Health professionals' recommendations on the use of fluoride varnish for caries prevention in preschool children.

BACKGROUND: Fluoride varnish (FV) is widely recommended for caries prevention in preschool children, despite its anticaries benefits being uncertain and modest. Dentists often report using clinical practice guidelines (CPGs) as a source of scientific information. AIM: To identify and analyze recommendations for clinical practice on the use of FV for caries prevention in preschool children and to assess the methodological quality of the CPG on this topic. DESIGN: Two researchers independently used 12 search strategies and searched the first five pages of Google Search™ and three guideline databases for recommendations freely available to health professionals on the use of FV for caries prevention in preschoolers. Then, they retrieved and recorded recommendations that met the eligibility criteria and extracted the data. A third researcher resolved disagreements. Each included CPG was appraised using the AGREE II instrument. RESULTS: Twenty-nine documents were included. Recommendations varied according to age, patients' caries risk, and application frequency. Of the six CPGs, only one scored above 70% in the AGREE II overall assessment. CONCLUSION: Recommendations on the use of FV lacked scientific evidence, and CPGs were of poor quality. Application of FV is widely recommended despite recent evidence showing an uncertain, modest, and possibly not clinically relevant anticaries benefit. Dentists should be aware that it is necessary to critically appraise CPGs since they may be of poor quality.

Adherence to Self-care and Quality of Life of Patients with Diabetic Foot Ulcers Treated with Low-Level Laser Therapy: An Exploratory Study.

OBJECTIVE: To evaluate the quality of life (QoL) of patients with a diabetic foot ulcer undergoing treatment with low-level laser therapy (LLLT) at 904 nm and its association with self-care. METHODS: In this randomized, exploratory study, participants were divided into the following four groups: control group (CG) with LLLT placebo, LLLT group 1 (LG1) at 10 J/cm2, LLLT group 2 (LG2) at 8 J/cm2, and LLLT group 3 (LG3) at 4 J/cm2. Participants received light therapy (or placebo) twice a week, for a total of 20 sessions. Researchers assessed participants' QoL using the Short-Form 36 questionnaire. RESULTS: Sixty-two participants were included in the analysis (CG = 18, LG1 = 14, LG2 = 17, LG3 = 13). The LG1 group showed a higher proportion of healing, whereas the CG group showed a lower proportion than the other groups. The LG1 group showed a relationship between physical limitations and blood glucose monitoring, pain and foot care, and general health status (GHS) and foot care. The GL2 group showed a relationship between physical limitations and blood glucose monitoring, vitality and foot care, and GHS and diet. CONCLUSIONS: Low-level laser therapy had a positive impact on QoL as assessed by the Short-Form 36 questionnaire (functional capacity, vitality, and pain domains), and there was a positive association between QoL and self-care in the LLLT groups (physical limitations, pain, GHS, and vitality domains).

Air velocity spatial variability in open Compost-Bedded Pack Barn system with positive pressure ventilation.

In Compost-Bedded Pack Barn (CBP) systems, air velocity is linked with the thermal comfort of housed dairy cattle and bedding quality and, therefore, assessing ventilation efficiency is essential. In this context, the objective of this study was to evaluate and characterize dependence and spatial distribution of air velocity at the 1.5 m height (vair,M) and at bedding level (vair,B) in an open CBP system with positive pressure ventilation. The study was conducted in 2021, in a facility located in the Zona da Mata region, Minas Gerais, Brazil. The facility area was divided into a mesh composed of 55 equidistant points, where vair,M and vair,B data were collected in the morning (09:00 a.m.) and afternoon (03:00 p.m.) periods, during three weeks in Brazilian winter. Geostatistics techniques were used to assess dependence and spatial distribution. In both periods evaluated, there were a strong occurrence of spatial dependence and non-uniform vair,M and vair,B distributions. The vair,M and vair,B values were lower than recommended (1.8 m∙s-1) in more than 65.0% of the area. Adequate ventilation levels were observed only in the first 20.0 m of the facility, from Southeast to Northwest, because of the fan lines present.

Acute and sub-acute toxicity study of ethanol extract from Nectandra leucantha Nees & Mart. (Lauraceae) barks.

