Neuroanatomical correlates of visually evoked sexual arousal in human males

Brain areas activated in human male sexual behavior have not been characterized precisely. For the first time, positron emission tomography (PET) was used to identify the brain areas activated in healthy males experiencing visually evoked sexual arousal. Eight male subjects underwent six measurements of regional brain activity following the administration of [15O]H2O as they viewed three categories of film clips: sexually explicit clips, emotionally neutral control clips, and humorous control clips inducing positive but nonsexual emotions. Statistical Parametric Mapping was used to identify brain regions demonstrating an increased activity associated with the sexual response to the visual stimulus. Visually evoked sexual arousal was characterized by a threefold pattern of activation: the bilateral activation of the inferior temporal cortex, a visual association area; the activation of the right insula and right inferior frontal cortex, which are two paralimbic areas relating highly processed sensory information with motivational states; and the activation of the left anterior cingulate cortex, another paralimbic area known to control autonomic and neuroendocrine functions. Activation of some of these areas was positively correlated with plasma testosterone levels. Although this study should be considered preliminary, it identified brain regions whose activation was correlated with visually evoked sexual arousal in males.

Duration of mentally simulated movement: a review

The authors review studies of mentally simulated movements. In automatic or cyclical movements, actual and motor imagery (MI) durations are similar. When athletes simulate only dynamic phases of movement or perform MI just before competing, however, environmental and time constraints lead to an underestimation of actual duration. Conversely, complex attention-demanding movements take longer to image. Finally, participants can modify the speed of MI voluntarily when they receive specific instructions. To complete the available data, the authors compared imagined and actual durations in tennis and gymnastics. Results showed systematic and disproportionate overestimation of actual duration. The authors found a relationship between complex motor skills and MI duration. They discuss the factors leading to over- and underestimation and the hypotheses that could be tested.

The phylogeny of the insulin-like growth factors

The insulin-like growth factors are major regulators of growth and development in mammals and their presence in lower vertebrates suggests that they played a similarly fundamental role throughout vertebrate evolution. While originally perceived simply as mediators of growth hormone, on-going research in mammals has revealed several hierarchical layers of complexity in the regulation of ligand bioavailability and signal transduction. Our understanding of the biological role and mechanisms of action of these important growth factors in mammals patently requires further elucidation of the IGF hormone system in the simple model systems that can be found in lower vertebrates and protochordates. This review contrasts our knowledge of the IGF hormone system in mammalian and nonmammalian models through comparison of tissue and developmental distributions and gene structures of IGF system components in different taxa. We also discuss the evolutionary origins of the system components and their possible evolutionary pathways.

Survival and function of mesenchymal stem cells (MSCs) depend on glucose to overcome exposure to long-term, severe and continuous hypoxia

Use of mesenchymal stem cells (MSCs) has emerged as a potential new treatment for various diseases but has generated marginally successful results. A consistent finding of most studies is massive death of transplanted cells. The present study examined the respective roles of glucose and continuous severe hypoxia on MSC viability and function with respect to bone tissue engineering. We hereby demonstrate for the first time that MSCs survive exposure to long-term (12 days), severe (pO₂ < 1.5 mmHg) hypoxia, provided glucose is available. To this end, an in vitro model that mimics the hypoxic environment and cell-driven metabolic changes encountered by grafted sheep cells was established. In this model, the hallmarks of hypoxia (low pO₂, hypoxia inducible factor-1α expression and anaerobic metabolism) were present. When conditions switched from hypoxic (low pO₂) to ischemic (low pO₂ and glucose depletion), MSCs exhibited shrinking, decreased cell viability and ATP content due to complete exhaustion of glucose at day 6; these results provided evidence that ischemia led to the observed massive cell death. Moreover, MSCs exposed to severe, continuous hypoxia, but without any glucose shortage, remained viable and maintained both their in vitro proliferative ability after simulation with blood reperfusion at day 12 and their in vivo osteogenic ability. These findings challenge the traditional view according to which severe hypoxia per se is responsible for the massive MSC death observed upon transplantation of these cells and provide evidence that MSCs are able to withstand exposure to severe, continuous hypoxia provided that a glucose supply is available.

