Potent, orally active inhibitors of lipoprotein-associated phospholipase A(2): 1-(biphenylmethylamidoalkyl)-pyrimidones.

A series of 1-(biphenylmethylamidoalkyl)-pyrimidones has been designed as nanomolar inhibitors of recombinant lipoprotein-associated phospholipase A(2) with high potency in whole human plasma. 5-(Pyrazolylmethyl) derivative 16 and 5-(methoxypyrimidinylmethyl) derivative 27 demonstrated excellent pharmacodynamic profiles which correlated well with their pharmacokinetic effects.     

Human proximity and habitat fragmentation are key drivers of the rangewide bonobo distribution

Habitat loss and hunting threaten bonobos (Pan paniscus), Endangered (IUCN) great apes endemic to lowland rainforests of the Democratic Republic of Congo. Conservation planning requires a current, data-driven, rangewide map of probable bonobo distribution and an understanding of key attributes of areas used by bonobos. We present a rangewide suitability model for bonobos based on a maximum entropy algorithm in which data associated with locations of bonobo nests helped predict suitable conditions across the species’ entire range. We systematically evaluated available biotic and abiotic factors, including a bonobo-specific forest fragmentation layer (forest edge density), and produced a final model revealing the importance of simple threat-based factors in a data poor environment. We confronted the issue of survey bias in presence-only models and devised a novel evaluation approach applicable to other taxa by comparing models built with data from geographically distinct sub-regions that had higher survey effort. The model’s classification accuracy was high (AUC = 0.82). Distance from agriculture and forest edge density best predicted bonobo occurrence with bonobo nests more likely to occur farther from agriculture and in areas of lower edge density. These results suggest that bonobos either avoid areas of higher human activity, fragmented forests, or both, and that humans reduce the effective habitat of bonobos. The model results contribute to an increased understanding of threats to bonobo populations, as well as help identify priority areas for future surveys and determine core bonobo protection areas.     

A Novel Model of Lethal Hendra Virus Infection in African Green Monkeys and the Effectiveness of Ribavirin Treatment

