5-Aryl-4-carboxamide-1,3-oxazoles: potent and selective GSK-3 inhibitors

5-Aryl-4-carboxamide-1,3-oxazoles are a novel, potent and selective series of GSK-3 inhibitors. The optimization of the series to yield compounds with cell activity and brain permeability is described.     

A reliability analysis of cardiac repolarization time markers

Only a limited number of studies have addressed the reliability of extracellular markers of cardiac repolarization time, such as the classical marker RT_eg defined as the time of maximum upslope of the electrogram T wave. This work presents an extensive three-dimensional simulation study of cardiac repolarization time, extending the previous one-dimensional simulation study of a myocardial strand by Steinhaus [B.M. Steinhaus, Estimating cardiac transmembrane activation and recovery times from unipolar and bipolar extracellular electrograms: a simulation study, Circ. Res. 64 (3) (1989) 449]. The simulations are based on the bidomain - Luo-Rudy phase I system with rotational fiber anisotropy and homogeneous or heterogeneous transmural intrinsic membrane properties. The classical extracellular marker RT_eg is compared with the gold standard of fastest repolarization time RT_tap, defined as the time of minimum derivative during the downstroke of the transmembrane action potential (TAP). Additionally, a new extracellular marker RT90_eg is compared with the gold standard of late repolarization time RT90_tap, defined as the time when the TAP reaches 90% of its resting value. The results show a good global match between the extracellular and transmembrane repolarization markers, with small relative mean discrepancy (?1.6%) and high correlation coefficients (?0.92), ensuring a reasonably good global match between the associated repolarization sequences. However, large local discrepancies of the extracellular versus transmembrane markers may ensue in regions where the curvature of the repolarization front changes abruptly (e.g. near front collisions) or is negligible (e.g. where repolarization proceeds almost uniformly across fiber). As a consequence, the spatial distribution of activation-recovery intervals (ARI) may provide an inaccurate estimate of (and weakly correlated with) the spatial distribution of action potential durations (APD).     

Effects of pollination timing on seed paternity and seed mass in Silene latifolia (Caryophyllaceae)

Background and Aims

Competition among genetically different pollen donors within one recipient flower may play an important role in plant populations, increasing offspring genetic diversity and vigour. However, under field conditions stochastic pollen arrival times may result in disproportionate fertilization success of the first-arriving pollen, even to the detriment of the recipient plant''s and offspring fitness. It is therefore critical to evaluate the relative importance of arrival times of pollen from different donors in determining siring success.

Methods

Hand pollinations and genetic markers were used to investigate experimentally the effect of pollination timing on seed paternity, seed mass and stigmatic wilting in the the dioecious plant Silene latifolia. In this species, high prevalence of multiply-sired fruits in natural populations suggests that competition among different donors may often take place (at fertilization or during seed development); however, the role of variation due to pollen arrival times is not known.

Key Results

First-arriving pollen sired significantly more seeds than later-arriving pollen. This advantage was expressed already before the first pollen tubes could reach the ovary. Simultaneously with pollen tube growth, the stigmatic papillae wilted visibly. Individual seeds were heavier in fruits where one donor sired most seeds than in fruits where both donors had more even paternity shares.

Conclusions

In field populations of S. latifolia, fruits are often multiply-sired. Because later-arriving pollen had decreased chances of fertilizing the ovules, this implies that open-pollinated flowers often benefit from pollen carry-over or pollinator visits within short time intervals, which may contribute to increase offspring genetic diversity and fitness.Key words: Reproduction, reproductive success, pollen, siring success, microsatellite DNA, paternity, pollen tube growth, seed mass, Silene alba, stigma wilting     

How does breeding system variation modulate sexual antagonism?

The study of sexually antagonistic (SA) traits remains largely limited to dioecious (separate sex), mobile animals. However, the occurrence of sexual conflict is restricted neither by breeding system (the mode of sexual reproduction, e.g. dioecy or hermaphroditism) nor by sessility. Here, we synthesize how variation in breeding system can affect the evolution and expression of intra- and inter-locus sexual conflicts in plants and animals. We predict that, in hermaphrodites, SA traits will (i) display lower levels of polymorphism; (ii) respond more quickly to selection; and (iii) involve unique forms of interlocus conflict over sex allocation, mating roles and selfing rates. Explicit modelling and empirical tests in a broader range of breeding systems are necessary to obtain a general understanding of the evolution of SA traits.     

Impact of Previous Virological Treatment Failures and Adherence on the Outcome of Antiretroviral Therapy in 2007

Background

Combination antiretroviral treatment (cART) has been very successful, especially among selected patients in clinical trials. The aim of this study was to describe outcomes of cART on the population level in a large national cohort.

Methods

Characteristics of participants of the Swiss HIV Cohort Study on stable cART at two semiannual visits in 2007 were analyzed with respect to era of treatment initiation, number of previous virologically failed regimens and self reported adherence. Starting ART in the mono/dual era before HIV-1 RNA assays became available was counted as one failed regimen. Logistic regression was used to identify risk factors for virological failure between the two consecutive visits.

