Early detection of interstitial lung disease in rheumatic diseases: A joint statement from the Portuguese Pulmonology Society, the Portuguese Rheumatology Society, and the Portuguese Radiology and Nuclear Medicine Society

INTRODUCTION

Interstitial lung disease (ILD) contributes significantly to morbidity and mortality in connective tissue disease (CTD). Early detection and accurate diagnosis are essential for informing treatment decisions and prognosis in this setting. Clear guidance on CTD-ILD screening, however, is lacking.

OBJECTIVE

To establish recommendations for CTD-ILD screening based on the current evidence.

METHOD

Following an extensive literature research and evaluation of articles selected for their recency and relevance to the characterization, screening, and management of CTD-ILD, an expert panel formed by six pulmonologists from the Portuguese Society of Pulmonology, six rheumatologists from the Portuguese Society of Rheumatology, and six radiologists from the Portuguese Society of Radiology and Nuclear Medicine participated in a multidisciplinary discussion to produce a joint statement on screening recommendations for ILD in CTD.

RESULTS

The expert panel achieved consensus on when and how to screen for ILD in patients with systemic sclerosis, rheumatoid arthritis, mixed connective tissue disease, Sjögren syndrome, idiopathic inflammatory myopathies and systemic lupus erythematous.

CONCLUSIONS

Despite the lack of data on screening for CTD-ILD, an expert panel of pulmonologists, rheumatologists and radiologists agreed on a series of screening recommendations to support decision-making and enable early diagnosis of ILD to ultimately improve outcomes and prognosis in patients with CTD.

Approaching the airway in prehospital emergency is a common and potentially life-saving practice

Management by the environment is complex, which means a much higher percentage of difficult airways than in a regulated environment such as the operating room. Failure or prolonged attempt to tracheal intubation is associated with unfavorable outcomes and serious complications. Acute epiglottitis is a life-threatening disorder, classified as a medical emergency within the diseases of the upper respiratory airway and characterized by its sudden and deadly evolution if rapid intubation is not achieved to allow oxygenation of the patient. We describe a 36-year-old male patient with stridor, dyspnea e hypoxemia due to total obstruction of airway, caused by an acute epiglottitis. We aim to highlight this unusual injury and its management from the prehospital until discharge illustrating the severity of the clinical presentation, current treatment and outcome.

Modulation of persistent current in graphene quantum rings

We investigate the effect of long-range impurity potentials on the persistent current of graphene quantum rings in the presence of an uniform perpendicular magnetic field. The impurity potentials are modeled as finite regions of the ring with a definite length. We show that, due to the relativistic and massless character of the charge carriers in graphene, the effect of such non-uniform potentials on the energy spectrum and on the persistent current of the rings can be reliably modeled by assuming a non-perturbed ring and including an additional phase due to the interaction of the charge carriers with the potential. In addition, the results show the presence of localized states in the impurity regions. Moreover, we show that for the case of a potential created by a p-n-p junction, the persistent current can be modulated by controlling the voltage at the junction.

Approaching the airway in prehospital emergency is a common and potentially life-saving practice

Management by the environment is complex, which means a much higher percentage of difficult airways than in a regulated environment such as the operating room. Failure or prolonged attempt to tracheal intubation is associated with unfavorable outcomes and serious complications. Acute epiglottitis is a life-threatening disorder, classified as a medical emergency within the diseases of the upper respiratory airway and characterized by its sudden and deadly evolution if rapid intubation is not achieved to allow oxygenation of the patient. We describe a 36-year-old male patient with stridor, dyspnea e hypoxemia due to total obstruction of airway, caused by an acute epiglottitis. We aim to highlight this unusual injury and its management from the prehospital until discharge illustrating the severity of the clinical presentation, current treatment and outcome.

Gate potential-controlled current switching in graphene Y-junctions

In this work we investigate the ballistic transport of electrons through three-terminal graphene-based devices. The system consists of a Y-shaped junction formed by three armchair-edged graphene nanoribbons with a rectangular gate potential applied to one of the output branches, whereby current control can be established by the controlling of the refractive index in graphene p-n junctions. Transport properties are obtained by using the Landauer-Büttiker formalism and the tight-binding model within the nearest-neighbor approximation, which allows the calculation of the conductance as function of the Fermi energy, the applied potential, and the system size, as well as the current density. The results demonstrate that the applied electric field can tune the current transmission between the input and two output leads and, consequently, the proposed system acts as a current switch.

Burnout among Portuguese radiographers during the COVID-19 pandemic

INTRODUCTION

The COVID-19 pandemic has had a global impact, including in health services, placing health professionals under enormous tension, pressure, and stress. Professionals involved in the care, diagnosis, and treatment of COVID-19-infected patients have been subject to emotional and physical distress that can potentially enhance the development of occupational diseases. The aim of this study was to assess the impact of the COVID-19 pandemic on the incidence of burnout among Portuguese radiographers.

METHODS

This was a cross-sectional, quantitative study. Burnout levels were estimated using the Maslach Burnout Inventory-Human Services Survey, composed of 22 questions. Specific questions were developed to characterize the socio-demographic situation and the impact of the pandemic on the radiographers. Data were descriptively analyzed and Mann-Whitney and Kruskal-Wallis tests were used for correlation analysis.

RESULTS

The study sample comprised 386 radiographers, 68.7% of whom where female and 31.3% male. The mean sample age was 36.3 (±9.1) years. A total of 43.5% and 45.5% of subjects had a high level of emotional exhaustion and depersonalization, respectively, and 59.8% experienced low personal accomplishment. Altogether, 23.3% of study participants were at high risk of burnout in the three dimensions assessed and 77.2% in at least one.