Autonomic nervous system response patterns specificity to basic emotions

The aim of this study was to test the assumption that the autonomic nervous system responses to emotional stimuli are specific. A series of six slides was randomly presented to the subjects while six autonomic nervous system (ANS) parameters were recorded: skin conductance, skin potential, skin resistance, skin blood flow, skin temperature and instantaneous respiratory frequency. Each slide induced a basic emotion: happiness, surprise, anger, fear, sadness and disgust. Results have been first considered with reference to electrodermal responses (EDR) and secondly through thermo-vascular and respiratory variations. Classical as well as original indices were used to quantify autonomic responses. The six basic emotions were distinguished by Friedman variance analysis. Thus, ANS values corresponding to each emotion were compared two-by-two. EDR distinguished 13 emotion-pairs out of 15. 10 emotion-pairs were separated by skin resistance as well as skin conductance ohmic perturbation duration indices whereas conductance amplitude was only capable of distinguishing 7 emotion-pairs. Skin potential responses distinguished surprise and fear from sadness, and fear from disgust, according to their elementary pattern analysis in form and sign. Two-by-two comparisons of skin temperature, skin blood flow (estimated by the new non-oscillary duration index) and instantaneous respiratory frequency, enabled the distinction of 14 emotion-pairs out of 15. 9 emotion-pairs were distinguished by the non-oscillatory duration index values. Skin temperature was demonstrated to be different i.e. positive versus negative in response to anger and fear. The instantaneous respiratory frequency perturbation duration index was the only one capable of separating sadness from disgust. From the six ANS parameters study, different autonomic patterns were identified, each characterizing one of the six basic emotion used as inducing signals. No index alone, nor group of parameters (EDR and thermovascular for instance) were capable of distinguishing each emotion from another. However, electrodermal, thermo-vascular and respiratory responses taken as a whole, redundantly separated each emotion thus demonstrating the specificity of autonomic patterns.

Where are persons with intellectual disabilities in medical research? A survey of published clinical trials

BACKGROUND

Persons with intellectual disabilities (ID) are exposed to the same medical interventions as everyone else. Given the unique health profiles of many persons with ID, it cannot be assumed that they will react to medical treatments the same as persons without ID. It is not clear if medical clinical trials routinely include persons with ID. The purpose of this research survey was to examine the inclusion of persons with ID in medical research trials, and to determine whether accommodations and/or study modifications could have been made to promote greater inclusion in medical research.

METHOD

Three hundred randomised control and clinical trials published between 2007 and 2011 in the six highest impact medical journals were randomly selected. Each study was reviewed for inclusion of persons with ID, and possible accommodations that could have been put in place without compromising research integrity. Corresponding authors received a follow-up survey to determine whether persons with ID were included, but were not mentioned in the article.

RESULTS

Only 6 (2%) of 300 randomly chosen studies clearly included persons with ID. Over 90% of studies were designed in ways that would automatically exclude persons with ID from participating. The author survey revealed three additional studies including persons with ID. Most persons with ID could have participated in at least 70% of the studies with simple accommodations and/or minor procedural modifications.

DISCUSSION

The findings highlight the exclusion of persons with ID in medical research. Efforts are needed to increase inclusion through research policy initiatives and education.

Muscular responses during motor imagery as a function of muscle contraction types

This study was designed to gain more insight into the mechanisms underlying motor imagery (MI). While there is ample evidence that motor performance and MI share common central neural mechanisms, the question whether MI is accompanied by subliminal electromyographic (EMG) activity remained unsolved. Thirty right-handed volunteers were asked to lift or to imagine lifting a weighted dumbbell using different types of muscle contraction, i.e. heavy concentric, light concentric, isometric and eccentric contractions. EMG activity from 9 muscles of the dominant arm (agonist, antagonist, synergist and fixator muscles) was monitored. Autonomic nervous system responses were also recorded on the non-dominant hand, thus attesting mental activity at the peripheral level. A significant increased pattern of EMG activity was recorded in all muscles during MI, when compared to the rest condition, while the goniometric data did not reveal any movement. Although being subliminal, the magnitude of this activation was found to be correlated to the mental effort required to lift a weight mentally, as more EMG activity was recorded during imaginary lifting of heavy than light concentric contractions. When considering the different types of contraction, our results provided evidence of selective changes in EMG activity. Especially, the imagined eccentric condition elicited a significant weaker muscular activity than all other conditions. In addition, the changes in the EMG pattern mirrored those usually observed during physical movement. These findings support the hypotheses of a selective effect of MI at the level of muscular activity and of incomplete inhibition of the motor command during MI.

