Sesquiterpene lactones from Anthemis carpatica Willd

Four new eudesmanolides and two new guaianolides were isolated from the aerial parts of Anthemis carpatica Willd. and their structures elucidated by spectral methods. In addition, seven known sesquiterpene lactones were identified.     

Role of the C-terminal chain in human interferongamma stability: an electrostatic study

Electrostatic interactions in two structures of human interferon gamma (hIFNgamma), corresponding to interferon molecule alone and bound to its receptor, were analyzed on the basis of a continuum dielectric model. It was found that a number of titratable groups, mainly basic, show large pK shifts and remain in their neutral forms at physiologically relevant pH. The fact that these groups are largely common to both structures and that most of them belong to the set of most conserved sites suggests that this is a property inherent to the hIFNgamma molecule rather than an artifact of the crystal packing. His111 was also found deprotonated at neutral pH. It was concluded that receptor recognition involving His111 is driven by aromatic coupling of His111 and Tyr52 from the receptor rather than by electrostatic interactions. The structure corresponding to hIFNgamma in complex with its receptor shows a reduction in number and in degree of desolvation of the buried titratable sites. This finding suggested that on receptor binding, hIFNgamma adopts energetically more favorable, relaxed, conformation. It was experimentally shown that in contrast to the full-size hIFNgamma, the construct having 21 amino acid residues deleted from the C-terminus is soluble. The hydrophobicity profile analysis suggested that factors other than the exposure of hydrophobic parts of the molecule are responsible for the low stability and propensity for aggregation. On the basis of these results, it was assumed that the electrostatic influence of the C-terminal part contributes particularly to the low solvent exposure of the titratable groups, and hence to the low structural stability and propensity for aggregation of the recombinant hIFNgamma. Proteins 2001;43:125-133.     

Comparative study of Tanacetum species growing in Bulgaria

Chemical investigation of the Bulgarian species Tanacetum. parthenium, T. millefolium, T. achilleifolium, T. corymbosum and T. macrophyllum afforded in addition to 24 known sesquiterpene lactones a new 12, 8-eudesmanolide 22. Besides, four known highly oxigenated terpenoids and a new keto-diol 30 of the rare iphionane skeleton were also isolated. The structures were elucidated on the basis of their spectral properties. The accumulation of the different sesquiterpene lactones in the studied species and there classification is discussed.     

Elevated rates of horizontal gene transfer in the industrialized human microbiome

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Habitat complexity: approaches and future directions

Habitat complexity is one of the most important factors structuring biotic assemblages, yet we still lack basic understanding of the underlying mechanisms. Although it is one of the primary targets in conservation management, no methods are available for comparing complexity across ecosystems, and system-specific qualitative assessment predominates. Despite its overwhelming importance for faunal diversity and abundance, there has been surprisingly little interest in examining its effects on other community and ecosystem attributes. We discuss possibilities of such effects, outlining potentially fruitful areas for future research, and argue that complexity may be implicated in community persistence and ecosystem stability by acting as a decoupling mechanism in predator–prey interactions. We provide a brief overview of methods used to quantify complexity in different ecosystems, highlighting contributions of the current issue of Hydrobiologia, and discuss potential application of these approaches for cross-ecosystem comparisons. Better understanding of the role of habitat complexity resulting from such comparisons is critically important for preservation of biodiversity and ecosystem function in an era of unprecedented habitat loss.     

Social Support and Health in Diabetes Patients: An Observational Study in Six European Countries in an Era of Austerity

Introduction

Support from individual social networks, community organizations and neighborhoods is associated with better self-management and health outcomes. This international study examined the relative impact of different types of support on health and health-related behaviors in patients with type 2 diabetes.

Methods

Observational study (using interviews and questionnaires) in a sample of 1,692 type 2 diabetes patients with 5,433 connections from Bulgaria, Greece, Netherlands, Norway, Spain, and the United Kingdom. Outcomes were patient-reported health status (SF-12), physical exercise (RAPA), diet and smoking (SDCSCA). Random coefficient regression models were used to examine linkages with individual networks, community organizations, and neighborhood type (deprived rural, deprived urban, or affluent urban).

Results

Patients had a median of 3 support connections and 34.6% participated in community organizations. Controlled for patients’ age, sex, education, income and comorbidities, large emotional support networks were associated with decrease of non-smoking (OR = 0.87). Large practical support networks were associated with worse physical and mental health (B = -0.46 and -0.27 respectively) and less physical activity (OR = 0.90). Participation in community organizations was associated with better physical and mental health (B = 1.39 and 1.22, respectively) and, in patients with low income, with more physical activity (OR = 1.53).

Discussion

Participation in community organizations was most consistently related to better health status. Many diabetes patients have individual support networks, but this study did not provide evidence to increase their size as a public health strategy. The consistent association between participation in community organizations and health status provides a clear target for interventions and policies.     

Daunorubicin Derivatives Obtained from Daunorubicin and Nucleoside Dialdehydes

Abstract

Nucleoside dialdehydes were obtained by periodate oxidation of adenosine, cytidine, guanosine, uridine or 6-azauridine in the presence of Dowex (1×8; CH₃COO). Reductive alkylation of daunorubicin with these dialdehydes in the presence of NaBH₃CN produced a series of 3′-deamino-3′-(4-morpholino)daunorubicin or 13-(R, S)-dihydrodaunorubicin derivatives, the latter being mixtures of two diastereomers at 13-C atom. The morpholino-daunorubicin derivatives containing nucleic base moieties are less cytotoxic than cyanomorpholino-daunorubicin, morpholino-daunorubicin and even than the parent antibiotic.     

Trophic complexity of small fish in nearshore food webs

Small nearshore fishes are an important part of lacustrine and functional diversity and link pelagic and benthic habitats by serving as prey for larger nearshore and offshore fishes. However, the trophic complexity of these small nearshore fishes is often unrecognized and detailed studies of their role in food webs are lacking. Here, we examined niche space patterns of small nearshore fish species using Bayesian analyses of carbon and nitrogen stable isotope data in nine freshwater lakes that are among the largest lakes in Minnesota. We found considerable variability in niche areas within species and high variability in niche overlap across species. At the assemblage level, niche overlap (average diet overlap of all species pairs at a lake) decreased as whole-lake species richness increased, possibly indicating a greater degree of resource specialization in more speciose lakes. Overall fish niche space was weakly but significantly related to niche space of their invertebrate prey. Although nearshore benthic resources contributed to fish diets in all lakes, all fish species also had non-negligible and variable contributions from pelagic zooplankton. This inter- and intraspecific variability in trophic niche space likely contributes to the multi-level trophic complexity, functional diversity, and potentially food web resilience to ecosystem changes.

     

Adenosine and blood platelets

Adenosine is an important regulatory metabolite and an inhibitor of platelet activation. Adenosine released from different cells or generated through the activity of cell-surface ectoenzymes exerts its effects through the binding of four different G-protein-coupled adenosine receptors. In platelets, binding of A₂ subtypes (A_2A or A_2B) leads to consequent elevation of intracellular cyclic adenosine monophosphate, an inhibitor of platelet activation. The significance of this ligand and its receptors for platelet activation is addressed in this review, including how adenosine metabolism and its A₂ subtype receptors impact the expression and activity of adenosine diphosphate receptors. The expression of A₂ adenosine receptors is induced by conditions such as oxidative stress, a hallmark of aging. The effect of adenosine receptors on platelet activation during aging is also discussed, as well as potential therapeutic applications.