CONCLUSION

Study results showed that radiographers were at high risk of developing burnout in the COVID-19 pandemic setting. Health institutions should actively monitor these professional's mental health and develop restorative strategies that enable their emotional wellbeing, preventing absenteeism and increasing patients' quality of care.

IMPLICATIONS FOR PRACTICE

Burnout of health professionals has a strong impact on health services organization, resulting in increased absenteeism and error probability, frequent work delays, low productivity and job satisfaction, inter- and intra-professional conflicts, high job turnover, high job quit, and decreased quality of care perceived by users.

Predicting lung nodules malignancy

BACKGROUND

It is critical to developing an accurate method for differentiating between malignant and benign solitary pulmonary nodules. This study aimed was to establish a predicting model of lung nodules malignancy in a real-world setting.

METHODS

The authors retrospectively analysed the clinical and computed tomography (CT) data of 121 patients with lung nodules, submitted to percutaneous CT-guided transthoracic biopsy, between 2014 and 2015. Multiple logistic regression was used to screen independent predictors for malignancy and to establish a clinical prediction model to evaluate the probability of malignancy.

RESULTS

From a total of 121 patients, 75 (62%) were men and with a mean age of 64.7 years old. Multivariate logistic regression analysis identified six independent predictors of malignancy: age, gender, smoking status, current extra-pulmonary cancer, air bronchogram and nodule size (p<0.05). The area under the curve (AUC) was 0.8573.

CONCLUSIONS

The prediction model established in this study can be used to assess the probability of malignancy in the Portuguese population, thereby providing help for the diagnosis of lung nodules and the selection of follow-up interventions.

Current modulation in graphene p-n junctions with external fields

In this work we describe a proposal for a graphene-based nanostructure that modulates electric current even in the absence of a gap in the band structure. The device consists of a graphene p-n junction that acts as a Veselago lens that focuses ballistic electrons on the output lead. Applying external (electric and magnetic) fields changes the position of the output focus, reducing the transmission. Such device can be applied to low power field effect transistors, which can benefit from graphene's high electronic mobility.

Heterozygous TERT gene mutation associated with familial idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease of unknown cause that occurs sporadically, but it can also occur in families and so named as Familial Pulmonary Fibrosis (FPF). Some forms of FPF overlaps IPF features, namely the radiological and histological pattern of usual interstitial pneumonia (UIP). Genetic and environmental factors commonly play an important role in the pathogenesis of FPF and the most commonly identified mutations involve the telomerase complex. Here, we report a rare case of FPF in a male at the age of 44, in whom genetic testing showed heterozygous variants for the telomerase reverse transcriptase gene (TERT). Our report highlights the importance of compiling a thorough family history in younger patients identified with UIP serving as a resource for identifying the current and future genetic links to disease. Families with UIP hold a great promise in defining UIP pathogenesis, potentially suggesting targets for the development of future therapies.

Melissa officinalis L. ethanolic extract inhibits the growth of a lung cancer cell line by interfering with the cell cycle and inducing apoptosis

Melissa officinalis is a plant from the family Lamiaceae, native in Europe particularly in the Mediterranean region. Given our interest in identifying extracts and compounds capable of inhibiting tumor cell growth, and given the antioxidant content and the high consumption of Melissa officinalis in Portugal, this study aimed to test the tumor cell growth inhibitory activity of five different extracts of this plant (aqueous, methanolic, ethanolic, hydromethanolic and hydroethanolic) in three human tumor cell lines: MCF-7, AGS and NCI-H460. All extracts decreased cell growth in all cell lines in a concentration-dependent manner. The ethanolic extract was the most potent one, presenting a GI50 concentration of approximately 100.9 μg mL-1 in the NCI-H460 lung cancer cells. This extract was characterized by LC-DAD-ESI/MS regarding its phenolic composition, revealing rosmarinic acid as the most abundant compound. The GI75 concentration of this extract affected the cell cycle profile of these cells. In addition, both the GI50 and the GI75 concentrations of the extract induced cellular apoptosis. Moreover, treatment of NCI-H460 cells with this extract caused a decrease in pro-caspase 3 and an increase in p53 levels. This study emphasizes the relevance of the study of natural products as inhibitors of tumor cell growth.

Learning curve for transbronchial lung cryobiopsy in diffuse lung disease

INTRODUCTION

Transbronchial lung cryobiopsy (TBLC) is increasingly used in the diagnosis of diffuse lung disease (DLD), but no data have yet been published on the learning curve associated with this technique.

AIM

To evaluate diagnostic yield, lung tissue sample length and area, and procedure-related complications in a cohort of TBLC procedures to define the learning curve and threshold for proficiency.

METHODS

Retrospective analysis of the first 100 TBLCs performed in different segments of the same lobe in patients with suspected DLD. We compared diagnostic yield, sample length and area, and complications between consecutive groups of patients.

RESULTS

The overall diagnostic yield for TBLC was 82%. Median sample length was 5.4mm (IQR, 5-6) and median area was 19.5mm2 (IQR, 13.3-25). Pneumothorax was the most common complication (18%). On comparing the two groups of 50 consecutive patients, a significant difference was found for diagnostic yield (74% vs 90%; p=0.04), sample length (5.0mm [2.5-16] vs 6.0mm [4-12;] p<0.01) and area (17.5mm2 [6-42] vs 21.5mm2 [10-49]; p<0.01). Logarithm regression was applied to median diagnostic yield and sample length and area for groups of 10 consecutive patients to define the learning curve, which plateaued after approximately 70 procedures.

CONCLUSIONS

Our findings suggest that proficiency in TBLC is achieved at approximately the 70th procedure; however they need to be validated in more series and cohorts.