Nectandra leucantha has been used in traditional medicine. Several metabolites isolated from N. leucantha extracts displayed immunomodulatory, antileishmanial properties, but the determination of the toxicological profile in mammals has not previously been performed. In this study, the ethanol extract from N. leucantha barks (EENl) was characterized by HPLC/HRESIMS. To study acute toxicity, female mice received EENl in a single dose of 100, 300, 1000, or 2000 mg/kg bw. Later, sub-acute toxicity was introduced in female and male mice by oral gavage at 100, 500 or 1000 mg/kg bw for 28 consecutive days. Hematological and biochemical profiles from the blood as well as histological analysis from the liver and kidney were performed. The HPLC/HRESIMS analysis of the EENl revealed the presence of six neolignans chemically related to dehydrodieugenol B. In the oral acute and sub-chronic studies, EENl did not produce in all doses evaluated any alteration in behavior, biochemical, hematological, body weight gain and food intake or sudden death in Swiss mice. In addition, histopathological data did not reveal any disturbance in liver and kidney morphology after 28 days of EENl treatment. Our results indicate that EENl at dosage levels up to 2000 mg/kg bw is non-toxic and can be considered safe for mammals.

Causal validation of the risk for corneal injury in critically ill adults.

BACKGROUND: The validity of a nursing diagnosis depends on a continuous investigation process in different populations to provide clinical evidence. The risk for corneal injury nursing diagnosis was approved in 2013 and only reviewed in 2017, demonstrating the need to perform a clinical validation to improve it. AIM: To perform a causal validation of the risk for corneal injury nursing diagnosis in critically ill adults. STUDY DESIGN: A prospective cohort study was performed in two intensive critical care units in Northern Brazil with adults aged over 18 years without corneal injury at admission. The patients were evaluated for 10 days, using a data collection tool composed of risk factors for the risk for corneal injury nursing diagnosis. The independent variables were described through absolute and relative frequency. The accuracy measures and risk factors were identified through Cox regression, considering a 95% confidence interval. RESULTS: The nurses assessed 209 critically ill adults and identified that 76.0% of them presented the risk for corneal injury nursing diagnosis, with 16.3% developing a corneal injury, all having previously presented the risk for corneal injury nursing diagnosis. The risk factors identified were eyeball exposure (hazard ratio: 1.78; 95% CI: 1.27-2.51), Glasgow score < 6 (hazard ratio: 1.73; 95% CI: 1.15-2.60) and periorbital oedema (hazard ratio: 1.43; 95% CI: 1.03-1.99), with these factors showing high specificity, and the mechanical ventilation variable, showing high sensitivity, with ROC curve of .86. CONCLUSION: Eyeball exposure, Glasgow score < 6 and periorbital oedema are the risk factors of the risk for corneal injury nursing diagnosis, in critically ill adults. These risk factors guide nursing interventions. This causal validation can improve the risk for corneal injury nursing diagnosis levels of evidence in the NANDA International Taxonomy. RELEVANCE TO CLINICAL PRACTICE: It is necessary to guide nursing interventions for critically ill adults with lowered level of consciousness and corneal exposure for the prevention of corneal injury.

Watermelon Reduces the Toxicity of Cisplatin Treatment in C57BL/6 Mice with Induced Melanoma.

An alternative to reduce the undesirable effects of antineoplastic agents has been the combination of classical treatments with nutritional strategies aimed at reducing systemic toxicity without decreasing the antitumor activity of already used drugs. Within this context, this study evaluated the possible reduction of toxicity when cisplatin treatment is combined with watermelon pulp juice supplementation in C57BL/6 mice with melanoma. Watermelon is a fruit rich in vitamins, minerals, proteins, lycopene, carotene, and xanthophylls, which has shown effectiveness in the treatment of cardiovascular diseases, weight loss, urinary infections, gout, hypertension, and mutagenicity. The following parameters were analyzed: animal survival, bone marrow genotoxicity, serum creatinine and urea, histopathological features of the tumor tissue, tumor weight and volume, and weight of non-tumor tissues (kidney, liver, spleen, heart, and lung). The results showed that watermelon had no antitumor effect but reduced the toxicity of cisplatin, as demonstrated by an increase in the number of bone marrow cells and a decrease in serum creatinine and urea levels. The data suggest that watermelon pulp juice can be an alternative for reducing the side effects of antineoplastic agents.

