The interaction of osteoblasts with bone-implant materials: 1. The effect of physicochemical surface properties of implant materials

This comparative study of various surface treatments of commercially available implant materials is intended as guidance for orientation among particular surface treatment methods in term of the cell reaction of normal human osteoblasts and blood coagulation. The influence of physicochemical surface parameters such as roughness, surface free energy and wettability on the response of human osteoblasts in the immediate vicinity of implants and on the blood coagulation was studied. The osteoblast proliferation was monitored and the expression of tissue mediators (TNF-alpha, IL-8, MMP-1, bone alkaline phosphatase, VCAM-1, TGF-beta) was evaluated after the cell cultivation onto a wide range of commercially available materials (titanium and Ti6Al4V alloy with various surface treatments, CrCoMo alloy, zirconium oxide ceramics, polyethylene and carbon/carbon composite). The formation of a blood clot was investigated on the samples immersed in a freshly drawn whole rabbit blood using scanning electron microscope. The surfaces with an increased osteoblast proliferation exhibited particularly higher surface roughness (here R(a) 3.5 microm) followed by a high polar part of the surface free energy whereas the effect of wettability played a minor role. The surface roughness was also the main factor regulating the blood coagulation. The blood clot formation analysis showed a rapid coagulum formation on the rough titanium-based surfaces. The titanium with an etching treatment was considered as the most suitable candidate for healing into the bone tissue due to high osteoblast proliferation, the highest production of osteogenesis markers and low production of inflammatory cytokines and due to the most intensive blood clot formation.     

The intracellular Arabidopsis COPT5 transport protein is required for photosynthetic electron transport under severe copper deficiency

Copper is an essential micronutrient that functions as a redox cofactor in multiple plant processes, including photosynthesis. Arabidopsis thaliana possesses a conserved family of CTR-like high-affinity copper transport proteins denoted as COPT1-5. COPT1, the only family member that is functionally characterized, participates in plant copper acquisition. However, little is known about the function of the other Arabidopsis COPT proteins in the transport and distribution of copper. Here, we show that a functional fusion of COPT5 to the green fluorescent protein localizes in Arabidopsis cells to the prevacuolar compartment. Plants defective in COPT5 do not exhibit any significant phenotype under copper-sufficient conditions, but their growth is compromised under copper limitation. Under extreme copper deficiency, two independent copt5 knockout mutant lines exhibit severe defects in vegetative growth and root elongation, low chlorophyll content, and impairment in the photosynthetic electron transfer. All these phenotypes are rescued when the wild-type copy of the COPT5 gene is retransformed into a copt5 knockout line or when copper, but not other metals, are added to the medium. COPT5 is expressed in vascular tissues, with elevated levels in roots. Taken together, these results suggest that COPT5 plays an important role in the plant response to environmental copper scarcity, probably by remobilizing copper from prevacuolar vesicles, which could act as internal stores or recycling vesicles to provide the metal cofactor to key copper-dependent processes such as photosynthesis.     

High risk of early sub-therapeutic penicillin concentrations after intramuscular benzathine penicillin G injections in Ethiopian children and adults with rheumatic heart disease

IntroductionIntramuscular benzathine penicillin G (BPG) injections are a cornerstone of secondary prophylaxis to prevent acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Uncertainties regarding inter-ethnic and preparation variability, and target exposure profiles of BPG injection are key knowledge gaps for RHD control.MethodsTo evaluate BPG pharmacokinetics (PK) in patients receiving 4-weekly doses in Ethiopia, we conducted a prospective cohort study of ARF/RHD patients attending cardiology outpatient clinics. Serum samples were collected weekly for one month after injection and assayed with a liquid chromatography-mass spectroscopy assay. Concentration-time datasets for BPG were analyzed by nonlinear mixed effects modelling using NONMEM.ResultsA total of 190 penicillin concentration samples from 74 patients were included in the final PK model. The median age, weight, BMI was 21 years, 47 kg and 18 kg/m², respectively. When compared with estimates derived from Indigenous Australian patients, the estimate for median (95% confidence interval) volume of distribution (V/F) was lower (54.8 [43.9–66.3] l.70kg^-1) whilst the absorption half-life (t_1/2-abs2) was longer (12.0 [8.75–17.7] days). The median (IQR) percentage of time where the concentrations remained above 20 ng/mL and 10 ng/mL within the 28-day treatment cycle was 42.5% (27.5–60) and 73% (58.5–99), respectively.ConclusionsThe majority of Ethiopian patients receiving BPG as secondary prophylaxis to prevent RHD do not attain target concentrations for more than two weeks during each 4-weekly injection cycle, highlighting the limitations of current BPG strategies. Between-population variation, together with PK differences between different preparations may be important considerations for ARF/RHD control programs.     