Impact of antibiotic therapy in severe community-acquired pneumonia: Data from the Infauci study

Antibiotic therapy (AT) is the cornerstone of the management of severe community-acquired pneumonia (CAP). However, the best treatment strategy is far from being established. To evaluate the impact of different aspects of AT on the outcome of critically ill patients with CAP, we performed a post hoc analysis of all CAP patients enrolled in a prospective, observational, multicentre study. Of the 502 patients included, 76% received combination therapy, mainly a β-lactam with a macrolide (80%). AT was inappropriate in 16% of all microbiologically documented CAP (n=177). Hospital and 6months mortality were 34% and 35%. In adjusted multivariate logistic regression analysis, combination AT with a macrolide was independently associated with a reduction in hospital (OR 0.17, 95%CI 0.06-0.51) and 6months (OR 0.21, 95%CI 0.07-0.57) mortality. Prolonged AT (>7days) was associated with a longer ICU (14 vs. 7days; p<0.001) and hospital length of stay (LOS) (25 vs. 17days; p<0.001). Combination AT with a macrolide may be the most suitable AT strategy to improve both short and long term outcome of severe CAP patients. AT >7days had no survival benefit and was associated with a longer LOS.

Use of nebulized antimicrobials for the treatment of respiratory infections in invasively mechanically ventilated adults: a position paper from the European Society of Clinical Microbiology and Infectious Diseases

With an established role in cystic fibrosis and bronchiectasis, nebulized antibiotics are increasingly being used to treat respiratory infections in critically ill invasively mechanically ventilated adult patients. Although there is limited evidence describing their efficacy and safety, in an era when there is a need for new strategies to enhance antibiotic effectiveness because of a shortage of new agents and increases in antibiotic resistance, the potential of nebulization of antibiotics to optimize therapy is considered of high interest, particularly in patients infected with multidrug-resistant pathogens. This Position Paper of the European Society of Clinical Microbiology and Infectious Diseases provides recommendations based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology regarding the use of nebulized antibiotics in invasively mechanically ventilated adults, based on a systematic review and meta-analysis of the existing literature (last search July 2016). Overall, the panel recommends avoiding the use of nebulized antibiotics in clinical practice, due to a weak level of evidence of their efficacy and the high potential for underestimated risks of adverse events (particularly, respiratory complications). Higher-quality evidence is urgently needed to inform clinical practice. Priorities of future research are detailed in the second part of the Position Paper as guidance for researchers in this field. In particular, the panel identified an urgent need for randomized clinical trials of nebulized antibiotic therapy as part of a substitution approach to treatment of pneumonia due to multidrug-resistant pathogens.

Electronic confinement in graphene quantum rings due to substrate-induced mass radial kink

We investigate localized states of a quantum ring confinement in monolayer graphene defined by a circular mass-related potential, which can be induced e.g. by interaction with a substrate that breaks the sublattice symmetry, where a circular line defect provides a change in the sign of the induced mass term along the radial direction. Electronic properties are calculated analytically within the Dirac-Weyl approximation in the presence of an external magnetic field. Analytical results are also compared with those obtained by the tight-binding approach. Regardless of its sign, a mass term [Formula: see text] is expected to open a gap for low-energy electrons in Dirac cones in graphene. Both approaches confirm the existence of confined states with energies inside the gap, even when the width of the kink modelling the mass sign transition is infinitely thin. We observe that such energy levels are inversely proportional to the defect line ring radius and independent on the mass kink height. An external magnetic field is demonstrated to lift the valley degeneracy in this system and easily tune the valley index of the ground state in this system, which can be polarized on either K or [Formula: see text] valleys of the Brillouin zone, depending on the magnetic field intensity. Geometrical changes in the defect line shape are considered by assuming an elliptic line with different eccentricities. Our results suggest that any defect line that is closed in a loop, with any geometry, would produce the same qualitative results as the circular ones, as a manifestation of the topologically protected nature of the ring-like states investigated here.

Mid-regional proadrenomedullin: An early marker of response in critically ill patients with severe community-acquired pneumonia?

BACKGROUND

Mid-regional proadrenomedullin (MR-proADM) is a novel biomarker with potential prognostic utility in patients with community-acquired pneumonia (CAP).

PURPOSE

To evaluate the value of MR-proADM levels at ICU admission for further severity stratification and outcome prediction, and its kinetics as an early predictor of response in severe CAP (SCAP).

MATERIALS AND METHODS

Prospective, single-center, cohort study of 19 SCAP patients admitted to the ICU within 12h after the first antibiotic dose.

RESULTS

At ICU admission median MR-proADM was 3.58nmol/l (IQR: 2.83-10.00). No significant association was found between its serum levels at admission and severity assessed by SAPS II (Spearman's correlation=0.24, p=0.31) or SOFA score (SOFA<10: <3.45nmol/l vs. SOFA≥10: 3.90nmol/l, p=0.74). Hospital and one-year mortality were 26% and 32%, respectively. No significant difference in median MR-proADM serum levels was found between survivors and non-survivors and its accuracy to predict hospital mortality was bad (aROC 0.53). After 48h of antibiotic therapy, MR-proADM decreased in all but 5 patients (median -20%; IQR -56% to +0.1%). Its kinetics measured by the percent change from baseline was a good predictor of clinical response (aROC 0.80). The best discrimination was achieved by classifying patients according to whether MR-proADM decreased or not within 48h. No decrease in MR-proADM serum levels significantly increased the chances of dying independently of general severity (SAPS II-adjusted OR 174; 95% CI 2-15,422; p=0.024).

CONCLUSIONS

In SCAP patients, a decrease in MR-proADM serum levels in the first 48h after ICU admission was a good predictor of clinical response and better outcome.