Immunoprophylactic properties of the Corynebacterium pseudotuberculosis-derived MBP:PLD:CP40 fusion protein.

Caseous lymphadenitis (CLA) is a disease that affects small ruminants, and the best way to prevent its spread on a herd is through immunoprophylaxis. Thus, we aimed to evaluate the MBP:PLD:CP40 fusion protein as a new CLA immunogen. The fusion protein was constructed by combining Corynebacterium pseudotuberculosis PLD and CP40 proteins with maltose-binding protein (MBP) as an intrinsic adjuvant. The antigenicity, allergenic potential, prediction of B epitopes, binding to MHC receptors, and docking on the Toll-Like 2 receptor were evaluated in silico. MBP:PLD:CP40 was expressed and purified. 40 BALB/c were divided into four groups (G1 - control, G2 - Saponin, G3 - MBP:PLD:CP40, and G4 - rPLD + rCP40). Total IgG, IgG1, and IgG2a were quantified, and the expressions of cytokines after splenocyte in vitro stimulation were assessed. Mice were challenged 42 days after the first immunization. The in silico analysis showed that MBP:PLD:CP40 has immunogenic potential, does not have allergic properties, and can dock on the TRL2 receptor. MBP:PLD:CP40 stimulated the production of IgG1 antibodies in a fivefold proportion to IgG2a, and TNF and IL-17 were significantly expressed in response to the antigenic stimuli. When rPLD and rCP40 were used together for immunization, they could induce IFN-γ and IL-12, but with no detectable antibody production. The G3 and G4 groups presented a survival of 57.14% and 42.86%, respectively, while the G1 and G2 mice were all dead 15 days after the challenge. MBP:PLD:CP40 partially protected the mice against C. pseudotuberculosis infection and can be considered a potential new CLA immunogen. KEY POINTS: • The fusion protein induced more IgG1 than IgG2a antibodies; • The fusion protein also induced the expression of the TNF and IL-17 cytokines; • Mice inoculated with MBP:PLD:CP40 presented a 57.14% survival.

Hypericin, a medicinal compound from St. John's Wort, inhibits genotoxicity induced by mutagenic agents in V79 cells.

This study evaluated the cytotoxic, genotoxic, and the modulatory effects on DNA damage of hypericin in Chinese hamster lung fibroblasts (V79 cells). The hypericin is a natural polycyclic quinone, mainly extracted from St. John's Wort (Hypericum perforatum L.). Along with hyperforin, the hypericins are responsible for the antidepressant activity of St. John's Wort. Cytotoxicity was assessed by the XTT colorimetric assay and the nuclear division index (NDI). The genotoxic activity was studied by the micronucleus test at concentrations of 30, 60, 120, and 240 µg/mL. Mutagenic agents, methyl methanesulfonate (MMS, 44 µg/mL), doxorubicin (DXR, 0.5 µg/mL), and etoposide (VP16, 1 µg/mL) were used in combination with different concentrations of hypericin in order to evaluate the modulatory effect on DNA damage. Results showed that the hypericin was cytotoxic at concentrations above 156.2 µg/mL and genotoxic above 120 µg/mL. The hypericin significantly reduced DNA damage frequency induced by DXR, at concentrations of 30 and 60 µg/mL, and MMS at a concentration of 30 µg/mL, but was unable to reduce damage when combined with VP-16. These results demonstrate the non-photoactivated hypericin toxicological safety limits, its protective effect on DNA damage and provide a basis for future studies that may characterize better its chemopreventive mechanism.

Neuroprotective Effect of 3-[(4-Chlorophenyl)selanyl]-1-methyl-1H-indole on Hydrogen Peroxide-Induced Oxidative Stress in SH-SY5Y Cells.

