Relationship between alirocumab, PCSK9, and LDL-C levels in four phase 3 ODYSSEY trials using 75 and 150 mg doses

BACKGROUND: Alirocumab is a monoclonal antibody to proprotein convertase subtilisin/kexin type 9 (PCSK9). OBJECTIVE: Changes in PCSK9, alirocumab, and low-density lipoprotein cholesterol (LDL-C) levels were assessed after treatment with alirocumab at doses of 75 or 150 mg every 2 weeks (Q2W). METHODS: Data were analyzed from 4 phase 3 trials (MONO; COMBO II; FH I; LONG TERM); all but MONO enrolled patients on statins. Three trials evaluated alirocumab 75 mg Q2W, with possible dose increase to 150 mg Q2W at week 12 based on week 8 LDL-C; LONG TERM studied alirocumab 150 mg Q2W. RESULTS: Patients on background statin therapy had higher mean baseline free PCSK9 concentrations vs patients not on statin. After alirocumab administration, increased alirocumab concentrations were associated with dramatic reductions in circulating free PCSK9, resulting in significant LDL-C reductions and a corresponding increase in inactive PCSK9:alirocumab complex. Alirocumab dose increase was associated with a further lowering of PCSK9 and LDL-C. Patients with higher baseline LDL-C levels (>160 mg/dL) were more likely to have their dose increased. LDL-C reductions with alirocumab were consistent between patients with baseline PCSK9 levels above or below the median when the dose increase strategy was used. When started as alirocumab 150 mg Q2W, patients with PCSK9 levels above vs below the median had a greater LDL-C reduction. CONCLUSIONS: Alirocumab-induced changes in PCSK9 and LDL-C levels were consistent with the known physiologic relationship between PCSK9, LDL receptor, and LDL-C levels, as well as statin-induced increases in PCSK9 production. (C) 2019 National Lipid Association. Published by Elsevier Inc.Peer reviewe

3-D Ultrastructure of O. tauri: Electron Cryotomography of an Entire Eukaryotic Cell

The hallmark of eukaryotic cells is their segregation of key biological functions into discrete, membrane-bound organelles. Creating accurate models of their ultrastructural complexity has been difficult in part because of the limited resolution of light microscopy and the artifact-prone nature of conventional electron microscopy. Here we explored the potential of the emerging technology electron cryotomography to produce three-dimensional images of an entire eukaryotic cell in a near-native state. Ostreococcus tauri was chosen as the specimen because as a unicellular picoplankton with just one copy of each organelle, it is the smallest known eukaryote and was therefore likely to yield the highest resolution images. Whole cells were imaged at various stages of the cell cycle, yielding 3-D reconstructions of complete chloroplasts, mitochondria, endoplasmic reticula, Golgi bodies, peroxisomes, microtubules, and putative ribosome distributions in-situ. Surprisingly, the nucleus was seen to open long before mitosis, and while one microtubule (or two in some predivisional cells) was consistently present, no mitotic spindle was ever observed, prompting speculation that a single microtubule might be sufficient to segregate multiple chromosomes

Robustness of circadian clocks to daylight fluctuations: hints from the picoeucaryote Ostreococcus tauri

The development of systemic approaches in biology has put emphasis on identifying genetic modules whose behavior can be modeled accurately so as to gain insight into their structure and function. However most gene circuits in a cell are under control of external signals and thus quantitative agreement between experimental data and a mathematical model is difficult. Circadian biology has been one notable exception: quantitative models of the internal clock that orchestrates biological processes over the 24-hour diurnal cycle have been constructed for a few organisms, from cyanobacteria to plants and mammals. In most cases, a complex architecture with interlocked feedback loops has been evidenced. Here we present first modeling results for the circadian clock of the green unicellular alga Ostreococcus tauri. Two plant-like clock genes have been shown to play a central role in Ostreococcus clock. We find that their expression time profiles can be accurately reproduced by a minimal model of a two-gene transcriptional feedback loop. Remarkably, best adjustment of data recorded under light/dark alternation is obtained when assuming that the oscillator is not coupled to the diurnal cycle. This suggests that coupling to light is confined to specific time intervals and has no dynamical effect when the oscillator is entrained by the diurnal cycle. This intringuing property may reflect a strategy to minimize the impact of fluctuations in daylight intensity on the core circadian oscillator, a type of perturbation that has been rarely considered when assessing the robustness of circadian clocks

Amyloid Precursor Protein Is Required for Normal Function of the Rod and Cone Pathways in the Mouse Retina

Amyloid precursor protein (APP) is a transmembrane glycoprotein frequently studied for its role in Alzheimer's disease. Our recent study in APP knockout (KO) mice identified an important role for APP in modulating normal neuronal development in the retina. However the role APP plays in the adult retina and whether it is required for vision is unknown. In this study we evaluated the role of APP in retinal function and morphology comparing adult wildtype (WT) and APP-KO mice. APP was expressed on neuronal cells of the inner retina, including horizontal, cone bipolar, amacrine and ganglion cells in WT mice. The function of the retina was assessed using the electroretinogram and although the rod photoreceptor responses were similar in APP-KO and WT mice, the post-photoreceptor, inner retinal responses of both the rod and cone pathways were reduced in APP-KO mice. These changes in inner retinal function did not translate to a substantial change in visual acuity as assessed using the optokinetic response or to changes in the gross cellular structure of the retina. These findings indicate that APP is not required for basic visual function, but that it is involved in modulating inner retinal circuitry