Global survey on nebulization of antimicrobial agents in mechanically ventilated patients: a call for international guidelines

Nebulized antimicrobial agents are increasingly administered for treatment of respiratory infections in mechanically ventilated (MV) patients. A structured online questionnaire assessing the indications, dosages and recent patterns of use for nebulized antimicrobial agents in MV patients was developed. The questionnaire was distributed worldwide and completed by 192 intensive care units. The most common indications for using nebulized antimicrobial agent were ventilator-associated tracheobronchitis (VAT; 58/87), ventilator-associated pneumonia (VAP; 56/87) and management of multidrug-resistant, Gram-negative (67/87) bacilli in the respiratory tract. The most common prescribed nebulized agents were colistin methanesulfonate and sulfate (36/87, 41.3% and 24/87, 27.5%), tobramycin (32/87, 36.7%) and amikacin (23/87, 26.4%). Colistin methanesulfonate, amikacin and tobramycin daily doses for VAP were significantly higher than for VAT (p < 0.05). Combination of parenteral and nebulized antibiotics occurred in 50 (86%) of 58 prescriptions for VAP and 36 (64.2%) of 56 of prescriptions for VAT. The use of nebulized antimicrobial agents in MV patients is common. There is marked heterogeneity in clinical practice, with significantly different in use between patients with VAP and VAT. Randomized controlled clinical trials and international guidance on indications, dosing and antibiotic combinations to improve clinical outcomes are urgently required.

AVE 0991, a non-peptide mimic of angiotensin-(1-7) effects, attenuates pulmonary remodelling in a model of chronic asthma

BACKGROUND AND PURPOSE

AVE 0991 (AVE) is a non-peptide compound, mimic of the angiotensin (Ang)-(1-7) actions in many tissues and pathophysiological states. Here, we have investigated the effect of AVE on pulmonary remodelling in a murine model of ovalbumin (OVA)-induced chronic allergic lung inflammation.

EXPERIMENTAL APPROACH

We used BALB/c mice (6-8 weeks old) and induced chronic allergic lung inflammation by OVA sensitization (20 μg·mouse(-1) , i.p., four times, 14 days apart) and OVA challenge (1%, nebulised during 30 min, three times per·week, for 4 weeks). Control and AVE groups were given saline i.p and challenged with saline. AVE treatment (1 mg·kg(-1) ·per day, s.c.) or saline (100 μL·kg(-1) ·per day, s.c.) was given during the challenge period. Mice were anaesthetized 72 h after the last challenge and blood and lungs collected. In some animals, primary bronchi were isolated to test contractile responses. Cytokines were evaluated in bronchoalveolar lavage (BAL) and lung homogenates.

KEY RESULTS

Treatment with AVE of OVA sensitised and challenged mice attenuated the altered contractile response to carbachol in bronchial rings and reversed the increased airway wall and pulmonary vasculature thickness and right ventricular hypertrophy. Furthermore, AVE reduced IL-5 and increased IL-10 levels in the BAL, accompanied by decreased Ang II levels in lungs.

CONCLUSIONS AND IMPLICATIONS

AVE treatment prevented pulmonary remodelling, inflammation and right ventricular hypertrophy in OVA mice, suggesting that Ang-(1-7) receptor agonists are a new possibility for the treatment of pulmonary remodelling induced by chronic asthma.

Impact of infection on admission and of the process of care on mortality of patients admitted to the Intensive Care Unit: the INFAUCI study

A prospective, cohort, clinical, observational study was performed in 14 Intensive Care Units (ICUs) to evaluate the contemporary epidemiology, morbi-mortality and determinants of outcome of the population with an infection on admission. All 3766 patients admitted during a consecutive 12-month period were screened. Their median age was 63 [26-83], 61.1% were male and 69.8% had significant comorbidities. On admission to the ICU 1652 patients (43.9%) had an infection, which was community acquired in 68.2% (one-fifth with healthcare-associated criteria) and ward-acquired in the others. Roughly half presented to the ICU with septic shock. As much as 488 patients with community-acquired infections were deemed stable enough to be first admitted to the ward, but had similar mortality to unstable patients directly admitted to the ICU (35.9% vs. 35.1%, p 0.78). Only 48.3% of this infected population had microbiological documentation and almost one-quarter received inappropriate initial antibiotic therapy. This, along with comorbidities, was a main determinant of mortality. Overall, infected patients on admission had higher mortality both in the ICU (28.0% vs. 19.9%, p <0.001) and in the hospital (38.2% vs. 27.5%, p <0.001) and even after being discharged to the ward (14.2% vs. 9.6%, p <0.001). Also, patients not infected on admission who acquired an infection in the ICU, had an increased risk of dying in the hospital (odds ratio 1.41 [1.12-1.83]). Consequently, infection, regardless of its place of acquisition, was associated with increased mortality. Improving the process of care, especially first-line antibiotic appropriateness, and preventing ICU-acquired infections, may lead to better outcomes.

The electronic properties of graphene and graphene ribbons under simple shear strain

A tight-binding model is used to study the energy band of graphene and graphene ribbon under simple shear strain. The ribbon consists of lines of carbon atoms in an armchair or zigzag orientation where a simple shear strain is applied in the x-direction keeping the atomic distances in the y-direction unchanged. Such modification in the lattice gives an energy band that differs in several aspects from the one without any shear and with pure shear. The changes in the spectrum depend on the line displacement of the ribbon, and also on the modified hopping parameter. It is also shown that this simple shear strain tunes the electronic properties of both graphene and graphene ribbon, opening and closing energy gaps for different displacements of the system. The modified density of states is also shown.