Extensive data have reported the involvement of oxidative stress in the pathogenesis of neuropsychiatric disorders, prompting the pursuit of antioxidant molecules that could become adjuvant pharmacological agents for the management of oxidative stress-associated disorders. The 3-[(4-chlorophenyl)selanyl]-1-methyl-1H-indole (CMI) has been reported as an antioxidant and immunomodulatory compound that improves depression-like behavior and cognitive impairment in mice. However, the exact effect of CMI on specific brain cells is yet to be studied. In this context, the present study aimed to evaluate the antioxidant activity of CMI in H2O2-induced oxidative stress on human dopaminergic neuroblastoma cells (SH-SY5Y) and to shed some light into its possible mechanism of action. Our results demonstrated that the treatment of SH-SY5Y cells with 4 µM CMI protected them against H2O2 (343 µM)-induced oxidative stress. Specifically, CMI prevented the increased number of reactive oxygen species (ROS)-positive cells induced by H2O2 exposure. Furthermore, CMI treatment increased the levels of reduced glutathione in SH-SY5Y cells. Molecular docking studies demonstrated that CMI might interact with enzymes involved in glutathione metabolism (i.e., glutathione peroxidase and glutathione reductase) and H2O2 scavenging (i.e., catalase). In silico pharmacokinetics analysis predicted that CMI might be well absorbed, metabolized, and excreted, and able to cross the blood-brain barrier. Also, CMI was not considered toxic overall. Taken together, our results suggest that CMI protects dopaminergic neurons from H2O2-induced stress by lowering ROS levels and boosting the glutathione system. These results will facilitate the clinical application of CMI to treat nervous system diseases associated with oxidative stress.

Komagataella pastoris KM71H modulates neuroimmune and oxidative stress parameters in animal models of depression: A proposal for a new probiotic with antidepressant-like effect.

Many studies have suggested that imbalance of the gut microbial composition leads to an increase in pro-inflammatory cytokines and promotes oxidative stress, and this are directly associated with neuropsychiatric disorders, including major depressive disorder (MDD). Clinical data indicated that the probiotics have positive impacts on the central nervous system and thus may have a key role to treatment of MDD. This study examined the benefits of administration of Komagataella pastoris KM71H (8 log UFC·g-1/animal, intragastric route) in attenuating behavioral, neurochemical, and neuroendocrine changes in animal models of depressive-like behavior induced by repeated restraint stress and lipopolysaccharide (0.83 mg/kg). We demonstrated that pretreatment of mice with this yeast prevented depression-like behavior induced by stress and an inflammatory challenge in mice. We believe that this effect is due to modulation of the permeability of the blood-brain barrier, restoration in the mRNA levels of the Nuclear factor kappa B, Interleukin 1ß, Interferon γ, and Indoleamine 2 3-dioxygenase, and prevention of oxidative stress in the prefrontal cortices, hippocampi, and intestine of mice and of the decrease the plasma corticosterone levels. Thus, we conclude that K. pastoris KM71H has properties for a new proposal of probiotic with antidepressant-like effect, arising as a promising therapeutic strategy for MDD.

Discovery of New Hits as Antitrypanosomal Agents by In Silico and In Vitro Assays Using Neolignan-Inspired Natural Products from Nectandra leucantha.

In the present study, the phytochemical study of the n-hexane extract from flowers of Nectandra leucantha (Lauraceae) afforded six known neolignans (1-6) as well as one new metabolite (7), which were characterized by analysis of NMR, IR, UV, and ESI-HRMS data. The new compound 7 exhibited potent activity against the clinically relevant intracellular forms of T. cruzi (amastigotes), with an IC50 value of 4.3 µM and no observed mammalian cytotoxicity in fibroblasts (CC50 > 200 µM). Based on the results obtained and our previous antitrypanosomal data of 50 natural and semi-synthetic related neolignans, 2D and 3D molecular modeling techniques were employed to help the design of new neolignan-based compounds with higher activity. The results obtained from the models were important to understand the main structural features related to the biological response of the neolignans and to aid in the design of new neolignan-based compounds with better biological activity. Therefore, the results acquired from phytochemical, biological, and in silico studies showed that the integration of experimental and computational techniques consists of a powerful tool for the discovery of new prototypes for development of new drugs to treat CD.

