Comparison of physical properties of two exogenous surfactants: new parameter.

The pulmonary surfactant has essential physical properties for normal lung function. The most important property is the surface tension. In this work, it was evaluated the surface tension of two commercial exogenous surfactants used in surfactant replacement therapy, poractant alfa (Curosurf, Chiesi Farmaceuticals, Italy) and beractant (Survanta, Abbott Laboratories, USA) using new parameters. A Langmuir film balance (Minitrough, KSV Instruments, Finland) was used to measure surface tension of poractant alfa and beractant samples. For both samples, we prepared a solution of 1 mg/m dissolved in chloroform (100π`), which was applied over a subphase of milli-Q water (175 ml) in the chamber of the balance. The chamber has two moving barriers that can change its surface area between a maximal value of 112.5 cm 2 , and a minimal value of 22.5 cm 2, defining a balance cycle. Each surfactant had its surface tension evaluated during 20 balance cycles for three times. Four quantities were calculated from the experiment: Minimum Surface Tension (MTS), defined as the surface tension at minimal surface area during the first cycle; Mean Work Cycle (MWC), defined as the mean hysteresis area of the measured surface tension curve of the last 16 balance cycles; Critical Active Surface Area in Compression (CASAC) or in Expansion (CASAE), defined as the maximal chamber area where the surfactant is active on the surface in compression or expansion. The t-test was applied to verify for statistical significance of the results. Comproved with the MST is the same reported in literature, the differences between MWC, CASAC, and CASAE were statistically significant (p<0.001). The MWC, CASAC and CASAE were higher for poractant alfa than for beractant. A higher MWC for poractant alfa means higher elastic recoil of the lung in comparison with beractant. Using a different methodology, our results showed that poractant alfa is probably more effective in a surfactant replacement therapy than beractant due the use of poractant alfa in relation to the use of beractant in preterm infants with Respiratory Distress Syndrome (RDS).CNPqFAPES

Nebuliser therapy in the intensive care unit

The relationship between identity, lived experience, sexual practices and the language through which these are conveyed has been widely debated in sexuality literature. For example, ‘coming out’ has famously been conceptualised as a ‘speech act’ (Sedgwick 1990) and as a collective narrative (Plummer 1995), while a growing concern for individuals’ diverse identifications in relations to their sexual and gender practices has produced interesting research focusing on linguistic practices among LGBT-identified individuals (Leap 1995; Kulick 2000; Cameron and Kulick 2006; Farqhar 2000). While an explicit focus on language remains marginal to literature on sexualities (Kulick 2000), issue of language use and translation are seldom explicitly addressed in the growing literature on intersectionality. Yet intersectional perspectives ‘reject the separability of analytical and identity categories’ (McCall 2005:1771), and therefore have an implicit stake in the ‘vernacular’ language of the researched, in the ‘scientific’ language of the researcher and in the relationship of continuity between the two. Drawing on literature within gay and lesbian/queer studies and cross-cultural studies, this chapter revisits debates on sexuality, language and intersectionality. I argue for the importance of giving careful consideration to the language we choose to use as researchers to collectively define the people whose experiences we try to capture. I also propose that language itself can be investigated as a productive way to foreground how individual and collective identifications are discursively constructed, and to unpack the diversity of lived experience. I address intersectional complexity as a methodological issue, where methodology is understood not only as the methods and practicalities of doing research, but more broadly as ‘a coherent set of ideas about the philosophy, methods and data that underlie the research process and the production of knowledge’ (McCall 2005:1774). My points are illustrated with examples drawn from my ethnographic study on ‘lesbian’ identity in urban Russia, interspersed with insights from existing literature. In particular, I aim to show that an explicit focus on language can be a productive way to explore the intersections between the global, the national and the local in cross-cultural research on sexuality, while also addressing issues of positionality and accountability to the communities researched

Tracheal suctioning improves gas exchange but not hemodynamics in asphyxiated lambs with meconium aspiration.

BackgroundCurrent neonatal resuscitation guidelines recommend tracheal suctioning of nonvigorous neonates born through meconium-stained amniotic fluid.MethodsWe evaluated the effect of tracheal suctioning at birth in 29 lambs with asphyxia induced by cord occlusion and meconium aspiration during gasping.ResultsTracheal suctioning at birth (n = 15) decreased amount of meconium in distal airways (53 ± 29 particles/mm(2) lung area) compared to no suction (499 ± 109 particles/mm(2); n = 14; P &lt; 0.001). Three lambs in the suction group had cardiac arrest during suctioning, requiring chest compressions and epinephrine. Onset of ventilation was delayed in the suction group (146 ± 11 vs. 47 ± 3 s in no-suction group; P = 0.005). There was no difference in pulmonary blood flow, carotid blood flow, and pulmonary or systemic blood pressure between the two groups. Left atrial pressure was significantly higher in the suction group. Tracheal suctioning resulted in higher Pao2/FiO2 levels (122 ± 21 vs. 78 ± 10 mm Hg) and ventilator efficiency index (0.3 ± 0.05 vs.0.16 ± 0.03). Two lambs in the no-suction group required inhaled nitric oxide. Lung 3-nitrotyrosine levels were higher in the suction group (0.65 ± 0.03 ng/µg protein) compared with the no-suction group (0.47 ± 0.06).ConclusionTracheal suctioning improves oxygenation and ventilation. Suctioning does not improve pulmonary/systemic hemodynamics or oxidative stress in an ovine model of acute meconium aspiration with asphyxia