Severity assessment tools in ICU patients with 2009 influenza A (H1N1) pneumonia

The aim of this study was to determine if severity assessment tools (general severity of illness and community-acquired pneumonia specific scores) can be used to guide decisions for patients admitted to the intensive care unit (ICU) due to pandemic influenza A pneumonia. A prospective, observational, multicentre study included 265 patients with a mean age of 42 (±16.1) years and an ICU mortality of 31.7%. On admission to the ICU, the mean pneumonia severity index (PSI) score was 103.2 ± 43.2 points, the CURB-65 score was 1.7 ± 1.1 points and the PIRO-CAP score was 3.2 ± 1.5 points. None of the scores had a good predictive ability: area under the ROC for PSI, 0.72 (95% CI, 0.65-0.78); CURB-65, 0.67 (95% CI, 0.59-0.74); and PIRO-CAP, 0.64 (95% CI, 0.56-0.71). The PSI score (OR, 1.022 (1.009-1.034), p 0.001) was independently associated with ICU mortality; however, none of the three scores, when used at ICU admission, were able to reliably detect a low-risk group of patients. Low risk for mortality was identified in 27.5% of patients using PIRO-CAP, but above 40% when using PSI (I-III) or CURB65 (<2). Observed mortality was 13.7%, 13.5% and 19.4%, respectively. Pneumonia-specific scores undervalued severity and should not be used as instruments to guide decisions in the ICU.

[Positive bronchoalveolar lavage and quantitative cultures results in suspected late-onset ventilator associated penumonia evaluation--retrospective study]

INTRODUCTION

Bronchoalveolar lavage (BAL) with quantitative cultures has been used in order to increase ventilator associated pneumonia (VAP) diagnosis specificity, although the accurate technique for this entity diagnosis remains controversial.

OBJECTIVES

To evaluate the influence of using positive BAL and quantitative cultures results in microbiologic diagnosis and treatment of patients with suspected late VAP and prior antibiotherapy.

MATERIAL AND METHODS

Retrospective analysis of intensive care unit (UCI) patients, during a one year period, with clinical suspicion of late VAP and prior use of antibiotics that presented a growth in BAL cultures.

RESULTS

Of 243 BAL performed, there were 71 (29.2%) positive cultures (60 patients, 76.7% male, 54 ± 19 years). BAL was done after 13 days (median) of invasive mechanical ventilation, 11 days of ICU antibiotherapy and in the day in which a new antibiotic for VAP suspicion was started. Colony forming units (CFU)/ml count was performed in 71.8% and endotracheal aspirate (ETA) simultaneously collected for qualitative analysis in 85.9%. Therapeutic approach was changed in 38.0%: correction (16.9%), de-escalation (12.7%) and directed antibiotherapy start (8.4%). Therapeutic changes were made in the presence of CFU > 10(4) in 84.2% and in agreement with ETA in 70.8%. In cases in which antibiotherapy was maintained (62.0%), quantitative cultures would have allowed de-escalation in 9.1%. Changes in prescription were more frequent when CFU was > 10(4) (48.5%), comparing with situations in which counts were lower and BAL analysis was qualitative (28.9%), p = 0.091. There were no significant differences between patients submitted to different therapeutic approaches concerning to ICU mortality or length of stay.

CONCLUSION

In late onset VAP, positive BAL and quantitative cultures allowed therapeutic changes, leading to antibiotic adequacy and consumption reduction, which can however be maximised.

Fractal spectrum of charge carriers in quasiperiodic graphene structures

In this work we investigate the interaction of charge carriers in graphene with a series of p-n-p junctions arranged according to a deterministic quasiperiodic substitutional Fibonacci sequence. The junctions create a potential landscape with quantum wells and barriers of different widths, allowing the existence of quasi-confined states. Spectra of quasi-confined states are calculated for several generations of the Fibonacci sequence as a function of the wavevector component parallel to the barrier interfaces. The results show that, as the Fibonacci generation is increased, the dispersion branches form energy bands distributed as a Cantor-like set. Besides, for a quasiperiodic set of potential barriers, we obtain the electronic tunneling probability as a function of energy, which shows a striking self-similar behavior for different generation numbers.

Image quantification for radiation dose calculations--limitations and uncertainties

Radiation dose calculations in nuclear medicine depend on quantification of activity via planar and/or tomographic imaging methods. However, both methods have inherent limitations, and the accuracy of activity estimates varies with object size, background levels, and other variables. The goal of this study was to evaluate the limitations of quantitative imaging with planar and single photon emission computed tomography (SPECT) approaches, with a focus on activity quantification for use in calculating absorbed dose estimates for normal organs and tumors. To do this we studied a series of phantoms of varying complexity of geometry, with three radionuclides whose decay schemes varied from simple to complex. Four aqueous concentrations of ⁹⁹mTc, ¹³¹I, and ¹¹¹In (74, 185, 370, and 740 kBq mL⁻¹) were placed in spheres of four different sizes in a water-filled phantom, with three different levels of activity in the surrounding water. Planar and SPECT images of the phantoms were obtained on a modern SPECT/computed tomography (CT) system. These radionuclides and concentration/background studies were repeated using a cardiac phantom and a modified torso phantom with liver and "tumor" regions containing the radionuclide concentrations and with the same varying background levels. Planar quantification was performed using the geometric mean approach, with attenuation correction (AC), and with and without scatter corrections (SC and NSC). SPECT images were reconstructed using attenuation maps (AM) for AC; scatter windows were used to perform SC during image reconstruction. For spherical sources with corrected data, good accuracy was observed (generally within ±10% of known values) for the largest sphere (11.5 mL) and for both planar and SPECT methods with ⁹⁹mTc and ¹³¹I, but were poorest and deviated from known values for smaller objects, most notably for ¹¹¹In. SPECT quantification was affected by the partial volume effect in smaller objects and generally showed larger errors than the planar results in these cases for all radionuclides. For the cardiac phantom, results were the most accurate of all of the experiments for all radionuclides. Background subtraction was an important factor influencing these results. The contribution of scattered photons was important in quantification with ¹³¹I; if scatter was not accounted for, activity tended to be overestimated using planar quantification methods. For the torso phantom experiments, results show a clear underestimation of activity when compared to previous experiment with spherical sources for all radionuclides. Despite some variations that were observed as the level of background increased, the SPECT results were more consistent across different activity concentrations. Planar or SPECT quantification on state-of-the-art gamma cameras with appropriate quantitative processing can provide accuracies of better than 10% for large objects and modest target-to-background concentrations; however when smaller objects are used, in the presence of higher background, and for nuclides with more complex decay schemes, SPECT quantification methods generally produce better results.

