Effects of photodynamic therapy on Enterococcus faecalis biofilms.

Microbial biofilms are involved in almost all infectious pathologies of the oral cavity. This has led to the search for novel therapies specifically aimed at biofilm elimination. In this study, we used atomic force microscopy (AFM) to visualize injuries and to determine surface roughness, as well as confocal laser scanning microscopy (CLSM) to enumerate live and dead bacterial cells, to determine the effects of photodynamic therapy (PDT) on Enterococcus faecalis biofilms. The AFM images showed that PDT consisting of methylene blue and a 670-nm diode laser (output power 280 mW during 30 s) or toluidine blue and a 628-nm LED light (output power 1000 mW during 30 s) induced severe damage, including cell lysis, to E. faecalis biofilms, with the former also causing an important increase in surface roughness. These observations were confirmed by the increase in dead cells determined using CLSM. Our results highlight the potential of PDT as a promising method to achieve successful oral disinfection.

Does avian conspicuous colouration increase or reduce predation risk?

Animals often announce their unprofitability to predators through conspicuous coloured signals. Here we tested whether the apparently conspicuous colour designs of the four European Coraciiformes and Upupiformes species may have evolved as aposematic signals, or whether instead they imply a cost in terms of predation risk. Because previous studies suggested that these species are unpalatable, we hypothesized that predators could avoid targeting them based on their colours. An experiment was performed where two artificial models of each bird species were exposed simultaneously to raptor predators, one painted so as to resemble the real colour design of these birds, and the other one painted using cryptic colours. Additionally, we used field data on the black kite's diet to compare the selection of these four species to that of other avian prey. Conspicuous models were attacked in equal or higher proportions than their cryptic counterparts, and the attack rate on the four species increased with their respective degree of contrast against natural backgrounds. The analysis of the predator's diet revealed that the two least attacked species were negatively selected in nature despite their abundance. Both conspicuous and cryptic models of one of the studied species (the hoopoe) received fewer attacks than cryptic models of the other three species, suggesting that predators may avoid this species for characteristics other than colour. Globally, our results suggest that the colour of coraciiforms and upupiforms does not function as an aposematic signal that advises predators of their unprofitability, but also that conspicuous colours may increase predation risk in some species, supporting thus the handicap hypothesis.

Glucose control and outcome in patients with stable diabetes and previous coronary, cerebrovascular or peripheral artery disease. Findings from the FRENA Registry.

AIM: The aim of this study was to address the controversy over the influence of intensive glucose control on the risk for cardiovascular events in patients with Type 2 diabetes. METHODS: FRENA is an ongoing registry of stable outpatients with symptomatic coronary artery disease, cerebrovascular disease or peripheral artery disease. We compared the incidence of subsequent ischaemic events (myocardial infarction, stroke or critical limb ischaemia) in patients with Type 2 diabetes and mean HbA(1c) levels < 7.0% (< 53 mmol/mol) vs. those with HbA(1c) levels > 7.0% (> 53 mmol/mol). RESULTS: Of 974 patients with Type 2 diabetes, 480 (49%) had mean HbA(1c) levels < 7% (< 53 mmol/mol). Over a mean follow-up of 14 months, 126 patients (13%) had subsequent ischaemic events: myocardial infarction (43), stroke (29) and critical limb ischaemia (64). The incidence of subsequent ischaemic events was significantly lower in patients with mean HbA(1c) levels < 7.0% (< 53 mmol/mol) than in those with HbA(1c) levels > 7.0% (> 53 mmol/mol) (8.6 vs. 14 per 100 patient-years; rate ratio 0.6; 95% CI 0.4-0.9). These differences persisted after adjusting for potential confounders. However, this better outcome was only found in patients presenting with coronary artery disease (rate ratio 0.4; 95% CI 0.2-0.8), not in those with cerebrovascular disease (rate ratio 0.9; 95% CI 0.4-2.0) or peripheral artery disease (rate ratio 0.8; 95% CI 0.5-1.3). Patients with mean HbA(1c) levels < 7.0% (< 53 mmol/mol) also had a lower mortality (rate ratio 0.6; 95% CI 0.3-0.99). CONCLUSIONS: In secondary prevention, patients with diabetes and HbA(1c) levels < 7.0% (< 53 mmol/mol) had a lower incidence of subsequent ischaemic events and a lower mortality than those with HbA(1c) levels > 7.0% (> 53 mmol/mol). These differences appeared only in patients with coronary artery disease.

Clinical presentation and early course of type 1 diabetes in patients with and without thyroid autoimmunity.

OBJECTIVE: To evaluate the prevalence of thyroid autoimmunity (TAI) in patients with recent-onset type 1 diabetes and to determine the influence of TAI on the clinical presentation and evolution of type 1 diabetes. RESEARCH DESIGN AND METHODS: We studied 111 newly diagnosed type 1 diabetes patients > 13 years old. The diagnosis of TAI was based on medical history and measurement of thyroid peroxidase (microsomal) antibodies (TPOAs). Clinical presentation of diabetes, beta-cell autoimmune markers (GADAs and 1A2As), and evolution of insulin-secretory reserves and metabolic control during the first 2 years of follow-up were analyzed. Differences between groups were evaluated by Student's t test or the chi 2 test. The influence of TAI on follow-up data was evaluated by multiple logistic regression analysis. RESULTS: TAI was present in 31 patients (14 TPOA+ patients with normal thyroid function, 12 TPOA+ patients with thyroid dysfunction, and 5 patients with previously diagnosed TAI). TAI was more prevalent in women than in men (43.7 vs. 15.9%, P = 0.001). beta-Cell autoimmunity was more prevalent in patients with TAI than in those without TAI (93.5 vs. 76.3%, P = 0.03). The evolution of insulin requirements, metabolic control, and insulin-secretory reserves was comparable in the two groups. CONCLUSIONS: TAI is present in many type 1 diabetes patients at the time of diagnosis and is associated with a high prevalence of thyroid dysfunction. The clinical presentation of diabetes and the evolution of metabolic control and insulin-secretory reserves are not influenced by the presence of TAI. Patients with type 1 diabetes should be screened for TAI at diagnosis.

