Social Inference from Middle to Older Adulthood.

OBJECTIVE: Inferring the emotional state or the true meaning of another person's utterance is a key aspect of social cognition and critical for successful social interactions. In this study, we assess age-related differences in emotion recognition and sincere and sarcastic social exchanges in the context of cognitive and demographic factors. METHOD: One hundred and eighty-seven adults ranging from middle to older adulthood completed the Mini-SEA Emotion Recognition test and Part B of The Awareness of Social Inference Test - Short Form (TASIT-S). Fluid intelligence and executive abilities were also assessed. Sex differences and the relationship with education level were also investigated. Regression models were used to assess age-related differences controlling for baseline cognitive and demographic factors. RESULTS: Age was negatively associated with accuracy for inferring sincere social exchanges. No differences were identified for accuracy for inferring sarcastic exchanges. Likewise, no age differences were identified for emotion recognition (Mini-SEA). Fluid intelligence was associated with accuracy for inferring sincere exchanges, but this was independent of age-related effects. A female advantage was identified for emotion recognition. CONCLUSION: Age is associated with difficulty in inferring sincere exchanges, which is not explained by fluid intelligence, verbal abstract reasoning, or auditory verbal attention. A female advantage in emotion recognition is consistent with findings reported in younger adults. Both age and sex should be considered in clinical assessments using the Mini-SEA and the TASIT-S.

Response initiation and inhibition and the relationship with fluid intelligence across the adult lifespan.

BACKGROUND: Cognitive processes associated with frontal lobe functioning are often termed "executive functions." Two such processes are initiation and inhibition or the starting and stopping of responses. It has recently been claimed dysfunction of executive abilities can be explained by a single measure of fluid intelligence. Here, we test this claim, specifically for the executive abilities of response initiation and inhibition, across the healthy lifespan. METHOD: In a cohort of 336 healthy adults (18-89 years), initiation and inhibition were assessed with the Hayling test, Stroop test, and phonemic and semantic verbal fluency. All participants also completed a measure of fluid intelligence. The relationship between fluid intelligence and executive measures was explored across the lifespan using a continuous approach. Mediation models were computed to assess whether age-related decline across the four initiation/inhibition tasks could be fully explained by a single measure of fluid intelligence. RESULTS: Age was negatively correlated with response initiation/inhibition and fluid intelligence. The mediation analyses identified only partial mediation of fluid intelligence for age and Hayling performance. By contrast, fluid intelligence did not mediate performance on the Stroop test or phonemic and semantic verbal fluency. CONCLUSIONS: Response initiation/inhibition are not able to be explained by fluid intelligence. The results support a multifactorial theory of executive functions and provide evidence for the inclusion of multiple specific executive measures in a thorough neuropsychological assessment of age-related cognitive decline.

Diet and lupus: what do the patients think?

OBJECTIVES: Cardiovascular disease is the leading cause of mortality in patients with systemic lupus erythematosus. Therefore, using diet to control blood lipid levels and modify cardiovascular disease risk could be a promising therapeutic strategy to control disease symptoms. The primary objective of this study was to learn about systemic lupus erythematosus patient experiences with diet, including their opinion on considering diet as a therapeutic option. The secondary objective was to obtain this information in a cost- and time-effective manner. METHODS: A lay summary and a 15-question diet-based online survey were publicly available for 3 weeks. Social media was used to promote the survey through relevant charities, hospitals and research groups. RESULTS: A total of 300 responses were received, 284 from patients with systemic lupus erythematosus. Patients reported that there was a lack of clinical counselling regarding diet, with only 24% stating their doctor had spoken to them about diet. Despite this, 100% of patients stated they would change their diet if they knew it would help their symptoms and 83% would take part in a future diet-based clinical trial. Text analysis of patient research suggestions identified a particular interest in using diet to treat fatigue and manage disease flares. CONCLUSIONS: This project successfully gathered patient information regarding diet and systemic lupus erythematosus over a short timeframe using an anonymous social media platform. The survey provided evidence that patients support further research and potential diet intervention studies investigating the effect of diet on the symptoms of systemic lupus erythematosus.

