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An educational activity is proposed that uses software for proteomic analysis and databases available for free on the Internet to estimate the structure and function of a hypothetical protein from its coding nucleotide sequence. This bioinformatics activity is recommended for integrated introductory courses that address the structure function relationship in proteins.

Biological systems exhibit strong dynamic variations; for example, a system may have a tendency towards either a steady state, periodic behaviour or chaotic oscillations. These findings, explained ...

Cytosolic Ca2+ concentration ([Ca2+]) has an important role in spermatozoa and hence it regulates fertilization. In male germinal cells, there are indirect evidences that this ion could regulate ph...

Cytosolic Ca2+ concentration ([Ca2+]) has an important role in spermatozoa and hence it regulates fertilization. In male germinal cells, there are indirect evidences that this ion could regulate physiological processes in spermatogenesis. Since little is known about Ca2+ homeostasis in spermatogenic cells, in this work we propose a mathematical model that accounts for experimental [Ca2+] dynamics triggered by blockade of the SERCA transport ATPase with thapsigargin in round rat spermatids, without external Ca2+ and with different extracellular lactate concentrations. The model included three homogeneous calcium compartments and Ca2+-ATPase activities sensitive and insensitive to thapsigargin, and it adjusted satisfactorily the experimental calcium dynamic data. Moreover, an extended version of the model satisfactorily adjusted the stationary states of calcium modulated by extracellular lactate, which is consistent with the participation of a low affinity lactate transporter and further lactate metabolism in these cells. Further studies and modeling would be necessary to shed some light into the relation between Ca2+-lactate-ATP homeostasis and cell–cell interactions in the seminiferous tubules that are expected to modulate Ca2+ dynamics by hormonal factors or energetic substrates in meiotic and postmeiotic spermatogenic cells.

The mean of the solute flux through membrane pores depends on the random distribution and permeability of the pores. Mathematical models including such randomness factors make it possible to obtain statistical parameters for pore characterization. Here, assuming that pores follow a Poisson distribution in the lipid phase and that their permeabilities follow a Gaussian distribution, a mathematical model for solute dynamics is obtained by applying a general result from a previous work regarding any number of different kinds of randomly distributed pores. The new proposed theory is studied using experimental parameters obtained elsewhere, and a method for finding the mean single pore flux rate from liposome flux assays is suggested. This method is useful for pores without requiring studies by patch-clamp in single cells or single-channel recordings. However, it does not apply in the case of ion-selective channels, in which a more complex flux law combining the concentration and electrical gradient is required.

Many of the metals in landfill constitute valuable and scarce natural resources. It has already been recognised that the recovery of these elements is critical for the sustainability of a number of industries. Arsenic (which is an essential part of the production of transistors and LEDs) is predicted to run out sometime in the next five to 50 years if consumption continues at the present rate. Nickel used for anything involving stainless steel and platinum group metals (PGMs) used in catalytic converters, fertilisers and others are also identified as critical materials (CM) to the EU economy at risk of depletion However, despite the increasing demand, none of this supply is supported by recycling. This is due to the high cost of recovery from low concentrations when compared to conventional mining. As demonstrated by the two pilot case studies of this study, mining landfill sites only for their metals content is not expected to be financially viable. However, other opportunities such as Waste-derived fuels from excavated materials exist which if combined , form the concept of ‘enhanced landfill mining’. have the potential to be highly energetic. The energy potential is comparable to the levels of energy of Refuse-Derived Fuels (RDF) produced from non-landfilled wastes.

Given a genetic code formed by 64 codons, we calculate the number of partitions of the set of encoding amino acid codons. When there are 0–3 stop codons, the results indicate that the most probable number of partitions is 19 and/or 20. Then, assuming that in the early evolution the genetic code could have had random variations, we suggest that the most probable number of partitions of the set of encoding amino acid codons determined the actual number 20 of standard amino acids.

Qualitative questions are proposed to assess the understanding of solubility and some of its applications. To improve those results, a simple quantitative problem on the precipitation of proteins is proposed. © 2014 by The International Union of Biochemistry and Molecular Biology, 43(1):3–5, 2015.

