The social context of anxiety and depression: exploring the role of anxiety and depression in the lives of Australian adults with epilepsy.

AIM: To examine key determinants of anxiety and depression in a community sample of people with epilepsy. METHOD: Data were analyzed from the 2010 Australian Epilepsy Longitudinal Survey, examining living with epilepsy in Australia. The HADS was analyzed, and Pearson correlations and block recursive regression were undertaken to identify key associations between anxiety, depression, and a range of variables and to identify key determinants of anxiety and depression. RESULTS: Key factors to influence anxiety were social aspects of stigma, effectiveness of seizure control, whether in employment, and the number of different epilepsy drugs. Determinants for depression were social aspects of stigma, whether in employment, and the effectiveness of seizure control. Stigma was also found to be an important mediating variable for employment, control, and the number of drugs. CONCLUSION: Understanding the mechanisms involved in anxiety and depression in a community sample of people with epilepsy requires the inclusion of opportunities for paid employment and the effects of psychosocial factors such as stigma. Without this fuller social context, there are limitations on understanding factors that influence anxiety and depression and how to deal with the outcomes.

Relationships between muscle contributions to walking subtasks and functional walking status in persons with post-stroke hemiparesis.

BACKGROUND: Persons with post-stroke hemiparesis usually walk slowly and asymmetrically. Stroke severity and functional walking status are commonly predicted by post-stroke walking speed. The mechanisms that limit walking speed, and by extension functional walking status, need to be understood to improve post-stroke rehabilitation methods. METHODS: Three-dimensional forward dynamics walking simulations of hemiparetic subjects (and speed-matched controls) with different levels of functional walking status were developed to investigate the relationships between muscle contributions to walking subtasks and functional walking status. Muscle contributions to forward propulsion, swing initiation and power generation were analyzed during the pre-swing phase of the gait cycle and compared between groups. FINDINGS: Contributions from the paretic leg muscles (i.e., soleus, gastrocnemius and gluteus medius) to forward propulsion increased with improved functional walking status, with the non-paretic leg muscles (i.e., rectus femoris and vastii) compensating for reduced paretic leg propulsion in the limited community walker. Contributions to swing initiation from both paretic (i.e., gastrocnemius, iliacus and psoas) and non-paretic leg muscles (i.e., hamstrings) also increased as functional walking status improved. Power generation was also an important indicator of functional walking status, with reduced paretic leg power generation limiting the paretic leg contribution to forward propulsion and leg swing initiation. INTERPRETATION: These results suggest that deficits in muscle contributions to the walking subtasks of forward propulsion, swing initiation and power generation are directly related to functional walking status and that improving output in these muscle groups may be an effective rehabilitation strategy for improving post-stroke hemiparetic walking.

The INO80 family of chromatin-remodeling enzymes: regulators of histone variant dynamics.

The evolutionarily conserved INO80 family of ATP-dependent chromatin-remodeling enzymes has roles in many nuclear processes, including transcription, DNA repair, and DNA replication. Here, we discuss the in vivo and in vitro properties of these enzymes, focusing on recent studies which suggest that members of this family govern the deposition and removal of the histone variant H2A.Z.

Differences in self-selected and fastest-comfortable walking in post-stroke hemiparetic persons.

Post-stroke hemiparetic walking is typically asymmetric. Assessment of symmetry is often performed at either self-selected or fastest-comfortable walking speeds to gain insight into coordination deficits and compensatory mechanisms. However, how walking speed influences the level of asymmetry is unclear. This study analyzed relative changes in paretic and non-paretic leg symmetry to assess whether one speed is more effective at highlighting asymmetries in hemiparetic walking and whether there is a systematic effect of speed on asymmetry. Forty-six subjects with chronic hemiparesis walked at their self-selected and fastest-comfortable speeds on an instrumented split-belt treadmill. Relative proportions (paretic leg value/(paretic+non-paretic leg value)) were computed at each speed for step length (PSR), propulsion (PP), and joint moment impulses at the ankle and hip. Thirty-six subjects did not change their step length symmetry with speed, while three subjects changed their step length values toward increased asymmetry and seven changed toward increased symmetry. Propulsion symmetry did not change uniformly with speed for the group, with 15 subjects changing their propulsion values toward increased asymmetry while increasing speed from their self-selected to fastest-comfortable and 11 decreasing the asymmetry. Both step length and propulsion symmetry were correlated with ankle impulse proportion at self-selected and fastest-comfortable speed (cf., hip impulse proportion), but ratios (self-selected value/fastest-comfortable value) of the proportion measures (PSR and PP) showed that neither step length nor propulsion symmetry correlated with the ankle impulse proportions. Thus, the individual kinetic mechanisms used to increase speed could not be predicted from PSR or PP.