Reliability of tuberculin skin test measurement

BACKGROUND

Important management decisions depend on results of the tuberculin skin test. However, the test is subject to several potential errors, and its reliability has not been adequately studied.

OBJECTIVE

To ascertain the reliability of tuberculin skin testing.

DESIGN

Cross-sectional study.

SETTING

University hospital.

PARTICIPANTS

96 persons who received a tuberculin skin test.

MEASUREMENTS

Ballpoint-pen and palpation measures of induration.

RESULTS

Global intra- and interobserver reliability coefficients of the ballpoint-pen technique were high. Five percent of the time, however, a second measurement by the same observer could be at least 2.7 mm less to 3.0 mm more than the first measurement and the measurement from the second observer could be at least 3.4 mm less to 3.7 mm more than the measurement from the first observer. This could lead to the reclassification of a positive test result as negative or vice versa. The area of imprecision was 38% less broad for the ballpoint-pen technique than for the palpation technique.

CONCLUSION

Reading of tuberculin skin tests may frequently result in misclassifications when measurements are close to the cutoff point that separates negative from positive results.

Imagery quality estimated by autonomic response is correlated to sporting performance enhancement

It is now well established that mental imagery practice improves motor skills, but performance efficiency depends on many factors: the main one being individual differences. The aim of this study is to evaluate performance improvement with imagery quality estimated during ANS recording. Volleyball training ("receiving serve") afforded us the experimental paradigm. Subjects were required to pass an opponent's serve to a given team mate. The receiver's performance was evaluated from the accuracy of his pass to the targeted team mate. From these first test results, subjects were divided into two equivalent groups: imagers and controls. After mental practice the two groups were submitted to a posttest similar to the first one. During the pretest, posttest actual practice as well as the last session of corresponding mental rehearsal, six autonomic parameters were continuously recorded. Furthermore, and for the first time, a grade obtained from four different aspects of this response permits qualitative evaluation of each subject's mental imagery. This estimation, based on the well-established link between performance and autonomic response, is validated by the fact that good correlation was obtained between this grade and the performance improvement of each of the "imager" group subjects.

Exchangeable copper: a reflection of the neurological severity in Wilson's disease

BACKGROUND AND PURPOSE

The severity of Wilson's disease (WD) is linked to free copper accumulating in the liver and brain. Exchangeable copper (CuEXC) is a new technique to determine plasmatic copper and is useful in the diagnosis of WD. It is hypothesized that it may also enable a good evaluation of extra-hepatic involvement and its severity.

METHODS

Forty-eight newly diagnosed WD patients were prospectively evaluated using hepatic, neurological, ophthalmological and brain magnetic resonance imaging (MRI) scores. Three phenotypic presentations were distinguished: pre-symptomatic, hepatic and extra-hepatic. CuEXC was determined in addition to standard copper assays before decoppering therapy. Correlations between biological parameters and the different scores were determined and compared in the hepatic and extra-hepatic groups.

RESULTS

Extra-hepatic patients had significantly higher CuEXC values than those with the hepatic form (P < 0.0001). The overall ability of CuEXC to separate the two forms was satisfactory, with an area under the curve of 0.883 (95% confidence interval 0.771-0.996) and an optimal threshold for extra-hepatic diagnosis of 2.08 μmol/l (sensitivity 85.7%; specificity 94.1%). In extra-hepatic patients, CuEXC was the only biological marker to be positively correlated with the Unified Wilson Disease Rating Score (r = 0.45, P = 0.016), the Kayser-Fleischer ring score (r = 0.46, P = 0.014) and the brain MRI score (r = 0.38, P = 0.048), but it was not correlated with the hepatic score.