Interaction between PARP-1 and HIF-2α in the hypoxic response.

Hypoxia-inducible factors (HIFs) mediate the transcriptional adaptation of hypoxic cells. The extensive transcriptional programm regulated by HIFs involves the induction of genes controlling angiogenesis, cellular metabolism, cell growth, metastasis, apoptosis, extracellular matrix remodeling and others. HIF is a heterodimer of HIF-α and HIF-ß subunits. In addition to HIF-1α, HIF-2α has evolved as an isoform that contributes differently to the hypoxic adaptation by performing non-redundant functions. Poly (ADP-ribose) polymerase-1 (PARP-1) is a nuclear protein involved in the control of DNA repair and gene transcription by modulating chromatin structure and acting as part of gene-specific enhancer/promoter-binding complexes. Previous results have shown that PARP-1 regulates HIF-1 activity. In this study, we focused on the cross-talk between HIF-2α and PARP-1. By using different approaches to suppress PARP-1, we show that HIF-2α mRNA expression, protein levels and HIF-2-dependent gene expression, such as ANGPTL4 and erythropoietin (EPO), are regulated by PARP-1. This regulation occurs at both the transcriptional and post-trancriptional level. We also show a complex formation between HIF-2α with PARP-1. This complex is sensitive to PARP inhibition and seems to protect against the von Hippel-Lindau-dependent HIF-2α degradation. Finally, we show that parp-1(-/-) mice display a significant reduction in the circulating hypoxia-induced EPO levels, number of red cells and hemoglobin concentration. Altogether, these results reveal a complex functional interaction between PARP-1 and the HIF system and suggest that PARP-1 is involved in the fine tuning of the HIF-mediated hypoxic response in vivo.

Class 1 integrons in environmental and clinical isolates of Pseudomonas aeruginosa.

The aims of this study were to ascertain the presence and spread of class 1 integrons amongst environmental and clinical isolates of Pseudomonas aeruginosa and to characterise their variable regions. A total of 76 isolates (56 clinical and 20 environmental) were studied. The presence of plasmids was explored, and polymerase chain reaction (PCR) was used for integron detection. All amplicons were sequenced. PCR detected class 1 integrons in 26 of the 56 clinical isolates; environmental isolates were integron-free. No plasmids were found, thus all the integrons found are possibly on the chromosome. Most isolates presented one amplicon, except PA110514 and PA116136, which showed two PCR products each. Variable regions revealed that 18 strains carried only one gene involved in aminoglycoside resistance, whereas in 3 strains gene cassettes were not found. The most prevalent cassettes amongst isolates were those encoding aminoglycoside adenyltransferase B (aadB). Several of the strains had acquired the same or a highly similar cassette array as those detected in geographically distant P. aeruginosa. This finding suggests that contact with bacterial reservoirs contributes to the evolution of this pathogen towards multiresistance. Empty structures found may represent a reservoir increasing the capacity to adapt to the environment. However, these integrons are not retained when the selective pressure disappears. It is hypothesised that integrons containing gene cassettes are crucial vehicles for the rapid horizontal transfer of resistance. If this is so, reduced use of antibiotics may lead to a significant decrease in the carriage of integrons amongst P. aeruginosa strains.

[Autoimmune thyroid pathology in recently diagnosed diabetes mellitus type 1]. / Patología tiroidea autoinmunitaria en diabetes mellitus tipo 1 de reciente diagnóstico.

OBJECTIVE: To analyze the prevalence of autoimmune thyroid disease among adult patients with recently diagnosed diabetes mellitus type I and its possible correlation with beta-cell autoimmunity markers (ICA, GAD, and IA 2) and with the presentation characteristics of diabetes mellitus. PATIENTS AND METHODS: A total of 100 patients diagnosed from 1992 to 1996 were included and anti-thyroid antibodies (Ac), anti-thyroglobulin (aTG) and antiperoxidase (aTPO) were measured. A comparison followed of the clinical characteristics, biochemical markers, and beta-cell immunity markers between the group of patients with positive and negative antibody determinations. Differences between groups were compared by the Student "t" test and non-parametric tests were used for cases not fulfilling the application conditions. RESULTS: Among the 100 patients, 25 had Ac+, two with previously known thyroid pathology and eight diagnosed at that moment. The group with Ac+ was characterized by a predominance of females (68% vs 32%; p = 0.001), lower bicarbonate levels (18.6 +/- 6.1 vs 21.3 +/- 6.4; p = 0.026) and higher requirements for insulin at discharge (0.77 +/- 0.22 vs 0.59 +/- 0.25 IU/kg; p = 0.002). Among patients in the Ac+ group, patients with thyroid pathology were characterized by a higher prevalence of females (90% vs 53.3%; p = 0.05) and a higher percentage of individuals with high anti-TPO titres (80% vs 33.3% higher than 400 IU/ml; p = 0.02). ICAs (66.6% vs 26.6% higher than 40 U JDF; p = 0.05) and IA2 (44.4% vs 0% higher than 12 IU/ml, p = 0.01). CONCLUSIONS: There is a high prevalence of thyroid pathology prevalence among our adult population with recently diagnosed DMI. Patients with thyroid autoimmunity have higher antibody titres to beta-cell and a somewhat more severe clinical presentation form. Prospective studies are required to determine the long term relevance of these differences.