Saturation of high-frequency oscillations of R-R intervals in healthy subjects and patients after acute myocardial infarction during ambulatory conditions

This study was designed to assess the relationship between R-R interval length and heart rate (HR) variability in healthy subjects and patients after an acute myocardial infarction (AMI). Twenty-four-hour ambulatory ECG recordings were obtained for 76 healthy subjects and 82 post-AMI patients. The high-frequency (HF, 0.15-0.4 Hz) spectral power of R-R intervals was analyzed in 5-min sequences over 24 h and plotted as a function of the corresponding mean R-R interval length. Quadratic regression model was used to study the relationship between R-R interval length and HF power. If a distinct deflection point (R-R0) occurred in the quadratic regression (r >0.50) model before maximum R-R interval, indicating the plateau of HF power, the relationship between R-R interval and HF power was defined as saturated. Otherwise, the relationship was defined as linear (r >0.50) or low correlated (r >0.50). The relationship was saturated in 35, linear in 38, and low correlated in 3 healthy subjects. In post-AMI patients, the relationship was saturated in 9 subjects, linear in 44 subjects, and low correlated in 29 patients. The HF power analyzed from the 24-h period did not differ between the saturated and linear groups, but when analyzed from the linear portion only, HF spectral power was smaller in the linear than the saturated group both among healthy subjects (P <0.05) and post-AMI patients (P <0.05). Saturation of the HF oscillations of R-R intervals is a common phenomenon in healthy subjects and also present in post-AMI patients during ambulatory conditions. This saturation effect may bias the quantification of cardiac vagal function when HR variability is analyzed from Holter recordings.     

Short-term recovery of benthos following disturbance from stream habitat rehabilitation

The recovery of benthic macroinvertebrates after disturbance from stream rehabilitation was studied in the River Livojoki, northern Finland. The stream that had been channelized for log transport was rehabilitated on 1 July 1992 by digging holes and inserting boulders. We measured habitat characteristics and sampled benthic animals before and after rehabilitation, including an unrehabilitated control site. The immediate effect of rehabilitation was a slight decrease in the abundances of benthic insects. Recolonization occurred rapidly, within 10 days. Disturbance of the rehabilitation did not have a detectable effect on the macroinvertebrate community. Most species-level changes and community patterns reflected seasonal life history events. Timing of such rehabilitation work can be critical for the recovery rate, which depends on the colonization abilities of the species present after disturbance. We suggest that many disturbances (including minor floods and moderate rehabilitation procedures) may have only small, short-term effects on benthic communities. We emphasize the importance of considering seasonality in studies of disturbance in streams.     

Application of aptamers in diagnostics,drug-delivery and imaging

Aptamers are small, single-stranded oligonucleotides (DNA or RNA) that bind to their target with high specificity and affinity. Although aptamers are analogous to antibodies for a wide range of target recognition and variety of applications, they have significant advantages over antibodies. Since aptamers have recently emerged as a class of biomolecules with an application in a wide array of fields, we need to summarize the latest developments herein. In this review we will discuss about the latest developments in using aptamers in diagnostics, drug delivery and imaging. We begin with diagnostics, discussing the application of aptamers for the detection of infective agents itself, antigens/toxins (bacteria), biomarkers (cancer), or a combination. The ease of conjugation and labelling of aptamers makes them a potential tool for diagnostics. Also, due to the reduced off-target effects of aptamers, their use as a potential drug delivery tool is emerging rapidly. Hence, we discuss their use in targeted delivery in conjugation with siRNAs, nanoparticles, liposomes, drugs and antibodies. Finally, we discuss about the conjugation strategies applicable for RNA and DNA aptamers for imaging. Their stability and self-assembly after heating makes them superior over protein-based binding molecules in terms of labelling and conjugation strategies.     

