REPIMPACT - a prospective longitudinal multisite study on the effects of repetitive head impacts in youth soccer

Brain Imaging and Behavior - Repetitive head impacts (RHI) are common in youth athletes participating in contact sports. RHI differ from concussions; they are considered hits to the head that...     

Is there an anti-androgen withdrawal syndrome for enzalutamide?

Background

The anti-androgen withdrawal syndrome (AAWS) can be seen in one-third of patients after discontinuation of first-generation non-steroidal anti-androgen therapy. With the introduction of new agents for anti-androgen therapy as well as alternate mechanisms of action, new therapeutic options before and after docetaxel chemotherapy have arisen (Ohlmann et al. in World J Urol 30(4):495–503, 2012). The question regarding the occurrence of an enzalutamide withdrawal syndrome (EWS) has not been evaluated yet. In this study, we assess prostate-specific antigen (PSA) response after discontinuation of enzalutamide.

Methods

In total 31 patients with metastatic castration-resistant prostate cancer (mCRPC) underwent an enzalutamide withdrawal and were evaluated. Data were gathered from 6 centres in Germany. Patients with continuous oral administration of enzalutamide with rising serum PSA levels were evaluated, starting from enzalutamide withdrawal until subsequent therapy was initiated, follow-up ended or death of the patient occurred. Statistical evaluation was performed applying one-sided binomial testing using R-statistical software, version 3.0.1.

Results

Mean withdrawal follow-up was 6.5 weeks (range 1–26.1 weeks). None of the 31 patients showed a PSA decline. Mean relative PSA rise over all patients was 73.9 % (range 0.5–440.7 %) with a median of 44.9 %.

Conclusions

If existent, an AAWS is at least very rare for enzalutamide in patients with mCRPC after taxane-based chemotherapy and does not play a clinical role in this setting. This may be attributed to the different pharmacodynamics of enzalutamide. Longer duration of therapy or a longer withdrawal interval may reveal a rare EWS in the future.     

HDL in Children with CKD Promotes Endothelial Dysfunction and an Abnormal Vascular Phenotype

Endothelial dysfunction begins in early CKD and contributes to cardiovascular mortality. HDL is considered antiatherogenic, but may have adverse vascular effects in cardiovascular disease, diabetes, and inflammatory conditions. The effect of renal failure on HDL properties is unknown. We studied the endothelial effects of HDL isolated from 82 children with CKD stages 2–5 (HDL^CKD), who were free of underlying inflammatory diseases, diabetes, or active infections. Compared with HDL from healthy children, HDL^CKD strongly inhibited nitric oxide production, promoted superoxide production, and increased vascular cell adhesion molecule-1 expression in human aortic endothelial cells, and reduced cholesterol efflux from macrophages. The effects on endothelial cells correlated with CKD grade, with the most profound changes induced by HDL from patients on dialysis, and partial recovery observed with HDL isolated after kidney transplantation. Furthermore, the in vitro effects on endothelial cells associated with increased aortic pulse wave velocity, carotid intima-media thickness, and circulating markers of endothelial dysfunction in patients. Symmetric dimethylarginine levels were increased in serum and fractions of HDL from children with CKD. In a longitudinal follow-up of eight children undergoing kidney transplantation, HDL-induced production of endothelial nitric oxide, superoxide, and vascular cell adhesion molecule-1 in vitro improved significantly at 3 months after transplantation, but did not reach normal levels. These results suggest that in children with CKD without concomitant disease affecting HDL function, HDL dysfunction begins in early CKD, progressing as renal function declines, and is partially reversed after kidney transplantation.Patients with CKD no longer die from renal failure but from cardiovascular disease. There is an independent, graded association between a reduced eGFR and the risk of death and cardiovascular events.¹ Typically, patients with CKD develop calcification in the tunica media of their arteries,² but a concomitant process of endothelial damage leading to atherosclerosis is also³ present beginning in predialysis CKD.^4,5LDL is crucially involved in the pathogenesis of atherosclerotic cardiovascular disease in the general population,⁶ whereas HDL is thought to be antiatherogenic by promoting reverse cholesterol transport and exerting direct protective endothelial effects.⁷ HDL from healthy participants increases the bioavailability of nitric oxide (NO) by activating endothelial NO synthase inducing vasodilation and decreasing arterial BP. Moreover, HDL diminishes the production of reactive oxygen species such as superoxide (SO) radicals, which have been demonstrated to reduce NO bioavailability leading to endothelial dysfunction and promoting atherogenesis. However, recent evidence suggests that HDL may lose its vasoprotective properties in patients with manifest cardiovascular disease (e.g., coronary artery disease), diabetes, or inflammatory disease states (e.g., antiphospholipid syndrome).^8–10 Similarly, in adults on dialysis, HDL has reduced cholesterol efflux capacity and proinflammatory effects on mononuclear cells.^11–13 Observational studies have shown a strong association between high HDL levels and reduced risk of cardiovascular disease in the general population¹⁴ but not in dialysis patients.¹⁵Cardiac and vascular damage has also been documented in children on dialysis,^2,16,17 and cardiovascular disease accounts for the majority of deaths in pediatric dialysis patients.¹⁷ In contrast with adult patients with CKD, in whom cardiovascular risk factors such as diabetes dyslipidemia, hypertension, and smoking are highly prevalent,¹⁸ CKD in children is mainly caused by inherited disorders such as malformations of the kidney or urinary tract.¹⁸ Accordingly, examining HDL function in children who are free of “traditional” cardiovascular risk factors and underlying inflammatory diseases and who are nonsmokers gives us an unique opportunity to study the effects of renal failure on the vascular functions of HDL.We studied the endothelial properties of HDL in a cohort of children at different stages of CKD on dialysis and after transplantation and compared them with healthy children. Furthermore, to determine the clinical relevance of in vitro effects of HDL, we examined its relationship with clinical measures of the vascular phenotype as well as circulating markers of endothelial dysfunction. Finally, to show a causal link between renal function and HDL properties, we examined children on dialysis and 3 months after kidney transplantation. This study allowed us to examine when HDL dysfunction develops during the natural history of renal decline, its effects on vascular function, and the potential for recovery after kidney transplantation.     

