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Lordelo R, Branco R, Gama F, Morais PV. Assessment of antimicrobial resistance, biofilm formation, and surface modification potential in hospital strains of Pseudomonas aeruginosa and Klebsiella pneumoniae. Heliyon 2024; 10:e30464. [PMID: 38711646 PMCID: PMC11070870 DOI: 10.1016/j.heliyon.2024.e30464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/12/2024] [Accepted: 04/26/2024] [Indexed: 05/08/2024] Open
Abstract
The occurrence of healthcare-associated infections is a multifactorial phenomenon related to hospital space contamination by bacteria. The ESKAPE group, specifically Pseudomonas aeruginosa and Klebsiella pneumoniae, play a relevant role in the occurrence of these infections. Therefore, comprehensive research is needed to identify characteristics that justify the prevalence of these species in the healthcare environment. In this line, the study aimed to determine the antimicrobial resistance, biofilm formation, and the potential for polymer degradation in a collection of 33 P. aeruginosa strains and 2 K. pneumoniae strains sampled from various equipment and non-critical surfaces in a Portuguese hospital. Antimicrobial susceptibility tests revealed that none of the strains was categorized as multidrug-resistant (non-MDR). An assessment of their biofilm-forming capabilities indicated that 97 % of the strains exhibited biofilm-producing characteristics. Notably, within this group, the majority of P. aeruginosa and half of K. pneumoniae strains were classified as strong biofilm producers. Furthermore, the strains were evaluated for their potential to cause damage or change medical devices, namely infusion sets, nasal cannula, and urinary catheters. Three P. aeruginosa strains, two strong and one moderate biofilm producers, showed the highest ability to modify surfaces of the nasal cannula and infusion sets. Additionally, the Chi-square test revealed a statistically significant relationship between the presence of P. aeruginosa strains and the water accession spots. In conclusion, this work suggests that bacteria from this group hold a significant ability to grow in the healthcare environment through the degradation of non-critical materials. This suggests a potential concern for the persistence and proliferation of these organisms in hospital environments, emphasizing the importance of robust infection control measures to mitigate the risks associated with bacterial growth on such surfaces.
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Affiliation(s)
- Roberta Lordelo
- University of Coimbra, Centre for Mechanical Engineering Material and Processes, ARISE, Department of Life Sciences, Coimbra, Portugal
| | - Rita Branco
- University of Coimbra, Centre for Mechanical Engineering Material and Processes, ARISE, Department of Life Sciences, Coimbra, Portugal
| | - Fernando Gama
- Health Sciences Research Unit: Nursing (UICISA: E), Portugal and Health School of the Polytechnic Institute of Viseu, Portugal
| | - Paula V. Morais
- University of Coimbra, Centre for Mechanical Engineering Material and Processes, ARISE, Department of Life Sciences, Coimbra, Portugal
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Vaz LM, Branco R, Morais PV, Guiomar AJ. Sterilized Polyhexanide-Releasing Chitosan Membranes with Potential for Use in Antimicrobial Wound Dressings. Membranes (Basel) 2023; 13:877. [PMID: 37999363 PMCID: PMC10673555 DOI: 10.3390/membranes13110877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/26/2023] [Accepted: 11/03/2023] [Indexed: 11/25/2023]
Abstract
Wound infection is a common complication of chronic wounds. It can impair healing, which may not occur without external help. Antimicrobial dressings (AMDs) are a type of external help to infected chronic wounds. In this study, highly porous membranes made of only chitosan and containing the antiseptic polyhexanide (poly(hexamethylene biguanide); PHMB) were prepared by cryogelation, aiming to be used in AMDs. These membranes exhibited a water swelling capacity of 748%, a water drop penetration time of 11 s in a dry membrane and a water vapor transmission rate of 34,400 g H2O/m2/24 h when in contact with water. The best drug loading method involved simultaneous loading by soaking in a PHMB solution and sterilization by autoclaving, resulting in sterilized, drug-loaded membranes. When these membranes and a commercial PHMB-releasing AMD were assayed under the same conditions, albeit far from the in vivo conditions, their drug release kinetics were comparable, releasing PHMB for ca. 6 and 4 h, respectively. These membranes exhibited high antibacterial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are bacterial species commonly found in infected wounds and blood clotting activity. The obtained results suggest that these membranes may have potential for use in the development of AMDs.
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Affiliation(s)
- Luís M. Vaz
- Chemical Process Engineering and Forest Products Research Centre, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal;
| | - Rita Branco
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal; (R.B.); (P.V.M.)
| | - Paula V. Morais
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal; (R.B.); (P.V.M.)
| | - António Jorge Guiomar
- Chemical Process Engineering and Forest Products Research Centre, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal;
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Wang Y, Branco R, Penzel T, Schoebel C. Effects of sacubitril-valsartan initiation on sleep apnea in chronic heart failure. Sleep Med 2022. [DOI: 10.1016/j.sleep.2022.05.669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Rito B, Almeida D, Coimbra C, Vicente D, Francisco R, Branco R, Weigand H, Morais PV. Post-measurement compressed calibration for ICP-MS-based metal quantification in mine residues bioleaching. Sci Rep 2022; 12:16007. [PMID: 36163387 PMCID: PMC9512927 DOI: 10.1038/s41598-022-19620-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
Bioleaching is an actual economical alternative to treat residues, which allows, depending on the chosen strategy, two possible outcomes: (1) a leachate enriched with target metals, or (2) a residue enriched in target metals through the leaching of interfering components (IC). This work aimed to study the metals released by bioprocessing the Panasqueira mine tailings, as a strategy to increase critical metals' relative concentration in residues. Biostimulation of the local microbiota was compared to a bioaugmentation approach using the autochthonous Diaphorobacter polyhydroxybutyrativorans strain B2A2W2. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was selected to study the metals released in the leachate through multi-element external standards. A new data treatment method was developed to use a preliminary sweep of intensities to quantify the non-initial target metals concentration in the leachate, based on preliminary ICP-MS intensity measurements. The results demonstrated that biostimulation was an efficient bioleaching strategy for the IC silicon, aluminium, magnesium, selenium, manganese, zinc, iron, and copper, by decreasing concentration, resulting in a relative increase in the gallium and yttrium (10x) levels in the treated residue. The strategy followed to quantify a large number of elements with ICP-MS using a reduced number of data points for calibration proved valid and speeded up the analytical process.
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Affiliation(s)
- Beatriz Rito
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Diogo Almeida
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal.,School of Chemistry, University of St. Andrews, Fife, Scotland, UK
| | - Carina Coimbra
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Diogo Vicente
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Romeu Francisco
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Rita Branco
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Harald Weigand
- Competence Centre for Sustainable Engineering and Environmental Systems, THM University of Applied Sciences, Wiesenstr. 14, 35390, Giessen, Germany
| | - Paula Vasconcelos Morais
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal.
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Chung AP, Francisco R, Morais PV, Branco R. Genome mining to unravel potential metabolic pathways linked to gallium bioleaching ability of bacterial mine isolates. Front Microbiol 2022; 13:970147. [PMID: 36188007 PMCID: PMC9518604 DOI: 10.3389/fmicb.2022.970147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Gallium (Ga) is considered a high-tech Critical Metal, used in the manufacture of several microelectronic components containing either gallium arsenide (GaAs) or gallium nitride (GaN). The current high demand for this critical metal urges the development of effective recovery processes from secondary resources such as mine tailings or electronic recycling material. The importance of bioleaching as a biotechnological process to recover metals prompted this study, where an integrative approach combining experimental and genomic analysis was undertaken to identify potential mechanisms involved in bioleaching ability and strategies to cope with high metal(loid)s concentrations in five mine isolates. The Clusters of Orthologous Group (COG) annotation showed that the “amino acid transport and metabolism” [E] was the most predominant functional category in all genomes. In addition, the KEEG pathways analysis also showed predicted genes for the biosynthetic pathways of most amino acids, indicating that amino acids could have an important role in the Ga leaching mechanism. The presence of effective resistance mechanisms to Ga and arsenic (As) was particularly important in GaAs bioleaching batch assays, and might explain the divergence in bioleaching efficiency among the bacterial strains. Rhodanobacter sp. B2A1Ga4 and Sphingomonas sp. A2-49 with higher resistance, mainly to As, were the most efficient bioleaching strains under these conditions. In bioleaching assays using cell-free spent medium Arthrobacter silviterrae A2-55 with lower As resistance outperformed all the other stains. Overall, higher efficiency in Ga leaching was obtained in bioleaching assays using GaAs when compared to GaN.