Electrostatically confined quantum rings in bilayer graphene

We propose a new system where electron and hole states are electrostatically confined into a quantum ring in bilayer graphene. These structures can be created by tuning the gap of the graphene bilayer using nanostructured gates or by position-dependent doping. The energy levels have a magnetic field (B(0)) dependence that is strikingly distinct from that of usual semiconductor quantum rings. In particular, the eigenvalues are not invariant under a B(0) --> -B(0) transformation and, for a fixed total angular momentum index m, their field dependence is not parabolic, but displays two minima separated by a saddle point. The spectra also display several anticrossings, which arise due to the overlap of gate-confined and magnetically confined states.

Prediction of Dairy Housing Construction Costs

Dairy farms in Galicia and elsewhere in Europe are going through a transition phase to adapt to modern dairy technology, improve labor efficiency, and increase in size and scale. Expanding a dairy herd and building housing for more cows can be very expensive. A poor decision during expansion can result in serious financial difficulties even to the point of making the farm economically unviable. Dairy managers must carefully evaluate existing alternatives and must select an optimal strategy. To aid this decision, a computer spreadsheet application has been developed that predicts the cost per cow and cost per unit of area of alternative designs as functions of the number of cows to be housed. The spreadsheet is, in principle, applicable to a wide variety of designs and to housing for livestock other than dairy cattle. However, the current database allows comparison among six of the dairy housing designs that have been used most widely in Galicia in recent years. From projected financial results of the developed model, it was concluded that differing designs were preferred for different farm circumstances. Preferred designs for farms with 60 to 200 cows were either four rows of facing free stalls or four rows of tail-to-tail free stalls, which have virtually the same costs. Whereas for farms with fewer than 60 cows, the preferred design was two rows of tail-to-tail free stalls, designs with three rows of free stalls were generally more costly per cow. Results of design calculations must be integrated with other farm management considerations in choosing a particular design.

Treatment of the afebrile patient after catheter withdrawal: drugs and duration

Catheter-related infections constitute 10-15% of all nosocomial infections, and constitute a relevant and growing problem, with an impact that is far from irrelevant, especially in the intensive care unit. The most frequent pathogens implicated come from the skin flora; Gram-positive cocci are responsible for about two-thirds of the infections, and Candida has emerged as another important cause. Questions about drug, route of administration, dosage and duration of antibiotherapy for patients who have become apyretic and with no signs of sepsis after catheter removal are still under debate, and far from being definitively answered. Decisions regarding these questions are based on three main factors: namely, which is the microoorganism responsible for the infection, what was the time to response, and what kind of patient are we dealing with? However, the microorganism is clearly the main factor in making a decision. In summary, all catheter-related infections should be treated with appropriate antibiotics, regardless of the removal of the catheter, with parenteral drugs, using high doses and short courses, namely 1 week, and de-escalating to narrow-spectrum drugs on the basis of susceptibility tests as soon as possible. Staphylococcus aureus catheter-related infections constitute an exception, needing longer courses, as it is difficult to predict who will be high-risk patients.

Additions to the mycobiota of the weed Lantana camara (Verbenaceae) in southeastern Brazil

A sequel to the work of systematic surveying the mycobiota of Lantana camara, aimed at finding potential biocontrol agents, was carried out during 1995-1996 covering part of its centre of origin in Brazil (state of Minas Gerais). Fifty-eight sampling sites, representing the four main climatic types in the state of Minas Gerais, were surveyed. Additional ad hoc collections were made in the states of Bahia, Espírito Santo, Parana, Rio de Janeiro and São Paulo. Fifteen fungal species were recorded in association with L. camara including the previously undescribed species Phomopsis lantanae-glutinosae sp. nov. Five fungi are also newly recorded on this host in Brazil: Cercospora lantanicola, Corynespora cassiicola, Meliola ambigua, Mycovellosiella lantaniphila and Phornopsis lantanae. The following fungi, previously recorded on L. camara in Brazil, are recorded here for the first time in Minas Gerais: Dendryphielia aspera, Micropustulomyces mucilaginosus, Mycovellosiella lantanae, Pseudocercospora guianensis and Puccinia lantanae.