The henipaviruses, Hendra virus (HeV) and Nipah virus (NiV), are emerging zoonotic paramyxoviruses that can cause severe and often lethal neurologic and/or respiratory disease in a wide variety of mammalian hosts, including humans. There are presently no licensed vaccines or treatment options approved for human or veterinarian use. Guinea pigs, hamsters, cats, and ferrets, have been evaluated as animal models of human HeV infection, but studies in nonhuman primates (NHP) have not been reported, and the development and approval of any vaccine or antiviral for human use will likely require efficacy studies in an NHP model. Here, we examined the pathogenesis of HeV in the African green monkey (AGM) following intratracheal inoculation. Exposure of AGMs to HeV produced a uniformly lethal infection, and the observed clinical signs and pathology were highly consistent with HeV-mediated disease seen in humans. Ribavirin has been used to treat patients infected with either HeV or NiV; however, its utility in improving outcome remains, at best, uncertain. We examined the antiviral effect of ribavirin in a cohort of nine AGMs before or after exposure to HeV. Ribavirin treatment delayed disease onset by 1 to 2 days, with no significant benefit for disease progression and outcome. Together our findings introduce a new disease model of acute HeV infection suitable for testing antiviral strategies and also demonstrate that, while ribavirin may have some antiviral activity against the henipaviruses, its use as an effective standalone therapy for HeV infection is questionable.Hendra virus (HeV) and Nipah virus (NiV) are members of the genus Henipavirus (family Paramyxoviridae) that can cause severe respiratory illness and/or encephalitis in a wide variety of mammals, including horses, pigs, and humans (7, 23). HeV was identified as the causative agent of an acute respiratory disease in horses in 1994 in Queensland, Australia (23), and to date there have been 14 outbreaks in Australia since, with at least one occurrence per year since 2006, most recently in May 2010 (ProMed-mail no. 20100522.1699 [International Society for Infectious Diseases, http://www.promedmail.org]). Every outbreak of HeV has involved horses as the initial infected host, and there have been a total of seven human cases arising from exposure to infected horses. Four human fatalities have occurred (22), with the most recent occurring in August of 2009 (ProMed-mail no. 20090826.2998 and 20090903.3098). All patients initially presented with influenza-like illnesses (ILIs) after an incubation period of 7 to 16 days. While two individuals recovered from ILI, one patient developed pneumonitis and died from multiorgan failure. Three of the lethal cases developed encephalitic manifestations (mild confusion and ataxia), with two patients experiencing seizures (22, 23, 27).Data on the histopathology of fatal human HeV cases are limited, but the pathology includes small necrotic plaques in the cerebrum and cerebellum, in addition to mild parenchymal inflammation (21, 27). Severe parenchymal inflammation and necrosis were observed in the lungs. More extensive histopathologic data are available from 32 autopsies of fatal human NiV cases (28). Similarly to the HeV cases, pathology was characterized by systemic vasculitis and parenchymal necrosis in the central nervous system (CNS), while in the lung, pathological findings mainly included vasculitis, fibrinoid necrosis, alveolar hemorrhage, pulmonary edema, and aspiration pneumonia. Other organs that were affected included heart, kidney, and spleen and showed generally mild or focal inflammation. The development of syncytial multinucleated endothelial cells is characteristic of both HeV and NiV (27, 28). At present, the details of the pathogenesis and histopathological changes mediated by either HeV or NiV infection in humans are naturally derived from only the late phases of the disease course, and therefore a relevant animal model is needed that mimics the disease progression seen in humans.Pteropid fruit bats, commonly known as flying foxes in the family Pteropodidae, are the principle natural reservoirs for both NiV and HeV (reviewed in reference 3). However, these henipaviruses display a broad species tropism, and in addition to bats, horses and humans, natural and/or experimental infection of HeV has been demonstrated in guinea pigs, hamsters, pigs, cats, and ferrets (25). Experimental infections of Syrian hamsters with HeV is lethal, and animals show disease similar to that of human cases, including respiratory and neurological symptoms, depending on the dose (11; unpublished data). In this model, viral RNA can be detected in various organs of infected hamsters, including brain, lung, kidney, heart, liver, and spleen. The main histopathological findings included parenchymal infection in various organs, including the brain, with vasculitis and syncytial multinucleated endothelial cells in many blood vessels (11). While this model is useful in studying pathogenesis, it is limited in the availability of reagents to do so.There are currently no vaccines or treatments licensed for human use. Several in vitro studies have shown that ribavirin is effective against both HeV and NiV infection (1, 2, 29). An open-label ribavirin treatment trial was run during an outbreak of NiV in Malaysia in 1998 and reported to reduce mortality by 36% (6). Of the seven recorded human HeV cases, three patients were treated with ribavirin, one of whom survived (22). In the most recent outbreak of HeV in Australia, three additional people received ribavirin treatment in combination with chloroquine after suspected exposure to HeV-contaminated secretions from infected horses. While all three individuals survived, infection was not confirmed, and therefore it remains unknown whether the treatment had any beneficiary effect (ProMed-mail no. 20090826.2998). In addition, two animal studies in hamsters showed that ribavirin treatment delays but does not prevent death from NiV or HeV infection (8, 10). Therefore, an animal model with greater relevance to humans and that recapitulates the disease processes seen in human cases of HeV is needed to get a better answer to whether ribavirin might be effective against henipavirus infections. In addition, the U.S. FDA implemented the “Animal Efficacy Rule,” which specifically applies to the development of therapeutic products when human efficacy studies are not possible or ethical, such as is often the case with highly virulent pathogens like HeV (24). Essentially, this rule allows for the evaluation of vaccines or therapeutics using data derived from studies carried out in at least two animal models. The licensure of any therapeutic modalities for HeV will require a thorough evaluation of HeV pathogenesis in nonhuman primates (NHPs).In the present study, we report the development and characterization of a new nonhuman primate (NHP) model of lethal HeV infection in the African green monkey (AGM). The pathogenesis and disease progression in the AGM upon HeV infection essentially mirrored the lethal disease episodes seen among human cases of HeV. Using this new model, the efficacy of ribavirin treatment against lethal challenge with HeV was examined. Here we have shown that ribavirin treatment can significantly delay but not prevent death of AGMs from lethal HeV infection. In addition to severe respiratory symptoms in all animals, prolonged disease progression in ribavirin-treated animals was also marked by the appearance of neurological symptoms.     