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Paula CT, Madeira AB, Pereira P, Branco R, Morais PV, Coelho JF, Fonseca AC, Serra AC. ROS-degradable PEG-based wound dressing films with drug release and antibacterial properties. Eur Polym J 2022. [DOI: 10.1016/j.eurpolymj.2022.111447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Lordelo R, Botelho JRS, Morais PV, de Sousa HC, Branco R, Dias AMA, Reis MS. Evaluation of the Microbiological Effectiveness of Three Accessible Mask Decontamination Methods and Their Impact on Filtration, Air Permeability and Physicochemical Properties. Int J Environ Res Public Health 2022; 19:ijerph19116567. [PMID: 35682153 PMCID: PMC9180249 DOI: 10.3390/ijerph19116567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/16/2022]
Abstract
The need to secure public health and mitigate the environmental impact associated with the massified use of respiratory protective devices (RPD) has been raising awareness for the safe reuse of decontaminated masks by individuals and organizations. Among the decontamination treatments proposed, in this work, three methods with the potential to be adopted by households and organizations of different sizes were analysed: contact with nebulized hydrogen peroxide (H2O2); immersion in commercial bleach (NaClO) (sodium hypochlorite, 0.1% p/v); and contact with steam in microwave steam-sanitizing bags (steam bag). Their decontamination effectiveness was assessed using reference microorganisms following international standards (issued by ISO and FDA). Furthermore, the impact on filtration efficiency, air permeability and several physicochemical and structural characteristics of the masks, were evaluated for untreated masks and after 1, 5 and 10 cycles of treatment. Three types of RPD were analysed: surgical, KN95, and cloth masks. Results demonstrated that the H2O2 protocol sterilized KN95 and surgical masks (reduction of >6 log10 CFUs) and disinfected cloth masks (reduction of >3 log10 CFUs). The NaClO protocol sterilized surgical masks, and disinfected KN95 and cloth masks. Steam bags sterilized KN95 and disinfected surgical and cloth masks. No relevant impact was observed on filtration efficiency.
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Affiliation(s)
- Roberta Lordelo
- Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal; (R.L.); (R.B.)
| | - José Rafael S. Botelho
- Chemical Process Engineering and Forest Products Research Centre (CIEPQPF), Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, Pólo II—Pinhal de Marrocos, 3030-790 Coimbra, Portugal; (J.R.S.B.); (H.C.d.S.); (A.M.A.D.)
| | - Paula V. Morais
- Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal; (R.L.); (R.B.)
- Correspondence: (P.V.M.); (M.S.R.)
| | - Hermínio C. de Sousa
- Chemical Process Engineering and Forest Products Research Centre (CIEPQPF), Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, Pólo II—Pinhal de Marrocos, 3030-790 Coimbra, Portugal; (J.R.S.B.); (H.C.d.S.); (A.M.A.D.)
| | - Rita Branco
- Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal; (R.L.); (R.B.)
| | - Ana M. A. Dias
- Chemical Process Engineering and Forest Products Research Centre (CIEPQPF), Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, Pólo II—Pinhal de Marrocos, 3030-790 Coimbra, Portugal; (J.R.S.B.); (H.C.d.S.); (A.M.A.D.)
| | - Marco S. Reis
- Chemical Process Engineering and Forest Products Research Centre (CIEPQPF), Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, Pólo II—Pinhal de Marrocos, 3030-790 Coimbra, Portugal; (J.R.S.B.); (H.C.d.S.); (A.M.A.D.)
- Correspondence: (P.V.M.); (M.S.R.)
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Sardinha Abrantes S, Branco R, Landim E, Souto Miranda M, Costa A, Nazaré A. 202 Acute postpartum pulmonary edema – A case report. Eur J Obstet Gynecol Reprod Biol 2022. [DOI: 10.1016/j.ejogrb.2021.11.064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Caldeira JB, Chung AP, Piedade AP, Morais PV, Branco R. A DedA Family Membrane Protein in Indium Extrusion in Rhodanobacter sp. B2A1Ga4. Front Microbiol 2021; 12:772127. [PMID: 34925279 PMCID: PMC8679861 DOI: 10.3389/fmicb.2021.772127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/20/2021] [Indexed: 01/27/2023] Open
Abstract
Indium (In) is a critical metal widely used in electronic equipment, and the supply of this precious metal is a major challenge for sustainable development. The use of microorganisms for the recovery of this critical high-tech element has been considered an excellent eco-friendly strategy. The Rhodanobacter sp. B2A1Ga4 strain, highly resistant to In, was studied in order to disclose the bacterial mechanisms closely linked to the ability to cope with this metal. The mutation of the gene encoding for a DedA protein homolog, YqaA, affected drastically the In resistance and the cellular metabolic activity of strain Rhodanobacter sp. B2A1Ga4 in presence of this metal. This indicates that this protein plays an important role in its In resistance phenotype. The negative impact of In might be related to the high accumulation of the metal into the mutant cells showing In concentration up to approximately 4-fold higher than the native strain. In addition, the expression of the yqaA gene in this mutant reverted the bacterial phenotype with a significant decrease of In accumulation levels into the cells and an increase of In resistance. Membrane potential measurements showed similar values for native and mutant cells, suggesting that there was no loss of proton-motive force in the mutant cells. The results from this study suggest a potential role of this DedA family protein as a membrane transporter involved in the In efflux process. The mutant strain also has the potential to be used as a biotool in bioaccumulation strategies, for the recovery of In in biomining activities.
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Affiliation(s)
- Joana B Caldeira
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Coimbra, Portugal
| | - Ana Paula Chung
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Coimbra, Portugal
| | - Ana Paula Piedade
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Mechanical Engineering, Coimbra, Portugal
| | - Paula V Morais
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Coimbra, Portugal
| | - Rita Branco
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Coimbra, Portugal
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Santos MRE, Mendonça PV, Branco R, Sousa R, Dias C, Serra AC, Fernandes JR, Magalhães FD, Morais PV, Coelho JFJ. Light-Activated Antimicrobial Surfaces Using Industrial Varnish Formulations to Mitigate the Incidence of Nosocomial Infections. ACS Appl Mater Interfaces 2021; 13:7567-7579. [PMID: 33538168 DOI: 10.1021/acsami.0c18930] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Evidence has shown that hospital surfaces are one of the major vehicles of nosocomial infections caused by drug-resistant pathogens. Smart surface coatings presenting multiple antimicrobial activity mechanisms have emerged as an advanced approach to safely prevent this type of infection. In this work, industrial waterborne polyurethane varnish formulations containing for the first time cationic polymeric biocides (SPBs) combined with photosensitizer curcumin were developed to afford contact-active and light-responsive antimicrobial surfaces. SPBs were prepared by atom transfer radical polymerization, which allows control over the polymer features that influence antimicrobial efficiency (e.g., molecular weight), while natural curcumin was employed to impart photodynamic activity to the surface. Antibacterial testing against Gram-negative Escherichia coli revealed that glass surfaces coated with the new formulations displayed photokilling effect under white-light (42 mW/cm2) irradiation within only 15 min of exposure. In addition, it was observed a combined antimicrobial effect between the two biocides (cationic SPB and curcumin), with a higher reduction in the number of viable bacteria observed for the surfaces containing cationic SPB/curcumin mixtures in comparison with the one obtained for surfaces only with polymer or without biocides. The waterborne industrial varnish formulations allowed the formation of homogeneous films without the need for addition of a coalescing agent, which can be potentially applied in diverse surface substrates to reduce bacterial transmission infections in healthcare environments.
