Identification of novel small-molecule histone deacetylase inhibitors by medium-throughput screening using a fluorigenic assay

Cationic peptides, known to disrupt bacterial membranes, are being developed as promising agents for therapeutic intervention against infectious disease. In the present study, we investigate structure-activity relationships in the bacterial membrane disruptor betapep-25, a peptide 33-mer. For insight into which amino acid residues are functionally important, we synthesized alanine-scanning variants of betapep-25 and assessed their ability to kill bacteria (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) and to neutralize LPS (lipopolysaccharide). Activity profiles were found to vary with the bacterial strain examined. Specific cationic and smaller hydrophobic alkyl residues were crucial to optimal bactericidal activity against the Gram-negative bacteria, whereas larger hydrophobic and cationic residues mediated optimal activity against Gram-positive Staph. aureus. Lysine-substituted norleucine (n-butyl group) variants demonstrated that both charge and alkyl chain length mediate optimal activity. In terms of LPS neutralization, activity profiles were essentially the same against four species of LPS (E. coli 055 and 0111, Salmonella enterica serotype Typhimurium and Klebsiella pneumoniae), and different for two others (Ps. aeruginosa and Serratia marcescens), with specific hydrophobic, cationic and, surprisingly, anionic residues being functionally important. Furthermore, disulfide-bridged analogues demonstrated that an anti parallel beta-sheet structure is the bioactive conformation of betapep-25 in terms of its bactericidal, but not LPS endotoxin neutralizing, activity. Moreover, betapep-25 variants, like the parent peptide, do not lyse eukaryotic cells. This research contributes to the development and design of novel antibiotics.     

Hospital Recorded Morbidity and Breast Cancer Incidence: A Nationwide Population-Based Case-Control Study

Introduction

Chronic diseases and their complications may increase breast cancer risk through known or still unknown mechanisms, or by shared causes. The association between morbidities and breast cancer risk has not been studied in depth.

Methods

Data on all Danish women aged 45 to 85 years, diagnosed with breast cancer between 1994 and 2008 and data on preceding morbidities were retrieved from nationwide medical registries. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression associating the Charlson comorbidity score (measured using both the original and an updated Charlson Comorbidity Index (CCI)) with incident breast cancer. Furthermore, we estimated associations between 202 morbidity categories and incident breast cancer, adjusting for multiple comparisons using empirical Bayes (EB) methods.

Results

The study included 46,324 cases and 463,240 population controls. Increasing CCI score, up to a score of six, was associated with slightly increased breast cancer risk. Among the Charlson diseases, preceding moderate to severe renal disease (OR = 1.25, 95% CI: 1.06, 1.48), any tumor (OR = 1.17, 95% CI: 1.10, 1.25), moderate to severe liver disease (OR = 1.86, 95% CI: 1.32, 2.62), and metastatic solid tumors (OR = 1.49, 95% CI: 1.17, 1.89), were most strongly associated with subsequent breast cancer. Preceding myocardial infarction (OR = 0.89, 95% CI: 0.81, 0.99), connective tissue disease (OR = 0.87, 95% CI: 0.80, 0.94), and ulcer disease (OR = 0.91, 95% CI: 0.83, 0.99) were most strongly inversely associated with subsequent breast cancer. A history of breast disorders was associated with breast cancer after EB adjustment. Anemias were inversely associated with breast cancer, but the association was near null after EB adjustment.

Conclusions

There was no substantial association between morbidity measured with the CCI and breast cancer risk.     

Dynamic effective connectivity of inter-areal brain circuits

Anatomic connections between brain areas affect information flow between neuronal circuits and the synchronization of neuronal activity. However, such structural connectivity does not coincide with effective connectivity (or, more precisely, causal connectivity), related to the elusive question “Which areas cause the present activity of which others?”. Effective connectivity is directed and depends flexibly on contexts and tasks. Here we show that dynamic effective connectivity can emerge from transitions in the collective organization of coherent neural activity. Integrating simulation and semi-analytic approaches, we study mesoscale network motifs of interacting cortical areas, modeled as large random networks of spiking neurons or as simple rate units. Through a causal analysis of time-series of model neural activity, we show that different dynamical states generated by a same structural connectivity motif correspond to distinct effective connectivity motifs. Such effective motifs can display a dominant directionality, due to spontaneous symmetry breaking and effective entrainment between local brain rhythms, although all connections in the considered structural motifs are reciprocal. We show then that transitions between effective connectivity configurations (like, for instance, reversal in the direction of inter-areal interactions) can be triggered reliably by brief perturbation inputs, properly timed with respect to an ongoing local oscillation, without the need for plastic synaptic changes. Finally, we analyze how the information encoded in spiking patterns of a local neuronal population is propagated across a fixed structural connectivity motif, demonstrating that changes in the active effective connectivity regulate both the efficiency and the directionality of information transfer. Previous studies stressed the role played by coherent oscillations in establishing efficient communication between distant areas. Going beyond these early proposals, we advance here that dynamic interactions between brain rhythms provide as well the basis for the self-organized control of this “communication-through-coherence”, making thus possible a fast “on-demand” reconfiguration of global information routing modalities.     

