The structure of latherin, a surfactant allergen protein from horse sweat and saliva

Latherin is a highly surface-active allergen protein found in the sweat and saliva of horses and other equids. Its surfactant activity is intrinsic to the protein in its native form, and is manifest without associated lipids or glycosylation. Latherin probably functions as a wetting agent in evaporative cooling in horses, but it may also assist in mastication of fibrous food as well as inhibition of microbial biofilms. It is a member of the PLUNC family of proteins abundant in the oral cavity and saliva of mammals, one of which has also been shown to be a surfactant and capable of disrupting microbial biofilms. How these proteins work as surfactants while remaining soluble and cell membrane-compatible is not known. Nor have their structures previously been reported. We have used protein nuclear magnetic resonance spectroscopy to determine the conformation and dynamics of latherin in aqueous solution. The protein is a monomer in solution with a slightly curved cylindrical structure exhibiting a ‘super-roll’ motif comprising a four-stranded anti-parallel β-sheet and two opposing α-helices which twist along the long axis of the cylinder. One end of the molecule has prominent, flexible loops that contain a number of apolar amino acid side chains. This, together with previous biophysical observations, leads us to a plausible mechanism for surfactant activity in which the molecule is first localized to the non-polar interface via these loops, and then unfolds and flattens to expose its hydrophobic interior to the air or non-polar surface. Intrinsically surface-active proteins are relatively rare in nature, and this is the first structure of such a protein from mammals to be reported. Both its conformation and proposed method of action are different from other, non-mammalian surfactant proteins investigated so far

Frog foams and natural protein surfactants

Foams and surfactants are relatively rare in biology because of their potential to harm cell membranes and other delicate tissues. However, in recent work we have identified and characterized a number of natural surfactant proteins found in the foam nests of tropical frogs and other unusual sources. These proteins, and their associated foams, are relatively stable and bio-compatible, but with intriguing molecular structures that reveal a new class of surfactant activity. Here we review the structures and functional mechanisms of some of these proteins as revealed by experiments involving a range of biophysical and biochemical techniques, with additional mechanistic support coming from more recent site-directed mutagenesis studies

Aqueous solubilization of C60 fullerene by natural protein surfactants, latherin and ranaspumin-2

C60 fullerene is not soluble in water and dispersion usually requires organic solvents, sonication or vigorous mechanical mixing. However, we show here that mixing of pristine C60 in water with natural surfactant proteins latherin and ranaspumin-2 (Rsn-2) at low concentrations yields stable aqueous dispersions with spectroscopic properties similar to those previously obtained by more vigorous methods. Particle sizes are significantly smaller than those achieved by mechanical dispersion alone, and concentrations are compatible with clusters approximating 1:1 protein:C60 stoichiometry. These proteins can also be adsorbed onto more intractable carbon nanotubes. This promises to be a convenient way to interface a range of hydrophobic nanoparticles and related materials with biological macromolecules, with potential to exploit the versatility of recombinant protein engineering in the development of nano-bio interface devices. It also has potential consequences for toxicological aspects of these and similar nanoparticles

Resonance assignments for latherin, a natural surfactant protein from horse sweat

Latherin is an intrinsically surfactant protein of ~23 kDa found in the sweat and saliva of horses. Its function is probably to enhance the translocation of sweat water from the skin to the surface of the pelt for evaporative cooling. Its role in saliva may be to enhance the wetting, softening and maceration of the dry, fibrous food for which equines are adapted. Latherin is unusual in its relatively high content of aliphatic amino acids (~25 % leucines) that might contribute to its surfactant properties. Latherin is related to the palate, lung, and nasal epithelium carcinoma-associated proteins (PLUNCs) of mammals, at least one of which is now known to exhibit similar surfactant activity to latherin. No structures of any PLUNC protein are currently available. 15N,13C-labelled recombinant latherin was produced in Escherichia coli, and essentially all of the resonances were assigned despite the signal overlap due to the preponderance of leucines. The most notable exceptions include a number of residues located in an apparently dynamic loop region between residues 145 and 154. The assignments have been deposited with BMRB accession number 19067

Effects of a single interprofessional simulation session on medical and nursing students’ attitudes toward interprofessional learning and professional identity: a questionnaire study