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Affiliation(s)
- Madson R E Santos
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - Patrícia V Mendonça
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - Rita Branco
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Ruben Sousa
- LEPABE Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Carla Dias
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - Arménio C Serra
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - José R Fernandes
- Centre for Chemistry, Vila Real (CQVR), Physics Department, School of Science and Technology (ECT), University of Trás-dos-Montes e Alto Douro, 5000-801 Vila Real, Portugal
| | - Fernão D Magalhães
- LEPABE Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Paula V Morais
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Jorge F J Coelho
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
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Caldeira JB, Morais PV, Branco R. Exploiting the biological response of two Serratia fonticola strains to the critical metals, gallium and indium. Sci Rep 2020; 10:20348. [PMID: 33230153 PMCID: PMC7683552 DOI: 10.1038/s41598-020-77447-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 11/10/2020] [Indexed: 12/30/2022] Open
Abstract
The use of microorganisms that allows the recovery of critical high-tech elements such as gallium (Ga) and indium (In) has been considered an excellent eco-strategy. In this perspective, it is relevant to understand the strategies of Ga and In resistant strains to cope with these critical metals. This study aimed to explore the effect of these metals on two Ga/In resistant strains and to scrutinize the biological processes behind the oxidative stress in response to exposure to these critical metals. Two strains of Serratia fonticola, A3242 and B2A1Ga1, with high resistance to Ga and In, were submitted to metal stress and their protein profiles showed an overexpressed Superoxide Dismutase (SOD) in presence of In. Results of inhibitor-protein native gel incubations identified the overexpressed enzyme as a Fe-SOD. Both strains exhibited a huge increase of oxidative stress when exposed to indium, visible by an extreme high amount of reactive oxygen species (ROS) production. The toxicity induced by indium triggered biological mechanisms of stress control namely, the decrease in reduced glutathione/total glutathione levels and an increase in the SOD activity. The effect of gallium in cells was not so boisterous, visible only by the decrease of reduced glutathione levels. Analysis of the cellular metabolic viability revealed that each strain was affected differently by the critical metals, which could be related to the distinct metal uptakes. Strain A3242 accumulated more Ga and In in comparison to strain B2A1Ga1, and showed lower metabolic activity. Understanding the biological response of the two metal resistant strains of S. fonticola to stress induced by Ga and In will tackle the current gap of information related with bacteria-critical metals interactions.
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Affiliation(s)
- Joana B Caldeira
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Paula V Morais
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Rita Branco
- University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
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Abstract
Vanadium is a transition metal that has been added recently to the EU list of Raw Critical Metals. The growing needs of vanadium primarily in the steel industry justify its increasing economic value. However, because mining of vanadium sources (i. e. ores, concentrates and vanadiferous slags) is expanding, so is vanadium environmental contamination. Bioleaching comes forth as smart strategy to deal with supply demand and environmental contamination. It requires organisms that are able to mobilize the metal and at the same time are resistant to the leachate generated. Here, we investigated the molecular mechanisms underlying vanadium resistance in Ochrobactrum tritici strains. The highly resistant strain 5bvl1 was able to grow at concentrations > 30 mM vanadate, while the O. tritici type strain only tolerated < 3 mM vanadate concentrations. Screening of O. tritici single mutants (chrA, chrC, chrF and recA) growth during vanadate exposure revealed that vanadate resistance was associated with chromate resistance mechanisms (in particular ChrA, an efflux pump and ChrC, a superoxide dismutase). We also showed that sensitivity to vanadate was correlated with increased accumulation of vanadate intracellularly, while in resistant cells this was not found. Other up-regulated proteins found during vanadate exposure were ABC transporters for methionine and iron, suggesting that cellular responses to vanadate toxicity may also induce changes in unspecific transport and chelation of vanadate.
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Affiliation(s)
- Mariana Cruz Almeida
- CEMMPRE, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Rita Branco
- CEMMPRE, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Paula V. Morais
- CEMMPRE, Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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Coimbra C, Branco R, Morais PV. Efficient bioaccumulation of tungsten by Escherichia coli cells expressing the Sulfitobacter dubius TupBCA system. Syst Appl Microbiol 2019; 42:126001. [PMID: 31326140 DOI: 10.1016/j.syapm.2019.126001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 07/05/2019] [Accepted: 07/09/2019] [Indexed: 01/30/2023]
Abstract
Tungsten (W) is a valuable element with considerable industrial and economic importance that belongs to the European Union list of critical metals with a high supply risk. Therefore, the development of effective and new methods for W recovery is essential to ensure a sustainable supply. In the present study, the Sulfitobacter dubius W transport system TupABC was explored in order to demonstrate both its functionality in Escherichia coli cells and to construct a bioaccumulator (EcotupW). The complete gene cluster tupBCA or partial gene cluster tupBC were cloned in an expression vector and transformed into E. coli. Metal accumulation was evaluated when each construct strain was grown with three separate metal oxyanions (tungstate, molybdate or chromate). The specificity of the bioaccumulator was determined by competition assays using cells grown with mixed solutions of metal oxyanions (W/Mo and W/Cr). The results showed the relevance of the TupA protein in the TupABC transporter system to W-uptake and also allowed Mo and Cr accumulations, although with amounts 1.7 and 2.9-fold lower than W, respectively. To identify the importance of the valine residue in the accumulation efficiency of the VTTS motif, site-directed mutagenesis of tupA was performed. A mutant with a threonine residue, instead of the respective valine, confirmed that W was internalized by nearly double the amount compared to the native form. The findings indicated that cells carrying the native S. dubius TupABC system were great W-bioaccumulators and could be promising tools for W recovery.
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Affiliation(s)
- C Coimbra
- CEMMPRE - Center of Mechanical Engineering, Materials and Processes, University of Coimbra, Coimbra, 3030-788, Portugal
| | - R Branco
- CEMMPRE - Center of Mechanical Engineering, Materials and Processes, University of Coimbra, Coimbra, 3030-788, Portugal; Department of Life Sciences, University of Coimbra, Coimbra, 3001-401, Portugal.
| | - P V Morais
- CEMMPRE - Center of Mechanical Engineering, Materials and Processes, University of Coimbra, Coimbra, 3030-788, Portugal; Department of Life Sciences, University of Coimbra, Coimbra, 3001-401, Portugal
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Santos MRE, Mendonça PV, Almeida MC, Branco R, Serra AC, Morais PV, Coelho JFJ. Increasing the Antimicrobial Activity of Amphiphilic Cationic Copolymers by the Facile Synthesis of High Molecular Weight Stars by Supplemental Activator and Reducing Agent Atom Transfer Radical Polymerization. Biomacromolecules 2019; 20:1146-1156. [PMID: 29969557 DOI: 10.1021/acs.biomac.8b00685] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Infections caused by bacteria represent a great motif of concern in the health area. Therefore, there is a huge demand for more efficient antimicrobial agents. Antimicrobial polymers have attracted special attention as promising materials to prevent infectious diseases. In this study, a new polymeric system exhibiting antimicrobial activity against a range of Gram-positive and Gram-negative bacterial strains at micromolar concentrations (e.g., 0.8 μM) was developed. Controlled linear and star-shaped copolymers, comprising hydrophobic poly(butyl acrylate) (PBA) and cationic poly(3-acrylamidopropyl)trimethylammonium chloride) (PAMPTMA) segments, were obtained by supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) at 30 °C. The antibacterial activity of the polymers was studied by varying systematically the molecular weight (MW), hydrophilic/hydrophobic balance, and architecture. The MW was found to exert the greatest influence on the antimicrobial activity of the polymers, with minimum inhibitory concentration values decreasing with increasing MW. Live/dead membrane integrity assays and scanning electron microscopy analysis confirmed the bactericidal character of the synthesized PAMPTMA- (b)co-PBA polymers.