Executive functioning in schizophrenia: Unique and shared variance with measures of fluid intelligence.

OBJECTIVE: Patients with schizophrenia often display deficits on tasks thought to measure "executive" processes. Recently, it has been suggested that reductions in fluid intelligence test performance entirely explain deficits reported for patients with focal frontal lesions on classical executive tasks. For patients with schizophrenia, it is unclear whether deficits on executive tasks are entirely accountable by fluid intelligence and representative of a common general process or best accounted for by distinct contributions to the cognitive profile of schizophrenia. METHOD: In the current study, 50 patients with schizophrenia and 50 age, sex and premorbid intelligence matched controls were assessed using a broad neuropsychological battery, including tasks considered sensitive to executive abilities, namely the Hayling Sentence Completion Test (HSCT), word fluency, Stroop test, digit-span backwards, and spatial working memory. Fluid intelligence was measured using both the Matrix reasoning subtest from the Weschler Abbreviated Scale of Intelligence (WASI) and a composite score derived from a number of cognitive tests. RESULTS: Patients with schizophrenia were impaired on all cognitive measures compared with controls, except smell identification and the optimal betting and risk-taking measures from the Cambridge Gambling Task. After introducing fluid intelligence as a covariate, significant differences remained for HSCT suppression errors, and classical executive function tests such as the Stroop test and semantic/phonemic word fluency, regardless of which fluid intelligence measure was included. CONCLUSIONS: Fluid intelligence does not entirely explain impaired performance on all tests considered as reflecting "executive" processes. For schizophrenia, these measures should remain part of a comprehensive neuropsychological assessment alongside a measure of fluid intelligence.

Accuracy of regenerating motor neurons: influence of diffusion in denervated nerve.

Following injury to a peripheral nerve the denervated distal nerve segment undergoes remarkable changes including loss of the blood-nerve barrier, Schwann cell proliferation, macrophage invasion, and the production of many cytokines and neurotrophic factors. The aggregate consequence of such changes is that the denervated nerve becomes a permissive and even preferred target for regenerating axons from the proximal nerve segment. The possible role that an original end-organ target (e.g. muscle) may play in this phenomenon during the regeneration period is largely unexplored. We used the rat femoral nerve as an in vivo model to begin to address this question. We also examined the effects of disrupting communication with muscle in terms of accuracy of regenerating motor neurons as judged by their ability to correctly project to their original terminal nerve branch. Our results demonstrate that the accuracy of regenerating motor neurons is dependent upon the denervated nerve segment remaining in uninterrupted continuity with muscle. We hypothesized that this influence of muscle on the denervated nerve might be via diffusion-driven movement of biomolecules or the active axonal transport that continues in severed axons for several days in the rat, so we devised experiments to separate these two possibilities. Our data show that disrupting ongoing diffusion-driven movement in a denervated nerve significantly reduces the accuracy of regenerating motor neurons.

Schwann cell influence on motor neuron regeneration accuracy.

Extensive peripheral nerve injuries can result in the effective paralysis of the entire limb or distal portions of the limb. The major determinant of functional recovery after lesions in the peripheral nervous system is the accurate regeneration of axons to their original target end-organs. We used the mouse femoral nerve as a model to study motor neuron regeneration accuracy in terms of regenerating motor neurons projecting to their original terminal pathway to quadriceps muscle vs. the inappropriate pathway to skin. Using a variety of surgical manipulations and the selective removal of Schwann cells in the distal nerve via molecular targeting, we have examined the respective roles of end-organ influence (muscle) vs. Schwann cells in this model system. We found evidence of a hierarchy of trophic support that regulates motor neuron regeneration accuracy with muscle contact being the most potent, followed by the number or density of Schwann cells in the distal nerve branches. Manipulating the relative levels of these sources of influence resulted in predictable projection patterns of motor neurons into the terminal pathway either to skin or to muscle.