No effect of PCSK9 inhibitor alirocumab on the incidence of diabetes in a pooled analysis from 10 ODYSSEY Phase 3 studies

AIMS: Statins have modest adverse effects on glycaemic control. Alirocumab, a proprotein convertase subtilisin/kexin type 9 inhibitor, lowers low-density lipoprotein cholesterol. This study assessed the effects of alirocumab on new-onset diabetes and pre-diabetes incidence in individuals without diabetes at baseline. METHODS AND RESULTS: Pooled analysis of 10 ODYSSEY Phase 3 trials (n = 4974) of 24–104 weeks duration. Six trials (n = 4211) were ≥52 weeks in length. Most patients received background maximally tolerated statin. Alirocumab effect on the rate of diabetes-related treatment-emergent adverse events (TEAEs), and/or fasting plasma glucose (FPG) and glycated haemoglobin A(1C) (HbA(1C)) was measured at baseline and every 12–24 weeks. Transition to diabetes analysis combined TEAE and FPG/HbA(1C) laboratory data. At baseline, 30.7% of individuals had diabetes and were excluded from the current analysis. The remaining 3448 individuals without diabetes had pre-diabetes (39.6%) or were normoglycaemic (29.7%). The hazard ratio (HR; 95% confidence interval) for diabetes-related TEAEs in alirocumab was 0.64 (0.36–1.14) vs. placebo and 0.55 (0.22–1.41) vs. ezetimibe. The HR associated for transition from pre-diabetes to new-onset diabetes for alirocumab was 0.90 (0.63–1.29) vs. placebo and 1.10 (0.57–2.12) vs. ezetimibe. Mean change in FPG/HbA(1C) over time showed no difference between treatment groups in patients without diabetes. CONCLUSIONS: There was no evidence of an effect of alirocumab on transition to new-onset diabetes in 3448 individuals without diabetes at baseline with a follow-up period of 6–18 months, compared to either placebo or ezetimibe. Longer follow-up with larger number of individuals is needed to conclusively rule out an effect

Do Meio- and Macrobenthic Nematodes Differ in Community Composition and Body Weight Trends with Depth?

Nematodes occur regularly in macrobenthic samples but are rarely identified from them and are thus considered exclusively a part of the meiobenthos. Our study compares the generic composition of nematode communities and their individual body weight trends with water depth in macrobenthic (>250/300 µm) samples from the deep Arctic (Canada Basin), Gulf of Mexico (GOM) and the Bermuda slope with meiobenthic samples (<45 µm) from GOM. The dry weight per individual (µg) of all macrobenthic nematodes combined showed an increasing trend with increasing water depth, while the dry weight per individual of the meiobenthic GOM nematodes showed a trend to decrease with increasing depth. Multivariate analyses showed that the macrobenthic nematode community in the GOM was more similar to the macrobenthic nematodes of the Canada Basin than to the GOM meiobenthic nematodes. In particular, the genera Enoploides, Crenopharynx, Micoletzkyia, Phanodermella were dominant in the macrobenthos and accounted for most of the difference. Relative abundance of non-selective deposit feeders (1B) significantly decreased with depth in macrobenthos but remained dominant in the meiobenthic community. The occurrence of a distinct assemblage of bigger nematodes of high dry weight per individual in the macrobenthos suggests the need to include nematodes in macrobenthic studies

Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans

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Diversity of Meiofauna from the 9°50′N East Pacific Rise across a Gradient of Hydrothermal Fluid Emissions

Background: We studied the meiofauna community at deep-sea hydrothermal vents along a gradient of vent fluid emissions in the axial summit trought (AST) of the East Pacific Rise 9 degrees 50'N region. The gradient ranged from extreme high temperatures, high sulfide concentrations, and low pH at sulfide chimneys to ambient deep-sea water conditions on bare basalt. We explore meiofauna diversity and abundance, and discuss its possible underlying ecological and evolutionary processes. Methodology/Principal Findings: After sampling in five physico-chemically different habitats, the meiofauna was sorted, counted and classified. Abundances were low at all sites. A total of 52 species were identified at vent habitats. The vent community was dominated by hard substrate generalists that also lived on bare basalt at ambient deep-sea temperature in the axial summit trough (AST generalists). Some vent species were restricted to a specific vent habitat (vent specialists), but others occurred over a wide range of physico-chemical conditions (vent generalists). Additionally, 35 species were only found on cold bare basalt (basalt specialists). At vent sites, species richness and diversity clearly increased with decreasing influence of vent fluid emissions from extreme flow sulfide chimney (no fauna), high flow pompei worm (S: 4-7, H-loge': 0.11-0.45), vigorous flow tubeworm (S: 8-23; H-loge': 0.44-2.00) to low flow mussel habitats (S: 28-31; H-loge': 2.34-2.60). Conclusions/Significance: Our data suggest that with increasing temperature and toxic hydrogen sulfide concentrations and increasing amplitude of variation of these factors, fewer species are able to cope with these extreme conditions. This results in less diverse communities in more extreme habitats. The finding of many species being present at sites with and without vent fluid emissions points to a non endemic deep-sea hydrothermal vent meiofaunal community. This is in contrast to a mostly endemic macrofauna but similar to what is known for meiofauna from shallow-water vents

Structure and evolution of the plant cation diffusion facilitator family of ion transporters

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