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Affiliation(s)
- Madson R E Santos
- Department of Chemical Engineering, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3030-790 , Portugal
| | - Patrícia V Mendonça
- Department of Chemical Engineering, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3030-790 , Portugal
| | - Mariana C Almeida
- Department of Life Sciences, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3001-401 , Portugal
| | - Rita Branco
- Department of Life Sciences, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3001-401 , Portugal
| | - Arménio C Serra
- Department of Chemical Engineering, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3030-790 , Portugal
| | - Paula V Morais
- Department of Life Sciences, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3001-401 , Portugal
| | - Jorge F J Coelho
- Department of Chemical Engineering, CEMMPRE, Centre for Mechanical Engineering, Materials and Processes , University of Coimbra , Coimbra 3030-790 , Portugal
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Branco R, Silva J, Ferreira JM, Costa J, Capela C, Berto F, Santos L, Antunes F. Fatigue behaviour of maraging steel samples produced by SLM under constant and variable amplitude loading. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.prostr.2020.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Coimbra C, Farias P, Branco R, Morais PV. Tungsten accumulation by highly tolerant marine hydrothermal Sulfitobacter dubius strains carrying a tupBCA cluster. Syst Appl Microbiol 2017; 40:388-395. [DOI: 10.1016/j.syapm.2017.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 06/13/2017] [Accepted: 06/25/2017] [Indexed: 10/19/2022]
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Santos MRE, Fonseca AC, Mendonça PV, Branco R, Serra AC, Morais PV, Coelho JFJ. Recent Developments in Antimicrobial Polymers: A Review. Materials (Basel) 2016; 9:ma9070599. [PMID: 28773721 PMCID: PMC5456892 DOI: 10.3390/ma9070599] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 07/01/2016] [Accepted: 07/14/2016] [Indexed: 12/12/2022]
Abstract
Antimicrobial polymers represent a very promising class of therapeutics with unique characteristics for fighting microbial infections. As the classic antibiotics exhibit an increasingly low capacity to effectively act on microorganisms, new solutions must be developed. The importance of this class of materials emerged from the uncontrolled use of antibiotics, which led to the advent of multidrug-resistant microbes, being nowadays one of the most serious public health problems. This review presents a critical discussion of the latest developments involving the use of different classes of antimicrobial polymers. The synthesis pathways used to afford macromolecules with antimicrobial properties, as well as the relationship between the structure and performance of these materials are discussed.
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Affiliation(s)
- Madson R E Santos
- CEMUC, Department of Chemical Engineering, University of Coimbra, Coimbra 3030-790, Portugal.
| | - Ana C Fonseca
- CEMUC, Department of Chemical Engineering, University of Coimbra, Coimbra 3030-790, Portugal.
| | - Patrícia V Mendonça
- CEMUC, Department of Chemical Engineering, University of Coimbra, Coimbra 3030-790, Portugal.
| | - Rita Branco
- CEMUC, Department of Life Sciences, University of Coimbra, Coimbra 3001-401, Portugal.
| | - Arménio C Serra
- CEMUC, Department of Chemical Engineering, University of Coimbra, Coimbra 3030-790, Portugal.
| | - Paula V Morais
- CEMUC, Department of Life Sciences, University of Coimbra, Coimbra 3001-401, Portugal.
| | - Jorge F J Coelho
- CEMUC, Department of Chemical Engineering, University of Coimbra, Coimbra 3030-790, Portugal.
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Branco R, Morais PV. Two superoxide dismutases from TnOtchr are involved in detoxification of reactive oxygen species induced by chromate. BMC Microbiol 2016; 16:27. [PMID: 26944876 PMCID: PMC4779226 DOI: 10.1186/s12866-016-0648-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 02/29/2016] [Indexed: 11/29/2022] Open
Abstract
Background Superoxide dismutases (SOD) have been reported as the most relevant bacterial enzymes involved in cells protection from reactive oxygen species (ROS). These toxic species are often the product of heavy metal stress. Results Two genes, chrC and chrF, from TnOtchr genetic determinant of strain Ochrobactrum tritici 5bvl1 were cloned in Escherichia coli in order to overexpress the respective proteins. Both proteins were purified and characterized as superoxide dismutases. ChrC was confirmed as being a Fe-SOD, and the enzymatic activity of the ChrF, not inhibited by hydrogen peroxide or potassium cyanide, suggested its inclusion in the Mn-SOD family. This identification was supported by chemical quantification of total metal content in purified enzyme. Both enzymes showed a maximum activity between pH 7.2-7.5. ChrF retained nearly full activity over a broader range of pH and was slightly more thermostable than ChrC. The genes encoding these enzymes in strain O. tritici 5bvl1 were inactivated, developing single and double mutants, to understand the contribution of these enzymes in detoxification mechanism of reactive oxygen species induced by chromate. During chromate stress, assays using fluorescent dyes indicated an increase of these toxic compounds in chrC, chrF and chrC/chrF mutant cells. Conclusions In spite of the multiple genes coding for putative superoxide dismutase enzymes detected in the genome of O. tritici 5bvl1, the ChrC and ChrF might help the strain to decrease the levels of reactive oxygen species in cells.
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Affiliation(s)
- Rita Branco
- CEMUC-Department of Mechanical Engineering, University of Coimbra, 3030-788, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, 3001-401, Coimbra, Portugal.
| | - Paula V Morais
- CEMUC-Department of Mechanical Engineering, University of Coimbra, 3030-788, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, 3001-401, Coimbra, Portugal.
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Branco R, Sousa T, Piedade AP, Morais PV. Immobilization of Ochrobactrum tritici As5 on PTFE thin films for arsenite biofiltration. Chemosphere 2016; 146:330-337. [PMID: 26735734 DOI: 10.1016/j.chemosphere.2015.12.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 12/01/2015] [Accepted: 12/08/2015] [Indexed: 06/05/2023]
Abstract
Ochrobactrum tritici SCII24T bacteria is an environmental strain with high capacity to resist to arsenic (As) toxicity, which makes it able to grow in the presence of As(III). The inactivation of the two functional arsenite efflux pumps, ArsB and ACR3_1, resulted in the mutant O. tritici As5 exhibiting a high accumulation of arsenite. This work describes a method for the immobilization of the mutant cells O. tritici As5, on a commercial polymeric net after sputtered modified by the deposition of poly(tetrafluoroethylene) (PTFE) thin films, and demonstrates the capacity of immobilized cells to accumulate arsenic from solutions. Six different set of deposition parameters for PTFE thin films were developed and tested in vitro regarding their ability to immobilize the bacterial cells. The surface that exhibited a mild zeta potential value, hydrophobic characteristics, the lowest surface free energy but with a high polar component and the appropriate ratio of chemical reactive groups allowed cells to proliferate and to grow as a biofilm. These immobilized cells maintained their ability to accumulate the surrounding arsenite, making it a great arsenic biofilter to be used in bioremediation processes.
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Affiliation(s)
- Rita Branco
- CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Tânia Sousa
- Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Ana P Piedade
- CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal
| | - Paula V Morais
- CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal.