The impact and recovery of asteroid 2008 TC(3).

In the absence of a firm link between individual meteorites and their asteroidal parent bodies, asteroids are typically characterized only by their light reflection properties, and grouped accordingly into classes. On 6 October 2008, a small asteroid was discovered with a flat reflectance spectrum in the 554-995 nm wavelength range, and designated 2008 TC(3) (refs 4-6). It subsequently hit the Earth. Because it exploded at 37 km altitude, no macroscopic fragments were expected to survive. Here we report that a dedicated search along the approach trajectory recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95 kg. Analysis of one of these meteorites shows it to be an achondrite, a polymict ureilite, anomalous in its class: ultra-fine-grained and porous, with large carbonaceous grains. The combined asteroid and meteorite reflectance spectra identify the asteroid as F class, now firmly linked to dark carbon-rich anomalous ureilites, a material so fragile it was not previously represented in meteorite collections.

The specificity of motor neurone regeneration (preferential reinnervation).

The major determinant of functional recovery after lesions in the peripheral nervous system is the accurate regeneration of axons to their original target end-organs. Unfortunately, regenerating motor axons are often misrouted to sensory target end-organs, and sensory axons formerly innervating skin are often misrouted to muscle. As such regeneration is robust, but often inaccurate, a better understanding of how regenerating axons reinnervate terminal pathways would be of fundamental interest to basic and clinical neuroscience. This review will consider the underlying cellular and molecular mechanisms that influence the accuracy of peripheral nerve regeneration, within the context of 'preferential motor reinnervation' (PMR). Much previous work with PMR has utilized the rodent femoral nerve and has shown that regenerating motor axons preferentially, albeit incompletely, reinnervate a distal terminal nerve branch to muscle (quadriceps) vs. skin (saphenous). One interpretation of this body of work has been that Schwann cell tubes have a specific identity that can be recognized by regenerating motor axons and that influences their subsequent behaviour. We disagree with that interpretation, and suggest motor and cutaneous pathways are not inherently different in terms of their ability to support regeneration of motor axons. In fact, recent experiments indicate under certain conditions motor axons will preferentially reinnervate the inappropriate terminal cutaneous pathway instead of the appropriate pathway to muscle. We suggest that it is the relative level of trophic support provided by each nerve branch that determines whether motor axons will remain in that particular branch. Within the context of the femoral nerve model, our results suggest a hierarchy of trophic support for regenerating motor axons with muscle contact being the highest, followed by the length of the terminal nerve branch and/or contact with skin.

Axotomized mouse retinal ganglion cells containing melanopsin show enhanced survival, but not enhanced axon regrowth into a peripheral nerve graft.

Melanopsin is found in only approximately 2% of mouse retinal ganglion cells (RGCs), making these RGCs uniquely and directly photosensitive. Given that the majority of RGCs die after axotomy and that grafting of a peripheral nerve to the eye provides a permissive environment for axon regrowth, the present study examined the survival and axonal regrowth of melanopsin-containing RGCs in mice. One month after optic nerve transection and grafting, RGCs with regrown axons were labeled from the grafts and retinae were processed to visualize melanopsin and TUJ1. Melanopsin-positive and negative RGCs were counted and compared to axotomized RGCs from ungrafted eyes and uninjured RGCs. Melanopsin-positive RGCs showed a 3-fold increase in survival rate compared to non-melanopsin RGCs. Despite this enhanced survival, melanopsin-containing RGCs did not show increased axon regrowth into nerve grafts.

Survival of adult rat retinal ganglion cells with regrown axons in peripheral nerve grafts: a comparison of graft attachment with suture of fibrin glue.

OBJECT: The goal of this study was to examine whether the method of attachment of a peripheral nerve graft would have an effect on retinal ganglion cell (RGC) regeneration. METHODS: The number of adult rat RGCs with regrown axons in a peripheral nerve graft was compared under two grafting conditions: 1) attachment of the graft to the optic nerve stump made using a suture; and 2) attachment made using fibrin glue. Counts of RGCs retrogradely labeled with FluoroGold from the grafts 1 month after attachment revealed approximately seven times the number of RGCs in the fibrin-glue group compared with the suture group. CONCLUSIONS: The use of fibrin glue may be a useful tool for enhancing the regrowth of central nervous system neuron axons into peripheral nervous system grafts.

