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Biomedical subjects

R Tenreiro

Publications and source records attributed to R Tenreiro.

11 recordsLinked to original sources
PubMed2006

Biodegradability testing using standardized microbial communities as inoculum.

Reference materials are important tools for maintaining high-quality assurance standards, including for biological materials. A significant number of environmental international standards, including biodegradability and toxicity, involve utilization of activated sludge (AS) inocula. The absence of inoculum standardization in these tests is a potential source of error influencing the results. In this study three defined microbial consortia, two commercial inocula and a designed bacterial inoculum, were evaluated as an AS alternative seed for the Zahn-Wellens test, using diethylene glycol as the reference chemical. The results showed that to achieve diethylene glycol biodegradation with these inocula, a number of 10(5) colony-forming units per milliliter of effective degrader microorganisms had to be present. Moreover, the addition of AS supernatant to the test mixtures improved inocula performance (the biodegradability curves), bringing them closer to those obtained with AS inocula. Among the three defined consortia, the designed inoculum replicates bested the AS behavior in the range of concentrations tested, with degradation completed in 12-14 days. Comparisons of the community substrate utilization profiles corroborated these results, showing that the designed inoculum profile was the most similar to the AS profile. The biodegradability and metabolism results provided support for the assertion that the designed inoculum can be used in the Zahn-Wellens test and as a base to develop reference inocula for other biodegradability and toxicity tests.

Bacteria↗
PubMed2004

Case of aortic endocarditis caused by Lactobacillus casei.

A case of Lactobacillus aortic valve endocarditis in a 53-year-old immunocompetent patient with past history of rheumatic fever is reported. Clinical symptoms began after a dental extraction and the patient's diet included several yogurts per day. Blood, bone marrow cultures and the replaced aortic valve were positive for Lactobacillus: The clinical isolate was identified as Lactobacillus casei by 16S rDNA sequencing.

Aortic Valve↗
PubMed2004

Internal transcribed spacer 2 amplicon as a molecular marker for identification of Peronospora parasitica (crucifer downy mildew).

AIMS: The purpose of the study was to characterize the internal transcribed spacer (ITS) regions of Peronospora parasitica (crucifer downy mildew) in order to evaluate their potential as molecular markers for pathogen identification. METHODS AND RESULTS: PCR amplification of ribosomal RNA gene block (rDNA) spacers (ITS1 and ITS2) performed in 44 P. parasitica isolates from different Brassica oleracea cultivars and distinct geographic origins, revealed no length polymorphisms. ITS restriction analysis with three endonucleases, confirmed by sequencing, showed no fragment length polymorphisms among isolates. Furthermore, ITS amplification with DNA isolated from infected host tissues also allowed the detection of the fungus in incompatible interactions. The combination of the universal ITS4 and ITS5 primers, for amplification of full ITS, with a new specific forward internal primer for ITS2 (PpITS2F), originates a P. parasitica specific amplicon, suitable for diagnosis. CONCLUSIONS: As ITS2 regions of P. parasitica, B. oleracea, other B. oleracea fungal pathogens and other Peronospora species are clearly distinct, a fast and reliable molecular identification method based on multiplex PCR amplification of full ITS and P. parasitica ITS2 is proposed for the diagnosis of crucifer downy mildew. SIGNIFICANCE AND IMPACT OF THE STUDY: The method can be applied to diagnose the disease in the absence of fungal reproductive structures, thus being useful to detect nonsporulating interactions, early stages of infection on seedlings, and infected young leaves packed in sealed plastic bags. Screening of seed stocks in sanitary control is also a major application of this diagnostic method.

Brassica↗
PubMed2003

Genetic relatedness of Portuguese almond cultivars assessed by RAPD and ISSR markers.

Randomly amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were used to analyse the genetic diversity of Portuguese Prunus dulcis cultivars and their relationship to important foreign cultivars. Of the primers tested, 6 (out of 60) RAPD and 5 (out of 18) ISSR primers were selected for their reproducibility and high polymorphism. Out of 124 polymerase chain reaction fragments that were scored, 120 (96.8%) were polymorphic. All the plants could be discriminated and constitute a very heterogeneous group. Five unidentified almond plants found in the region of Foz Côa (north Portugal) and wild almond (P. webbii) from Italy and Spain were also included. Four main groups of plants could be distinguished: P. dulcis cultivars; one Foz Côa plant; P. webbii; and P. persica (outgroup). The segregating Foz Côa plant may represent a feral individual or a hybrid between P. dulcis and P. webbii.

Genetic Markers↗
PubMed2003

Alternative inocula as activated sludge surrogate culture for a toxicity test.