CONCLUSIONS

Exchangeable copper determination is useful when diagnosing WD as a value >2.08 μmol/l is indicative of the severity of the extra-hepatic involvement. In the case of purely hepatic presentation, atypical or mild neurological signs, it should encourage physicians to search for lesions in the brain and eyes.

Molecular cloning and characterization of esterase-6, a serine hydrolase of Drosophila

The Est-6 gene of Drosophila melanogaster was cloned by screening libraries with synthetic oligonucleotides corresponding to tryptic peptides from purified esterase-6 (Est-6) protein. cDNA clones were isolated that hybridized in situ to the site of Est-6 on chromosome 3 at 69A1. Inserts in putative Est-6 cDNA clones were 1.85 kilobases (kb) long, and blot hybridization analysis of electrophoretically fractionated RNA, using a cDNA clone as a probe, revealed two transcripts, of 1.68 and 1.83 kb. The two transcripts showed the same developmental profile as the Est-6 protein. Neither transcript was detected in an Est-6-null line. The cDNA fragment was homologous to a 2.3-kb EcoRI-BamHI fragment in genomic clones, and this region was interrupted by the 8-kb B104 transposable element in the Est-6-null line. Conceptual translation of the cDNA sequence revealed a protein of 548 residues with 19% sequence similarity to acetylcholinesterase from the Torpedo ray.

Autonomic nervous system correlates in movement observation and motor imagery

The purpose of the current article is to provide a comprehensive overview of the literature offering a better understanding of the autonomic nervous system (ANS) correlates in motor imagery (MI) and movement observation. These are two high brain functions involving sensori-motor coupling, mediated by memory systems. How observing or mentally rehearsing a movement affect ANS activity has not been extensively investigated. The links between cognitive functions and ANS responses are not so obvious. We will first describe the organization of the ANS whose main purposes are controlling vital functions by maintaining the homeostasis of the organism and providing adaptive responses when changes occur either in the external or internal milieu. We will then review how scientific knowledge evolved, thus integrating recent findings related to ANS functioning, and show how these are linked to mental functions. In turn, we will describe how movement observation or MI may elicit physiological responses at the peripheral level of the autonomic effectors, thus eliciting autonomic correlates to cognitive activity. Key features of this paper are to draw a step-by step progression from the understanding of ANS physiology to its relationships with high mental processes such as movement observation or MI. We will further provide evidence that mental processes are co-programmed both at the somatic and autonomic levels of the central nervous system (CNS). We will thus detail how peripheral physiological responses may be analyzed to provide objective evidence that MI is actually performed. The main perspective is thus to consider that, during movement observation and MI, ANS activity is an objective witness of mental processes.

Intracellular calcium signals measured with indo-1 in isolated skeletal muscle fibres from control and mdx mice

1. Intracellular free calcium concentration ([Ca2+]i) was measured with the fluorescent indicator indo-1 in single skeletal fibres enzymatically isolated from the flexor digitorum brevis and interosseus muscles of control and dystrophic mdx C57BL/10 mice. Measurements were taken from a portion of fibre that was voltage clamped to allow detection of depolarization-induced changes in [Ca2+]i. 2. The mean (+/- s.e.m.) initial resting [Ca2+]i from all control and mdx fibres tested was 56 +/- 5 nM (n = 72) and 48 +/- 7 nM (n = 57), respectively, indicating no significant overall difference between the two groups. However, when comparing a batch of control and mdx fibres obtained from mice older than approximately 35 weeks, resting [Ca2+]i was significantly lower in mdx (16 +/- 4 nM, n = 11) than in control fibres (71 +/- 10 nM, n = 14). 3. Changes in [Ca2+]i elicited by short (5-35 ms) depolarizing pulses from -80 to 0 mV showed similar properties in control and mdx fibres. After a 5 ms duration pulse the mean time constant of [Ca2+]i decay was, however, significantly elevated in mdx as compared to control fibres, by a factor of 1.5-2. For longer pulses, no significant difference could be detected. 4. In response to 50 ms duration depolarizing pulses of various amplitudes the threshold for detection of an [Ca2+]i change and the peak [Ca2+]i reached for a given potential were similar in control and mdx fibres. 5. Overall results show that mdx skeletal muscle fibres are quite capable of handling [Ca2+]i at rest and in response to membrane depolarizations.