Energetics and regulations of formate and hydrogen metabolism by Methanobacterium formicicum

Accumulation of formate to millimolar levels was observed during the growth of Methanobacterium formicicum species on H₂–CO₂. Hydrogen was also produced during formate metabolism by M. formicicum. The amount of formate accumulated in the medium or the amount H₂ released in gas phase was influenced by the bicarbonate concentration. The formate hydrogenlyase system was constitutive but regulated by formate. When methanogenesis was inhibited by addition of 2-bromoethane sulfonate, M. formicicum synthesized formate from H₂ plus HCO _inf3 ^sup- or produced H₂ from formate to a steady-state level at which point the Gibbs free energy (G) available for formate synthesis or H₂ production was approximately -2 to -3 kJ/reaction. Formate conversion to methane was inhibited in the presence of high H₂ pressure. The relative rates of conversion of formate and H₂ were apparently controlled by the G available for formate synthesis, hydrogen production, methane production from formate and methane production from H₂. Results from ¹⁴C-tracer tests indicated that a rapid isotopic exchange between HCOO^- and HCO _inf3 ^sup- occurred during the growth of M. formicicum on H₂–CO₂. Data from metabolism of ¹⁴C-labelled formate to methane suggested that formate was initially split to H₂ and HCO _inf3 ^sup- and then subsequently converted to methane. When molybdate was replaced with tungstate in the growth media, the growth of M. formicicum strain MF on H₂–CO₂ was inhibited although production of methane was not Formate synthesis from H₂ was also inhibited.     

Enzyme-coding genes as molecular clocks: The molecular evolution of animal alpha-amylases

Summary We constructed a cDNA library for the beetle,Tribolium castaneum. This library was screened using a cloned amylase gene fromDrosophila melanogaster as a molecular probe. Beetle amylase cDNA clones were isolated from this bank, and the nucleotide sequence was obtained for a cDNA clone with a coding capacity for 228 amino acids. Both the nucleotide sequence and predicted amino acid sequence were compared to our recent results forD. melanogaster alpha-amylases, along with published sequences for other alpha-amylases. The results show that animal alpha-amylases are highly conserved over their entire length. A borader comparison, which includes plant and microbial alpha-amylase sequences, indicates that parts of the gene are conserved between prokaryotes, plants, and animals. We discuss the potential importance of this and other enzyme-coding genes for the construction of molecular phylogenies and for the study of the general question of molecular clocks in evolution.     

Hormonal regulation of estradiol biosynthesis, aromatase activity, and aromatase mRNA in rat ovarian follicles and corpora lutea

To determine the molecular basis for changes in aromatase (P450arom) activity in rat ovarian follicles and corpora lutea, seven clones for rat P450arom cDNA have been identified and isolated from a rat granulosa cell λgtll cDNA expression library using a 62 mer deoxyoligonucleotide probe (derived from an amino acid sequence of purified human placental aromatase) and a human placental P450arom cDNA probe. One of the rat P450arom cDNA clones contained an insert 1.2 kb in size. Both the human 1.8 kb cDNA and the rat 1.2 kb cDNA probes hybridized to a single species of P450arom mRNA that was 2.6 kb in size. Northern blot analysis revealed that corpora lutea isolated on day 15 of pregnancy contained high amounts of P450arom mRNA, whereas granulosa cells of antral follicles of hormonally primed, hypophysectomized rats (i.e., those from which mRNA was isolated to construct the cDNA library) contained only low amounts of P450arom mRNA. The lower amounts of P450arom in granulosa cells of preovulatory follicles in the estradiol-follicle-stimulating hormone primed hypophysectomized rats were unexpected because follicles incubated in medium containing testosterone substrate produce more estradiol than do corpora lutea isolated on day 15 of pregnancy and incubated under similar conditions. Additional studies will determine the hormonal events responsible for the elevated amounts and constitutive maintenance of P450arom mRNA and aromatase activity in luteal cells in vivo and in vitro.     

