Combined scanning electrochemical and fluorescence microscopies using a tetrazine as a single redox and luminescent (electrofluorochromic) probe.

The possibility of using a single electroactive and luminescent molecule both as a redox mediator and as a fluorophore in an experiment combining in situ Scanning Electrochemical Microscopy (SECM) and epifluorescence microscopy was validated. The usual working modes of SECM, namely positive and negative feedback as well as generation-collection, were used and the fluorescence images, intensity and spectra were recorded for each configuration. The tip potential, tip-substrate distance and, in the case of a conducting substrate, the substrate potential are the parameters that are likely to control the fluorescence. It is shown that the tip can be used to switch on and off the luminescence and that the modulation amplitude maximum is sensitive to the nature of the substrate. Approach curves based on this fluorescence modulation amplitude can be obtained showing a higher sensitivity than the classical electrochemical ones.

Diagnostic accuracy of urinary dipstick to exclude catheter-associated urinary tract infection in ICU patients: a reappraisal.

OBJECTIVES: We wanted to assess the diagnostic accuracy of urinary dipstick testing in excluding catheter-associated urinary tract infection (CAUTI) in intensive care unit (ICU) patients with fever or hypothermia. METHODS: This was a prospective observational cohort study in a medical-surgical ICU. Patients with new-onset fever >38.3 °C or hypothermia <36 °C at least 48 h after urinary catheter insertion were included over a 2-year period. At each episode, a urinary dipstick test and a urine culture were performed as the criterion standard. Extensive microbiological investigations for extra-urinary infections were performed also. The performances of various urinary dipstick result combinations in ruling out CAUTI were compared based on the likelihood ratios (LR+ and LR-). RESULTS: Symptomatic CAUTI was diagnosed in 31 (24.4 %) of the 127 included patients (195 episodes of fever or hypothermia). LR+ was best for combined leukocyte esterase-positive and nitrite-positive dipstick results (overall population: 14.91; 95 % confidence interval [95 % CI], 5.53-40.19; patients without urinary symptoms: 15.63; 95 % CI, 5.76-42.39). LR- was best for either leukocyte esterase-positive or nitrite-positive dipstick results (overall population: 0.41; 95 % CI, 0.57-0.65; patients without urinary symptoms, 0.36; 95 % CI, 0.21-0.60). CONCLUSIONS: Urinary dipstick testing at the bedside does not help to rule out symptomatic CAUTI in medical or surgical ICU patients with fever or hypothermia.

Electrochemical monitoring of the fluorescence emission of tetrazine and bodipy dyes using total internal reflection fluorescence microscopy coupled to electrochemistry.

A very sensitive technique where an electrochemical cell is coupled to a total internal reflection fluorescence microscopy setup is described and applied for the first time to the electrochemical monitoring of the fluorescence of organic dyes in solution. It is shown that this setup basically allows both spatial and time resolution for the recorded fluorescence signal as a function of the electrode potential: indeed the variations of the emission intensity are recorded within the diffusion layer for a classical cyclic voltammetry or chronoamperometry experiment inducing the redox conversion of an emissive form into a non emissive one (and conversely). Simultaneously, the variations of the emissive state lifetime are measured to discriminate between a mechanism involving only the conversion into a non emissive form from one involving a quenching between the emitter and the electrogenerated species. The results concerning the investigation of the electrochemical monitoring of the fluorescence properties for two types of original dyes are presented, demonstrating the possibility to switch on and off the emission in a fully reversible way and to investigate in depth the mechanisms associated to this switch.

[Acute respiratory distress syndrome due to Toxocara cati infection]. / Syndrome de détresse respiratoire aiguë secondaire à une infection à Toxocara cati.

Human toxocarosis is a helminthozoonosis due to the migration of toxocara species larvae throughout the human body. Lung manifestations vary and range from asymptomatic infection to severe disease. Dry cough and chest discomfort are the most common respiratory symptoms. Clinical manifestations include a transient form of Loeffler's syndrome or an eosinophilic pneumonia. We report a case of bilateral pneumonia in an 80 year old caucasian man who developed very rapidly an acute respiratory distress syndrome, with a PaO2/FiO2 ratio of 55, requiring mechanical ventilation and adrenergic support. There was an increased eosinophilia in both blood and bronchoalveolar lavage fluid. Positive toxocara serology and the clinical picture confirmed the diagnosis of the "visceral larva migrans" syndrome. Intravenous corticosteroid therapy produced a rapid rise in PaO2/FiO2 before the administration of specific treatment. A few cases of acute pneumonia requiring mechanical ventilation due to toxocara have been published but this is, to our knowledge, is the first reported case of ARDS with multi-organ failure.

[Factor X deficiency and pregnancy]. / Déficit en facteur X et grossesse.

Factor X deficiency is one of the rarest inherited coagulation disorders. It is an autosomal recessive inherited disease. In its homozygous form factor X deficiency has an estimated prevalence of 1: 500,000. However in its heterozygous form it has an estimated frequency of 1: 500 to 1: 2000. Pregnancy in women with congenital factor X deficiency has been associated with adverse foetal outcomes. We report a case of pregnancy in a woman with factor X deficiency. She was treated early during labour with prophylactic replacement of prothrombin complex concentrates (Kaskadil). An initial infusion of 40 UI.kg-1 of factor X was followed by 20 UI.kg-1 every 24 hours during three days. During labour and peripartum maternal coagulation was screened. She delivered a healthy baby at 33 weeks of gestation. No episode of abnormal bleeding was observed. Therefore in this case, prophylactic therapy using prothrombin complex concentrates during labour and delivery did prevent severe haemorrhages.