Does Misery Love Company? Evidence from pharmaceutical markets before and after the Orphan Drug Act

With substantial fixed costs of drug development, more common conditions can support more products. If additional pharmaceutical products are beneficial, they will attract greater consumption and promote better health, e.g. greater longevity. We ask how market size measured by condition prevalence affects consumption and longevity. We document in condition cross sections that both the tendency to use a drug and longevity are higher for individuals with more prevalent conditions. We also make use of the 1983 Orphan Drug Act (ODA), which promoted development of drugs for the treatment of rare conditions. Longevity and drug use have grown more quickly for persons with rare diseases and even more quickly for persons with conditions with substantial orphan drug use.

In vivo effect of pneumonia on surfactant disaturated-phosphatidylcholine kinetics in newborn infants

Bacterial pneumonia in newborns often leads to surfactant deficiency or dysfunction, as surfactant is inactivated or its production/turnover impaired. No data are available in vivo in humans on the mechanism of surfactant depletion in neonatal pneumonia. We studied the kinetics of surfactant's major component, disaturated-phosphatidylcholine (DSPC), in neonatal pneumonia, and we compared our findings with those obtained from control newborn lungs

Surfactant phosphatidylcholine half-life and pool size measurements in premature baboons developing bronchopulmonary dysplasia

Because minimal information is available about surfactant metabolism in bronchopulmonary dysplasia, we measured half-lives and pool sizes of surfactant phosphatidylcholine in very preterm baboons recovering from respiratory distress syndrome and developing bronchopulmonary dysplasia, using stable isotopes, radioactive isotopes, and direct pool size measurements. Eight ventilated premature baboons received (2)H-DPPC (dipalmitoyl phosphatidylcholine) on d 5 of life, and radioactive (14)C-DPPC with a treatment dose of surfactant on d 8. After 14 d, lung pool sizes of saturated phosphatidylcholine were measured. Half-life of (2)H-DPPC (d 5) in tracheal aspirates was 28 +/- 4 h (mean +/- SEM). Half-life of radioactive DPPC (d 8) was 35 +/- 4 h. Saturated phosphatidylcholine pool size measured with stable isotopes on d 5 was 129 +/- 14 micro mol/kg, and 123 +/- 11 micro mol/kg on d 14 at autopsy. Half-lives were comparable to those obtained at d 0 and d 6 in our previous baboon studies. We conclude that surfactant metabolism does not change during the early development of bronchopulmonary dysplasia, more specifically, the metabolism of exogenous surfactant on d 8 is similar to that on the day of birth. Surfactant pool size is low at birth, increases after surfactant therapy, and is kept constant during the first 2 wk of life by endogenous surfactant synthesis. Measurements with stable isotopes are comparable to measurements with radioactive tracers and measurements at autopsy

Animal-derived surfactants for the treatment and prevention of neonatal respiratory distress syndrome: summary of clinical trials

J Wells Logan, Fernando R MoyaDepartment of Neonatology, Southeast Area Health Educational Center, New Hanover Regional Medical Center, Wilmington, NC, USAIntroduction: Available literature suggests that the advantage of animal-derived surfactants over first-generation synthetic agents derives from the presence of surface-active proteins and their phospholipid content. Here we summarize the results of clinical trials comparing animal-derived surfactant preparations with other animal-derived surfactants and with both first- and second-generation synthetic surfactants.Methods: Published clinical trials of comparisons of animal-derived surfactants were summarized and compared. Comparisons emphasized differences in (1) key surfactant components attributed with efficacy and (2) differences in published outcomes.Results: For the most important outcomes, mortality and chronic lung disease, currently available natural surfactants are essentially similar in efficacy. When examining secondary outcomes (pneumothorax, ventilator weaning, and need for supplemental oxygen), it appears that both calfactant and poractant have an advantage over beractant. The weight of the evidence, especially for study design and secondary outcomes, favors the use of calfactant. However, the superiority of poractant over beractant, when the higher initial dose of poractant is used, strengthens the case for use of poractant as well.Conclusions: Clinical trials suggest that the higher surfactant protein-B content in calfactant, and perhaps the higher phospholipid content in poractant (at higher initial dose), are the factors that most likely confer the observed advantage over other surfactant preparations. Keywords: surfactant, respiratory distress syndrome, phospholipids, surfactant proteins, chronic lung disease, bronchopulmonary dysplasi