Effects of Increasing Concentrations of Sodium Sulfite on Deoxynivalenol and Deoxynivalenol Sulfonate Concentrations of Maize Kernels and Maize Meal Preserved at Various Moisture Content

Under moderate climatic conditions, deoxynivalenol (DON) contamination occurs frequently on cereals. Detoxification measures are required to avoid adverse effects on farm animals. In the present study, a wet preservation method with sodium sulfite (Na₂SO₃) and propionic acid was tested to titrate the optimum Na₂SO₃-dose for maximum DON reduction of contaminated maize kernels and meal and to examine the interaction between dose and moisture content in dependence on the preservation duration. The DON concentration decreased with increasing amounts of supplemented Na₂SO₃ and with increasing duration of the preservation period in a bi-exponential fashion. Additionally, the feed structure and moisture content had a significant influence on the decontaminating effect. Variants with 30% moisture content favored higher DON reduction rates compared to 14% moisture, but especially at low moisture contents, DON reduction was more pronounced in maize kernels than in maize meal. In addition to the decrease of DON, a concomitant formation of three different DON sulfonates was observed which differed in their formation pattern over the time course of preservation. The overall results and statistical analysis clarified that Na₂SO₃ addition of 10 g/kg maize at 30% moisture for eight days was necessary to obtain a complete DON reduction.     

Mechanical and Air Permeability Performance of Novel Biobased Materials from Fungal Hyphae and Cellulose Fibers

Novel biobased materials from fungal hyphae and cellulose fibers have been proposed to address the increasing demand for natural materials in personal protective equipment (PPE). Materials containing commercially available kraft fibers (KF), laboratory-made highly fibrillated hemp fibers (HF) and fungal fibers (FF) obtained from fruiting bodies of lignicolous basidiomycetes growing in nature were prepared using paper production techniques and evaluated for their mechanical and air permeability properties. SEM and microscopy revealed the network structure of materials. The tensile index of materials was in the range of 8–60 Nm/g and air permeability ranged from 32–23,990 mL/min, depending on the composition of materials. HF was the key component for strength; however, the addition of FF to compositions resulted in higher air permeability. Chemical composition analysis (Fourier-transform infrared spectroscopy) revealed the presence of natural polysaccharides, mainly cellulose and chitin, as well as the appropriate elemental distribution of components C, H and N. Biodegradation potential was proven by a 30-day-long composting in substrate, which resulted in an 8–62% drop in the C/N ratio. Conclusions were drawn about the appropriateness of fungal hyphae for use in papermaking-like technologies together with cellulose fibers. Developed materials can be considered as an alternative to synthetic melt and spun-blown materials for PPE.     