Use of real-time qPCR to quantify members of the unculturable heterotrophic bacterial community in a deep sea marine sponge, Vetulina sp.

In this report, real-time quantitative PCR (TaqMan qPCR) of the small subunit (SSU) 16S-like rRNA molecule, a universal phylogenetic marker, was used to quantify the relative abundance of individual bacterial members of a diverse, yet mostly unculturable, microbial community from a marine sponge. Molecular phylogenetic analyses of bacterial communities derived from Caribbean Lithistid sponges have shown a wide diversity of microbes that included at least six major subdivisions; however, very little overlap was observed between the culturable and unculturable microbial communities. Based on sequence data of three culture-independent Lithistid-derived representative bacteria, we designed probe/primer sets for TaqMan qPCR to quantitatively characterize selected microbial residents in a Lithistid sponge, Vetulina, metagenome. TaqMan assays included specificity testing, DNA limit of detection analysis, and quantification of specific microbial rRNA sequences such as Nitrospira-like microbes and Actinobacteria up to 172 million copies per microgram per Lithistid sponge metagenome. By contrast, qPCR amplification with probes designed for common previously cultured sponge-associated bacteria in the genera Rheinheimera and Marinomonas and a representative of the CFB group resulted in only minimal detection of the Rheiheimera in total DNA extracted from the sponge. These data verify that a large portion of the microbial community within Lithistid sponges may consist of currently unculturable microorganisms.

Characterization of genetic markers for in vitro cell line identification of the marine sponge Axinella corrugata.

The marine sponge Axinella corrugata is being developed as a model organism for in vitro marine invertebrate research. Molecular genetics methods such as DNA fingerprinting [amplified fragment length polymorphism (AFLP) and single-stranded conformation polymorphism (SSCP)] and single-locus DNA sequence analyses were applied to this model to meet the primary objective of identifying positive A. corrugata-specific molecular markers that will aid in verifying cell identity in vitro and distinguish sponge cells from potential microbial contaminants. The extent of intra- and interspecific variation in these markers from geographically distinct samples of A. corrugata and closely related sponge taxa was also assessed. Two novel nuclear loci along with intervening transcribed spacer (ITS) regions of nuclear rRNA were characterized, although the latter appeared to better meet primary marker criteria, such as taxonomic specificity and high frequency of detection (via polymerase chain reaction [PCR]) from different individuals (n > 40) and cell cultures. Phylogenetic and phylogeographic analyses of ITS DNA sequences helped clarify taxonomies and also suggested species boundaries between and among western Atlantic and eastern Atlantic/Indian Ocean A. corrugata and Axinellidae samples. Patterns of genetic variation have important implications for the systematics, evolution, and chemical ecology of A. corrugata and related axinellids and are discussed.

The bromodomain: a regulator of ATP-dependent chromatin remodeling?

In eukaryotes, processes requiring access to DNA are inhibited by the structural packaging of the genome. A number of specialized ATP-dependent chromatin remodeling enzymes have evolved to overcome this inhibition. One subset of these enzymes, SWI/SNF, plays a critical role in the regulation of transcription, often functioning in concert with nuclear histone acetyltransferases (HATs). It remains unknown how these activities are coordinated. However, recent results revealing that the bromodomain, a motif common in these remodeling factors, constitutes an acetyl-lysine binding domain might provide insight into this process. Bromodomains may serve a role analogous to the signal transduction SH2 domain, by providing a means to recruit remodeling complexes to acetylated chromatin regions or to allosterically modify their function post-recruitment.