Serotonin 4 receptor (5-HT4R) internalization is isoform-specific: Effects of 5-HT and RS67333 on isoforms A and B

Serotonin 4 receptors (5-HT4Rs) are particularly abundant within the limbic system, where they constitute potential targets for the development of novel, rapid acting antidepressants. However, the population of limbic 5-HT4Rs is not homogenous, comprising various isoforms of which 5-HT4(a) and 5-HT4(b) are among the most abundant variants. Sequence divergence at their C-termini is predictive of specificity in isoform signalling and regulation, but the differences, if any, remain ill-defined. The present study compared isoforms 5-HT4(a) and 5-HT4(b) in their ability to undergo endocytic regulation following exposure to 5-HT and to the putatively fast acting antidepressant RS67333. Both ligands differed in their ability to induce internalization of either isoform, 5-HT being more effective than RS67333 in HEK293 cells and in neurons. In contrast, trafficking induced by 5-HT was isoform-specific. In particular, while PKC, GRK2 and βarrestin were necessary for 5-HT4(a)R internalization, sequestration of 5-HT4(b)Rs required PKC but not GRK2 and relied significantly less on βarrestin. After endocytosis, isoform (b) appeared scattered throughout the intracellular compartment and efficiently recycled to the membrane upon agonist removal. Isoform (a) accumulated in the perinuclear compartment and displayed little recycling. Isoform-specific subcellular distribution was present in HEK293 cells and in neurons. In neurons, where internalization by RS67333 was more pronounced than in HEK293 cells, receptors internalized by this ligand followed the same distribution pattern as observed with 5-HT. These results point to isoform-related differences in the way that 5-HTRs respond to different ligands. Such diversity should be taken into account when developing therapeutic agents that target 5-HT4Rs.     

Connectivity counts: disentangling effects of vegetation structure elements on the searching movement of a parasitoid

1. A heterogeneous habitat structure can have a profound impact on foraging carnivorous arthropods. In the present study, we examined which elements of complex vegetation structure influence the searching movement of a parasitoid model organism. 2. Previous field work showed that tall and dense vegetation reduces the parasitism success of the eulophid egg parasitoid Oomyzus galerucivorus while the probability of host egg deposition increased close to plant tips. 3. In laboratory bioassays, dried grass stems were arranged according to the natural situation in different setups. The wasps' walking time on stems increased with increasing stem height and density. High stem density decreased the walking time of the parasitoids on the ground and an increased stem height reduced the propensity to fly to the ground. Connectivity had a minor positive effect on the number of stem contacts, but considerably reduced the number of wasps reaching the upper part of grass stems by two‐thirds. 4. Thus, although enhanced vegetation complexity enhances walking activity of the parasitoids in the vegetation, laying eggs at the tip of long grass stems in dense vegetation can be an adaptive strategy for the host, as it maximises the number of connections between plant parts to cross by parasitoids before reaching the host. The connection points disorient the wasps, which lose time, reverse their direction or fly away.     