Lepidoptera pests collected in Eucalyptus urophylla (Myrtaceae) plantations during five years in Três Marias, State of Minas Gerais, Brazil

Lepidoptera pest species from eucalyptus were collected in Eucalyptus urophylla plantations in the region of Três Marias, State of Minas Gerais, Brazil, every 15 days from June 1989 to June 1994 with five light traps. Twelve primary and 15 secondary pest species were collected in the period with an average of 13,387 and 812 individuals per light trap, respectively. Most collected primary pest species were Stenalcidia grosica (Geometridae), Iridopsis subferaria (Geometridae), Eupseudosoma aberrans (Arctiidae) and Psorocampa denticulata (Notodontidae), totalizing for the study period an average of 5,450, 2,162, 2,436 and 1,458 individuals per light trap, respectively. Idalus admirabilis (Arctiidae) was the most collected secondary pest species, averaging 652 individuals/trap. Most primary pest species were collected during the dry season, from April to July, whereas most secondary pest species were collected during the rainy season, from January to March. These differences on seasonal occurrence between the two groups could be due to the fact that many secondary pest species of Eucalyptus in Brazil pupate in the soil, and they need humidity to complete its pupal stage.

Production and characterization of a mouse monoclonal antibody against the Gag p26 protein of human immunodeficiency virus type 2: identification of a new antigenic epitope

One anticapsid (p26) mouse monoclonal antibody was developed after immunization with recombinant p26 Gag protein and was tested for reactivity with different HIV-1 and HIV-2 isolates by ELISA and Western blot analysis. This antibody, named R26.1, reacted with all HIV-2 isolates tested and with recombinant p26 proteins, but no HIV-1 isolates. The epitope of antibody R26.1 was mapped to residues 50-71 in the N-terminal domain of the capsid protein, a highly conserved region in all HIV-2 isolates sequenced to date. This monoclonal antibody may be useful for the detection of HIV-2, and for the discrimination between HIV-1 and HIV-2 infections. Likewise, the identified epitope may be useful for the detection of p26 antibodies in HIV-2-infected individuals.

Quantitation of human immunodeficiency virus type 2 DNA in peripheral blood mononuclear cells by using a quantitative-competitive PCR assay

A new quantitative-competitive PCR-based human immunodeficiency virus type 2 (HIV-2) proviral DNA assay (QC-PCR) was developed and used to determine the proviral load in HIV-2-infected individuals. Proviral load varied considerably, with means of 1,831 copies per 10(6) peripheral blood mononuclear cells for asymptomatic subjects (n = 19) and 2,587 for AIDS patients (n = 2). HIV-2 viral and proviral loads also varied significantly over time in asymptomatic patients. These data suggest that a high level of virus replication occurs throughout the asymptomatic phase of HIV-2 infection.

Amplification of full-length HIV-2 envelope genes

In contrast to HIV-1, no studies have been published on the genetic and functional analysis of the envelope gene of primary NSI isolates of HIV-2. However several studies on HIV-1 have shown that NSI strains are the most frequently transmitted strains and probably the most important strains in the pathogenesis of HIV infection. Furthermore, it has been shown that the genetic and biological characteristics of primary isolates of HIV-1 differ widely from those of T-cell-line adapted isolates. Two different polymerase chain reaction (PCR) methods, nested-polymerase chain reaction and overlapp-extension amplification, were used to amplify the envelope genes from a primary non-syncytium-inducing HIV-2 isolate, HIV-2ALI, and from the T-cell line adapted syncytium-inducing isolate, HIV-2ROD. These methods could amplify the complete envelope gene from both viruses. Nested-polymerase chain reaction method was highly sensitive, enabling the amplification of one proviral copy of HIV-2ALI in 10000 peripheral blood mononuclear cells. The use of the methods described herein may help to expand our knowledge on the genetic diversity of HIV-2 as well as on the structure and function of the envelope glycoproteins of primary HIV-2 isolates.

Detection of HIV-1 DNA by polymerase chain reaction incorporation of digoxigenin-11-dUTP and hybridization to immobilized probes

We have developed a new non-isotopic polymerase chain reaction (PCR) based method for the detection of the human immunodeficiency virus type 1 (HIV-1) DNA in clinical samples. In this method a two step PCR is used to amplify and label HIV-1 DNA segments by incorporation of digoxigenin-11-dUTP (dig-dUTP). Digoxigenin labelled amplified products are hybridized to membrane immobilized complementary DNA probes. Hybridization is detected non-radioactively by incubating the filters with antidigoxigenin antibody conjugated with alkaline phosphatase followed by a standard phosphatase assay. With this method the detection limit was between 1 and 10 HIV-1 DNA copies in a background of 1 microgram of human genomic DNA. Furthermore, we were able to detect HIV-1 DNA in 41 out of 41 HIV-1 antibody positive individuals while 10 out of 10 HIV-1 seronegative individuals gave consistently negative results. Our data indicate that this simple non-isotopic technique is sensitive and specific for the detection of HIV-1 DNA in clinical samples and can constitute a good alternative to other non-isotopic methods described to date.

Detection of HIV1 proviral DNA by PCR and hybridization with digoxigenin labelled probes

One of the main obstacles for the introduction of PCR method to identify HIV1 proviral DNA in routine diagnostic laboratories is the use of radiolabelled oligodeoxynucleotide probes. Nonradioactive labelled probes have several advantages over radioactive labelling: they are stable for over 1 year, they can be produced easily in large amounts and they are safe. Polymerase chain reaction is an efficient and simple method to produce vector free inserts to use as probes. In this paper we describe a procedure for labelling DNA probes with digoxigenin-11-dUTP using the polymerase chain reaction. This non-radioactive labelling system was applied to detect HIV proviral sequences, amplified in vitro by PCR, from peripheral blood mononuclear cells DNA of infected subjects. We found identical sensitivities and specificities for probes synthesized with the non-radioactive and radioactive labelling procedures. The digoxigenin-11-dUTP can be efficiently incorporated during amplification of a DNA fragment using the polymerase chain reaction. This labelling and detection method proved to be specific, sensible and simple enough to be used in routine diagnostic laboratories for the detection of HIV1 infected individuals.