Chromatin: mysteries solved?

Over the past few years we have seen enormous progress in uncovering the critical roles that chromatin structure has on the control of gene expression, the regulation of developmental processes, and the control of cell cycle checkpoints. No longer is chromatin research the "last bastion of scoundrels." The recent intensity of chromatin research, however, might lead a young scientist to conclude that the field is saturated or that all the big mysteries have been solved. This view could not be further from the truth! Here I briefly outline four areas of chromatin research where new paradigms and mysteries are still waiting to be discovered.

The interactions of yeast SWI/SNF and RSC with the nucleosome before and after chromatin remodeling.

Interactions of the yeast chromatin-remodeling complexes SWI/SNF and RSC with nucleosomes were probed using site-specific DNA photoaffinity labeling. 5 S rDNA was engineered with photoreactive nucleotides incorporated at different sites in DNA to scan for the subunits of SWI/SNF in close proximity to DNA when SWI/SNF is bound to the 5 S nucleosome or to the free 5 S rDNA. The Swi2/Snf2 and Snf6 subunits of SWI/SNF were efficiently cross-linked at several positions in the nucleosome, whereas only Snf6 was efficiently cross-linked when SWI/SNF was bound to free DNA. DNA photoaffinity labeling of RSC showed that the Rsc4 subunit is in close proximity to nucleosomal DNA and not when RSC is bound to free DNA. After remodeling, the Swi2/Snf2 and Rsc4 subunits are no longer detected near the nucleosomal DNA and are evidently displaced from the surface of the nucleosome, indicating significant changes in SWI/SNF and RSC contacts with DNA after remodeling.

Chromatin remodeling enzymes: who's on first?

A central problem in the regulation of eukaryotic gene expression is understanding how gene-specific transcriptional activators orchestrate the recruitment of the myriad proteins that are required for transcription initiation. An emerging view indicates that activators must first target two types of chromatin remodeling enzyme to the promoter region: an ATP-dependent SWI/SNF-like complex and a histone acetyltransferase. These two enzymes appear to act synergistically to establish a local chromatin structure that is permissive for subsequent events. Furthermore, several recent studies indicate that the recruitment of chromatin remodeling enzymes must follow an obligatory, sequential order of events that is determined by either promoter context or cell-cycle position. Here we review recent developments concerning the role of chromatin remodeling enzymes in gene regulation, and propose several models to explain how different chromatin remodeling activities can be functionally coupled.

SWI/SNF chromatin remodeling requires changes in DNA topology.

ySWI/SNF complex belongs to a family of enzymes that use the energy of ATP hydrolysis to remodel chromatin structure. Here we examine the role of DNA topology in the mechanism of ySWI/SNF remodeling. We find that the ability of ySWI/SNF to enhance accessibility of nucleosomal DNA is nearly eliminated when DNA topology is constrained in small circular nucleosomal arrays and that this inhibition can be alleviated by topoisomerases. Furthermore, we demonstrate that remodeling of these substrates does not require dramatic histone octamer movements or displacement. Our results suggest a model in which ySWI/SNF remodels nucleosomes by using the energy of ATP hydrolysis to drive local changes in DNA twist.

Single-dose toxicity study of hepatic intra-arterial infusion of doxorubicin coupled to a novel magnetically targeted drug carrier.