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Sousa T, Branco R, Piedade AP, Morais PV. Hyper Accumulation of Arsenic in Mutants of Ochrobactrum tritici Silenced for Arsenite Efflux Pumps. PLoS One 2015; 10:e0131317. [PMID: 26132104 PMCID: PMC4489015 DOI: 10.1371/journal.pone.0131317] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 06/01/2015] [Indexed: 11/19/2022] Open
Abstract
Ochrobactrum tritici SCII24T is a highly As-resistant bacterium, with two previously described arsenic resistance operons, ars1 and ars2. Among a large number of genes, these operons contain the arsB and Acr3 genes that encode the arsenite efflux pumps responsible for arsenic resistance. Exploring the genome of O. tritici SCII24T, an additional putative operon (ars3) was identified and revealed the presence of the Acr3_2 gene that encodes for an arsenite efflux protein but which came to prove to not be required for full As resistance. The genes encoding for arsenite efflux pumps, identified in this strain, were inactivated to develop microbial accumulators of arsenic as new tools for bioremediation. Six different mutants were produced, studied and three were more useful as biotools. O. tritici wild type and the Acr3-mutants showed the highest resistance to As(III), being able to grow up to 50 mM of arsenite. On the other hand, arsB-mutants were not able to grow at concentrations higher than 1 mM As(III), and were the most As(III) sensitive mutants. In the presence of 1 mM As(III), the strain with arsB and Acr3_1 mutated showed the highest intracellular arsenic concentration (up to 17 ng(As)/mg protein), while in assays with 5 mM As(III), the single arsB-mutant was able to accumulate the highest concentration of arsenic (up to 10 ng(As)/mg protein). Therefore, arsB is the main gene responsible for arsenite resistance in O. tritici. However, both genes arsB and Acr3_1 play a crucial role in the resistance mechanism, depending on the arsenite concentration in the medium. In conclusion, at moderate arsenite concentrations, the double arsB- and Acr3_1-mutant exhibited a great ability to accumulate arsenite and can be seen as a promising bioremediation tool for environmental arsenic detoxification.
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Affiliation(s)
| | | | - Ana Paula Piedade
- CEMUC-Department of Mechanical Engineering, University of Coimbra, 3030–788 Coimbra, Portugal
| | - Paula V. Morais
- IMAR-CMA, Coimbra, Portugal
- Department of Life Sciences, University of Coimbra, Coimbra, Portugal
- * E-mail:
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Coelho C, Branco R, Natal-da-Luz T, Sousa JP, Morais PV. Evaluation of bacterial biosensors to determine chromate bioavailability and to assess ecotoxicity of soils. Chemosphere 2015; 128:62-69. [PMID: 25655820 DOI: 10.1016/j.chemosphere.2014.12.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 11/07/2014] [Accepted: 12/08/2014] [Indexed: 06/04/2023]
Abstract
Chromate can be considered a potent environmental contaminant and consequently, an understanding of chromate availability and toxicity to soil biology is essential for effective ecological assessment of metal impact in soils. This study shows the response of two bacterial bioreporters, pCHRGFP1 Escherichiacoli and pCHRGFP2 Ochrobactrumtritici, to increasing concentrations of chromate in two different soils. The bioreporters, carrying the regulatory gene chrB transcriptionally fused to the gfp reporter system, exhibited different features. In both, the fluorescence signal and the chromate concentration could be linearly correlated but E. coli biosensor functioned within the range of 0.5-2 μM and O. tritici biosensor within 2-10 μM chromate. The bioreporters were validated through comparative measurements using the chemical chromate methods of diphenylcarbazide and ionic chromatography. The bacterial sensors were used for the estimation of bioavailable fraction of chromate in a natural soil and OECD artificial soil, both spiked with chromate in increasing concentrations of 0-120 mg Cr(VI) kg(-1) of soil. OECD soil showed a faster chromate decrease comparing to the natural soil. The toxicity of soils amended with chromate was also evaluated by ecotoxicological tests through collembolan reproduction tests using Folsomia candida as test organism. Significant correlations were found between collembolans reproduction and chromate concentration in soil (lower at high chromate concentrations) measured by biosensors. Data obtained showed that the biosensors tested are sensitive to chromate presence in soil and may constitute a rapid and efficient method to measure chromate availability in soils.
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Affiliation(s)
| | | | | | - José Paulo Sousa
- IMAR-CMA, 3004-517 Coimbra, Portugal; Department of Life Sciences, FCTUC, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Paula V Morais
- IMAR-CMA, 3004-517 Coimbra, Portugal; Department of Life Sciences, FCTUC, University of Coimbra, 3001-401 Coimbra, Portugal.
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Farias P, Espírito Santo C, Branco R, Francisco R, Santos S, Hansen L, Sorensen S, Morais PV. Natural hot spots for gain of multiple resistances: arsenic and antibiotic resistances in heterotrophic, aerobic bacteria from marine hydrothermal vent fields. Appl Environ Microbiol 2015; 81:2534-43. [PMID: 25636836 PMCID: PMC4357944 DOI: 10.1128/aem.03240-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/21/2015] [Indexed: 11/20/2022] Open
Abstract
Microorganisms are responsible for multiple antibiotic resistances that have been associated with resistance/tolerance to heavy metals, with consequences to public health. Many genes conferring these resistances are located on mobile genetic elements, easily exchanged among phylogenetically distant bacteria. The objective of the present work was to isolate arsenic-, antimonite-, and antibiotic-resistant strains and to determine the existence of plasmids harboring antibiotic/arsenic/antimonite resistance traits in phenotypically resistant strains, in a nonanthropogenically impacted environment. The hydrothermal Lucky Strike field in the Azores archipelago (North Atlantic, between 11°N and 38°N), at the Mid-Atlantic Ridge, protected under the OSPAR Convention, was sampled as a metal-rich pristine environment. A total of 35 strains from 8 different species were isolated in the presence of arsenate, arsenite, and antimonite. ACR3 and arsB genes were amplified from the sediment's total DNA, and 4 isolates also carried ACR3 genes. Phenotypic multiple resistances were found in all strains, and 7 strains had recoverable plasmids. Purified plasmids were sequenced by Illumina and assembled by EDENA V3, and contig annotation was performed using the "Rapid Annotation using the Subsystems Technology" server. Determinants of resistance to copper, zinc, cadmium, cobalt, and chromium as well as to the antibiotics β-lactams and fluoroquinolones were found in the 3 sequenced plasmids. Genes coding for heavy metal resistance and antibiotic resistance in the same mobile element were found, suggesting the possibility of horizontal gene transfer and distribution of theses resistances in the bacterial population.