Early Retinal Function Deficit without Prominent Morphological Changes in the R6/2 Mouse Model of Huntington’s Disease

Huntington’s disease (HD) is an inherited neurodegenerative disorder that primarily affects the medium-size GABAergic neurons of striatum. The R6/2 mouse line is one of the most widely used animal models of HD. Previously the hallmarks of HD-related pathology have been detected in photoreceptors and interneurons of R6/2 mouse retina. Here we aimed to explore the survival of retinal ganglion cells (RGCs) and functional integrity of distinct retinal cell populations in R6/2 mice. The pattern electroretinography (PERG) signal was lost at the age of 8 weeks in R6/2 mice in contrast to the situation in wild-type (WT) littermates. This defect may be attributable to a major reduction in photopic ERG responses in R6/2 mice which was more evident in b- than a-wave amplitudes. At the age of 4 weeks R6/2 mice had predominantly the soluble form of mutant huntingtin protein (mHtt) in the RGC layer cells, whereas the aggregated form of mHtt was found in the majority of those cells from the 12-week-old R6/2 mice and onwards. Retinal astrocytes did not contain mHtt deposits. The total numbers of RGC layer cells, retinal astrocytes as well as optic nerve axons did not differ between 18-week-old R6/2 mice and their WT controls. Our data indicate that mHtt deposition does not cause RGC degeneration or retinal astrocyte loss in R6/2 mice even at a late stage of HD-related pathology. However, due to functional deficits in the rod- and cone-pathways, the R6/2 mice suffer progressive deficits in visual capabilities starting as early as 4 weeks; at 8 weeks there is severe impairment. This should be taken into account in any behavioral testing conducted in R6/2 mice.     

Bartonella henselae: Subversion of vascular endothelial cell functions by translocated bacterial effector proteins

Bartonella henselae (Bh) is a worldwide distributed zoonotic pathogen. Depending on the immune status of the infected individual this bacterium can cause a wide spectrum of clinical manifestations, ranging from cat scratch disease (CSD) to bacillary angiomatosis (BA) and bacillary peliosis (BP). BA and BP are characterized by tumor-like lesions at the skin or in the inner organs, respectively. These structures display pathological sprouting of capillaries with enlarged and hyperproliferated vascular endothelial cells (ECs) that are frequently found in close association with bacteria. Here we review the cellular changes observed upon Bh infection of ECs in vitro and outline the role of the VirB type IV secretion system (T4SS) and its translocated effector proteins in the modulation of EC signalling cascades. The current model how this virulence system could contribute to the vasoproliferative activity of Bh is described.     

Putative surface proteins encoded within a novel transferable locus confer a high-biofilm phenotype to Enterococcus faecalis

Enterococci are opportunistic pathogens and among the leading causes of nosocomial infections. Enterococcus faecalis, the dominant species among infection-derived isolates, has recently been recognized as capable of forming biofilms on abiotic surfaces in vitro as well as on indwelling medical devices. A few bacterial factors known to contribute to biofilm formation in E. faecalis have been characterized. To identify additional factors which may be important to this process, we utilized a Tn917-based insertional mutagenesis strategy to generate a mutant bank in a high-biofilm-forming E. faecalis strain, E99. The resulting mutant bank was screened for mutants exhibiting a significantly reduced ability to form biofilms. One mutant, P101D12, which showed greater than 70% reduction in its ability to form biofilms compared to the wild-type parent, was further characterized. The single Tn917 insertion in P101D12 was mapped to a gene, bee-2, encoding a probable cell wall-anchored protein. Sequence information for the region flanking bee-2 revealed that this gene was a member of a locus (termed the bee locus for biofilm enhancer in enterococcus) comprised of five genes encoding three putative cell wall-anchored proteins and two probable sortases. Contour-clamped homogeneous electric field gel and Southern hybridization analyses suggested that the bee locus is likely harbored on a large conjugative plasmid. Filter mating assays using wild-type E99 or mutant P101D12 as a donor confirmed that the bee locus could transfer conjugally at high frequency to recipient E. faecalis strains. This represents the first instance of the identification of a mobile genetic element conferring biofilm-forming property in E. faecalis.     