Finite difference solution for graded-index cylindrical dielectric waveguides: a scalar wave approximation

A simple numerical method based on finite differences to solve the scalar wave equation encountered in optical fibers is presented. The method uses the Ricatti transformation to the scalar wave equation and is capable of analyzing fibers of arbitrary refractive index profiles. Achieving errors as low as 0.005% for propagation constants is possible for lower-order modes. However, the error seems to increase for frequencies closer to cutoff.

The effects of layer properties on shear disturbance propagation in skin

The effects of the stratum corneum and dermis on shear wave propagation along the skin surface was investigated using a mathematical model. The skin was modeled as two distinct viscoelastic layers, one representing the stratum corneum and the other representing the dermis. The layers were supported by a semi-infinite visco-elastic half-space representing the subcutaneous fat. Physical and mechanical properties of the materials in the model were determined from the literature and from our own experimental measurements. Although the stratum corneum is very thin (12-15 microns), results showed that it could have a strong effect on the wave propagation due to its high stiffness relative to the dermis. Results of the analysis are discussed with respect to an experimental procedure used to determine age-related changes in mechanical properties of skin.

Dynamic measurement of the viscoelastic properties of skin

A wave propagation technique was used to measure the dynamic viscoelastic properties of excised skin when subjected to a low incremental strain. The propagation velocity, attenuation, and storage and loss moduli were determined from measured characteristics of a pulse propagating along a strip of skin. Experiments were conducted with the skin subjected to static stresses of 1500 Pa and 20,000 Pa. At low static stresses the skin response was viscoelastic with a loss tangent of approximately 0.6. In the frequency range of 0-1000 Hz, the wave velocity was relatively constant while the attenuation increased roughly linearly with frequency. However, results depended on the static stress. At the higher stress level the velocity was greater and the attenuation less than at the lower stress. At low stresses both the storage and loss moduli were relatively constant over the frequency range tested. The strong viscoelastic behavior of the tissue at higher frequencies is not predicted from models of the tissue determined from quasi-static test methods. In selecting a model to describe the behavior of skin, the test methods used for establishing the model must be consistent with its intended application.

Analysis of shear wave propagation in skin; application to an experimental procedure

An analysis of an experimental procedure used to determine age-related changes in the skin was performed. The experiment is based on the propagation of a shear wave through the skin. The analysis of the experiment was used to determine the effects of parameters such as properties of the skin and subcutaneous fat, skin thickness and experimental conditions on the propagation. Computer simulations showed that at lower frequencies (less than 1000 Hz), measured results depended strongly on skin thickness, while at higher frequencies (2000 Hz) the results were relatively insensitive to both skin thickness and the properties of the subcutaneous fat. Results also depended upon the distance between the applied shear disturbance and the measurement point. The analysis suggests that higher frequency (2000 Hz) experimental results are more indicative of mechanical properties of skin than lower frequency (less than 1000 Hz) results.

Expression in Escherichia coli and sequence analysis of the listeriolysin O determinant of Listeria monocytogenes

To evaluate the role of hemolysin production in the virulence of Listeria monocytogenes, we have undertaken the analysis of the chromosomal region containing hlyA, the gene coding for listeriolysin O. A recombinant cosmid, conferring a hemolytic phenotype to Escherichia coli, was shown to express listeriolysin O, by immunoblotting with a specific antiserum against listeriolysin O. The presence of hlyA on the cosmid was demonstrated by DNA hybridization with a probe previously shown to contain part of hlyA. The complete nucleotide sequence of hlyA has been determined. The deduced protein sequence reveals the presence of a putative 25-amino-acid signal sequence: the secreted form of listeriolysin O would have 504 amino acids, in agreement with the molecular weight of purified listeriolysin O (58,000). The protein sequence is highly homologous to those of streptolysin O and pneumolysin. A peptide of 11 amino acids conserved in the three proteins contains the unique cysteine known to be essential for lytic activity. By DNA-DNA hybridization, the listeriolysin O gene was detected in all L. monocytogenes strains tested, even in the nonhemolytic type strain. The gene was absent in other species of the genus Listeria.

Optical absorption characteristics of neutron irradiated heavy metal fluoride glasses

Samples of ZBLA and HBLA glasses were subjected to various fluences of neutron irradiation, and the spectral dependence of optical absorption was measured before and after irradiation. The IR edge was found to be unaffected by neutron irradiation for the fluences used. However, a red shift occurred at the UV edge which slightly recovered after three weeks.

Quantitative functional anatomy of the lower limb with application to human gait

A scheme was developed to classify muscles according to their primary, secondary and tertiary functions, e.g. a muscle which produces primarily a flexion moment may also produce secondary abduction and tertiary internal rotation moments. The functions of muscles crossing the hip and knee joints were computed based upon the changing relative positions of joint centers and muscle origins and insertions during one gait cycle. The function of several of the major muscles crossing the hip and knee joints is reported for the different limb positions corresponding to normal gait. It was found that the amount of force necessary to produce a given moment about a joint was dependent upon the limb position. In addition, the muscle functions changed significantly with limb position. Electrical stimulation of muscles of a paralyzed subject gave qualitative support to the results.

Intrauterine infection with mumps virus

The histopathologic study of 3 cases of gestational mumps is presented. The tissue studies was obtained from a spontaneous abortion (case 1) and from 2 therapeutic abortions (cases 2 and 3). Severe placental and fetal lesions were observed, indicating a probable association with maternal mumps. The main placental lesion was a diffuse proliferative necrotic villitis with severe lesions in the fetal vascular circuit, probably the cause of death. In the fetal viscera, areas of necrosis and mineralization were observed. Viral inclusions identical to those described in mumps infection were observed in the chorionic and fetal tissues.