The use of activated sludge to assess the potential toxicity and environmental impact of chemicals and wastewaters suffers from several drawbacks related to the heterogeneity, absence of standardization, and health risk associated with this mixed-sewage population. To search for reliable testing inoculum alternatives, the performance of two commercial inocula (BI-CHEM and BIOLEN M112), a garden-soil inoculum and a pure culture of Pseudomonas sp., was compared with an activated sludge inoculum (AS) in the inhibition respiration test ISO 8192-1986 (E). The respiration rates of microbial inocula were assayed for the reference compound 3,5-dichlorophenol. The acute toxicity values (IC(50)) ranged from 6.7 mg/L (Pseudomonas sp.) to 22.7 mg/L (garden soil), overlapping the expected values for activated sludge microorganisms despite the bacterial diversity. The assayed microbial inocula also showed higher reproducibility than AS and an overall similarity of catabolic profiles obtained with Biolog EcoPlates was observed between AS and some mixed inocula. These results point to the potential ability of such inocula as surrogate cultures in relevant activated sludge-based bioassays. New, well-defined, standardized, and safe tools will then be available for monitoring the ecological impact of hazardous substances and effluents, thus providing environmental protection.

Biological Assay↗
PubMed1999

Assessment of metronidazole susceptibility in Helicobacter pylori: statistical validation and error rate analysis of breakpoints determined by the disk diffusion test.

Metronidazole susceptibility of 100 Helicobacter pylori strains was assessed by determining the inhibition zone diameters by disk diffusion test and the MICs by agar dilution and PDM Epsilometer test (E test). Linear regression analysis was performed, allowing the definition of significant linear relations, and revealed correlations of disk diffusion results with both E-test and agar dilution results (r2 = 0.88 and 0.81, respectively). No significant differences (P = 0.84) were found between MICs defined by E test and those defined by agar dilution, taken as a standard. Reproducibility comparison between E-test and disk diffusion tests showed that they are equivalent and with good precision. Two interpretative susceptibility schemes (with or without an intermediate class) were compared by an interpretative error rate analysis method. The susceptibility classification scheme that included the intermediate category was retained, and breakpoints were assessed for diffusion assay with 5-microg metronidazole disks. Strains with inhibition zone diameters less than 16 mm were defined as resistant (MIC > 8 microg/ml), those with zone diameters equal to or greater than 16 mm but less than 21 mm were considered intermediate (4 microg/ml < MIC </= 8 microg/ml), and those with zone diameters of 21 mm or greater were regarded as susceptible (MIC </= 4 microg/ml). Error rate analysis applied to this classification scheme showed occurrence frequencies of 1% for major errors and 7% for minor errors, when the results were compared to those obtained by agar dilution. No very major errors were detected, suggesting that disk diffusion might be a good alternative for determining the metronidazole sensitivity of H. pylori strains.

Anti-Bacterial Agents↗
PubMed1994

Inter-strain relationships among wine leuconostocs and their divergence from other Leuconostoc species, as revealed by low frequency restriction fragment analysis of genomic DNA.

Thirty Leuconostoc oenos strains, representing 28 different isolates, were distributed into 20 genomic groups according to PFGE patterns of restriction digests. The 8 bp-specific enzymes Sfi I, Not I and Asc I cleaved the Leuc. oenos DNA in a mean of 17, 11 and four fragments respectively and Sma I produced more than 50 fragments per genome. The strain differentiating capacity of the four enzymes was similar; only two related genomic groups failed to be distinguished by Asc I or Not I. Genomic relationships between Leuc. oenos strains were quantified by numerical analysis of Not I and Sfi I banding patterns. More than half of the strains, including the starters ML34 and PSU-1, formed a major cluster. The average size of the Leuc. oenos genome was estimated as 1.86 Mb. Although similar values were obtained for the genomes of Leuc. mesenteroides, Leuc. pseudomesenteroides, Leuc. gelidum and Leuc. citreum, a significant divergence between wine and non-wine species was inferred from comparisons of genome cleavage frequencies, determined with five different enzymes.

Base Sequence↗
PubMed1993

Eosinophilic granuloma of the left ischium.

A case of eosinophilic granuloma in an unusual location (ischium) is presented. Eosinophilic granuloma, a benign lesion of bone, has many radiographic appearances that vary with location. The flat bone of the skull and pelvis are common sites of involvement. Although the iliac wings and pubic rami are not uncommon sites for such a lesion, the ischium is a rare site. This occurrence prompted us to report this case.

Adult↗
PubMed1984

Escherichia coli K-12 lysyl-tRNA synthetase mutant with a novel reversion pattern.

Fast-growing revertants have been selected from a slow-growing lysyl-tRNA synthetase mutant. All of the revertants had increased lysyl-tRNA synthetase activity compared with the mutant (5- to 85-fold), and in some revertants this amounted to two to three times the wild-type synthetase activity. Two-dimensional gel electrophoresis of a whole-cell extract of revertant IH2018 (1.5- to 2-fold wild-type synthetase activity) showed that the increase in synthetase activity is due to the induction of cryptic lysyl-tRNA synthetase forms and not to a change in the constitutive lysyl-tRNA synthetase. Genetic studies have shown that a locus termed rlu (for regulation of lysU ) which is cotransducible with purF at 49.5 min influences the amount of the cryptic lysyl-tRNA synthetase.

Amino Acyl-tRNA Synthetases↗