Relationship Between Visual and Kinesthetic Imagery, Field Dependence-Independence, and Complex Motor Skills

Abstract: Visual imagery (VI) involves self-visualization of action, whereas kinesthetic imagery (KI) implies somesthetic sensations elicited by action. Motor imagery (MI) has been shown to enhance motor performance but inconsistent results were obtained depending on the respective impacts of VI and KI. It is hypothesized here that the type of MI may interact with individual characteristics such as field dependence-independence. As subjects' movements can be mainly checked out through exteroceptive or proprioceptive information, task requirements were also expected to influence MI. Witkin's Group Embedded Figures Test was implemented with two groups (n1 = 10 gymnasts, n2 = 10 tennis players). Athletes were asked to imagine a complex motor skill by alternate use of VI and KI. Skin resistance was selected as a peripheral indicator of MI and recorded continuously. Autonomic responses were compared by computing the VI/KI ratio. Results taking both the field-dependence test and MI type into account were not as clear as expected. As hypothesized, gymnasts were more field-independent than tennis players. VI/KI ratio analysis showed that a similar pattern was observed in the gymnasts group (ratio close to 1.0), whatever the type of imagery. This suggests that gymnasts are equally able to perform VI and KI. Fifty percent of the tennis players group showed a ratio higher than 1.0, suggesting that VI was more effective than KI. Conversely, the remaining 50% showed a below-1.0 ratio, suggesting more effective KI. Thus, some tennis players may make better use of VI than KI, and conversely some may make better use of KI than VI. These results indicate that MI training may be relatively independent of task requirements and be based mainly upon individual characteristics such as MI abilities. Finally, results indicate systematic overestimation in self-estimation of movement duration during MI, which was greater during KI than during VI, suggesting that athletes have greater trouble in feeling than in visualizing movement.

Phoning while driving I: a review of epidemiological, psychological, behavioural and physiological studies

The impact of cell (mobile) phone use on driving performance has been widely questioned for 20 years. This paper reviews the literature to evaluate the extent to which phoning may impact behaviour with a risk to affect safety. After analysing epidemiological studies that give an overview of cell phone use, this paper examines the experimental results and focuses on variables showing that driving is impacted by holding a mobile-phone conversation. Information processing (e.g. reaction time and detection rate of cues related to driving information) and variables associated with vehicle control (e.g. lane-keeping, headway and vehicle speed) seem the most relevant. Although less studied than behavioural indices, physiological data give information about the supplementary potential strain that the driver may undergo under dual-task conditions. This first part of the review highlights common findings, questionable results and differences among studies, which originate from specific experimental designs with particular dependent variables, i.e. self-report, behavioural and physiological indicators. Finally, how drivers try to compensate for the additional load brought by phone use is described. STATEMENT OF RELEVANCE: The two papers review the influence of mobile-phone use on driving performance. While there is ample evidence that this dual task is likely to increase the risk of car crash, the review analyses the variables eliciting detrimental conditions and, conversely, those that may preserve acceptable conditions for safety, close to usual driving. The decision of answering or initiating a cell phone call while driving depends upon the complex interaction among several variables, including driving conditions and driver's own characteristics. In addition, this decision remains under driver's awareness of being able or not to manage the two tasks simultaneously.

Intramembrane charge movement and L-type calcium current in skeletal muscle fibers isolated from control and mdx mice