Early life stress enhances the vulnerability to chronic psychosocial stress and experimental colitis in adult mice

Early life stress enhances the vulnerability to both mood and chronic inflammatory disorders, suggesting a link between these stress-related disorders. To study this, we exposed male C57BL/6 mice to early life stress [maternal separation (MS), 3 h/d, d 1-14] and to adult chronic psychosocial stress [chronic subordinate colony housing (CSC)] and measured changes in neuroendocrine parameters and in the severity of a chemically induced colitis. In both unseparated and MS mice, 19 d of CSC exposure resulted in a transient decrease in body weight gain, increased anxiety-related behavior, and decreased vasopressin mRNA expression in the hypothalamic paraventricular nucleus compared with respective nonstressed mice. However, only CSC-stressed MS mice showed elevated CRH mRNA expression in the paraventricular nucleus and reduced plasma corticosterone. Subsequent treatment with dextran sulfate sodium (1%, 7 d) resulted in a more severe colonic inflammation in MS compared with unseparated mice. This was indicated by an increased histological damage score and increased TNF secretion (nonstressed MS mice), more severe body weight loss and inflammatory reduction in colon length (CSC-stressed MS mice), and increased interferon-gamma secretion (nonstressed and CSC-stressed MS mice). In conclusion, early life stress and subsequent exposure to chronic psychosocial stress in adulthood induced neuroendocrine abnormalities, which likely contributed to enhanced vulnerability to chemically induced colitis. The combined use of MS and CSC represents a potential animal model providing novel (patho)physiological insights into the complex interactions between neuroendocrine and inflammatory actions upon chronic stress exposure. These findings may further help to reveal mechanisms of hypocortisolemic disorders.     

Deaths following methotrexate overdoses by medical staff

Methotrexate (MTX) is an effective disease modifying antirheumatic drug (DMARD) with a relatively safe profile, and it is widely used to treat neoplastic diseases and dermatologic and rheumatologic disorders. As indications for use of MTX increase, more accidental overdoses are noted to occur. Typical problems include deficiencies in labeling, instructions, or packaging, as well as erroneous use. We describe 5 fatal cases of repeated oral overdose of MTX prescribed by physicians in the treatment of rheumatoid arthritis to focus attention on the design of the underlying system and the organizational practices as sources of problems.     

Expression of Phosphofructokinase in Skeletal Muscle Is Influenced by Genetic Variation and Associated With Insulin Sensitivity

Using an integrative approach in which genetic variation, gene expression, and clinical phenotypes are assessed in relevant tissues may help functionally characterize the contribution of genetics to disease susceptibility. We sought to identify genetic variation influencing skeletal muscle gene expression (expression quantitative trait loci [eQTLs]) as well as expression associated with measures of insulin sensitivity. We investigated associations of 3,799,401 genetic variants in expression of >7,000 genes from three cohorts (n = 104). We identified 287 genes with cis-acting eQTLs (false discovery rate [FDR] <5%; P < 1.96 × 10⁻⁵) and 49 expression–insulin sensitivity phenotype associations (i.e., fasting insulin, homeostasis model assessment–insulin resistance, and BMI) (FDR <5%; P = 1.34 × 10⁻⁴). One of these associations, fasting insulin/phosphofructokinase (PFKM), overlaps with an eQTL. Furthermore, the expression of PFKM, a rate-limiting enzyme in glycolysis, was nominally associated with glucose uptake in skeletal muscle (P = 0.026; n = 42) and overexpressed (Bonferroni-corrected P = 0.03) in skeletal muscle of patients with T2D (n = 102) compared with normoglycemic controls (n = 87). The PFKM eQTL (rs4547172; P = 7.69 × 10⁻⁶) was nominally associated with glucose uptake, glucose oxidation rate, intramuscular triglyceride content, and metabolic flexibility (P = 0.016–0.048; n = 178). We explored eQTL results using published data from genome-wide association studies (DIAGRAM and MAGIC), and a proxy for the PFKM eQTL (rs11168327; r² = 0.75) was nominally associated with T2D (DIAGRAM P = 2.7 × 10⁻³). Taken together, our analysis highlights PFKM as a potential regulator of skeletal muscle insulin sensitivity.     