Communication about Children's Clinical Trials as Observed and Experienced: Qualitative Study of Parents and Practitioners

Background

Recruiting children to clinical trials is perceived to be challenging. To identify ways to optimise recruitment and its conduct, we compared how parents and practitioners described their experiences of recruitment to clinical trials.

Methods and Findings

This qualitative study ran alongside four children''s clinical trials in 11 UK research sites. It compared analyses of semi-structured interviews with analyses of audio-recordings of practitioner-family dialogue during trial recruitment discussions. Parents from 59 families were interviewed; 41 had participated in audio-recorded recruitment discussions. 31 practitioners were interviewed. Parents said little in the recruitment discussions contributing a median 16% of the total dialogue and asking a median of one question. Despite this, parents reported a positive experience of the trial approach describing a sense of comfort and safety. Even if they declined or if the discussion took place at a difficult time, parents understood the need to approach them and spoke of the value of research. Some parents viewed participation as an ‘exciting’ opportunity. By contrast, practitioners often worried that approaching families about research burdened families. Some practitioners implied that recruiting to clinical trials was something which they found aversive. Many were also concerned about the amount of information they had to provide and believed this overwhelmed families. Whilst some practitioners thought the trial information leaflets were of little use to families, parents reported that they used and valued the leaflets. However, both parties agreed that the leaflets were too long and wanted them to be more reader-friendly.

Conclusions

Parents were more positive about being approached to enter their child into a clinical trial than practitioners anticipated. The concerns of some practitioners, that parents would be overburdened, were unfounded. Educating practitioners about how families perceive clinical trials and providing them with ‘moral’ support in approaching families may benefit paediatric research and, ultimately, patients.     

The Major Role of the Rab Ypt7p in Vacuole Fusion Is Supporting HOPS Membrane Association