Structure-activity relationship study of cytotoxic neolignan derivatives using multivariate analysis and computation-aided drug design.

Dehydrodieugenol B and five related natural neolignans were isolated from the Brazilian plant species Nectandra leucantha. Three of these compounds were shown to be active against murine (B16F10) and human (A2058) melanoma cells but non-toxic to human fibroblasts (T75). These results stimulated the preparation of a series of 23 semi-synthetic derivatives in order to explore structure-activity relationships and study the biological potential of these derivatives against B16F10 and A2058 cell lines. These structurally-related neolignan derivatives were analyzed by multivariate statistics and machine learning, which indicated that the most important characteristics were related to their three-dimensional structure and, mainly, to the substituents on the neolignan skeleton. The results suggested that the presence of hydroxyl or alkoxyl groups at positions 3, 4 and 5 (with appropriate sidechains) promoted an increase in electropological and charge density, which seem to be important for biological activity against murine (B16F10) and human (A2058) melanoma cells.

Evaluation of the effect of synthetic compounds derived from azidothymidine on MDA-MB-231 type breast cancer cells.

The present study aimed to investigate the effect of AZT derivates containing tellurium (Te) on human breast cancer cell lines and the mechanisms underlying cell death. The inhibitory effect of AZT and its derivatives (7m and 7r) was determined by the MTT assay (6.25, 12.5, 25, 50 and 100 µM in 24 and 48 h time points), meanwhile the induction of apoptosis and the cell cycle phases was investigated by flow cytometry. The MTT assay showed that AZT derivatives decreased the rate of cell proliferation at concentrations of 12.5 µM, while commercial AZT showed low antitumor potential. In flow cytometric analysis, we demonstrate that the AZT derivatives do not induce apoptosis at the concentration tested and promote the cell cycle arrest in the S phase. Besides, predicted absorption, distribution, metabolization, excretion and toxicity analysis suggest that the compounds possess a good pharmacokinetic profile and possibly less toxicity when compared to conventional AZT. These compounds containing tellurium in their formulation are potential therapeutic agents for breast cancer.

Evaluation of antioxidant activity and toxicity of sulfur- or selenium-containing 4-(arylchalcogenyl)-1H-pyrazoles.

Pyrazoles represent a significant class of heterocyclic compounds that exhibit pharmacological properties. The present study aimed to investigate the antioxidant potential of pyrazol derivative compounds in brain of mice in vitro and the effect of pyrazol derivative compounds in the oxidative damage and toxicity parameters in mouse brain and plasma of mice. The compounds tested were 3,5-dimethyl-1-phenyl-4-(phenylselanyl)-1H-pyrazol (1a), 3,5-dimethyl-4-(phenylselanyl)-1H-pyrazole (2a), 4-((4-methoxyphenyl)selanyl)-3,5-dimethyl-1-phenyl-1H-pyrazole (3a), 4-((4-chlorophenyl)selanyl)-3,5-dimethyl-1-phenyl-1H-pyrazole (4a), 3,5-dimethyl-1-phenyl-4-(phenylthio)-1H-pyrazole (1b), 3,5-dimethyl-4-(phenylthio)-1H-pyrazole (2b), 4-((4-methoxyphenyl)thio)-3,5-dimethyl-1-phenyl-1H-pyrazole (3b), 4-((4-chlorophenyl)thio)-3,5-dimethyl-1-phenyl-1H-pyrazole (4b), and 3,5-dimethyl-1-phenyl-1H-pyrazole (1c). In vitro, 4-(arylcalcogenyl)-1H-pyrazoles, at low molecular range, reduced lipid peroxidation and reactive species in mouse brain homogenates. The compounds also presented ferric-reducing ability as well nitric oxide-scavenging activity. Especially compounds 1a, 1b, and 1c presented efficiency to 1,1-diphenyl-2-picryl-hydrazyl-scavenging activity. Compounds 1b and 1c presented 2,20 -azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)-scavenging activity. In vivo assays demonstrated that compounds 1a, 1b, and 1c (300 mg/kg, intragastric, a single administration) did not cause alteration in the of δ-aminolevulinic acid dehydratase activity, an enzyme that exhibits high sensibility to prooxidants situations, in the brain, liver, and kidney of mice. Compound 1c reduced per se the lipid peroxidation in liver and brain of mice. Toxicological assays demonstrate that compounds 1a, 1b, and 1c did not present toxicity in the aspartate aminotransferase, alanine aminotransferase, urea, and creatinine levels in the plasma. In conclusion, the results demonstrated the antioxidant action of pyrazol derivative compounds in in vitro assays. Furthermore, the results showed low toxicity of compounds in in vivo assays.

