Glycosylation of Aromatic Amines I: Characterization of Reaction Products and Kinetic Scheme

The reactions of aliphatic and aromatic amines with reducing sugars are important in both drug stability and synthesis. The formation of glycosylamines in solution, the first step in the Maillard reaction, does not typically cause browning but results in decreased potency and is hence significant from the aspect of drug instability. The purpose of this research was to present (1) unreported ionic equilibria of model reactant (kynurenine), (2) the analytical methods used to characterize and measure reaction products, (3) the kinetic scheme used to measure reaction rates and (4) relevant properties of various reducing sugars that impact the reaction rate in solution. The methods used to identify the reversible formation of two products from the reaction of kynurenine and monosaccharides included LC mass spectrometry, UV spectroscopy, and 1-D and 2-D ¹H–¹H COSY NMR spectroscopy. Kinetics was studied using a stability-indicating HPLC method. The results indicated the formation of α and β glycosylamines by a pseudo first-order reversible reaction scheme in the pH range of 1–6. The forward reaction was a function of initial glucose concentration but not the reverse reaction. It was concluded that the reaction kinetics and equilibrium concentrations of the glycosylamines were pH-dependent and also a function of the acyclic content of the reacting glucose isomer.     

Culture conflict and coping in a group of aboriginal adolescents

Critical incidents adapted to presentation in picture form were used to investigate responses of Aboriginal adolescents from Elcho Island mission in the Northern Territory of Australia in conflict situations arising from culture contact. These Aboriginal youths are part of a complex environment where choice behaviour is mediated by specific and broader situational characteristics of the social environment. Results showed a relationship between conflict responses and orientation to traditional values and skills, but no apparent relationship between conflict responses and modern value orientation or psychopathology variables. Adolescents who attended high school in Darwin were seen as more mission and academically oriented than locally educated youth. Contrary to expected patterns, males appeared to be less involved in both mission and traditional activities and more restricted by traditional social expectations than were females.     

A physiological analogy of the niche for projecting the potential distribution of plants

Aim  To develop a physiologically based model of the plant niche for use in species distribution modelling. Location  Europe. Methods  We link the Thornley transport resistance (TTR) model with functions which describe how the TTR’s model parameters are influenced by abiotic environmental factors. The TTR model considers how carbon and nutrient uptake, and the allocation of these assimilates, influence growth. We use indirect statistical methods to estimate the model parameters from a high resolution data set on tree distribution for 22 European tree species. Results  We infer, from distribution data and abiotic forcing data, the physiological niche dimensions of 22 European tree species. We found that the model fits were reasonable (AUC: 0.79–0.964). The projected distributions were characterized by a false positive rate of 0.19 and a false negative rate 0.12. The fitted models are used to generate projections of the environmental factors that limit the range boundaries of the study species. Main conclusions  We show that physiological models can be used to derive physiological niche dimensions from species distribution data. Future work should focus on including prior information on physiological rates into the parameter estimation process. Application of the TTR model to species distribution modelling suggests new avenues for establishing explicit links between distribution and physiology, and for generating hypotheses about how ecophysiological processes influence the distribution of plants.     

Microbial Symbionts Accelerate Wound Healing via the Neuropeptide Hormone Oxytocin

Wound healing capability is inextricably linked with diverse aspects of physical fitness ranging from recovery after minor injuries and surgery to diabetes and some types of cancer. Impact of the microbiome upon the mammalian wound healing process is poorly understood. We discover that supplementing the gut microbiome with lactic acid microbes in drinking water accelerates the wound-healing process to occur in half the time required for matched control animals. Further, we find that Lactobacillus reuteri enhances wound-healing properties through up-regulation of the neuropeptide hormone oxytocin, a factor integral in social bonding and reproduction, by a vagus nerve-mediated pathway. Bacteria-triggered oxytocin serves to activate host CD4+Foxp3+CD25+ immune T regulatory cells conveying transplantable wound healing capacity to naive Rag2-deficient animals. This study determined oxytocin to be a novel component of a multi-directional gut microbe-brain-immune axis, with wound-healing capability as a previously unrecognized output of this axis. We also provide experimental evidence to support long-standing medical traditions associating diet, social practices, and the immune system with efficient recovery after injury, sustained good health, and longevity.     

Position dependence of ankle joint dynamics--II. Active mechanics

System identification techniques were used to examine the position dependence of active ankle joint mechanics. Subjects were required to maintain tonic contractions in either the tibialis anterior (TA) or triceps surae (TS) muscles while the ankle was stochastically displaced about different mean angular positions. The dynamic relation between ankle position and torque was determined for each mean position/tonic torque combination; a non-linear minimization technique was used to estimate the three parameters (inertial, viscous and elastic) of a second-order, underdamped system. Whereas the inertial parameter remained essentially invariant across all test conditions, the viscous and elastic (K) parameters became larger as the level of tonic activity increased and as the joint was rotated toward the extremes of the range of motion. The relation between K and torque was linear at all ankle angles. The slope of this relation remained constant at all mean positions during plantarflexor contractions; during dorsiflexor contractions the slope increased as the ankle was rotated from maximum plantarflexion to maximum dorsiflexion. These findings are discussed in terms of: the physiological correlates of ankle mean position, the relative significance of passive and active joint mechanics and contrasts in joint behaviour during active dorsiflexor and plantarflexor contractions.     

MAJOR CLADES OF THE ANGIOSPERMS

Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny.     

Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution

In order to study the relationships among mammalian alpha-globin genes, we have determined the sequence of the 3' flanking region of the human alpha 1 globin gene and have made pairwise comparisons between sequenced alpha-globin genes. The flanking regions were examined in detail because sequence matches in these regions could be interpreted with the least complication from the gene duplications and conversions that have occurred frequently in mammalian alpha-like globin gene clusters. We found good matches between the flanking regions of human alpha 1 and rabbit alpha 1, human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and horse alpha 1 and goat II alpha. These matches were used to align the alpha-globin genes in gene clusters from different mammals. This alignment shows that genes at equivalent positions in the gene clusters of different mammals can be functional or nonfunctional, depending on whether they corrected against a functional alpha-globin gene in recent evolutionary history. The number of alpha-globin genes (including pseudogenes) appears to differ among species, although highly divergent pseudogenes may not have been detected in all species examined. Although matching sequences could be found in interspecies comparisons of the flanking regions of alpha- globin genes, these matches are not as extensive as those found in the flanking regions of mammalian beta-like globin genes. This observation suggests that the noncoding sequences in the mammalian alpha-globin gene clusters are evolving at a faster rate than those in the beta-like globin gene clusters. The proposed faster rate of evolution fits with the poor conservation of the genetic linkage map around alpha-globin gene clusters when compared to that of the beta-like globin gene clusters. Analysis of the 3' flanking regions of alpha-globin genes has revealed a conserved sequence approximately 100-150 bp 3' to the polyadenylation site; this sequence may be involved in the expression or regulation of alpha-globin genes.