Head impact exposure in youth football—Are current interventions hitting the target?

Restrictions on heading in youth football have been implemented in some countries to limit head impact exposure. However, current interventions remain poorly guided by evidence. Our objective was to quantify heading exposure in youth football, assessing the effects of sex and age. Football matches played during an international youth football tournament with no heading restrictions were directly observed, including players from both sexes (11-19 years). The elite senior level was included for comparison, using video analysis. All heading events were registered, classified, and assigned to individual players. Heading rates were calculated for each sex and age group. We observed a total of 267 matches, corresponding to 4011 player hours (1927 player hours for females, 2083 player hours for males). Males headed more frequently than females (2.7 vs 1.8 headers/player hour; P < .001). Heading rates increased with age (ANOVA, P < .001), approaching the elite senior level for players 16 years and older. There was substantial variation within teams for all age and sex groups, with the widest range (1-18 headers) observed for girls aged 19. Girls younger than 12 years had the lowest exposure, with an average of <2 players per team heading the ball, each with 1-2 headers. In conclusion, age and sex influence head impact exposure in youth football, and warrants careful consideration when introducing injury prevention measures. Males are more frequently exposed than females, heading rates increase with age, and there is substantial variation between players. Heading is a rare event in the youngest age groups, especially among females.     

DEAD-box protein CYT-19 is activated by exposed helices in a group I intron RNA

DEAD-box proteins are nonprocessive RNA helicases and can function as RNA chaperones, but the mechanisms of their chaperone activity remain incompletely understood. The Neurospora crassa DEAD-box protein CYT-19 is a mitochondrial RNA chaperone that promotes group I intron splicing and has been shown to resolve misfolded group I intron structures, allowing them to refold. Building on previous results, here we use a series of tertiary contact mutants of the Tetrahymena group I intron ribozyme to demonstrate that the efficiency of CYT-19–mediated unfolding of the ribozyme is tightly linked to global RNA tertiary stability. Efficient unfolding of destabilized ribozyme variants is accompanied by increased ATPase activity of CYT-19, suggesting that destabilized ribozymes provide more productive interaction opportunities. The strongest ATPase stimulation occurs with a ribozyme that lacks all five tertiary contacts and does not form a compact structure, and small-angle X-ray scattering indicates that ATPase activity tracks with ribozyme compactness. Further, deletion of three helices that are prominently exposed in the folded structure decreases the ATPase stimulation by the folded ribozyme. Together, these results lead to a model in which CYT-19, and likely related DEAD-box proteins, rearranges complex RNA structures by preferentially interacting with and unwinding exposed RNA secondary structure. Importantly, this mechanism could bias DEAD-box proteins to act on misfolded RNAs and ribonucleoproteins, which are likely to be less compact and more dynamic than their native counterparts.DEAD-box proteins constitute the largest family of RNA helicases and function in all stages of RNA metabolism (1, 2). In vivo, many DEAD-box proteins have been implicated in assembly and conformational rearrangements of large structured RNAs and ribonucleoproteins (RNPs), including the ribosome, spliceosome, and self-splicing introns (3). Thus, it is important to establish how these proteins use their basic mechanisms of RNA binding and helix unwinding to interact with and remodel higher-order RNA structures.Structural and mechanistic studies have elucidated the basic steps of the ATPase cycle of DEAD-box proteins and have provided an understanding of the coupling between ATPase and duplex unwinding activities (4–11). The conserved helicase core consists of two flexibly linked RecA-like domains that contain at least 12 conserved motifs, including the D-E-A-D sequence in the ATP-binding motif II (3, 12). Binding of ATP and double-stranded RNA to domains 1 and 2, respectively, induces domain closure, which completes the formation of an ATPase active site at the domain interface and introduces steric clashes in the RNA binding site, leading to the displacement of one of the RNA strands (6, 7). ATP hydrolysis and inorganic phosphate release are then thought to regenerate the open enzyme conformation (4, 8, 13). Unlike conventional helicases, DEAD-box proteins have not been found to translocate, limiting the unwinding activity to short helices that can be disrupted in a single cycle of ATP binding