Fluoride Varnish and Dental Caries in Preschoolers: A Systematic Review and Meta-Analysis.

The aim of this study was to assess the effectiveness of fluoride varnish (FV) in reducing dentine caries at the patient, tooth, and surface levels as well as caries-related hospitalizations in preschoolers. We performed a systematic review of clinical trials of FV, alone or associated with an oral health program, compared with placebo, usual care, or no intervention. Bibliographical search included electronic searches of seven databases, registers of ongoing trials, and meeting abstracts, as well as hand searching. We performed random-effects meta-analyses and calculated confidence and prediction intervals. The search yielded 2,441 records; 20 trials were included in the review and 17 in at least one meta-analysis. Only one study had low risk of bias in all domains. We found no study reporting on caries-related hospitalizations. At the individual level, the pooled relative risk was 0.88 (95% confidence interval [CI] 0.81, 0.95); this means that in a population of preschool children with 50% caries incidence, we need to apply fluoride varnish in 17 children to avoid new caries in one child. At the tooth level, the pooled weighted mean difference was -0.30 (95% CI -0.69, 0.09) and at the surface level -0.77 (95% CI -1.23, -0.31). Considering the prediction intervals, none of the pooled estimates were statistically significant. We conclude that FV showed a modest and uncertain anticaries effect in preschoolers. Cost-effectiveness analyses are needed to assess whether FV should be adopted or abandoned by dental services.

Superparamagnetic Nanoparticles as High Efficiency Magnetic Resonance Imaging T2 Contrast Agent.

Nanoparticle-based magnetic resonance imaging T2 negative agents are of great interest, and much effort is devoted to increasing cell-loading capability while maintaining low cytotoxicity. Herein, two classes of mixed-ligand protected magnetic-responsive, bimetallic gold/iron nanoparticles (Au/Fe NPs) synthesized by a two-step method are presented. Their structure, surface composition, and magnetic properties are characterized. The two classes of sulfonated Au/Fe NPs, with an average diameter of 4 nm, have an average atomic ratio of Au to Fe equal to 7 or 8, which enables the Au/Fe NPs to be superparamagnetic with a blocking temperature of 56 K and 96 K. Furthermore, preliminary cellular studies reveal that both Au/Fe NPs show very limited toxicity. MRI phantom experiments show that r2/r1 ratio of Au/Fe NPs is as high as 670, leading to a 66% reduction in T2 relaxation time. These nanoparticles provide great versatility and potential for nanoparticle-based diagnostics and therapeutic applications and as imaging contrast agents.

Women's experience with contraception from the perspective of gender. / Vivência de mulheres quanto a contracepção na perspectiva de gênero.

OBJECTIVE: To analyse the experience of women with contraception from the perspective of gender. METHODS: Qualitative and exploratory-descriptive study conducted at three basic healthcare units in the city of Lagoa Seca - PB, Brazil, with 15 women interviewed between January and May 2013. The content analysis technique was used to process the data. RESULTS: Data analysis led to the core category 'women's contraceptive choices and their relationship with gender dynamics', that subsequently led to the subcategories 'unequal construction of gender identities in childhood and adolescence', 'outcome of gender dynamics in (contra)ception during adolescence', and ' medicalisation of the female body'. CONCLUSIONS: It was observed that the experience with contraception is related to the dynamics of gender, with the outcome of teenage pregnancy and the medicalization of the body.