Results

Of 4541 patients 31.2% and 68.8% had initiated therapy in the mono/dual and cART era, respectively, and been on treatment for a median of 11.7 vs. 5.7 years. At visit 1 in 2007, the mean number of previous failed regimens was 3.2 vs. 0.5 and the viral load was undetectable (<50 copies/ml) in 84.6% vs. 89.1% of the participants, respectively. Adjusted odds ratios of a detectable viral load at visit 2 for participants from the mono/dual era with a history of 2 and 3, 4, >4 previous failures compared to 1 were 0.9 (95% CI 0.4–1.7), 0.8 (0.4–1.6), 1.6 (0.8–3.2), 3.3 (1.7–6.6) respectively, and 2.3 (1.1–4.8) for >2 missed cART doses during the last month, compared to perfect adherence. From the cART era, odds ratios with a history of 1, 2 and >2 previous failures compared to none were 1.8 (95% CI 1.3–2.5), 2.8 (1.7–4.5) and 7.8 (4.5–13.5), respectively, and 2.8 (1.6–4.8) for >2 missed cART doses during the last month, compared to perfect adherence.

Conclusions

A higher number of previous virologically failed regimens, and imperfect adherence to therapy were independent predictors of imminent virological failure.     

Isolation of Human Monoclonal Antibodies That Potently Neutralize Human Cytomegalovirus Infection by Targeting Different Epitopes on the gH/gL/UL128-131A Complex

Human cytomegalovirus (HCMV) is a widely circulating pathogen that causes severe disease in immunocompromised patients and infected fetuses. By immortalizing memory B cells from HCMV-immune donors, we isolated a panel of human monoclonal antibodies that neutralized at extremely low concentrations (90% inhibitory concentration [IC₉₀] values ranging from 5 to 200 pM) HCMV infection of endothelial, epithelial, and myeloid cells. With the single exception of an antibody that bound to a conserved epitope in the UL128 gene product, all other antibodies bound to conformational epitopes that required expression of two or more proteins of the gH/gL/UL128-131A complex. Antibodies against gB, gH, or gM/gN were also isolated and, albeit less potent, were able to neutralize infection of both endothelial-epithelial cells and fibroblasts. This study describes unusually potent neutralizing antibodies against HCMV that might be used for passive immunotherapy and identifies, through the use of such antibodies, novel antigenic targets in HCMV for the design of immunogens capable of eliciting previously unknown neutralizing antibody responses.Human cytomegalovirus (HCMV) is a member of the herpesvirus family which is widely distributed in the human population and can cause severe disease in immunocompromised patients and upon infection of the fetus. HCMV infection causes clinical disease in 75% of patients in the first year after transplantation (58), while primary maternal infection is a major cause of congenital birth defects including hearing loss and mental retardation (5, 33, 45). Because of the danger posed by this virus, development of an effective vaccine is considered of highest priority (51).HCMV infection requires initial interaction with the cell surface through binding to heparan sulfate proteoglycans (8) and possibly other surface receptors (12, 23, 64, 65). The virus displays a broad host cell range (24, 53), being able to infect several cell types such as endothelial cells, epithelial cells (including retinal cells), smooth muscle cells, fibroblasts, leukocytes, and dendritic cells (21, 37, 44, 54). Endothelial cell tropism has been regarded as a potential virulence factor that might influence the clinical course of infection (16, 55), whereas infection of leukocytes has been considered a mechanism of viral spread (17, 43, 44). Extensive propagation of HCMV laboratory strains in fibroblasts results in deletions or mutations of genes in the UL131A-128 locus (1, 18, 21, 36, 62, 63), which are associated with the loss of the ability to infect endothelial cells, epithelial cells, and leukocytes (15, 43, 55, 61). Consistent with this notion, mouse monoclonal antibodies (MAbs) to UL128 or UL130 block infection of epithelial and endothelial cells but not of fibroblasts (63). Recently, it has been shown that UL128, UL130, and UL131A assemble with gH and gL to form a five-protein complex (thereafter designated gH/gL/UL128-131A) that is an alternative to the previously described gCIII complex made of gH, gL, and gO (22, 28, 48, 63).In immunocompetent individuals T-cell and antibody responses efficiently control HCMV infection and reduce pathological consequences of maternal-fetal transmission (13, 67), although this is usually not sufficient to eradicate the virus. Albeit with controversial results, HCMV immunoglobulins (Igs) have been administered to transplant patients in association with immunosuppressive treatments for prophylaxis of HCMV disease (56, 57), and a recent report suggests that they may be effective in controlling congenital infection and preventing disease in newborns (32). These products are plasma derivatives with relatively low potency in vitro (46) and have to be administered by intravenous infusion at very high doses in order to deliver sufficient amounts of neutralizing antibodies (4, 9, 32, 56, 57, 66).The whole spectrum of antigens targeted by HCMV-neutralizing antibodies remains poorly characterized. Using specific immunoabsorption to recombinant antigens and neutralization assays using fibroblasts as model target cells, it was estimated that 40 to 70% of the serum neutralizing activity is directed against gB (6). Other studies described human neutralizing antibodies specific for gB, gH, or gM/gN viral glycoproteins (6, 14, 26, 29, 34, 41, 52, 60). Remarkably, we have recently shown that human sera exhibit a more-than-100-fold-higher potency in neutralizing infection of endothelial cells than infection of fibroblasts (20). Similarly, CMV hyperimmunoglobulins have on average 48-fold-higher neutralizing activities against epithelial cell entry than against fibroblast entry (10). However, epitopes that are targeted by the antibodies that comprise epithelial or endothelial cell-specific neutralizing activity of human immune sera remain unknown.In this study we report the isolation of a large panel of human monoclonal antibodies with extraordinarily high potency in neutralizing HCMV infection of endothelial and epithelial cells and myeloid cells. With the exception of a single antibody that recognized a conserved epitope of UL128, all other antibodies recognized conformational epitopes that required expression of two or more proteins of the gH/gL/UL128-131A complex.