Insensitive blueberries: a total‐evidence analysis of Disterigma s.l. (Ericaceae) exploring transformation costs

Disterigma sensu lato (s.l.) is a polyphyletic genus of neotropical blueberries that comprises 37 species found in Central and South America, mostly in Andean cloud forests and páramos. The present phylogenetic analysis, based on molecular and morphological data for 84% of the species of Disterigma s.l., addressed the monophyly of the genus and identified the putative morphological synapomorphies of the main clades. The sensitivity of the phylogenetic hypotheses to the choice of analytical parameters was addressed in detail, by varying all possible parameters and applying different treatments for indel coding. A total of 29 transformation cost matrices were investigated and all these analyses were performed in POY 4, using direct optimization. A diagnosable Disterigma sensu stricto (s.s.) clade was recovered in all analyses, despite changes in the transformation costs. Additionally, none of the analyses refuted the segregation of D. trimerum, D. ulei, D. pentandrum, D. rimbachii, and D. bracteatum from Disterigma s.s. Although measurements of congruence are used to choose among alternative analytical parameter sets, the behaviour of the RILD index (rescaled incongruence length difference) in this study suggested that it may not be a good measure of congruence and that further studies are necessary to better understand its performance. © The Willi Hennig Society 2009.     

Development of a Novel Heart Failure Risk Tool: The Barcelona Bio-Heart Failure Risk Calculator (BCN Bio-HF Calculator)

Background

A combination of clinical and routine laboratory data with biomarkers reflecting different pathophysiological pathways may help to refine risk stratification in heart failure (HF). A novel calculator (BCN Bio-HF calculator) incorporating N-terminal pro B-type natriuretic peptide (NT-proBNP, a marker of myocardial stretch), high-sensitivity cardiac troponin T (hs-cTnT, a marker of myocyte injury), and high-sensitivity soluble ST2 (ST2), (reflective of myocardial fibrosis and remodeling) was developed.

Methods

Model performance was evaluated using discrimination, calibration, and reclassification tools for 1-, 2-, and 3-year mortality. Ten-fold cross-validation with 1000 bootstrapping was used.

Results

The BCN Bio-HF calculator was derived from 864 consecutive outpatients (72% men) with mean age 68.2±12 years (73%/27% New York Heart Association (NYHA) class I-II/III-IV, LVEF 36%, ischemic etiology 52.2%) and followed for a median of 3.4 years (305 deaths). After an initial evaluation of 23 variables, eight independent models were developed. The variables included in these models were age, sex, NYHA functional class, left ventricular ejection fraction, serum sodium, estimated glomerular filtration rate, hemoglobin, loop diuretic dose, β-blocker, Angiotensin converting enzyme inhibitor/Angiotensin-2 receptor blocker and statin treatments, and hs-cTnT, ST2, and NT-proBNP levels. The calculator may run with the availability of none, one, two, or the three biomarkers. The calculated risk of death was significantly changed by additive biomarker data. The average C-statistic in cross-validation analysis was 0.79.

Conclusions

A new HF risk-calculator that incorporates available biomarkers reflecting different pathophysiological pathways better allowed individual prediction of death at 1, 2, and 3 years.     

60-Day Chronic Exposure to Low Concentrations of HgCl2 Impairs Sperm Quality: Hormonal Imbalance and Oxidative Stress as Potential Routes for Reproductive Dysfunction in Rats

Mercury is a toxic and bio-accumulative heavy metal of global concern. While good deals of research have been conducted on the toxic effects of mercury, little is known about the mechanisms involved in the pathogenesis of male reproductive dysfunction induced by mercury. Therefore, the purpose of this study was to assess the effects and underlying mechanisms of chronic mercury exposure at low levels on male reproductive system of rats. Three-month-old male Wistar rats were divided into two groups and treated for 60 days with saline (i.m., Control) and HgCl₂ (i.m. 1^st dose: 4.6 µg/kg, subsequent doses 0.07 µg/kg/day). We analyzed sperm parameters, hormonal levels and biomarkers of oxidative stress in testis, epididymis, prostate and vas deferens. Mercury treatment decreased daily sperm production, count and motility and increased head and tail morphologic abnormalities. Moreover, mercury treatment decreased luteinizing hormone levels, increased lipid peroxidation on testis and decreased antioxidant enzymes activities (superoxide dismutase and catalase) on reproductive organs. Our data demonstrate that 60-day chronic exposure to low concentrations of HgCl₂ impairs sperm quality and promotes hormonal imbalance. The raised oxidative stress seems to be a potential mechanism involved on male reproductive toxicity by mercury.