Dystrophin-deficient muscle fibers from mdx mice are believed to suffer from increased calcium entry and elevated submembranous calcium level, the actual source and functional consequences of which remain obscure. Here we compare the properties of the dihydropyridine receptor as voltage sensor and calcium channel in control and mdx muscle fibers, using the silicone-voltage clamp technique. In control fibers charge movement followed a two-state Boltzmann distribution with values for maximal charge, midpoint voltage, and steepness of 23 +/- 2 nC/ micro F, -37 +/- 3 mV, and 13 +/- 1 mV (n = 7). Essentially identical values were obtained in mdx fibers and the time course of charge recovery from inactivation was also similar in the two populations (tau approximately 6 s). In control fibers the voltage dependence of the slow calcium current elicited by 100-ms-long pulses gave values for maximal conductance, apparent reversal potential, half-activation potential, and steepness factor of 156 +/- 15 S/F, 65.5 +/- 2.9 mV, -0.76 +/- 1.2 mV, and 6.2 +/- 0.5 mV (n = 17). In mdx fibers, the half-activation potential of the calcium current was slightly more negative (-6.2 +/- 1.2 mV, n = 16). Also, when using longer pulses, the time constant of calcium current decay was found to be significantly larger (by a factor of 1.5-2) in mdx than in control fibers. These changes in calcium current properties are unlikely to be primarily responsible for a dramatic alteration of intracellular calcium homeostasis. They may be speculated to result, at least in part, from remodeling of the submembranous cytoskeleton network due to the absence of dystrophin.

How many insulin-like growth factor binding proteins?

Mac25, connective tissue growth factor, the nov-oncogene and cyr61 have been proposed as insulin-like growth factor binding proteins (IGFBPs) although they bind the ligand with very low affinity. Sequence similarity between the candidate proteins and the recognised IGFBPs is restricted to a single cysteine-rich N-terminal domain. The cysteine-rich domain (CRD) can be found in other vertebrate and invertebrate proteins that are associated with the extracellular matrix but otherwise have vastly different functions. Characteristically, the proteins with the CRD have a modular architecture suggesting that exon shuffling has played a significant role in their evolution. Although the proposed candidate proteins may not be IGFBPs, linkage relationships of the latter suggest that two other IGFBPs may indeed exist.

Physiological and behavioural changes associated to the management of secondary tasks while driving

Sharing attention between two tasks requiring the same mental resources is supposed to increase the resulting strain. Phoning while driving may elicit cognitive interference between driving operations and conversation and consequently, may affect driving efficiency. The road scene cues may thus be perceived late or even omitted, increasing the probability to be involved in a critical situation. The aim of the experiment was to study how the additional strain elicited by a secondary task may change drivers' arousal with potential consequences on driving performance. Electrodermal activity, heart rate and reaction time (RT) were the dependent variables. Listening to the radio, holding an in-vehicle or a cell-phone conversation were the secondary communication tasks, performed by 10 participants during a driving sequence on a private circuit. Within nominal driving, each communication task was requested at random to prevent any habituation or anticipation. The cell-phone conversation made RT increase by about 20%, by comparison to the nominal driving condition. Nevertheless, the in-vehicle conversation impacted RT almost in the same proportion. Physiological data showed that arousal level increased as a function of dual-tasks requirements, the in-vehicle conversation eliciting the same strain as the remote conversation. With caution due to contextual differences between these two communication tasks, conversing with a passenger was thus as detrimental as using a cell-phone.

Monitoring galenical process development by near infrared chemical imaging: One case study

The objective of this study is to evaluate by NIR imaging the homogeneity of process intermediates obtained with different process parameters during the development of a new pharmaceutical solid form. The process under investigation is a solid dosage form based on extrusion. The parameters are two kinds of crystallizations, two sizes of particle of API, two screw speeds during the extrusion and two milling screens used to reduce the extrudates into a granulate form. Two kinds of intermediates are evaluated: the extrudates and the cores. Two approaches are used to analyze the data: the univariate NIR analysis which consists in wavelength selection and multivariate analysis, i.e., Classical Least Squares (CLS), which takes into account the whole spectra. The univariate method reveals good chemical homogeneity of the extrudates but differences in their physical aspect. CLS shows well-distributed excipients for all the cores; differences in the sizes of the granules have also been revealed. The univariate method can be applied on simple chemical systems such as binary mixtures. When complex samples are analyzed, multivariate analysis is the method of choice. This study demonstrates that NIR imaging can be a useful tool for the optimization of the process and for the selection of the final parameters of the process.