Annexin A9 is a periplakin interacting partner in membrane-targeted cytoskeletal linker protein complexes

Periplakin regulates keratin organisation and participates in the assembly of epidermal cornified envelopes. A proteomic approach identified annexin A9 as a novel interacting partner for periplakin N-terminus. The presence of annexin A9 in complexes with periplakin was confirmed by immunoblotting of proteins immunoprecipitated by anti-HA or anti-annexin A9 antibodies. Both endogenous and GFP-tagged annexin A9 co-localise with endogenous periplakin and transfected periplakin N-terminus at MCF-7 cell borders and aggregate after Okadaic acid treatment. Annexin A9 and periplakin co-localise in the epidermis and annexin A9 is up-regulated in differentiating keratinocytes, but the epidermal annexin A9 expression does not require periplakin.Structured summary of protein interactionsAnnexin-9 physically interacts with Periplakin by anti bait co-immunoprecipitation (View interaction) Periplakin physically interacts with Annexin-9 by anti tag co-immunoprecipitation (View Interaction: 1, 2) Periplakin and Annexin-9 colocalize by fluorescence microscopy (View Interaction: 1, 2, 3) Keratin-8 and Periplakin colocalize by fluorescence microscopy (View interaction)     

Overexpression of MicroRNA-200c Predicts Poor Outcome in Patients with PR-Negative Breast Cancer

Micro-RNAs are small, noncoding RNAs that act as tumor suppressors or oncogenes. MiR-200c is a member of the miR-200 family; it is known to be dysregulated in invasive breast carcinoma. MiR-200c maintains the epithelial-mesenchymal transition and inhibits cell migration and invasion. Recent studies showed that miR-200c regulated steroid hormone receptors, estrogen receptors (ER), and progesterone receptors (PR). The present study aimed to detect miR-200c in 172 invasive breast carcinoma cases selected from a prospective cohort enrolled in Kuopio, Eastern Finland, between 1990 and 1995. MiR-200c expression was determined with relative q-PCR, and results were compared to clinicopathological variables and patient outcome. We found that PR status combined with miR-200c expression was a significant marker of outcome. High miR-200c expression was associated with reduced survival in PR-negative cases (n = 68); low miR-200c expression indicated reduced survival in PR-positive cases (n = 86) (Cox regression: P = 0.002, OR = 3.433; and P = 0.004, OR = 4.176, respectively). In PR-negative cases, high miR-200c expression was associated with shortened relapse-free survival (Cox regression: P = 0.001, OR = 3.613); increased local/distant recurrence (Logistic regression: P = 0.006, OR = 3.965); and more frequent distant metastasis (Logistic regression: P = 0.015, OR = 3.390). We also found that high grade and low stage tumors were positively correlated with high miR-200c expression (Logistic regression for high grade tumors: P = 0.002, OR = 2.791 and for high stage tumors: P = 0.035, OR = 0.285). Our results indicated that miR-200c may play a role in invasive breast carcinoma. Furthermore, miR-200c combined with PR status provided a refined predictor of outcome. In future, a larger study is required to confirm our results. This data may provide a basis for new research target–progesterone receptor–regulated microRNAs in breast cancer.     

Cationic amphiphilic star and linear block copolymers: synthesis, self-assembly, and in vitro gene transfection

A series of amphiphilic star and linear block copolymers were synthesized using ATRP. The core consisted of either polystyrene (PS) or poly(n-butyl acrylate) (PBuA), having different glass-transition (T(g)) values. These polymers were used as macroinitiators in the polymerization of the cationic 2-(dimethylamino)ethyl methacrylate (DMAEMA). The polymers were used to study the effects of polymer architecture and flexibility on the self-assembling properties, DNA complexation, and transfection. All polymers formed core-shell micelles in aqueous solutions and condensed plasmid DNA. Linear PDMAEMA-PBuA-PDMAEMA has transfection efficiency comparable to PEI25K in ARPE19 cell line. Glassy state of the micellar core and star-shaped architecture decreased the DNA transfection compared with the rubbery and linear polymer structures. The polymers showed low cellular toxicity at low nitrogen/phosphate (n/p) ratios.