The toxicity of a single hepatic intra-arterial administration of doxorubicin (DOX) coupled to a magnetically targeted drug carrier (MTC) was evaluated in a swine model. MTC is a microparticle composite of elemental iron and activated carbon. MTC-DOX is a new formulation of doxorubicin absorbed to the MTC and is designed for site-specific delivery to a solid tumor in the presence of an externally applied magnetic field. The magnetic field induces extravasation of MTCs through the vascular wall, leading to localization and retention in the tissue at the targeted site. Eighteen swine were assigned to 6 treatment groups, including 3 control groups (vehicle control, doxorubicin, MTC), and 3 experimental groups that received the MTC-DOX preparation. Animals were given a single administration of test article, evaluated over 28 days, and then sacrificed. Signs of toxicity were monitored via clinical status, total body weight, gross and microscopic pathology, and serum chemistries. Angiography was used to determine the extent of any embolization present. There were no adverse effects observed in the DOX-alone group. Biologically significant, treatment-related gross and microscopic lesions were limited to the targeted area of the liver only in groups receiving > or =75 mg of MTC (with or without doxorubicin). The severity of liver necrosis correlated to the severity of embolization following treatment. Doxorubicin was not freely circulating in any of the MTC-DOX groups, suggesting successful localization to the targeted site. The no-adverse-effect level (NOAEL) was determined to be the MTC-DOX low-dose group.

Injury severity and neuropsychological and balance outcomes of four college athletes.

Recent evidence suggests significant short-term neurocognitive deficits following mild traumatic brain injury (MTBI) in sports. However, sequelae of mild head injuries is complicated by many factors including a history of multiple head injuries and injury severity. Few studies have considered the influence these variables may have on proper classification of a MTBI and their meaning for return-to-play guidelines. This study presents the short-term neuropsychological and balance outcomes of four college athletes who sustained mild head injuries of different severity (grade I, grade II, grade III and multiple head injured with a grade II based on American Academy of Neurology guidelines). The results demonstrated that self-report symptoms of concussion were slow to resolve in the grade III and multiple concussed individuals. For neuropsychological testing, Trails A & B, Symbol Digit Modalities Test and Digits Span Backwards were the most sensitive in identifying differences between the injuries. For balance assessments using the Neurocom Smart Balance System, the Sensory Organization Test and Reaction Time were also important variables in detecting differences among the various injuries. When these data are used together, it can assist physicians in determining safe return-to-play for athletes who sustain MTBI. There are contradindications in the numerous grading systems and return-to-play guidelines for MTBI. The results from this study provides new evidence which can be assimilated into a valid grading scale for MTBI sustained in sport.

Global role for chromatin remodeling enzymes in mitotic gene expression.

Regulation of eukaryotic gene expression requires ATP-dependent chromatin remodeling enzymes, such as SWI/SNF, and histone acetyltransferases, such as Gcn5p. Here we show that SWI/SNF remodeling controls recruitment of Gcn5p HAT activity to many genes in late mitosis and that these chromatin remodeling enzymes play a role in regulating mitotic exit. In contrast, interphase expression of GAL1, HIS3, PHO5, and PHO8 is accompanied by SWI/SNF-independent recruitment of Gcn5p HAT activity. Surprisingly, prearresting cells in late mitosis imposes a requirement for SWI/SNF in recruiting Gcn5p HAT activity to the GAL1 promoter, and GAL1 expression also becomes dependent on both chromatin remodeling enzymes. We propose that SWI/SNF and Gcn5p are globally required for mitotic gene expression due to the condensed state of mitotic chromatin.

Injuries to athletes with disabilities: identifying injury patterns.