Immunomodulatory and Antileishmanial Activity of Phenylpropanoid Dimers Isolated from Nectandra leucantha.

Three phenylpropanoid dimers (1-3) including two new metabolites were isolated from the extract of the twigs of Nectandra leucantha using antileishmanial bioassay-guided fractionation. The in vitro antiparasitic activity of the isolated compounds against Leishmania donovani parasites and mammalian cytotoxicity and immunomodulatory effects were evaluated. Compounds 1-3 were effective against the intracellular amastigotes within macrophages, with IC50 values of 26.7, 17.8, and 101.9 µM, respectively. The mammalian cytotoxicity, given by the 50% cytotoxic concentration (CC50), was evaluated against peritoneal macrophages. Compounds 1 and 3 were not toxic up to 290 µM, whereas compound 2 demonstrated a CC50 value of 111.2 µM. Compounds 1-3 also suppressed production of disease exacerbatory cytokines IL-6 and IL-10 but had minimal effect on nitric oxide production in L. donovani-infected macrophages, indicating that antileishmanial activity of these compounds is mediated via an NO-independent mechanism. Therefore, these new natural products could represent promising scaffolds for drug design studies for leishmaniasis.

A novel Bacillus pumilus-related strain from tropical landfarm soil is capable of rapid dibenzothiophene degradation and biodesulfurization.

BACKGROUND: The presence of organic sulfur-containing compounds in the environment is harmful to animals and human health. The combustion of these compounds in fossil fuels tends to release sulfur dioxide in the atmosphere, which leads to acid rain, corrosion, damage to crops, and an array of other problems. The process of biodesulfurization rationally exploits the ability of certain microorganisms in the removal of sulfur prior to fuel burning, without loss of calorific value. In this sense, we hypothesized that bacterial isolates from tropical landfarm soils can demonstrate the ability to degrade dibenzothiophene (DBT), the major sulfur-containing compound present in fuels. RESULTS: Nine bacterial isolates previously obtained from a tropical landfarm soil were tested for their ability to degrade dibenzothiophene (DBT). An isolate labeled as RR-3 has shown the best performance and was further characterized in the present study. Based on physiological aspects and 16 s rDNA sequencing, this isolate was found to be very closely related to the Bacillus pumillus species. During its growth, high levels of DBT were removed in the first 24 hours, and a rapid DBT degradation within the first hour of incubation was observed when resting cells were used. Detection of 2-hydroxybiphenyl (HBP), a marker for the 4S pathway, suggests this strain has metabolical capability for DBT desulfurization. The presence of MgSO4 in growth medium as an additional sulfur source has interfered with DBT degradation. CONCLUSIONS: To our knowledge, this is the first study showing that a Bacillus strain can metabolize DBT via the 4S pathway. However, further evidences suggest RR-3 can also use DBT (and/or its derivative metabolites) as carbon/sulfur source through another type of metabolism. Compared to other reported DBT-degrading strains, the RR-3 isolate showed the highest capacity for DBT degradation ever described in quantitative terms. The potential application of this isolate for the biodesulfurization of this sulfur-containing compound in fuels prior to combustion was discussed.

Biocatalytic response of multi-layer assembled collagen/hyaluronic acid nanoengineered capsules.

Biodegradable hollow capsules filled with fluorescently labelled bovine serum albumin (BSA) as a model drug were prepared via layer-by-layer (LbL) self-assembly of type-I collagen (COL) and hyaluronic acid (HA) using calcium carbonate micro-particles and co-precipitation method. Capsules loaded with fluorescein isothiocyanate (FITC)-BSA, tetramethylrhodamin isothiocyanate (TRITC)-BSA or Alex-Fluor-488-BSA, respectively, were characterised before and after core removal using Confocal Laser Scanning Microscopy (CLSM), whilst the morphologies of individual hollow capsules were assessed using Atomic Force Microscopy (AFM). The sustained release of the encapsulated FITC-BSA protein was attained using enzymatic degradation of the capsule shells by collagenase. The released profile of the fluorescently-labelled BSA indicated that it could be successfully controlled by modulating the number of layers and/or by collagen crosslinking either before or after the capsule's assembly.