Erythropoietin in Cerebrospinal Fluid: Age-related Reference Values and Relevance in Neurological Disease

We aimed to establish age-related reference values for Erythropoietin (EPO) in cerebrospinal fluid (CSF) and to evaluate concentrations in neurological diseases. CSF and serum EPO was measured in controls with tension-type headache (CTTH), in patients with ALS, dementia and depression using ELISA technique. Stability experiments showed CSF EPO to be stable for two and a half months and over two thaw/freeze cycles. A positive correlation of CSF EPO with age was found (P < 0.01). We found a CSF/serum EPO concentration ratio of 0.126, pointing towards an intrathecal synthesis of EPO. The ALS group showed significantly lowered CSF EPO compared to age-matched CTTH (P < 0.012), whereas the dementia and depression group showed no significant differences compared to CTTH. The establishment of age-related reference values in a large cohort of controls will improve the interpretation of future CSF EPO evaluations in neurological diseases. The authors have not reported any conflicts of interest.     

Immunogold labeling of cryosections from high-pressure frozen cells

Immunogold labeling of cryosections according to Tokuyasu (Tokuyasu KT. A technique for ultracyotomy of cell suspensions and tissues. J Cell Biol 1973;57:551–565), is an important and widely used method for immunoelectron microscopy. These sections are cut from material that is chemically fixed at room temperature (room temparature fixation, RTF). Lately in many morphological studies fast freezing followed by cryosubstitution fixation (CSF) is used instead of RTF. We have explored some new methods for applying immunogold labeling on cryosections from high‐pressure frozen cells (HepG2 cells, primary chondrocytes) and tissues (cartilage and exocrine pancreas). As immunolabeling has to be carried out on thawed and stable sections, we explored two ways to achieve this: (1) The section fixation method, as briefly reported before (Liou W et al. Histochem Cell Biol 1996;106:41–58 and Möbius W et al. J Histochem Cytochem 2002;50:43–55.) in which cryosections from freshly frozen cells were stabilized in mixtures of sucrose and methyl cellulose and varying concentrations of glutaraldehyde, formaldehyde and uranyl acetate (UA). Only occasionally does this method reveal section areas with excellent cell preservation and negatively stained membranes like Tokuyasu sections of RTF material. (Liou et al.) (2) The rehydration method, a novel approach, in which CSF with glutaraldehyde and/or osmium tetroxide (OsO₄) was followed by rehydration and cryosectioning as in the Tokuyasu method. Especially, the addition of UA and low concentrations of water to the CSF medium favored superb membrane contrast. Immunogold labeling was as efficient as with the Tokuyasu method.     

Intra‐thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales

Intra‐thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega‐3 fatty acids 18:4 n‐3 and 20:5 n‐3 were generally higher in more distal parts, while 20:4 n‐6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid‐fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g^?1 DW in the base, 3.04 mg · g^?1 DW in the mid frond). Intra‐thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega‐3/omega‐6 ratios.     

TSH compensates thyroid-specific IGF-I receptor knockout and causes papillary thyroid hyperplasia

Although TSH stimulates all aspects of thyroid physiology IGF-I signaling through a tyrosine kinase-containing transmembrane receptor exhibits a permissive impact on TSH action. To better understand the importance of the IGF-I receptor in the thyroid in vivo, we inactivated the Igf1r with a Tg promoter-driven Cre-lox system in mice. We studied male and female mice with thyroidal wild-type, Igf1r(+/-), and Igf1r(-/-) genotypes. Targeted Igf1r inactivation did transiently reduce thyroid hormone levels and significantly increased TSH levels in both heterozygous and homozygous mice without affecting thyroid weight. Histological analysis of thyroid tissue with Igf1r inactivation revealed hyperplasia and heterogeneous follicle structure. From 4 months of age, we detected papillary thyroid architecture in heterozygous and homozygous mice. We also noted increased body weight of male mice with a homozygous thyroidal null mutation in the Igf1r locus, compared with wild-type mice, respectively. A decrease of mRNA and protein for thyroid peroxidase and increased mRNA and protein for IGF-II receptor but no significant mRNA changes for the insulin receptor, the TSH receptor, and the sodium-iodide-symporter in both Igf1r(+/-) and Igf1r(-/-) mice were detected. Our results suggest that the strong increase of TSH benefits papillary thyroid hyperplasia and completely compensates the loss of IGF-I receptor signaling at the level of thyroid hormones without significant increase in thyroid weight. This could indicate that the IGF-I receptor signaling is less essential for thyroid hormone synthesis but maintains homeostasis and normal thyroid morphogenesis.     

Proteostasis and movement disorders: Parkinson's disease and amyotrophic lateral sclerosis

Parkinson's disease (PD) is a movement disorder that afflicts over one million in the U.S.; amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is less prevalent but also has a high incidence. The two disorders sometimes present together, making a comparative study of interest. Both ALS and PD are neurodegenerative diseases, and are characterized by the presence of intraneuronal inclusions; however, different classes of neurons are affected and the primary protein in the inclusions differs between the diseases, and in some cases is different in distinct forms of the same disease. These observations might suggest that the more general approach of proteostasis pathway alteration would be a powerful one in treating these disorders. Examining results from human genetics and studies in model organisms, as well as from biochemical and biophysical characterization of the proteins involved in both diseases, we find that most instances of PD can be considered as arising from the misfolding, and self-association to a toxic species, of the small neuronal protein α-synuclein, and that proteostasis strategies are likely to be of value for this disorder. For ALS, the situation is much more complex and less clear-cut; the available data are most consistent with a view that ALS may actually be a family of disorders, presenting similarly but arising from distinct and nonoverlapping causes, including mislocalization of some properly folded proteins and derangement of RNA quality control pathways. Applying proteostasis approaches to this disease may require rethinking or broadening the concept of what proteostasis means.     

Accommodating dynamic oceanographic processes and pelagic biodiversity in marine conservation planning

Pelagic ecosystems support a significant and vital component of the ocean's productivity and biodiversity. They are also heavily exploited and, as a result, are the focus of numerous spatial planning initiatives. Over the past decade, there has been increasing enthusiasm for protected areas as a tool for pelagic conservation, however, few have been implemented. Here we demonstrate an approach to plan protected areas that address the physical and biological dynamics typical of the pelagic realm. Specifically, we provide an example of an approach to planning protected areas that integrates pelagic and benthic conservation in the southern Benguela and Agulhas Bank ecosystems off South Africa. Our aim was to represent species of importance to fisheries and species of conservation concern within protected areas. In addition to representation, we ensured that protected areas were designed to consider pelagic dynamics, characterized from time-series data on key oceanographic processes, together with data on the abundance of small pelagic fishes. We found that, to have the highest likelihood of reaching conservation targets, protected area selection should be based on time-specific data rather than data averaged across time. More generally, we argue that innovative methods are needed to conserve ephemeral and dynamic pelagic biodiversity.