. More studies are necessary to test the efficacy of electric toothbrushes in relation to conventional toothbrushes for elderly patients.