Insulin-Like Growth Factor 1 (IGF-1) in Parkinson's Disease: Potential as Trait-, Progression- and Prediction Marker and Confounding Factors

Introduction

Biomarkers indicating trait, progression and prediction of pathology and symptoms in Parkinson''s disease (PD) often lack specificity or reliability. Investigating biomarker variance between individuals and over time and the effect of confounding factors is essential for the evaluation of biomarkers in PD, such as insulin-like growth factor 1 (IGF-1).

Materials and Methods

IGF-1 serum levels were investigated in up to 8 biannual visits in 37 PD patients and 22 healthy controls (HC) in the longitudinal MODEP study. IGF-1 baseline levels and annual changes in IGF-1 were compared between PD patients and HC while accounting for baseline disease duration (19 early stage: ≤3.5 years; 18 moderate stage: >4 years), age, sex, body mass index (BMI) and common medical factors putatively modulating IGF-1. In addition, associations of baseline IGF-1 with annual changes of motor, cognitive and depressive symptoms and medication dose were investigated.

Results

PD patients in moderate (130±26 ng/mL; p = .004), but not early stages (115±19, p>.1), showed significantly increased baseline IGF-1 levels compared with HC (106±24 ng/mL; p = .017). Age had a significant negative correlation with IGF-1 levels in HC (r = -.47, p = .028) and no correlation in PD patients (r = -.06, p>.1). BMI was negatively correlated in the overall group (r = -.28, p = .034). The annual changes in IGF-1 did not differ significantly between groups and were not correlated with disease duration. Baseline IGF-1 levels were not associated with annual changes of clinical parameters.

Discussion

Elevated IGF-1 in serum might differentiate between patients in moderate PD stages and HC. However, the value of serum IGF-1 as a trait-, progression- and prediction marker in PD is limited as IGF-1 showed large inter- and intraindividual variability and may be modulated by several confounders.     

Effects of Subinhibitory Concentrations of Ceftaroline on Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms

Ceftaroline (CPT) is a novel cephalosporin with in vitro activity against Staphylococcus aureus. Ceftaroline exhibits a level of binding affinity for PBPs in S. aureus including PBP2a of methicillin-resistant S. aureus (MRSA). The aims of this study were to investigate the morphological, physiological and molecular responses of MRSA clinical strains and MRSA biofilms to sub-MICs (1/4 and 1/16 MIC) of ceftaroline by using transmission, scanning and confocal microscopy. We have also used quantitative Real-Time PCR to study the effect of sub-MICs of ceftaroline on the expression of the staphylococcal icaA, agrA, sarA and sasF genes in MRSA biofilms. In one set of experiments, ceftaroline was able to inhibit biofilm formation in all strains tested at MIC, however, a strain dependent behavior in presence of sub-MICs of ceftaroline was shown. In a second set of experiments, destruction of preformed biofilms by addition of ceftaroline was evaluated. Ceftaroline was able to inhibit biofilm formation at MIC in all strains tested but not at the sub-MICs. Destruction of preformed biofilms was strain dependent because the biofilm formed by a matrix-producing strain was resistant to a challenge with ceftaroline at MIC, whereas in other strains the biofilm was sensitive. At sub-MICs, the impact of ceftaroline on expression of virulence genes was strain-dependent at 1/4 MIC and no correlation between ceftaroline-enhanced biofilm formation and gene regulation was established at 1/16 MIC. Our findings suggest that sub-MICs of ceftaroline enhance bacterial attachment and biofilm formation by some, but not all, MRSA strains and, therefore, stress the importance of maintaining effective bactericidal concentrations of ceftaroline to fight biofilm-MRSA related infections.     

Estimating Encounter Rates and Densities of Three Lemur Species in Northeastern Madagascar

Primate populations, including Madagascar’s lemurs, are threatened worldwide and conservationists need accurate population estimates to develop targeted conservation plans. We sought to fill knowledge gaps for three lemur taxa —white-fronted brown lemur (Eulemur albifrons); eastern woolly lemur (Avahi laniger); and Allocebus/Microcebus, a category combining observations of hairy-eared dwarf lemurs (Allocebus trichotis) and mouse lemurs (Microcebus spp.)— in northeastern Madagascar by estimating their density, examining how their encounter rates and densities vary across three different forest types, and monitoring trends in encounter rates and densities at resurveyed sites, using data from surveys at six forest sites over a 4-year period (2010–2013). Landscape density for white-fronted brown lemur, eastern woolly lemur, and Allocebus/Microcebus was 21.5 (SE 3.67), 57.7 (SE 9.17), and 39.1 (SE 9.55) individuals/km², respectively. There was no difference in density estimates at intact and intermediately degraded forest sites; however, we encountered white-fronted brown lemurs more often in intact forest (1.64 ± SE 0.40 individuals/km) than in intermediately degraded and degraded forest (0.15 ± SE 0.06 and 0.16 ± SE 0.06 individuals/km). In addition, we encountered white-fronted brown lemurs at lower rates in 2013 (0.15 ± SE 0.06 individuals/km) compared to 2010 (0.82 ± SE 0.12 individuals/km) at a resurveyed site. Our findings emphasize that primate researchers must account for variation in how lemur encounter rates and densities differ between intact and degraded forests, and although we observed a decline in white-fronted brown lemur encounter rate at our resurveyed site, we caution that changes in lemur encounter rates may simply reflect lower detection rates rather than lower density. Future research should focus on using conventional distance sampling techniques, which are infrequently used in primate studies, to provide more robust density estimates as a way to accurately assess trends and the effects of anthropogenic pressures on lemur populations.     