Netrin-1 and peripheral nerve regeneration in the adult rat.

Axonal guidance during development of the nervous system is thought to be highly regulated through interactions of axons with attractive, repulsive, and trophic cues. Similar mechanisms regulate axonal regeneration after injury. The netrins have been shown to influence the guidance of several classes of developing axons. Although netrins have been implicated as axonal guidance cues in the developing peripheral nervous system, there has been no direct evidence of netrin-1 expression in either developing or adult peripheral nerve. The present study utilized competitive PCR and immunohistochemistry to demonstrate the localization of netrin-1 within adult rat sciatic nerve. The expression of netrin-1 mRNA and protein was compared for normal or regenerated sciatic nerve 2 weeks following either a crush or a transection and repair injury. The PCR data show that netrin-1 mRNA is normally expressed at low levels in peripheral nerve, and similar low levels are found 2 weeks following a crush injury. However, 2 weeks following nerve transection and repair there is approximately a 40-fold increase in netrin-1 mRNA levels. Immunohistochemistry data show that Schwann cells are the major source of netrin-1 protein in peripheral nerve. Our results suggest that netrin-1 mRNA levels are profoundly affected during peripheral nerve injury and regeneration. The localization of netrin-1 to Schwann cells suggests that this protein is strategically situated to influence axon regeneration in adult peripheral nerve.

lambda RNA internal standards quantify sensitivity and amplification efficiency of mammalian gene expression profiling.

There is an increasing interest in being able to document simultaneous levels of multiple mRNAs from limited amounts of mammalian tissue. The combination of amplified antisense RNA (aRNA) and reverse Northern blot analysis is one technology that allows the measurement of relative levels of multiple mRNAs. However, potential problems exist with this approach, such as (i) unknown amplification efficiencies and sensitivity of detection, (ii) an inherent 3' bias of amplified products and (iii) cross-hybridization of homologous mRNAs with the gene targets. Each of these potential problems was addressed experimentally by the use of poly(A) RNA internal standards synthesized from lambda phage (lambda) DNA. The results showed detection levels of as few as 10 copies of the poly(A) RNA internal standards. The internal standards aid in the optimization of reaction conditions and also reduce dependence on traditional "housekeeping" genes whose mRNA levels might or might not change. The overall results of these experiments highlight and extend the general usefulness of amplified antisense aRNA and reverse Northern blot analysis to study mRNA expression profiles.

Changes in the expression of transcription factors ATF-2 and Fra-2 after axotomy and during regeneration in rat retinal ganglion cells.

The expression of one member of the bZip superfamily of transcription factors, c-Jun, is known to be induced by axotomy in retinal ganglion cells (RGCs) and is associated with axonal regrowth. This study used immunohistochemistry combined with retrograde labeling to examine the expression of two additional bZip transcription factors (ATF-2 and Fra-2) in identified adult rat RGCs under favorable and unfavorable conditions for axonal regrowth. For unfavorable regrowth conditions, ganlgion cell axons within the optic nerve were cut close to the eye. For favorable conditions, the optic nerve was replaced with an autologous peripheral nerve graft to allow axonal regrowth. At regular intervals, after axotomy alone or in conjunction with graft placement, the expression of these transcription factors was examined in retinal wholemounts using protein-specific antibodies. The strong cytoplasmic expression of Fra-2 seen in unaxotomized RGCs was reduced beginning 24 h after axotomy. Similarly, the strong nuclear expression of ATF-2 seen prior to axotomy was also reduced after axotomy. These reduction persisted in surviving ganglion cells throughout the 3 week study period. One to 6 months after axotomy and peripheral nerve graft placement, identified RGCs with regrown axons showed strong ATF-2 and Fra-2 expression, suggesting a return to basal conditions. These findings support roles for ATF-2 and Fra-2 in the survival and regeneration process of these central nervous system neurons after axotomy.

