Connecting concepts, creating worlds

Review of Aesthetics of Religion: A Connective Concept, eds. Alexandra Grieser and Jay Johnston, Religion and Reason, 58 (Berlin and Boston, de Gruyter, 2017)

Pain and peptic ulcer

Prom these varied observations on pain, spontaneous and induced, it is obvious that neither motor activity nor irritation by acid can be the sole cause of the pain of peptic ulcer. It is true that spasms of pain were observed which coincided with peristaltic waves of the duodenum in a patient with a duodenal ulcer deformity. It is also true that another patient was free of pain \?hen motility was reduced to a minimum and at a time v/hen the acid level remained high. On the other hand some patients had pain which was quite unrelated to motility. This pain would stop for 10 minutes or more and then resume while contractions continued uninterrupted. Even duodenal spasm could occur in patients with duodenal ulceration without caus¬ ing pain. It could hardly be argued that the ulcer was insensitive since a matter of a few minutes before or after the patient was in pain. During one episode of duodenal spasm a patient had pain for a minute but the pain then disappeared while the spasm continued for another few minutesIt has been suggested that acid causes pain by causing spasm (Hurst, I9H5 Kinsella, 19^4-8) but 35% of f*18 injections of 0.5% HC1 failed to produce any increase in tone or movement and the majority of these injections were followed by pain. The converse of this argument - that alkaline powders act by relaxing tone - is difficult to / 20. to sustain since 50>o of 18 injections of sodium "bicarbonate were followed "by increased tone or movement, usually with relief of pain. In one case the injection was followed' by duodenal spasm, relief of pain and spasm coinciding.The case for the acid theory of pain is not much better. Certainly in some of the experiments there was a relationship between increasing acid concentration and the onset of pain and also between decreasing acidity and relief of pain. Other experiments, however, showed no such relationship. Pain often disappeared when the acid¬ ity remained constant or even increased. Indeed pain was sometimes intermittent when no change could be detected in either acidity or motility. Relief of pain with sodium bicarbonate was usually poss¬ ible but there was sometimes a delay of 30 minutes before relief was obtained. Palmer also encountered long delays between the giving of alkali and the relief of pain. He found similar delay between the injection of acid and the onset of pain. If one has to allow for such long latent periods it makes interpretation of spontaneous pain rather difficult because the acid level in the stomach is con¬ stantly varying. Pickering took samples of gastric juice half hourly hut during this period there could have been considerable variations in acidity. Dne has seen the acid concentration rise from 2.3 mg. HCl/ml. of gastric juice to 3.35 nig. and fall again to 2 mg0 within the space of half an hour. The pain sensitivity of the ulcer may not be sufficiently great to follow such changes quickly. If pain takes some time to develop and reach its acme it is difficult to explain why it may disappear for a short time and then return while the acidity remains constant. Pain can occur in the absence of free acid as was shown in one case when there were several spasms of pain during a spell of achlorhydria lasting 38 minutes.Motility and acid may each cause pain but they obviously do nob account for all the facts. It is possible that Kinsella may be right in ascribing the intermittency of the pain to alterations in "blood flow through an ulcer area which is sensitive "because of in¬ flammation and oedema. Much, however, remains to be done to prove this theor

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

Breeding Distribution and Numbers of Black Guillemots in Jones Sound, N.W.T.

Aerial surveys of Jones Sound, N.W.T., reveal a highly clumped distribution of black guillemots in the early spring and throughout the breeding season. Black guillemots are uncommon throughout much of Jones Sound except at its mouth and in the western portion. By September most guillemots have left the area. Both early spring and breeding distributions appear to be influenced by the Hell Gate and Cardigan Strait polynya located in western Jones Sound between Ellesmere and Devon islands. Evidence presented suggests that annual variation in the distribution of ice edges in Jones Sound may influence distribution of breeding birds among suitable breeding sites.Key words: black guillemot, Cepphus grylle, breeding distribution, Jones Sound, aerial surveysRÉSUMÉ. Des relevés aériens effectués dans le détroit de Jones (T.N.-0.) indiquent une distribution trés regroupée de guillemots à miroir au début du printemps et durant toute la saison de reproduction. On ne trouve pas beaucoup de guillemots à miroir dans l’ensemble du détroit de Jones, sauf à son embouchure et dans la partie occidentale. Quand arrive septembre, la plupart des guillemots ont quitté la région. Les distributions du début du printemps et de la saison de reproduction semblent être influencées par les polynias de Hell Gate et de Cardigan Strait situées dans la partie occidentale du détroit de Jones, entre les îles Devon et Ellesmere. Les faits présentés suggèrent que la variation annuelle dans la distribution des lisières de glaces du détroit de Jones pourrait influencer la distribution des oiseaux reproducteurs aux divers sites qui se prêtent à la nidificationMots clés: guillemot à miroir, Cepphus grylle, distribution de la nidification, détroit de Jones, relevés aérien

Contracting issues associated with reduction of Repair Turnaround Time within the Contract Depot Maintenance (CDM)--program.

http://archive.org/details/contractingissue00pet

Survival of a diffusing particle in an expanding cage

We consider a Brownian particle, with diffusion constant D, moving inside an expanding d-dimensional sphere whose surface is an absorbing boundary for the particle. The sphere has initial radius L_0 and expands at a constant rate c. We calculate the joint probability density, p(r,t|r_0), that the particle survives until time t, and is at a distance r from the centre of the sphere, given that it started at a distance r_0 from the centre.Comment: 5 page

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