Biological membranes contain many domains enriched in phospholipid lipids and there is not yet clear explanation about how these domains can control the activity of phospholipid metabolizing enzymes. Here we used the surface dilution kinetic theory to derive general equations describing how complex substrate distributions affect the activity of enzymes following either the phospholipid binding kinetic model (which assumes that the enzyme molecules directly bind the phospholipid substrate molecules), or the surface-binding kinetic model (which assumes that the enzyme molecules bind to the membrane before binding the phospholipid substrate). Our results strongly suggest that, if the enzyme follows the phospholipid binding kinetic model, any substrate redistribution would increase the enzyme activity over than observed for a homogeneous distribution of substrate. Besides, enzymes following the surface-binding model would be independent of the substrate distribution. Given that the distribution of substrate in a population of micelles (each of them a lipid domain) should follow a Poisson law, we demonstrate that the general equations give an excellent fit to experimental data of lipases acting on micelles, providing reasonable values for kinetic parameters--without invoking special effects such as cooperative phenomena. Our theory will allow a better understanding of the cellular-metabolism control in membranes, as well as a more simple analysis of the mechanisms of membrane acting enzymes.

The polar requirement is an attribute of amino acids that is a major determinant of the structure and function of the proteins, and it plays a role in the flexibility and robustness of the genetic code. The viability of an organism depends on flexibility, which allows the exploration of new functions. However, robustness is necessary to protect the organism from deleterious changes derived from misreading errors and single-point mutations. Compared with random codes, the standard genetic code is one of the most robust against such errors. Here, using analytical and numerical calculations and the set of amino acid-encoding codons, we have proposed some local conditions that are necessary for the optimal robustness of the genetic code, and we explored the association between the local conditions and the robustness. The localness of the proposed conditions and the underlying evolutionary mechanism, which begins with a random code and progresses toward more efficient codes (e.g., the standard code), might be biologically plausible.

The static fluid mosaic model of biological membranes has been progressively complemented by a dynamic membrane model that includes phospholipid reordering in domains that are proposed to extend from nanometers to microns. Kinetic models for lipolytic enzymes have only been developed for homogeneous lipid phases. In this work, we develop a generalization of the well-known surface dilution kinetic theory to cases where, in a same lipid phase, both domain and nondomain phases coexist. Our model also allows understanding the changes in enzymatic activity due to a decrease of free substrate concentration when domains are induced by peptides. This lipid reordering and domain dynamics can affect the activity of lipolytic enzymes, and can provide a simple explanation for how basic peptides, with a strong direct interaction with acidic phospholipids (such as β-amyloid peptide), may cause a complex modulation of the activities of many important enzymes in lipid signaling pathways.

The focus of this work is on prediction of human error probabilities during the process of emergency musters on offshore oil and gas production platforms. Due to a lack of human error databases, and in particular human error data for offshore platform musters, an expert judgment technique, the Success Likelihood Index Methodology (SLIM), was adopted as a vehicle to predict human error probabilities. Three muster scenarios of varying severity (man overboard, gas release, and fire and explosion) were studied in detail. A panel of 24 judges active in the offshore oil and gas industry provided data for both the weighting and rating of six performance shaping factors. These data were subsequently processed by means of SLIM to calculate the probability of success for 18 muster actions ranging from point of muster initiator to the final actions in the temporary safe refuge (TSR). The six performance shaping factors considered in this work were stress, complexity, training, experience, event factors and atmospheric factors.

Fragestellung: Die Diagnostik und Therapie von periprothetischen Infektionen stellt immer noch eine grosse Herausforderung dar. Hierbei spielt der zweizeitige Endoprothesenwechsel in der Therapie ein wichtige Rolle. Trotz verbesserer Infektpersistenzdiagnostik werden im Rahmen von TEP-Replantationen[for full text, please go to the a.m. URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014)

Qualitative questions are proposed to assess the understanding of solubility and some of its applications. To improve those results, a simple quantitative problem on the precipitation of proteins is proposed.

When channels are randomly distributed in a population of vesicles, disregarding the number of channels per vesicle, these channels follow a Poisson distribution. This has been verified in many cases, determining the average of channels per vesicle. However, to determine kinetic parameters in population studies, a mathematical expression for the mean flux of solute through channels per vesicle is necessary. Hence, here, this mean flux is calculated, assuming Poisson distributed channels in a population of vesicle. Moreover, this result has been generalized to any number of different kinds of channels (i.e., channels with different permeabilities). These results, useful for in vitro experiments with mixed both channels and vesicles, can be supplemented with those from other techniques, in order to understanding how the nature of the lipid membrane affects kinetic parameters of channel.

