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PURPOSE: To investigate possible renal damage in healthy men exposed to extreme hypobaric hypoxia, using urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) concentration as biomarker. The value of NGAL as a biomarker of proximal tubular cell damage under hypoxic conditions was also tested in vitro experiments. METHODS: NGAL was assayed in a cohort of air cadets (n = 16) exposed to hypobaric hypoxia in a hypobaric chamber during their training program. In all subjects, urine creatinine (Cr) and urinary NGAL levels were measured immediately before, 3, and 24 h after hypobaric environment exposure. Three in vitro experiments using proximal tubular cell cultures were also performed to measure NGAL gene expression, NGAL secretion in the culture medium and to evaluate apoptosis under two cycles of hypoxia and reoxygenation. RESULTS: In the in vivo study, geometric means of urinary NGAL/Cr ratio measured 24 h after hypobaric hypoxia in the hypobaric chamber were significantly lower than baseline values (13.4 vs 25.9 ng/mg, p = 0.01). In cell cultures, hypoxia down-regulated NGAL gene expression without significantly changing NGAL secretion in the culture medium. Hypoxia significantly increased the percentage of apoptotic/necrotic cells, especially after the second hypoxia-reoxygenation cycle. CONCLUSIONS: Exposure to hypobaric-hypoxic environments does not cause significant and irreversible renal tubular injury in vivo and in vitro, except than in a late stage. The hypoxic insult does not seem to be mirrored by an increase of urinary NGAL in healthy men nor of NGAL gene expression in HK-2 cell culture or secretion in the culture medium in the in vitro conditions reported in the present study.

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Cellular and humoral immune responses to tetanus-diphtheria vaccine (Td) were assessed in human leukocyte antigen (HLA)-typed Italian military personnel who received multiple concomitant vaccines. Td-specific antibodies and T-lymphocytes were measured in individuals with one (group-1) and more than one (group-2) Td boosters. A third group (group-3), who received several vaccines, but not Td, was studied to verify the hypothesis of the polyclonal B-cell activation as mechanism for antibody persistence. The antibody response to Td toxoids was higher in group-1, who showed lower baseline antibody levels, than in group-2 subjects. The antibody response to tetanus was higher than to diphtheria toxoid in both groups. No correlation between antibody and cellular response, and no interference in the response to Td by co-administration of different vaccines were observed. HLA-DRB1∗01 allele was detected at significant higher frequency in subjects unable to double the baseline anti-diphtheria antibody levels after the vaccination. Anti-tetanus and diphtheria antibodies half-lives were assessed and the long-lasting persistence above the threshold for protection (0.1 IU/ml) was estimated in over 65 and 20 years, respectively. No significant increase of anti-diphtheria antibodies was observed in consequence of polyclonal B-cell activation. This study emphasizes the duration of Td vaccination-induced seroprotection, suggesting that re-vaccination should probably be performed at intervals longer than 10 years. No reciprocal interference by concomitantly administered vaccines has been observed. HLA-DRB1∗01 allele was significantly associated with anti-diphtheria defective response. Finally, this study does not confirm that anti-diphtheria antibody levels are maintained by polyclonal B-cell activation. Clinical trial registry: The study was registered with NCT01807780.

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STUDY OBJECTIVE: To determine the effect of positive end-expiratory pressure (PEEP) on the respiratory system and on cardiac function. DESIGN: Prospective randomized study. SETTING: Operating room. PATIENTS: 60 ASA physical status 1 women scheduled for pelvic laparoscopic surgery. INTERVENTIONS: Patients were ventilated normally during surgery; PEEP was modified depending on patient group allocation. Group A was the control group and did not receive PEEP. Group B received PEEP 5 cmH2O and Group C received PEEP 10 cmH2O. MEASUREMENTS: Respiratory parameters measured were partial pressure of arterial oxygen (PaO2), partial pressure of carbon dioxide (PaCO2), and end-tidal carbon dioxide tension (ETCO2). Cardiac parameters measured were left ventricular end-diastolic volume index (LVEDVI), ie, ratio of LVEDV/body surface area (BSA; [LVEDVI = end-diastolic volume [EDV]/BSA); left ventricular (LV) systolic function, tricuspid annular plane systolic excursion (TAPSE), right ventricular (RV) fractional area change (FAC), RV dimensions in the apical 4-chamber view, tracing basal and mid-cavity minor dimensions and longitudinal dimension, cardiac index, systolic pulmonary artery pressure (PASP), and systolic RV pressure (RVSP). Respiratory and cardiac measurements were recorded at T0 (baseline); T1 (after anesthesia induction, before pneumoperitoneum induction); at 10 (T2), 20 (T3), and 30 (T4) minutes after CO2 insufflation; and at the end of surgery (T5). MAIN RESULTS: Ventilation with PEEP at 10 cm H2O led to significant improvement in both respiratory and cardiac parameters. A reduction in pulmonary vascular resistance and enhanced washout of expiratory CO2 occurred. Ten and, to a lesser extent, 5 cm H2O of PEEP decreased LV stroke work. CONCLUSIONS: Ventilation with PEEP (up to 10 cm H2O) recruits the hypoventilated areas of the lungs and reduces cardiac afterload.

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BACKGROUND: The cardiac left ventricle responds to pressure overloads with mechanisms culminating in irreversible structural/functional cardiac alterations (left ventricular hypertrophy and/or diastolic dysfunction), inducing myocardial cells to secrete natriuretic peptides (NT-proBNP) antagonists of the renin-angiotensin-aldosterone system. The aim of this study was to evaluate the diagnostic accuracy of serum NT-proBNP levels in order to detect structural/functional cardiac diseases assessed by echocardiography. METHODS: A total of 126 consecutive newly diagnosed, never before treated, hypertensive patients (30-67 years) were enrolled, and clinical, echocardiography parameters and biochemical data were collected. Our reference was the presence of structural/functional cardiac disease (CSFD) and our index text was the serum NT-proBNP levels. RESULTS: NT-proBNP levels in CSFD patients were ~2 times higher than in non-CSFD subjects (median 61 vs 29 ng/L, n=50 and 76, respectively); in addition, 60% of CSFD subjects (only 14% of which with pathological levels, >125 ng/L), and 30% without CSFD showed NT-proBNP concentrations higher than 50 ng/L. However, ROC curves demonstrated a low specificity (38%) (calculated at 90% sensitivity at a cut-off of 22.5 ng/L). DISCUSSION: NT-proBNP levels, as a screening tool for cardiac structural/functional disease, appear to be limited, because of the low specificity. However, the strong association between its concentration and the establishment of irreversible cardiac hypertrophy prompts successive studies aimed to ascertain the use of its serum levels as an early alert indicator of disease severity.

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A patient with pulmonary hypertension (PH) during subacute cutaneous lupus erythematosus is described. Since the PH is characteristic of other connective tissue diseases (systemic sclerosis, Sharp syndrome), if a systemic lupus erythemtosus is coexistent, one should make a careful diagnostic screening (capillaroscopy, anti-centromere, or anti-Sc170, or anti-RNP antibodies) to show a possible overlap-syndrome.

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