Background Participation in simulation-based interprofessional education (sim-IPE) may affect students’ attitudes towards interprofessional learning (through gaining experience with others) and their professional identity (by increasing the ‘fit’ of group membership). We examined this in two questionnaire studies involving students from four universities in two areas of the UK. Method Questionnaire data were collected before and after students took part in a sim-IPE session consisting of three acute scenarios. Questionnaires included the Readiness for Interprofessional Learning Scale (RIPLS) and measures of professional identity derived from the social identity theory literature. In Study 1, only identification with Professional Group (doctor or nurse) was measured, while in Study 2 identification with Student Group (medical or nursing student) and the immediate interprofessional Team worked with in the simulation were also measured. Linear mixed effects regression analysis examined the effect of the simulation session, and differences between medical and nursing students, sites and identity measures. Results A total of 194 medical and 266 nursing students completed questionnaires. A five-item subset of RIPLS (RIPLSCore) was used in analysis. In both studies RIPLSCore increased for all groups following participation in sim-IPE, although this was larger for nursing students in Study 1. Nursing students had consistently higher RIPLSCore scores than medical students at one site. Effects of the session on identity varied between sites, and dimensions of identity. Notably, while positive emotions associated with group membership (Ingroup Affect) increased for Student Group, Professional Group and Team, the sense of belonging (Ingroup Ties) and importance (Centrality) of the group increased only for Team. Nursing students had consistently higher identification scores than medical students. Conclusions Participation in a sim-IPE session can improve attitudes towards interprofessional learning. It can also enhance professional identity, particularly as related to emotional aspects of group membership, with possible benefits for wellbeing. Changes in identification with the immediate Team suggest positive psychological consequences of ad hoc Team formation in the workplace. Differences between medical and nursing students suggest their differing opportunities to work with other professions during training may change baseline attitudes and identity. However, a single sim-IPE session can still have an additive effect

The ramifications of a delay in the national high-level waste repository program

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1988.Includes bibliographical references (leaves 299-300).by Scott Alan Vance.M.S

Can Backward-Chained, Ab-Initio Pilot Training Decrease Time to First Solo?

Flight simulation has made progressively significant inroads into pilot training at all levels of a pilot’s career – typically starting with training for the Instrument rating in light aircraft and concluding with Type Certification in transport category jetliners. This research was designed to explore if significant training inroads could also be offered to ab-initio pilots, those with no prior flight experience. An experimental group of four pilot trainees, without prior flight experience, were exposed to flight in a backwards-chained simulation starting from 4’ AGL (Above Ground Level). Graduated, exponential increments of both altitude and distance from landing were successively added to the simulation experienced by the pilots all the way through a standard FAA General Aviation traffic pattern to return the student pilot to the start of take-off. Once the pilot trainees had completed the backward-chained simulation, they flew the traffic pattern conventionally, in a forward chain prior to being placed in an identical aircraft (Cessna-172/G1000) for an actual flight with an appropriately-rated Certified Flight Instructor (CFI). After receiving a demonstration of a complete circuit in the traffic pattern by the CFI, all four pilot trainees were able to complete three, unassisted circuits in the traffic pattern. Backwards-chained initial flight instruction appears to have significant operational potential in accelerating (reducing) the time required for first solo of new pilots. It also warrants further investigation by other pilot training research institutions

Predictive modelling of student reviewing behaviors in an introductory programming course

In this paper, we developed predictive models based on students’ reviewing behaviors in an Introductory Programming course. These patterns were captured using an educational technology that students used to review their graded paper- based assessments. Models were trained and tested with the goal of identifying students’ academic performance and those who might be in need of assistance. The results of the retrospective analysis show a reasonable accuracy. This suggests the possibility of developing interventions for students, such as providing feedback in the form of effective reviewing strategies

Electric Shaft Currents In Turbomachinery.

LecturePg. 51-64Electrical damage to turbomachinery parts has caused a number of machinery failures and many hours of costly downtime. The problem of electrical voltages and currents being generated in non-electrical machines has puzzled both users and manufacturers of these equipment, and has prompted ongoing research at Texas A&M to help identify and better classify the different sources of these voltages and the mechanisms by which they cause damage to bearings, seals, and other critical machinery parts. Electrostatic and electromagnetic type voltages are often misidentified, a situation that might lead to a wrong or costly remedy. The distinctions between these two major sources of shaft voltages and currents are clearly drawn herein. Lubricating oil characteristics and their influence on the buildup of shaft voltage potential have also been carefully scrutinized. Breakdown voltages were generated and measured at different operating conditions to help highlight the influence of the different variables such as bearing clearance and dielectric strength of the oil