Role of Ca2-Independent Lysosomal Phospholipase A2 in Turnover of Lung Surfactant Phospholipids
Svante Cornell in Membrane Structure in Disease and Drug Therapy, 2000
Lung surfactant is an extracellular phospholipid and protein-rich material that forms an interfacial barrier between the pulmonary alveolar gas phase and the alveolar epithelial cell lining. The presence of lung surfactant is essential for life. Its primary physiological role is to maintain a low surface tension in the alveolar space of the lung, especially at low lung volumes, thereby stabilizing the alveoli and permitting efficient gas exchange. In the absence of surfactant, as illustrated by the respiratory distress syndrome (RDS) of the neonate, alveolar collapse compromises lung gas exchange, leading to asphyxia. Thus, the factors that determine the presence of adequate extracellular surfactant are of major importance for understanding normal respiratory physiology.
Case Study: Balanced Two-Way Treatment Structure with Unequal Subclass Numbers
George A. Milliken, Dallas E. Johnson in Analysis of Messy Data Volume 1, 2009
A bakery scientist wanted to study the effects of combining three different fats with each of three different surfactants on the speci c volume of bread loaves baked from doughs mixed from each of the nine treatment combinations. Four ours of the same type but from different sources were used as blocking factors. That is, loaves were made using all nine treatment combinations for each of the four ours. Unfortunately, one container of yeast turned out to be ineffective, and the data from the 10 loaves made with that yeast had to be removed from the analysis. Fortunately, all nine fat ¥ surfactant treatment combinations were observed at least once. The data are given in Table 12.1.
Surfactants
Graham Buckton in Interfacial Phenomena in Drug Delivery and Targeting, 2000
Surface active agents, or surfactants, are molecules which are characterised by having two regions in their chemical structure, one hydrophobic, and the other hydrophilic1 . The hydrophobic region would consist of a hydrocarbon chain, and the hydrophilic region can be an ionisable, polar, or water soluble group. Consequently, surfactants are often defined as being amphiphilic in that they have an attraction to both aqueous and oil phases. For many systems the polar region will be a small part of the overall molecule, but that is not always the case, as will be seen below.The amphiphilic nature of these molecules is such that part of the molecule will tend to be expelled from the bulk of a liquid in which they are dissolved (or dispersed), whilst the other part of the molecule will freely interact with the liquid. This leads to a tendency for the molecules to perform two functions; firsdy, they will be forced to liquid interfaces, and secondly, they will tend to align in an ordered fashion at those interfaces. The “adsorption” of surfactant molecules at the surface of a liquid will result in a fall in surface tension (see Chapter 1), and the adsorption to the interface between two liquids will reduce the interfacial tension and aid the formation of emulsions (see Chapter 1 and below). A further property of surfactants is that, as the concentration in solution rises, they will tend to selfassociate into structures known as micelles (see Section 5.2). The fundamental aspects of surfactant behaviour will be addressed in this chapter, but the role of surfactants has already been discussed on many occasions in the preceding chapters, and will be the subject of much of Part B of this book. The reason for surfactants being covered at all stages throughout this book is that they can influence most interfacial phenomena, and form a part of the everyday life of each and every one of us. This may be in a scientific context, or as a household aid, or as an environmental 1 Whilst it is most common to talk in terms of water, it is appropriate to note that the surfactant can function in non-aqueous systems, where there is a need for a part of the molecule to have an attraction for the solvent (lyophilic), and another part to have no attraction for the solvent (lyophobic).
Old and new uses of surfactant
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2010
Camilla Gizzi, Paola Papoff, Caterina Silvia Barbàra, Giulia Cangiano, Fabio Midulla, Corrado Moretti
Exogenous surfactant has been the primary life-saving therapy for respiratory distress syndrome (RDS) of preterm infants for many years. More recently, early surfactant treatment administered less invasively by transient endotracheal intubation and combined to nasal ventilation has been shown to further improve neonatal outcome by reducing the need of mechanical ventilation. In addition to RDS, other neonatal and pediatric respiratory disorders characterized by surfactant inactivation or dysfunction, such as pulmonary hemorrhage, aspiration pneumonia, and viral lower respiratory tract infection, might also be amenable to surfactant replacement therapy. However, the nature of lung injury and the influence of co-morbidities may reduce the efficacy of surfactant in these conditions. Currently under investigation are new syntethic surfactant formulations which may be more effective and resistant to inactivation than natural ones and could be produced at a lower cost. The use of surfactants to deliver drugs directly to the lung also seems to be a promising technique worthy of study.
Catheter and Laryngeal Mask Endotracheal Surfactant Therapy: the CALMEST approach as a novel MIST technique
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2017
Ilaria Vannozzi, Massimiliano Ciantelli, Francesca Moscuzza, Rosa T. Scaramuzzo, Davide Panizza, Emilio Sigali, Antonio Boldrini, Armando Cuttano
Purpose: Neonatal respiratory distress syndrome (RDS) is a major cause of mortality and morbidity among preterm infants. Although the INSURE (INtubation, SURfactant administration, Estubation) technique for surfactant replacement therapy is so far the gold standard method, over the last years new approaches have been studied, i.e. less invasive surfactant administration (LISA) or minimally invasive surfactant therapy (MIST). Here we propose an originally modified MIST, called CALMEST (Catheter And Laryngeal Mask Endotracheal Surfactant Therapy), using a particular laryngeal mask as a guide for a thin catheter to deliver surfactant directly in the trachea. Materials and methods: We performed a preliminary study on a mannequin and a subsequent in vivo pilot trial. Results and conclusions: This novel procedure is quick, effective and well tolerated and might represent an improvement in reducing neonatal stress. Ultimately, CALMEST offers an alternative approach that could be extremely useful for medical staff with low expertise in laryngoscopy and intubation.
The effect of surfactant composition on the chemical and structural properties of nanostructured lipid carriers
Published in Journal of Microencapsulation, 2014
Kullavadee Karn-orachai, Siwaporn Meejoo Smith, Sarunya Phunpee, Alongkot Treethong, Satit Puttipipatkhachorn, Sirapat Pratontep, Uracha Rungsardthong Ruktanonchai
Fine-tuning the nanoscale structure and morphology of nanostructured lipid carriers (NLCs) is central to improving drug loading and stability of the particles. The role of surfactant charge on controlling the structure, the physicochemical properties and the stability of NLCs has been investigated using three surfactant types (cationic, anionic, non-ionic), and mixed surfactants. Either one, a mixture of two, or a mixture of three surfactants were used to coat the NLCs, with these classified as one, two and three surfactant systems, respectively. The mixed (two and three) surfactant systems produced smaller NLC particles and yielded NLCs with lower crystallinity than the one surfactant system. The combined effects of the ionic and the non-ionic surfactants may play a key role in assisting the lipid-oil mixing, as well as maintaining colloidal repulsion between NLC particles. In contrast, for the three surfactant system, the lipid–oil mixture in the NLCs appeared less homogenous. This was also reflected in the results of the stability study, which indicated that NLC particle sizes in two surfactant systems appeared to be retained over longer periods than for other surfactant systems.
Related Knowledge Centers
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