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Affiliation(s)
- Pedro Farias
- IMAR-CMA and CEMUC, Coimbra, Portugal Instituto Piaget, Silves, Portugal
| | | | | | | | | | - Lars Hansen
- Department of Biology, Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Soren Sorensen
- Department of Biology, Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Paula V Morais
- IMAR-CMA and CEMUC, Coimbra, Portugal Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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Falcão F, Viegas E, Lopes C, Branco R, Parrinha A, Alves ML, Leal F, Pina V, Madureira B, Cavaco P, Santos S, Carreira S. Hospital pharmacist interventions in a central hospital. Eur J Hosp Pharm 2014. [DOI: 10.1136/ejhpharm-2014-000491] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Portela JL, Garcia PCR, Piva JP, Barcelos A, Bruno F, Branco R, Tasker RC. Intramuscular midazolam versus intravenous diazepam for treatment of seizures in the pediatric emergency department: a randomized clinical trial. Med Intensiva 2014; 39:160-6. [PMID: 24928286 DOI: 10.1016/j.medin.2014.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 10/25/2022]
Abstract
AIM To compare the therapeutic efficacy of intramuscular midazolam (MDZ-IM) with that of intravenous diazepam (DZP-IV) for seizures in children. DESIGN Randomized clinical trial. SETTING Pediatric emergency department. PATIENTS Children aged 2 months to 14 years admitted to the study facility with seizures. INTERVENTION Patients were randomized to receive DZP-IV or MDZ-IM. MAIN MEASUREMENTS Groups were compared with respect to time to treatment start (min), time from drug administration to seizure cessation (min), time to seizure cessation (min), and rate of treatment failure. Treatment was considered successful when seizure cessation was achieved within 5min of drug administration. RESULTS Overall, 32 children (16 per group) completed the study. Intravenous access could not be obtained within 5min in four patients (25%) in the DZP-IV group. Time from admission to active treatment and time to seizure cessation was shorter in the MDZ-IM group (2.8 versus 7.4min; p<0.001 and 7.3 versus 10.6min; p=0.006, respectively). In two children per group (12.5%), seizures continued after 10min of treatment, and additional medications were required. There were no between-group differences in physiological parameters or adverse events (p=0.171); one child (6.3%) developed hypotension in the MDZ-IM group and five (31%) developed hyperactivity or vomiting in the DZP-IV group. CONCLUSION Given its efficacy and ease and speed of administration, intramuscular midazolam is an excellent option for treatment of childhood seizures, enabling earlier treatment and shortening overall seizure duration. There were no differences in complications when applying MDZ-IM or DZP-IV.
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Affiliation(s)
- J L Portela
- Pediatric Emergency Department, Hospital Universitário de Santa Maria, Universidade Federal de Santa Maria (UFSM), Av. Roraima, Prédio 22, Campus, Bairro Camobi, Zip Code: 97105 900, Santa Maria, RS, Brazil; School of Medicine, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, Brazil
| | - P C R Garcia
- Department of Pediatrics, School of Medicine, PUCRS, Brazil; Hospital São Lucas, PUCRS, Porto Alegre, RS, Brazil.
| | - J P Piva
- Department of Pediatrics, School of Medicine, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil; Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - A Barcelos
- School of Medicine, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, Brazil; Pediatric Emergency Department, Hospital Universitário de Santa Maria, UFSM, Brazil
| | - F Bruno
- Department of Pediatrics, School of Medicine, PUCRS, Brazil; Hospital São Lucas, PUCRS, Porto Alegre, RS, Brazil
| | - R Branco
- Pediatric Intensive Care Locum Consultant, Addenbrooke's Hospital, Cambridge, UK
| | - R C Tasker
- Pediatric NeuroCritical Care Program, CHMC, Boston, USA; Harvard Medical School, USA
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Parrinha A, Lobo Alves M, Branco R, Goulão I, Fernandes C, Lopes C, Madureira B, Cavaco P, Santos S, Carreira S, Viegas E, Falcão F. CP-019 Hospital pharmacists’ interventions in a central hospital. Eur J Hosp Pharm 2014. [DOI: 10.1136/ejhpharm-2013-000436.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Branco R, Morais PV. Identification and characterization of the transcriptional regulator ChrB in the chromate resistance determinant of Ochrobactrum tritici 5bvl1. PLoS One 2013; 8:e77987. [PMID: 24223748 PMCID: PMC3817168 DOI: 10.1371/journal.pone.0077987] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 09/06/2013] [Indexed: 12/30/2022] Open
Abstract
Ochrobactrum tritici 5bvl1 is able to resist to high concentrations of chromate through the expression of an inducible chromate-resistant determinant, found in a mobile element (TnOtChr), which carries the genes, chrB, chrA, chrC and chrF. The regulation of chr operon present in TnOtChr, which is controlled by a transcriptional regulator, ChrB, was characterized in the current work. Fusions of chr promoter, or chr promoter and chrB gene, upstream of a gfp reporter gene, identified the most probable promoter sequence within the tnpR-chrB intergenic region. This region contains an AT-rich imperfect inverted repeat sequence, which overlaps a part of the −10 sequence. The results of the in vitro DNA-binding assays with purified ChrB (His- or no-tagged) showed that the protein binds directly to the chr promoter region. In order to identify the ChrB functional domain for sensing chromate stress and for DNA-binding, site-directed mutagenesis of ChrB was performed. Among several single amino acid mutants, three mutants (R180; R187 and H229) prevented chromate induction without any modification to the protein’s stability. Interestingly, two ChrB mutants (R18 and R23) were constitutively active, regardless of chromate stress conditions, indicating that the residues most probably belong to the protein-DNA binding site. As such, the ChrB was classified as a transcriptional regulator that recognizes a specific DNA sequence, regulating the expression of a chromate resistance determinant.
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Affiliation(s)
- Rita Branco
- IMAR-CMA-Marine and Environmental Research Centre, Coimbra, Portugal
- Interdisciplinary Research Institute, University of Coimbra, Coimbra, Portugal
| | - Paula V. Morais
- IMAR-CMA-Marine and Environmental Research Centre, Coimbra, Portugal
- Department of Life Sciences, FCTUC, University of Coimbra, Coimbra, Portugal
- * E-mail:
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Branco R, Cristóvão A, Morais PV. Highly sensitive, highly specific whole-cell bioreporters for the detection of chromate in environmental samples. PLoS One 2013; 8:e54005. [PMID: 23326558 PMCID: PMC3543429 DOI: 10.1371/journal.pone.0054005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 12/07/2012] [Indexed: 12/04/2022] Open
Abstract
Microbial bioreporters offer excellent potentialities for the detection of the bioavailable portion of pollutants in contaminated environments, which currently cannot be easily measured. This paper describes the construction and evaluation of two microbial bioreporters designed to detect the bioavailable chromate in contaminated water samples. The developed bioreporters are based on the expression of gfp under the control of the chr promoter and the chrB regulator gene of TnOtChr determinant from Ochrobactrum tritici 5bvl1. pCHRGFP1 Escherichia coli reporter proved to be specific and sensitive, with minimum detectable concentration of 100 nM chromate and did not react with other heavy metals or chemical compounds analysed. In order to have a bioreporter able to be used under different environmental toxics, O. tritici type strain was also engineered to fluoresce in the presence of micromolar levels of chromate and showed to be as specific as the first reporter. Their applicability on environmental samples (spiked Portuguese river water) was also demonstrated using either freshly grown or cryo-preserved cells, a treatment which constitutes an operational advantage. These reporter strains can provide on-demand usability in the field and in a near future may become a powerful tool in identification of chromate-contaminated sites.