Yeast vacuole fusion requires soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), the Rab GTPase Ypt7p, vacuolar lipids, Sec17p and Sec18p, and the homotypic fusion and vacuole protein sorting complex (HOPS). HOPS is a multisubunit protein with direct affinities for SNAREs, vacuolar lipids, and the GTP-bound form of Ypt7p; each of these affinities contributes to HOPS association with the organelle. Using all-purified components, we have reconstituted fusion, but the Rab Ypt7p was not required. We now report that phosphorylation of HOPS by the vacuolar kinase Yck3p blocks HOPS binding to vacuolar lipids, making HOPS membrane association and the ensuing fusion depend on the presence of Ypt7p. In accord with this finding in the reconstituted fusion reaction, the inactivation of Ypt7p by the GTPase-activating protein Gyp1–46p only blocks the fusion of purified vacuoles when Yck3p is present and active. Thus, although Ypt7p may contribute to other fusion functions, its central role is to bind HOPS to the membrane.Rab proteins are small GTP-binding proteins involved in multiple steps of membrane traffic, including protein sorting, vesicle transport, and SNARE³-dependent membrane fusion (1). Rabs in their GTP-bound state bind proteins that are essential for mediating Rab function, which are therefore termed “effectors.” These effectors are diverse and perform various biochemical functions. For membrane fusion, Rabs and their effectors support tethering, the initial membrane contact that is needed for the subsequent assembly of trans-SNARE complexes between membranes (1, 2). A central question in organelle trafficking, which we now address, is whether Rabs are only required for binding their effectors to the membrane or whether they also activate the bound effector or provide some additional essential function for membrane fusion.We study membrane fusion using isolated yeast vacuoles (3). Yeast vacuole fusion requires the Rab GTPase Ypt7p, the heterohexameric HOPS complex, four vacuolar SNAREs, the SNARE disassembly chaperones Sec17p and Sec18p, and chemically minor yet functionally essential lipids, termed “regulatory” lipids. The HOPS complex is an effector of Ypt7p (4) and belongs to a group of functionally conserved large multisubunit tethering complexes, many of which are Rab effectors (5). The Vps39p subunit of HOPS is a nucleotide exchange factor for Ypt7p (6). HOPS is also a SNARE chaperone; its Vps33p subunit is a Sec1p/Munc18-1 family (SM) protein, HOPS binds multiple vacuolar SNAREs (7–9), and it proofreads SNARE complex structure (10). HOPS also binds to specific phosphoinositides (8), and these are among the regulatory lipids that are important for fusion (11–13).We have recently reconstituted membrane fusion using proteoliposomes of pure vacuolar proteins and lipids (13). HOPS and the regulatory lipids are crucial for rapid fusion of proteoliposome pairs bearing the three Q-SNAREs on one proteoliposome and the R-SNARE on the other and are absolutely required when all four SNAREs are present on each proteoliposome and Sec17p and Sec18p are present. Ypt7p is not required, showing that HOPS can stimulate SNARE-dependent fusion in vitro even in the absence of its Rab, although Ypt7p stimulates the fusion of these proteoliposomes.4Yeast vacuole fusion can be negatively regulated either by GTPase-activating proteins (GAPs) (14, 15) that promote GTP hydrolysis by Ypt7p or by the kinase Yck3p, which phosphorylates the Vps41p subunit of HOPS (16) and the vacuolar SNARE Vam3p (15). Yck3p is a palmitoylated (17), vacuole-localized kinase of the casein kinase I family (18). The complete fragmentation of vacuoles in vivo, indicating a block of fusion, requires both Ypt7p inactivation by a RabGAP and the presence of Yck3p (15). Yck3p is necessary for efficient vacuole inheritance (16) and normal vacuole morphology (19), suggesting that its function is part of the normal mechanism of vacuole segregation during the cell cycle. Although Yck3p clearly regulates vacuole fusion through phosphorylation of HOPS, it remains unclear which activities of HOPS are inhibited by Yck3p phosphorylation and whether Yck3p must also phosphorylate other vacuole fusion proteins such as Vam3p to block fusion.We now show that phosphorylation of the Vps41p subunit of HOPS by purified Yck3p reduces HOPS binding to membrane lipids, thereby making HOPS association with the membrane and the ensuing fusion of reconstituted proteoliposomes dependent on active Ypt7p. These data with proteoliposomes are supported by assays with purified vacuoles; the RabGAP Gyp1–46p only inhibits the in vitro fusion of yck3Δ vacuoles when purified Yck3p is added. As for Ypt7p and HOPS, the major function of other Rabs may also be to act as membrane receptors for their effectors.     

The Detection of Novelty Relies on Dopaminergic Signaling: Evidence from Apomorphine's Impact on the Novelty N2

Despite much research, it remains unclear if dopamine is directly involved in novelty detection or plays a role in orchestrating the subsequent cognitive response. This ambiguity stems in part from a reliance on experimental designs where novelty is manipulated and dopaminergic activity is subsequently observed. Here we adopt the alternative approach: we manipulate dopamine activity using apomorphine (D1/D2 agonist) and measure the change in neurological indices of novelty processing. In separate drug and placebo sessions, participants completed a von Restorff task. Apomorphine speeded and potentiated the novelty-elicited N2, an Event-Related Potential (ERP) component thought to index early aspects of novelty detection, and caused novel-font words to be better recalled. Apomorphine also decreased the amplitude of the novelty-P3a. An increase in D1/D2 receptor activation thus appears to potentiate neural sensitivity to novel stimuli, causing this content to be better encoded.