New method for simultaneous determination of dissolved organic carbon and its stable carbon isotope ratio in liquid samples: environmental applications.

This study reports the development of an all-in-one elemental analyser isotope ratio mass spectrometry (EA-IRMS) system modified for simultaneous analysis of dissolved organic carbon (DOC) concentration and its stable carbon isotope footprint (δ13CDOC) in aqueous samples. The method involves a quantitative oxidation of DOC in a 200 µL liquid sample to CO2, after sample acidification and stripping by nitrogen. The detection limit of the method for DOC quantification was 0.2 mg C/L with an analytical precision of 12 %. Uncertainty of stable isotope determinations was 2 % at 0.2 mg DOC/L, while decreasing to 0.3 % at 20 mg DOC/L. Quantitative oxidation of DOC in aqueous samples was validated by using ring test water samples and Deep Sea reference seawater. The method performances of isotope analysis were evaluated by analysing different isotopic standard solutions. The applicability of the method was tested through the analysis of different environmental types of water, showing that δ13CDOC ranged from - 23.30 to -31.85 ‰, allowing to characterize samples of different environmental origin. The developed method offers several advantages including rapidity, use of small sample volumes and minimal sample pre-treatment, making it a valuable tool for routine DOC concentration measurements paired with isotopic characterization.

Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTPH) is associated with considerable morbidity and mortality. Its incidence after pulmonary embolism and associated risk factors are not well documented. METHODS: We conducted a prospective, long-term, follow-up study to assess the incidence of symptomatic CTPH in consecutive patients with an acute episode of pulmonary embolism but without prior venous thromboembolism. Patients with unexplained persistent dyspnea during follow-up underwent transthoracic echocardiography and, if supportive findings were present, ventilation-perfusion lung scanning and pulmonary angiography. CTPH was considered to be present if systolic and mean pulmonary-artery pressures exceeded 40 mm Hg and 25 mm Hg, respectively; pulmonary-capillary wedge pressure was normal; and there was angiographic evidence of disease. RESULTS: The cumulative incidence of symptomatic CTPH was 1.0 percent (95 percent confidence interval, 0.0 to 2.4) at six months, 3.1 percent (95 percent confidence interval, 0.7 to 5.5) at one year, and 3.8 percent (95 percent confidence interval, 1.1 to 6.5) at two years. No cases occurred after two years among the patients with more than two years of follow-up data. The following increased the risk of CTPH: a previous pulmonary embolism (odds ratio, 19.0), younger age (odds ratio, 1.79 per decade), a larger perfusion defect (odds ratio, 2.22 per decile decrement in perfusion), and idiopathic pulmonary embolism at presentation (odds ratio, 5.70). CONCLUSIONS: CTPH is a relatively common, serious complication of pulmonary embolism. Diagnostic and therapeutic strategies for the early identification and prevention of CTPH are needed.

Helicobacter pylori infection diagnosis in hospitalised elderly patients: the stool antigen test (HpSA) in comparison with other methods.

BACKGROUND AND AIMS: Helicobacter pylori (Hp) infection prevalence increases with age. In elderly patients, who often do not collaborate and who are affected by multiple pathologies, worldwide-recognised invasive and non-invasive methods (histology and Urea Breath Test) are not easy to apply. A new test based on the detection of Hp antigens in the stool (HpSA test) is now available. The aim of our study was to evaluate the sensitivity and specificity of the HpSA test, and the interference of drugs (acid suppression, antibiotics) on test performance. METHODS: Hp infection was detected by UBT, HpSA and histology in 122 hospitalised elderly subjects, divided into two groups according to therapy in the last month. Subjects were classified as being Hp-positive if two test results (histology and UBT) were positive, and Hp-negative if the same two test results were negative. RESULTS: The sensitivity and specificity of the HpSA test compared with two tests (histology and UBT) were respectively 76 and 95%. In the group of patients who had not received drugs, the sensitivity and specificity of the HpSA test were respectively 76 and 96%. Instead, in the group of patients who had received pharmacological therapy, sensitivity and specificity values were respectively 67 and 100%. HpSA-positive patients had received acid suppression for 9.2 +/- 8.9 days, and false-negative patients for 27.2 +/- 9.9 days. CONCLUSIONS: The HpSA test is simple, inexpensive, and non-invasive for Hp detection, especially in elderly subjects with no compliance. It is influenced only after several days by therapy common in the elderly.