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Affiliation(s)
- Rita Branco
- IMAR, 3004-517 Coimbra, Portugal
- Escola Universitária Vasco da Gama, Mosteiro de S. Jorge de Milréu, Estrada da Conraria, Castelo Viegas – Coimbra, Portugal
| | - Armando Cristóvão
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Department of Life Sciences, FCTUC, University of Coimbra, Coimbra, Portugal
| | - Paula V. Morais
- IMAR, 3004-517 Coimbra, Portugal
- Department of Life Sciences, FCTUC, University of Coimbra, Coimbra, Portugal
- * E-mail:
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Morais PV, Branco R, Francisco R. Chromium resistance strategies and toxicity: what makes Ochrobactrum tritici 5bvl1 a strain highly resistant. Biometals 2011; 24:401-10. [DOI: 10.1007/s10534-011-9446-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 03/24/2011] [Indexed: 11/30/2022]
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Gerediaga GD, Elizagaray E, Canto-Morereira N, Albuquerque C, Branco R, Beirão I, Grande T. [Contralateral occlusion of the internal carotid artery in the study of carotid stenosis using Doppler ultrasonography]. Rev Neurol 2009; 48:406-411. [PMID: 19340780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
INTRODUCTION AND AIMS The degree of stenosis measured by Doppler ultrasonography in patients with contralateral occlusion of the internal carotid artery (ICA) is assumed to be overestimated. We propose to measure the extent to which this phenomenon affects the capacity of Doppler ultrasonography to classify stenoses. PATIENTS AND METHODS A retrospective study of 47 patients was conducted using Doppler ultrasonography and digital subtraction angiography; all subjects had confirmed unilateral occlusion of the ICA and stenoses of the contralateral ICA. Curves were traced plotting the degree of stenosis against the peak systolic velocity (PSV) and its ratio in the ICA and in the common carotid artery (VICA/VCCA). The curves were compared with their equivalents with no contralateral occlusion found in the literature. Later, the cases of stenosis were classified into groups of less than 50, 50-69 and more than 70%, and the main statistical values were calculated. RESULTS The PSV in the stenoses between 40-50% presents more than 1 standard deviation (SD) above the mean. There were no significant deviations in other degrees of stenosis (p > 0.4). The VICA/VCCA showed a similar parallelism, but with deviations lower than 1 SD (p = 0.56). Seventeen per cent of the stenoses were over-classified, and this conditioned a sensitivity of 84, 71 and 100%, and a specificity of 100, 94 and 88% for the groups of less than 50, 50-69 and over 70%, respectively. The VICA/VCCA over-classified 41% of the stenoses; sensitivity was seen to be 56, 43 and 100% and specificity was 90, 64 and 87%. Diagnostic accuracy of the PSV and VICA/VCCA stands at 83 and 57%, respectively. CONCLUSIONS Contralateral occlusion leads to over-classification of the PSV. There is a tendency to over-classify, although this does not affect the overall diagnostic accuracy. The VICA/VCCA does not offer greater diagnostic accuracy in classifying stenoses with contralateral occlusion.
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Affiliation(s)
- G D Gerediaga
- Unidad de Neurorradiología, Hospital São Teotónio, Viseu, Portugal.
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Branco R, Chung AP, Morais PV. Sequencing and expression of two arsenic resistance operons with different functions in the highly arsenic-resistant strain Ochrobactrum tritici SCII24T. BMC Microbiol 2008; 8:95. [PMID: 18554386 PMCID: PMC2440759 DOI: 10.1186/1471-2180-8-95] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 06/13/2008] [Indexed: 11/16/2022] Open
Abstract
Background Arsenic (As) is a natural metalloid, widely used in anthropogenic activities, that can exist in different oxidation states. Throughout the world, there are several environments contaminated with high amounts of arsenic where many organisms can survive. The most stable arsenical species are arsenate and arsenite that can be subject to chemically and microbiologically oxidation, reduction and methylation reactions. Organisms surviving in arsenic contaminated environments can have a diversity of mechanisms to resist to the harmful effects of arsenical compounds. Results The highly metal resistant Ochrobactrum tritici SCII24 was able to grow in media with arsenite (50 mM), arsenate (up to 200 mM) and antimonite (10 mM). This strain contains two arsenic and antimony resistance operons (ars1 and ars2), which were cloned and sequenced. Sequence analysis indicated that ars1 operon contains five genes encoding the following proteins: ArsR, ArsD, ArsA, CBS-domain-containing protein and ArsB. The ars2 operon is composed of six genes that encode two other ArsR, two ArsC (belonging to different families of arsenate reductases), one ACR3 and one ArsH-like protein. The involvement of ars operons in arsenic resistance was confirmed by cloning both of them in an Escherichia coli ars-mutant. The ars1 operon conferred resistance to arsenite and antimonite on E. coli cells, whereas the ars2 operon was also responsible for resistance to arsenite and arsenate. Although arsH was not required for arsenate resistance, this gene seems to be important to confer high levels of arsenite resistance. None of ars1 genes were detected in the other type strains of genus Ochrobactrum, but sequences homologous with ars2 operon were identified in some strains. Conclusion A new strategy for bacterial arsenic resistance is described in this work. Two operons involved in arsenic resistance, one giving resistance to arsenite and antimonite and the other giving resistance to arsenate were found in the same bacterial strain.
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Affiliation(s)
- Rita Branco
- IMAR-Laboratory of Microbiology 3004-517 Coimbra, Portugal.
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Morais PV, Paulo C, Francisco R, Branco R, Paula Chung A, da Costa MS. Leucobacter luti sp. nov., and Leucobacter alluvii sp. nov., two new species of the genus Leucobacter isolated under chromium stress. Syst Appl Microbiol 2006; 29:414-21. [PMID: 16316733 DOI: 10.1016/j.syapm.2005.10.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Indexed: 11/16/2022]
Abstract
Two strains designated RF6(T) and RB10(T) were isolated, from activated sludge and from river sediments, respectively, both systems receiving chromium contaminated water. Phylogenetic analysis showed that strain RF6(T)and strain RB10(T) represented two new species of the genus Leucobacter. Strain RB10(T) can be distinguished from RF6(T) by its ability to grow at 37 degrees C, by showing a different optimum pH, by cell wall amino acids different relative amount and by having the fatty acid strait C16:0 as the third most abundant fatty acid. On the basis of the distinct peptidoglycan composition, 16S ribosomal DNA sequence analysis, DNA-DNA reassociation values, and phenotypic characteristics we are of the opinion that strain RF6(T) represents a new species of the genus Leucobacter for which we propose the name Leucobacter luti (CIP 108818(T)=LMG 23118) and that strain RB10(T) represents an additional new species of the same genus for which we propose the name Leucobacter alluvii (CIP 108819(T)=LMG 23117).
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Affiliation(s)
- Paula V Morais
- Departamento Bioquímica, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Apartado 3126, 3001-401 Coimbra, Portugal.
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Branco R, Chung AP, Veríssimo A, Morais PV. Impact of chromium-contaminated wastewaters on the microbial community of a river. FEMS Microbiol Ecol 2005; 54:35-46. [PMID: 16329970 DOI: 10.1016/j.femsec.2005.02.014] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Revised: 12/14/2004] [Accepted: 02/16/2005] [Indexed: 11/28/2022] Open
Abstract
The influence of chromium on the microbial community structure was analyzed in a river system subjected to long-term chromium contamination, by plating and by sequencing 16S rRNA genes cloned from DNA extracted from the river sediments. We also analyzed the influence of chromium on the ability of the microbial community to resist and reduce Cr(VI) and on its resistance to antibiotics. Shifts in the microbial community structure were analyzed by amplified ribosomal DNA restriction analysis fingerprinting. The isolates obtained were phylogenetically related to Actinobacteria, Firmicutes, Bacteroidetes and Proteobacteria, whereas Acidobacteria and Deltaproteobacteria were only revealed by clone analyses. Cr(VI)-resistant and Cr(VI)-reducing strains were isolated in all sites examined. However, each sample site had a microbial community with a different antibiotic resistance pattern. Our study seems to indicate that in this river ecosystem chromium influenced the microbial communities, altering some of their functional characteristics, such as the percentage of the microbial community able to resist or to reduce Cr(VI) and the phylogenetic groups isolated, but it did not affect the structural diversity. Furthermore, the concentration of Cr(VI) in the sediments could not be correlated with a lower number of bacteria or lower index of generic diversity, neither with the ability of the microbial community to resist or to reduce higher Cr(VI) concentrations.