Designation of Streptomycete 16S and 23S rRNA-based target regions for oligonucleotide probes.

The 16S and 23S rRNA of various Streptomyces species were partially sequenced and screened for the presence of stretches that could define all members of the genus, groups of species, or individual species. Nucleotide 929 (Streptomyces ambofaciens nomenclature [J.L. Pernodet, M.T. Alegre, F. Boccard, and M. Guerineau, Gene 79:33-46, 1989]) is a nucleotide highly unique to Streptomyces species which, in combination with flanking regions, allowed the designation of a genus-specific probe. Regions 158 through 203 of the 16S rRNA and 1518 through 1645 of the 23S rRNA (helix 54 [Pernodet et al., Gene 79:33-46, 1989]) have a high potential to define species, whereas the degree of variation in regions 982 through 998 and 1102 through 1122 of the 16S rRNA is less pronounced but characteristic for at least certain species. Alone or in combination with each other, these regions may serve as target sites for synthetic oligonucleotide probes and primers to be used in the determination of pure cultures and in the characterization of community structures. The specificity of several probes is demonstrated by dot blot hybridization.     

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Immunohistochemical distribution of galectin-1, galectin-3, and olfactory marker protein in human olfactory epithelium

The expression pattern of galectin-1 and galectin-3 in the human olfactory epithelium was investigated in relation to olfactory marker protein (OMP) using confocal laser immunofluorescence in human specimens and postmortem biopsies. OMP expression was found in olfactory receptor neurons (ORNs) in the olfactory mucosa and in fibers of the olfactory nerve crossing the submucous connective tissue. Galectin-1 was expressed in both the connective tissue of the nasal cavity and in the basal layer of the olfactory epithelium. In contrast, galectin-3 expression was limited to cells of the upper one-third of the olfactory epithelium. Expression of galectin-3 occurred in a subset of OMP-positive cells. However, between areas of galectin-1 and galectin-3 expression in the lower and upper portion of the epithelium, OMP-positive ORNs did not stain for both galectins. Considering the potential role of galectin-1 and galectin-3 in cell differentiation and maturation, the differential localization of galectins in the olfactory epithelium appears to be consistent with a significant role of these molecules in the physiological turnover of ORNs. Accepted: 20 December 1999     

Nectar sugar composition of European Caryophylloideae (Caryophyllaceae) in relation to flower length,pollination biology and phylogeny

Floral nectar composition has been explained as an adaptation to factors that are either directly or indirectly related to pollinator attraction. However, it is often unclear whether the sugar composition is a direct adaptation to pollinator preferences. Firstly, the lower osmolality of sucrose solutions means that they evaporate more rapidly than hexose solutions, which might be one reason why sucrose‐rich nectar is typically found in flowers with long tubes (adapted to long‐tongued pollinators), where it is better protected from evaporation than in open or short‐tubed flowers. Secondly, it can be assumed that temperature‐dependent evaporation is generally lower during the night than during the day so that selection pressure to secrete nectar with high osmolality (i.e. hexose‐rich solutions) is relaxed for night‐active flowers pollinated at night. Thirdly, the breeding system may affect selection pressure on nectar traits; that is, for pollinator‐independent, self‐pollinated plants, a lower selective pressure on nectar traits can be assumed, leading to a higher variability of nectar sugar composition independent of pollinator preferences, nectar accessibility and nectar protection. To analyse the relations between flower tube length, day vs. night pollination and self‐pollination, the nectar sugar composition was investigated in 78 European Caryophylloideae (Caryophyllaceae) with different pollination modes (diurnal, nocturnal, self‐pollination) using high‐performance liquid chromatography (HPLC). All Caryophylleae species (Dianthus and relatives) were found to have nectar with more than 50% sucrose, whereas the sugar composition of Sileneae species (Silene and relatives) ranged from 0% to 98.2%. In the genus Silene, a clear dichotomous distribution of sucrose‐ and hexose‐dominant nectars is evident. We found a positive correlation between the flower tube length and sucrose content in Caryophylloideae, particularly in day‐flowering species, using both conventional analyses and phylogenetically independent contrasts.