Translating niche features: Modelling differential exposure of Argentine reptiles to global climate change

Global climate change affects the distributions of ectotherms and may be the cause of several conservation problems, such as great displacement of climatic suitable spaces for species and, consequently, important reductions of the extent of liveable places, threatening the existence of many of them. Species exposure (and hence vulnerability) to global climate change is linked to features of their climatic niches (such as the relative position of the inhabited localities of each species in the climatic space), and therefore to characteristics of their geographic ranges (such as the extent of the distributions or altitudinal range inhabited by the species). In order to analyze the pattern of response of Argentine reptiles to global climate change, we ran phylogenetic generalized least squares models using species exposure to global climate change as a response variable, and (i) niche properties (breadth and position of the species in the climate space) and (ii) general features of the distribution of species (maximum latitude, altitudinal range, maximum elevation, distributional range and proximity to the most important dispersal barrier) as predictors. Our results suggest that the best way to explain climate change exposure is by combining breadth and position of climatic niche of the species or combining geographic features that are indicators of both niche characteristics. Our best model shows that in our study area, species with the narrowest distributional ranges that also inhabit the highest elevations are the most exposed to the effects of global climate change. In this sense, reptile species from Yungas, Puna and Andes ecoregions could be especially vulnerable to the effects of climate change. We believe that these types of models may represent an interesting tool for determining species and places particularly threatened by the effects of global climate change, which should be strongly considered in conservation planning.     

Long range physical cell-to-cell signalling via mitochondria inside membrane nanotubes: a hypothesis

Coordinated interaction of single cells by cell-to-cell communication (signalling) enables complex behaviour necessary for the functioning of multicellular organisms. A quite newly discovered cell-to-cell signalling mechanism relies on nanotubular cell-co-cell connections, termed “membrane nanotubes” (MNTs). The present paper presents the hypothesis that mitochondria inside MNTs can form a connected structure (mitochondrial network) which enables the exchange of energy and signals between cells. It is proposed that two modes of energy and signal transmission may occur: electrical/electrochemical and electromagnetic (optical). Experimental work supporting the hypothesis is reviewed, and suggestions for future research regarding the discussed topic are given.     

Metabolite Profiling of Anti‐Addictive Alkaloids from Four Mexican Tabernaemontana Species and the Entheogenic African Shrub Tabernanthe iboga (Apocynaceae)

Ibogaine and other ibogan type alkaloids present anti‐addictive effects against several drugs of abuse and occur in different species of the Apocynaceae family. In this work, we used gas chromatography‐mass spectrometry (GC/MS) and principal component analysis (PCA) in order to compare the alkaloid profiles of the root and stem barks of four Mexican Tabernaemontana species with the root bark of the entheogenic African shrub Tabernanthe iboga. PCA demonstrated that separation between species could be attributed to quantitative differences of the major alkaloids, coronaridine, ibogamine, voacangine, and ibogaine. While T. iboga mainly presented high concentrations of ibogaine, Tabernaemontana samples either showed a predominance of voacangine and ibogaine, or coronaridine and ibogamine, respectively. The results illustrate the phytochemical proximity between both genera and confirm previous suggestions that Mexican Tabernaemontana species are viable sources of anti‐addictive compounds.     