Participation in sport activities for people with disabilities continues to gain in popularity. With participation in sports, there is an inherent risk of injury. A review of current sport epidemiological studies was used and we concluded that injury patterns for this population are similar to those for athletes without disabilities. Injury data from Paralympic competitions dating back to 1976 indicate that most elite athletes with disabilities seek medical care for illness and musculo-skeletal injuries. However, there are very limited injury data regarding Winter Paralympic events or skiing injuries. For those athletes who participate in Summer Paralympic events, abrasions, strains, sprains and contusions are more common than fractures and dislocations. However, location of injuries appears to be disability and sport dependent. Lower extremity injuries are more common in ambulatory athletes (visually impaired, amputee, cerebral palsy) and upper extremity injuries are more frequent in athletes who use a wheelchair. While it appears that the majority of the injuries occurring in this population are minor in nature, inconsistencies in the definition of injury in the literature make this conclusion tenuous. When injuries are expressed as time lost in participation, 52% of injuries resulted in 7 days lost or less, 29% in 8 to 21 days lost and 19% in greater than 22 days lost. The only prospective study addressing injury rates of athletes with disabilities in a manner consistent with other sport epidemiological studies found an injury rate of 9.3 injuries per 1000 athlete-exposures (AE). This injury rate is less than American football (10.1 to 15/1000 AE) and soccer (9.8/1000 AE), and greater than basketball (7.0/1000 AE). It is unclear whether comparative statistics such as these take into consideration the number of illness and injury episodes that resulted from the disability. Further complicating epidemiological studies for athletes with disabilities is the definition of the population and samples of convenience which are frequently used. These samples are often not representative of the multiplicity of disability conditions, levels of competition and range of sport activities available. Prospective studies comparing athletes to sedentary control individuals to measure differences in injury rates, type and frequency between and within disability groups, sports and levels of competition are desperately needed to further the knowledge of injury trends and develop and establish accurate injury prevention programmes.

Actin-related proteins (Arps): conformational switches for chromatin-remodeling machines?

The actin superfamily of ATPases includes cytoskeletal actins, the stress 70 proteins (e.g. hsc70), sugar kinases, glycerol kinase, and several prokaryotic cell cycle proteins. Although these proteins share limited sequence identity, they all appear to maintain a similar tertiary structure, the "actin fold", which may serve to couple ATP hydrolysis to protein conformational changes. Recently, an actin-related protein (Arp) subfamily has been identified based on sequence homology to conventional actin. Although some Arps are clearly involved in cytoskeletal functions, both actin and/or Arps have been found as stoichiometric subunits of several nuclear chromatin-remodeling enzymes. Here we present two related models in which actin and/or Arps function as conformational switches that control either the activity or the assembly of chromatin-remodeling machines.

ATP-dependent chromatin remodeling: going mobile.

Members of the ATP-dependent class of chromatin remodeling enzymes are found in all eukaryotes where they play key roles in many DNA-mediated processes. Each of these enzymes are multi-subunit assembles that hydrolyze approximately 1000 ATP/min. The energy of ATP hydrolysis is used to disrupt the chromatin structure which can be scored by enhanced factor binding, disruption of the DNase I cleavage pattern of mononucleosomes, formation of dinucleosomes, movements of histone octamers in cis and in trans, and by generation of nuclease hypersensitive sites. Here the biochemical properties of these enzymes are reviewed and the manner in which ATP-driven nucleosome movements might account for many of these diverse activities is discussed.

Recruitment of chromatin remodeling machines.

The assembly of eukaryotic DNA into folded nucleosomal arrays has drastic consequences for many nuclear processes that require access to the DNA sequence, including RNA transcription, DNA replication, recombination, and repair. Two types of highly conserved chromatin remodeling enzymes have been implicated as regulators of the repressive nature of chromatin structure: ATP-dependent remodeling complexes and nuclear histone acetyltransferases (HATs). Recent studies indicate that both types of enzymes can be recruited to chromosomal loci through either physical interactions with transcriptional activators or via the global accessibility of chromatin during S phase of the cell cycle. Here we review these recent observations and discuss the implications for gene-specific regulation by chromatin remodeling machines.

Understanding "active" chromatin: a historical perspective of chromatin remodeling.

Two phenomena have long been observed to correlate with transcriptionally active chromatin: increased histone acetylation and increased sensitivity to nucleases, including specific patterns of nuclease hypersensitivity in the promoters of active or inducible genes. Work in recent years has at last identified protein complexes required to form these hallmarks of active chromatin: histone acetyltransferases (HATs) and ATP-dependent chromatin remodeling complexes. This review traces the history of these discoveries, including the development of essential tools that allowed the major advances in the field, and describes the current understanding of the interactions between HATs and ATP-dependent remodelers.