In Piemonte, stone has always been the most widely used raw material for buildings, characterizing the architectural identity of the city of Turin. All kinds of rocks, metamorphic, igneous, and sedimentary, are represented, including gneisses, marbles, granitoids, and, less commonly, limestones. The great variety of ornamental stones is clearly due to the highly composite geological nature of the Piemonte region related to the presence of the orogenic Alpine chain and the sedimentary Tertiary Piemonte Basin. This paper provides a representative list of the most historic ornamental stones of Piemonte, which have been used over the centuries in buildings and architecture. The main stones occurring in Turin have been identified and described from a petrographic and mineralogical point of view in order to find out the corresponding geological units and quarry sites, from which they were exploited. This allows the associated cultural and scientific interest of stones to be emphasized in the architecture of a town which lies between a mountain chain and a hilly region.

Here we study the distribution of randomly generated partitions of the set of amino acid-coding codons. Some results are an application from a previous work, about the Stirling numbers of the second kind and triplet codes, both to the cases of triplet codes having four stop codons, as in mammalian mitochondrial genetic code, and hypothetical doublet codes. Extending previous results, in this work it is found that the most probable number of blocks of synonymous codons, in a genetic code, is similar to the number of amino acids when there are four stop codons, as well as it could be for a primigenious doublet code. Also it is studied the integer partitions associated to patterns of synonymous codons and it is shown, for the canonical code, that the standard deviation inside an integer partition is one of the most probable. We think that, in some early epoch, the genetic code might have had a maximum of the disorder or entropy, independent of the assignment between codons and amino acids, reaching a state similar to “code freeze” proposed by Francis Crick. In later stages, maybe deterministic rules have reassigned codons to amino acids, forming the natural codes, such as the canonical code, but keeping the numerical features describing the set partitions and the integer partitions, like a “fossil numbers”; both kinds of partitions about the set of amino acid-coding codons.

We have created an activity in which students can visualize a theoretical neural network whose states evolve according to a well-known simple law. This activity provided an uncomplicated approach to a paradigm commonly represented through complex mathematical formulation. From their observations

The 2009 New England Chapter of the American College of Sports Medicine Meeting was held at the Rhode Island Convention Center in Providence, Rhode Island on November 5-6. The meeting was attended by 751 professionals and students from clinical, academic, and government institutions. In total, the conference had 35 professional presentations and over 30 free communication presentations. The number of registrants, number of sessions, vendors, and conference survey results are presented below. The schedule grid for all presentations is also attached, as is the conference brochure.

SUMMARY 1. One hundred and forty-six infants with congenital esophageal atresia, tracheoesophageal fistula, or both, were observed on the endoscopic service of The Children's Memorial Hospital between 1947 and 1964. One hundred and twenty-three, or 84.2 per cent, were Type III, 12 were Type IV (“H”), and 10 were Type I with both segments blind. One had an esophageal atresia with both upper and lower segments entering the trachea. 2. Laryngeal problems included congenital anomalies, paralyses, and postoperative edema. Twelve infants had laryngeal paralyses: 6 bilateral, 2 right and 4 left cord paralysis. Laryngeal paralysis invariably increased the respiratory and deglutition difficulties of the postoperative period. 3. Tracheal problems included congenital tracheomalacia and stenoses. The most serious post-surgical complications occur at the site of the fistula leading to the lower esophageal segment. Obstruction due to inversion of the edges, granulomas, and too tight a closure were present in 14 infants. Diverticula, consisting of a residual piece of the lower esophageal segment not completely removed, were found in 11 infants. There were 12 recurrent tracheoesophageal fistulas. 4. Bronchial secretions, chemical bronchitis, and atelectasis constitute the principal bronchopulmonary complications. These appear to increase in severity with delay in closure of the tracheoesophageal fistula. The alteration of respiratory physiology associated with resection of portions of several ribs may play a part in increasing the severity of the bronchopulmonary problems. 5. Esophageal strictures were present in 103 of the 146 infants; 93 at the site of a direct end-to-end anastomosis, 8 at the esophagogastric, -colic, or -jejunal site, and 2 at the cologastric site. Early recognition and treatment of the narrowing lumen in the immediate postoperative period is stressed. Swallowing function is usually normal until semisolids are added to the infant diet, at which time the anastomosis stricture is already firm and tough. Techniques of bougienage in the early postoperative period and management of the late fibrous strictures are outlined. 6. Reanastomosis was necessary in 6 infants because of inability to reestablish a lumen endoscopically. All were dilated early in the postoperative period following the revision and have attained a normal swallowing function.