A phylogeographic study of the stoneplant Conophytum (Aizoaceae; Ruschioideae; Ruschieae) in the Bushmanland Inselberg Region (South Africa) suggests anemochory

The Bushmanland Inselberg Region (BIR) of South Africa provides an ideal system to study population interactions, as these inselbergs function as islands of Succulent Karoo surrounded by Nama Karoo vegetation. The population genetics of four Conophytum taxa endemic to the quartz-associated habitats of inselbergs in the BIR were investigated using amplified fragment length polymorphisms (AFLP), namely C. marginatum subsp. haramoepense, C. marginatum subsp. marginatum, C. maughanii, and C. ratum. Conophytum marginatum colonizes the quartz outcrops on the summits of the inselbergs, while C. maughanii and C. ratum occupy quartz patches at the summit and base of the inselbergs. A total of 24 populations were sampled to assess genetic differentiation between populations of each species, specifically between summit and base populations of C. ratum, eastern and western populations of C. maughanii and populations of the two subspecies of C. marginatum. Moderate levels of genetic differentiation were recovered between the summit and base populations of C. ratum, with an indication of some genetic connectivity between the populations. Slight differentiation between the eastern and western populations of C. maughanii was recovered, however, this was not reflected in the PCoA and STRUCTURE results. In C. marginatum, no significant genetic differentiation was recovered between populations of the subspecies. These results may reflect evidence of different dispersal mechanisms in the species, with the genetic connectivity between populations of C. ratum possibly indicating dispersal through hygrochastic capsules, while genetic connectivity between populations of C. maughanii and C. marginatum may, for the first time, suggest long-distance dispersal, i.e. anemochory. This study provides the first insights into population interactions across the BIR and highlights the importance of conservation in the region, particularly of the Gamsberg, in light of the recent mining activities.     

Sequentially Deposited versus Conventional Nonfullerene Organic Solar Cells: Interfacial Trap States,Vertical Stratification,and Exciton Dissociation

Bulk heterojunction (BHJ) nonfullerene organic solar cells prepared from sequentially deposited donor and acceptor layers (sq‐BHJ) have recently been shown to be highly efficient, environmentally friendly, and compatible with large area and roll‐to‐roll fabrication. However, the related photophysics at donor‐acceptor interface and the vertical heterogeneity of donor‐acceptor distribution, critical for exciton dissociation and device performance, have been largely unexplored. Herein, steady‐state and time‐resolved optical and electrical techniques are employed to characterize the interfacial trap states. Correlating with the luminescent efficiency of interfacial states and its nonradiative recombination, interfacial trap states are characterized to be about 40% more populated in the sq‐BHJ devices than the as‐cast BHJ (c‐BHJ), which probably limits the device voltage output. Cross‐sectional energy‐dispersive X‐ray spectroscopy and ultraviolet photoemission spectroscopy depth profiling directly visualize the donor–acceptor vertical stratification with a precision of 1–2 nm. From the proposed “needle” model, the high exciton dissociation efficiency is rationalized. This study highlights the promise of sequential deposition to fabricate efficient solar cells, and points toward improving the voltage output and overall device performance via eliminating interfacial trap states.     

Divergent responses of Atlantic cod to ocean acidification and food limitation

In order to understand the effect of global change on marine fishes, it is imperative to quantify the effects on fundamental parameters such as survival and growth. Larval survival and recruitment of the Atlantic cod (Gadus morhua) were found to be heavily impaired by end‐of‐century levels of ocean acidification. Here, we analysed larval growth among 35–36 days old surviving larvae, along with organ development and ossification of the skeleton. We combined CO₂ treatments (ambient: 503 µatm, elevated: 1,179 µatm) with food availability in order to evaluate the effect of energy limitation in addition to the ocean acidification stressor. As expected, larval size (as a proxy for growth) and skeletogenesis were positively affected by high food availability. We found significant interactions between acidification and food availability. Larvae fed ad libitum showed little difference in growth and skeletogenesis due to the CO₂ treatment. Larvae under energy limitation were significantly larger and had further developed skeletal structures in the elevated CO₂ treatment compared to the ambient CO₂ treatment. However, the elevated CO₂ group revealed impairments in critically important organs, such as the liver, and had comparatively smaller functional gills indicating a mismatch between size and function. It is therefore likely that individual larvae that had survived acidification treatments will suffer from impairments later during ontogeny. Our study highlights important allocation trade‐off between growth and organ development, which is critically important to interpret acidification effects on early life stages of fish.     

Conservation genetics: Linking science with practice

Conservation genetics is a well‐established scientific field. However, limited information transfer between science and practice continues to hamper successful implementation of scientific knowledge in conservation practice and management. To mitigate this challenge, we have established a conservation genetics community, which entails an international exchange‐and‐skills platform related to genetic methods and approaches in conservation management. First, it allows for scientific exchange between researchers during annual conferences. Second, personal contact between conservation professionals and scientists is fostered by organising workshops and by popularising knowledge on conservation genetics methods and approaches in professional journals in national languages. Third, basic information on conservation genetics has been made accessible by publishing an easy‐to‐read handbook on conservation genetics for practitioners. Fourth, joint projects enabled practitioners and scientists to work closely together from the start of a project in order to establish a tight link between applied questions and scientific background. Fifth, standardised workflows simplifying the implementation of genetic tools in conservation management have been developed. By establishing common language and trust between scientists and practitioners, all these measures help conservation genetics to play a more prominent role in future conservation planning and management.