Axotomy-induced regulation of c-Jun expression in regenerating rat retinal ganglion cells.

Antibodies to c-Jun, JunD, JunB, c-Fos, FosB and Krox-24 proteins were used to examine the expression of these transcription factors in identified adult rat retinal ganglion cells with regenerating axons in a peripheral nerve graft. First, expression in ganglion cells 1 month after graft placement was compared to expression in these neurons 5 to 6 months after grafting. Whereas strong c-Jun expression was seen in most ganglion cells one month after grafting, most 5- to 6-month ganglion cells showed only basal expression. The maintained nucleolar expression of FosB in both ganglion cell groups was the only other transcription factor seen. Second, transcription factor expression was examined in these short- and long-term regenerating neurons after a second axotomy caused by graft transection and compared to the effects of a single axotomy on expression in non-regenerating ganglion cells. Only c-Jun was re-expressed in the regenerating ganglion cells after re-axotomy.

A direct, general approach based on isobolograms for assessing the joint action of drugs in pre-clinical experiments.

Pharmacologists and other biologists frequently use methods based on the interpretation of isobolograms to quantify the extent of synergy or antagonism between drugs used in combination in pre-clinical studies. Most methods have been unsatisfactory from a statistical viewpoint, many because they have relied solely on visual evaluation, others because the methods have not taken into account the variability of the measurements. We describe a direct approach for quantifying the joint potency of two drugs, a central feature being the use of simple isobole models that lead directly to response surface models for the expected experimental outcomes. The approach is general in the sense that one can use it for discrete or continuous responses, different underlying probability distributions, linear or non-linear dose-response functions of the drugs used singly, and a variety of experimental designs. Our approach extends the suggestions made by Hewlett for measuring the joint potency of drugs, and is similar in spirit to the approaches proposed by Greco et al. and Weinstein et al. We describe the analysis of data from an in vitro experiment conducted to evaluate the efficacy of the antiviral drugs AZT and ddI used in combination.

Gene structure and amino acid sequences of alcohol dehydrogenases of Bacillus stearothermophilus.

Partial amino acid sequences of the two alcohol dehydrogenases of Bacillus stearothermophilus and the oligonucleotide sequence of a cloned fragment containing the gene for ADH 2334 were determined and compared with the known, derived ADH 1503 amino acid sequence. The two proteins are identical at 244 of 349 positions. ADH 2334 is encoded in a transcription unit containing an aldehyde dehydrogenase.

Immediate early gene expression in axotomized and regenerating retinal ganglion cells of the adult rat.

To determine if axotomy-induced immediate early gene (IEG) expression accompanies regenerative efforts in central nervous system (CNS) neurons, immunohistochemistry using antibodies to c-Jun, JunD, JunB, c-Fos, FosB and Krox-24 proteins was used to examine gene expression in identified adult rat retinal ganglion cells (RGCs) under two conditions: (1) after axotomy alone, and (2) 1 month after replacement of the optic nerve with an autologous peripheral nerve graft to allow axonal regrowth. Strong RGC c-Jun expression was induced 1 day, but not 3 h, after axotomy in most RGCs and was maintained in surviving cells throughout the 3-week study period. Axotomy also induced a limited number of RGCs to express Krox-24, but only transiently. c-Fos expression was also seen in a limited number of control RGCs, however, it was not induced by axotomy. Nucleolar FosB immunoreactivity in axotomized RGCs persisted 1 day after axotomy, but was subsequently lost. One month after axotomy and peripheral nerve graft placement, identified RGCs with regrown axons showed only nuclear c-Jun and nucleolar FosB expression. These findings support a role for IEG expression in the regeneration process of CNS neurons.

Behavior of motor units in human biceps brachii during a submaximal fatiguing contraction.