Stepwise control of osteogenic differentiation by 5-HT(2B) receptor signaling: nitric oxide production and phospholipase A2 activation

During development, antagonists of 5-HT(2) receptor subtypes cause morphological defects of mesodermal and neural crest derivatives including the craniofacial skeleton. We used an inducible mesoblastic cell line, C1, able to fully convert into osteocytes within 12 days, to assess the involvement of 5-HT(2) receptors during osteogenic differentiation. On day 5 of the osteogenic program, immediately before matrix mineralization, the cells selectively implement 5-HT(2B) receptors (5-HT(2B)R) which remain functional until terminal differentiation. In 5-HT-depleted medium, the receptor exhibits a constitutive activity leading to basal nitric oxide (NO) release and phospholipase A2 (PLA2)-dependent arachidonic acid (AA) production. Blockade of this intrinsic activity affects the efficiency of mineralization by decreasing calcium incorporation within the matrix by 40%. Optimal bone matrix mineralization involves both NO and PLA2 signaling pathways. Moreover, between day 5 and day 10, at the beginning of mineral deposition, the 5-HT(2B)R promotes prostaglandin E2 production through AA-dependent cyclooxygenase (COX) activation. From day 10 onwards, when C1 osteoblasts undergo conversion into osteocyte-like cells, COX activity is quenched. Altogether these observations indicate that the 5-HT(2B)R contributes in an autocrine manner to osteogenic differentiation and highlight a switch in the downstream targets of the receptor at the terminal stage of the program. Finally, in addition to its autocrine function, the 5-HT(2B)R responds to 5-HT by increasing NO production and AA release. These findings raise concern regarding the use of 5-HT(2B)R-related drugs that may interfere with bone metabolism in physiological or pathological situations.

Modulation of EMG power spectrum frequency during motor imagery

To provide evidence that motor imagery (MI) is accompanied by improvement of intramuscular conduction velocity (CV), we investigated surface electromyographic (EMG) activity of 3 muscles during the elbow flexion/extension. Thirty right-handed participants were asked to lift or to imagine lifting a weighted dumbbell under 3 types of muscular contractions, i.e. concentric, isometric and eccentric, taken as independent variables. The EMG activity of the agonist (long and short heads of biceps brachii) and the antagonist (long portion of triceps brachii) muscles was recorded and processed to determine the median frequency (MF) of EMG power spectrum as dependant variable. The MF was significantly higher during the MI sessions than during the resting condition while the participants remained strictly motionless. Moreover, the MF during imagined concentric contraction was significantly higher than during the eccentric. Thus, the MF variation was correlated to the type of contraction the muscle produced. During MI, the EMG patterns corresponding to each type of muscle contraction remained comparable to those observed during actual movement. In conclusion, specific motor programming is hypothesized to be performed as a function of muscle contraction type during MI.

Comparison of recombinant barramundi and human insulin-like growth factor (IGF)-I in juvenile barramundi (Lates calcarifer): in vivo metabolic effects, association with circulating IGF-binding proteins, and tissue localisation

The in vivo actions of human and fish insulin-like growth factor (IGF)-I have been compared to extend the understanding of the metabolism of IGFs in fish and to identify potential differences in their actions. The effects of acute administration of these proteins on the incorporation of glucose into muscle glycogen and leucine into liver protein in juvenile barramundi were investigated. In these in vivo metabolic assays, both baramundi IGF-I (bIGF-I) and human IGF-I (hIGF-I) increase the incorporation of D-[14C]glucose into muscle glycogen and [14C]leucine into liver protein. The distribution of radio-labeled human and barramundi IGF-I in the circulation and their uptake by tissue was also compared in juvenile barramundi (Lates calcarifer). Analysis of trichloroacetic acid-precipitable radioactivity in sequential samples following bolus injection of radiolabeled IGFs revealed that hIGF-I was degraded faster than bIGF-I. Neutral gel chromatography of these samples suggested that this difference is due to reduced affinity of hIGF-I, compared to bIGF-I, for the IGF-binding proteins (IGFBPs) present in the barramundi. Tissue uptake of [125I]-labeled hIGF-I and bIGF-I was similar except that [ 125I]bIGF-I uptake by the kidney exceeded that of hIGF-I. It is suggested that while some of the in vivo actions of IGFs in fish are conserved, functional differences between mammalian and teleostean IGFs exist, particularly with respect to their interactions with fish IGFBPs.