and hydrolysis (4, 8, 9, 14–16). This mechanism is compatible with the physiological roles of DEAD-box proteins, because cellular RNAs rarely contain continuous base-paired regions that are longer than one or two helical turns.The interactions of DEAD-box proteins with structured RNAs have been extensively studied using two homologous proteins that function as general RNA chaperones: CYT-19 from Neurospora crassa and Mss116 from Saccharomyces cerevisiae. In vivo, CYT-19 is required for efficient splicing of several mitochondrial group I introns and can promote splicing of group I and group II introns in yeast mutants that lack functional Mss116 (17, 18). Both proteins have been shown to act as general RNA chaperones during group I and group II intron folding in vitro and are thought to act primarily by reversing misfolding of the intron RNAs, although additional mechanisms may be used for some substrates (17–23). Importantly, the chaperone activities of these and other DEAD-box proteins correlate with their ATP-dependent helix unwinding activities, suggesting that DEAD-box proteins function by lowering the energy barriers for transitions between alternative structures that involve disruption of base pairs (24, 25).In vitro studies using the group I intron ribozyme from Tetrahymena thermophila have been instrumental in probing the chaperone mechanism of CYT-19 (17, 26–28). This ∼400-nt RNA folds into a compact, globular structure composed of a conserved core and a series of peripheral elements that encircle the core by forming long-range tertiary contacts (Fig. 1) (29–31). Upon addition of Mg²⁺ ions, the majority of the ribozyme population becomes trapped in a long-lived misfolded conformation, which then slowly refolds to the native state (32). The misfolded intermediate is remarkably similar to the native ribozyme, forming a complete native network of secondary and tertiary interactions and a globally compact fold (33, 34). Despite these similarities, refolding to the native state requires extensive unfolding, including disruption of all five peripheral tertiary contacts and the core helix P3 (33, 35). To explain these results, a topological error has been proposed, wherein two single-stranded joining elements are crossed incorrectly in the core of the misfolded ribozyme, and transient disruption of the surrounding native structure is required for refolding (33, 35).Open in a separate windowFig. 1.The Tetrahymena group I intron ribozyme. (A) Secondary structure and mutations. Peripheral elements are colored and thick arrows mark the long-range peripheral tertiary contacts. Paired regions (P) and loops that were mutated in this study (L) are labeled based on group I intron nomenclature in ref. 31. The mutated regions are enclosed in dashed boxes and labeled in bold, with sequence substitutions indicated nearby. Sequences that were deleted to construct the helix truncation mutants (Fig. 6) are enclosed in gray dashed boxes and the replacement nucleotides are shown in gray italic font. (B) Tertiary structure model of the ribozyme (31). Peripheral elements (colored surface) and the locations of the long-range peripheral tertiary contacts (circles) are highlighted using the same color scheme as in A. The ribozyme core is shown in silver. The block arrows indicate the approximate positions of tertiary contacts not visible in each respective view of the ribozyme. The figures were prepared using PyMOL.Given the structural similarity between the native and misfolded ribozyme, it is interesting that CYT-19 can accelerate refolding of the misfolded intermediate by at least an order of magnitude without detectably unfolding the native ribozyme (26). Insights into this apparent preference for the misfolded ribozyme came from studies of two ribozyme mutants in which the tertiary structure was destabilized, making the stability of the native ribozyme comparable to that of the misfolded intermediate (28). CYT-19 unfolded the native and misfolded conformers of these mutants with comparable efficiencies, suggesting that the efficiency of chaperone-mediated unfolding depended on the stability of ribozyme tertiary structure. However, the mutations studied were concentrated in one region of the ribozyme, leaving open the possibility that CYT-19 recognizes local disruptions rather than global stability.Here we investigate the roles of RNA stability in CYT-19-mediated unfolding of the Tetrahymena ribozyme by using a series of ribozyme mutants with disruptions of each of the five peripheral tertiary contacts. We observe a strong correlation between CYT-19 activity and global stability of ribozyme tertiary structure. Further, we find that the RNA-dependent ATPase activity of CYT-19 depends on the accessibility of secondary structure in the ribozyme. Our results lead to a general model for recognition and remodeling of unstable or incorrectly folded RNAs by a DEAD-box protein.