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Affiliation(s)
- Rita Branco
- Instituto do Ambiente e Vida, Coimbra, Portugal
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Morais PV, Francisco R, Branco R, Chung AP, da Costa MS. Leucobacter chromiireducens sp. nov, and Leucobacter aridicollis sp. nov., Two New Species Isolated From a Chromium Contaminated Environment. Syst Appl Microbiol 2004; 27:646-52. [PMID: 15612621 DOI: 10.1078/0723202042369983] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Two strains designated strains L-1T and L-9T were isolated from activated sludge of a treatment plant that receives wastewater from the tannery industry contaminated with chromium. Phylogenetic analysis showed that the organisms represented two new species of the genus Leucobacter. Strains L-1T and L-9T could be distinguished from the type strain of L. komagatae and from the type strain of "L. albus" by the B-type peptidoglycan composition, fatty acid composition, several phenotypic and physiological characteristics. The major fatty acids of the organisms were iso- and anteiso-branched C15:0 and C17:0, straight-chain C16:0 was also found in relatively high proportions. The organisms were halotolerant, grew in medium containing 9% NaCl, and all strains, including the type strain of L. komagatae grew in medium containing 5 mM Cr(VI). On the basis of the distinct peptidoglycan composition, 16S ribosomal DNA sequence analysis, percentage of DNA-DNA reassociation values, and phenotypic characteristics we are of the opinion that strain L-1T represents a new species of the genus Leucobacter for which we propose the name Leucobacter chromiireducens and that strain L-9T represents an additional new species of the same genus for which we propose the name Leucobacter aridicollis.
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MESH Headings
- Actinomycetales/chemistry
- Actinomycetales/classification
- Actinomycetales/growth & development
- Actinomycetales/isolation & purification
- Bacterial Typing Techniques
- Chromium/metabolism
- Chromium/pharmacology
- DNA, Bacterial/chemistry
- DNA, Bacterial/isolation & purification
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/isolation & purification
- Environmental Pollutants
- Fatty Acids/analysis
- Fatty Acids/isolation & purification
- Genes, rRNA
- Molecular Sequence Data
- Nucleic Acid Hybridization
- Osmotic Pressure
- Peptidoglycan/chemistry
- Peptidoglycan/isolation & purification
- Phylogeny
- RNA, Bacterial/genetics
- RNA, Ribosomal, 16S/genetics
- Saline Solution, Hypertonic/pharmacology
- Sequence Analysis, DNA
- Sewage/microbiology
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Affiliation(s)
- Paula V Morais
- Departamento Bioquimica, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Coimbra, Portugal.
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Abstract
Bacterial strain 5bvl1, isolated from a chromium-contaminated wastewater treatment plant and identified as Ochrobactrum tritici, was resistant to a broad range of antibiotics, to Cr(VI), Ni(II), Co(II), Cd(II), and Zn(II), and was able to grow in the presence of 5% NaCl and within the pH range 4–10. Characterization showed that strain 5bvl1 could be considered a halotolerant and alkalitolerant microorganism resistant to high concentrations of Cr(VI). This strain was able to grow aerobically in up to 10 mmol·L–1 Cr(VI). Cr(VI) resistance was independent of sulphate concentration. Under aerobic conditions strain 5bvl1 was also able to reduce high Cr(VI) concentrations (up to 1.7 mmol·L–1). Increasing concentrations of Cr(VI) in the medium lowered the growth rate of strain 5bv11 but the reduction in growth rate could not be directly correlated with the amount of Cr(VI) reduced. Unlike the type strain, which was only able to reduce Cr(VI), strain 5bvl1 was resistant to Cr(VI) and able to reduce it. Moreover, in strain 5bvl1, the rate and extent of Cr(VI)-reduction were higher than in the other strains of the genus Ochrobactrum. Ochrobactrum strain 5bvl1 resists high Cr(VI) concentrations and has a high Cr(VI)-reducing ability, making it a valuable tool in bioremediation.Key words: Ochrobactrum, Cr(VI) resistance, Cr(VI)-reduction, heavy metal, bioremediation.
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Affiliation(s)
- Rita Branco
- Instituto do Ambiente e Vida, Departamento de Zoologia, Universidade de Coimbra, Portugal
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Vasconcelos M, Afonso A, Branco R, Cavalheiro J. Guided bone regeneration using osteopatite granules and polytetrafluoroethylene membranes. J Mater Sci Mater Med 1997; 8:815-818. [PMID: 15348797 DOI: 10.1023/a:1018533217238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Granules of a modified hydroxyapatite, Osteopatite, were implanted in the right posterior tibiae of adult rabbits. We studied the extent of bone regeneration in bone holes. In the right tibiae, that were filled with granules of this biomaterial covered with a polytetrafluoro-ethylene (PTFE) membrane using, as a control, uncovered granules. In the left tibia, an empty hole was covered with PTFE membrane and a second hole was left empty to be used as a control. A histomorphometric study was carried out using light microscopy, four and eight weeks after the surgery. The covered granules presented a higher percentage of bone contact than the uncovered ones, and it was also possible to observe a better bone tissue organization, mainly produced by the immobilization action of the PTFE membrane. Empty bone defects covered with PTFE membranes, two months after implantation, presented large areas of Haversian bone and direct bone contact to the PTFE membrane.
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Affiliation(s)
- M Vasconcelos
- Faculty of Dental Medicine, University of Porto, Portugal
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Rocha PS, Rebocho L, Alvoeiro L, Lourenço G, Branco R, Victorino RM, de Moura MC. [Visceral leishmaniasis and HIV infection: the diagnostic and therapeutic problems]. ACTA MEDICA PORT 1993; 6:543-6. [PMID: 8140923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We present the case of an HIV-seropositive drug addict patient whose seropositivity was unknown until admission to hospital, where he presented with a clinical picture of fever splenomegaly and weight loss. A diagnosis of visceral leishmaniasis was established. We stress the diagnostic difficulties well expressed in the need to repeat the bone marrow aspirate to detect the presence of leishmanias. The lack of response to conventional antimonial therapy is discussed as well as the role of pentamidine as an alternative therapy.
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Affiliation(s)
- P S Rocha
- Serviço de Medicina 2, Hospital Universitário de Santa Maria, Lisboa
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Cavalheiro J, Branco R, Vasconcelos M, Oliveira A, Afonso A, Sousa H. [Prevention of alveolar bone resorption with the use of hydroxyapatite granules]. Stoma (Lisb) 1991; 2:7-10, 13-5. [PMID: 2038727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The authors describe in review the alveolar absorption according to bone physiology, and the absorption prevention using hydroxylapatite. Finally it is pointed the good preliminary results in a 30 patients study during 8 months using hydroxylapatite (OSTEOPATITE) and plaster particles in alveolar absorption prevention.
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Cavalheiro J, Branco R, Vasconcelos M. [Surgical applications of hydroxyapatite]. Stoma (Lisb) 1990; 2:7-9, 11, 13-5. [PMID: 2171151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Cavalheiro J, Branco R. [2 amalgam formulation mechanisms with high copper alloys]. Rev Port Estomatol Cir Maxilofac 1989; 30:185-93. [PMID: 2640352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Two high copper-containing amalgam alloys, one of them gas atomized and the other water atomized were used to study the reaction mechanism with mercury. Normal and subtrituration time were used. The observations of structures and evaluation of compressive strengths allowed the understanding of two different mechanisms of reaction.
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Abstract
Several physical properties were measured for two zinc phosphate and three polycarboxylate cements. The specimens were tested in compression 24 h after they had been made. Two series of specimens were examined. In one series the cement powders were given a correct treatment, protected from atmospheric humidity. In the other series the powders were exposed for 1 week to ambient conditions with the temperature varying between 20 degrees and 24 degrees C and the relative humidity between 40% and 59%. The zinc phosphate cements were characterized by high values of modulus of elasticity and by plastic deformations less than 0.2%. The polycarboxylate cements were more flexible and also exhibited large plastic deformations. Compared with the zinc phosphate cements, therefore, the polycarboxylate cements had high values of resilience and toughness. The storing of cement powders exposed to atmospheric humidity for 1 week did not change the measured properties of the polycarboxylate cements. However, both strength and resilience were significantly reduced for one phosphate cement.
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