The activity of 50 single motor units was recorded in the biceps brachii muscle of human subjects while they performed submaximal isometric elbow flexion contractions that were sustained to induce fatigue. The purposes of this study were to examine the influence of fatigue on motor unit threshold force and to determine the relationship between the threshold force of recruitment and the initial interimpulse interval on the discharge rates of single motor units during a fatiguing contraction. The discharge rate of most motor units that were active from the beginning of the contraction declined during the fatiguing contraction, whereas the discharge rates of most newly recruited units were either constant or increased slightly. The absolute threshold forces of recruitment and derecruitment decreased, and the variability of interimpulse intervals increased after the fatigue task. The change in motor unit discharge rate during the fatigue task was related to the initial rate, but the direction of the change in discharge rate could not be predicted from the threshold force of recruitment or the variability in the interimpulse intervals. The discharge rate of most motor units declined despite an increase in the excitatory drive to the motoneuron pool during the fatigue task.

Adaptation of cat motoneurons to sustained and intermittent extracellular activation.

1. The main purpose of this study was to quantify the adaptation of spinal motoneurons to sustained and intermittent activation, using an extracellular route of stimulating current application to single test cells, in contrast to an intracellular route, as has been used previously. In addition, associations were tested between firing rate properties of the tested cells and other type (size)-related properties of these cells and their motor units. 2. Motoneurons supplying the medial gastrocnemius muscle of the deeply anaesthetized cat were stimulated for 240 s with microelectrodes which passed sustained extracellular current at 1.25 times the threshold for repetitive firing. Many cells were also tested following a rest period with intermittent 1 s current pulses (duration 600 ms) at the same relative stimulus strength. Cell discharge was assessed from the EMG of the motor unit innervated by the test neuron. The motoneurons and their motor units were assigned to four categories (i.e. types FF, FR, S and F; where F = FF + FR) based on conventional criteria. In all, twenty F (16 FF, 4 FR) and fourteen S cells were studied with sustained stimulation. Thirty of these cells (17 F, 13 S) and an additional two cells (1 F, 1 S) were studied with intermittent stimulation. 3. The mean threshold current required for sustained firing for a period of > or = 2 s was not significantly different for F and S cells. However, most of the other measured parameters of motoneuron firing differed significantly for these two cell groups. For example, at 1.25 times the threshold current for repetitive firing, the mean firing duration in response to 240 s of sustained activation was 123 +/- 88 s (+/- S.D.) for F cells vs. 233 +/- 19 s for S cells. These values were significantly longer than those from a comparable, previously reported study that employed intracellular stimulation. With intermittent stimulation, the firing durations of F and S cells were not significantly different from each other. 4. All cells exhibited a delay from the onset of current to the first spike, followed by a brief accelerating discharge that was followed by a slower drop in firing rate. Some cells (21 of 34 with sustained activation; 20 of 32 with intermittent) exhibited doublet discharges (interspike intervals < or = 10 ms) that were intermingled with the more predominant singlet discharges. Doublets were more common in the S cell type.(ABSTRACT TRUNCATED AT 400 WORDS)

A lay educator approach to sickle cell disease education.

Over the past two decades, the number of Black Americans aware of sickle cell disease has increased. However, knowledge of the existence of the disease, and the higher risk Black Americans face, has not resulted in a widely held pool of accurate and meaningful information. For instance, observers are far less certain that the observed increased awareness has contributed to the capacity to (1) make informed parenting decisions at the grass roots level, (2) provide appropriate support to individuals and families experiencing sickle cell disease, (3) advise youth on issues related to genetic health, and (4) displace the impact of miseducation that occurred in the 70's. In the demonstration described in this paper, responsibility for sickle cell disease education is shared with community organizations and community members who are broadly representative of the community's demographic and cultural profiles. Through this process, meaningful knowledge about sickle cell disease is vested within a network of religious, civic, fraternal and social organizations. Additionally, this paper discusses needs assessment, recruitment, training and project evaluation for four classes of lay sickle cell disease educators as well as the beginning phase of their lay educator role.