The use of anabolic-androgenic steroids in sport and the preventive role of the pharmacist

The use of chemical substances to enhance physical activity is not a contemporary phenomenon; it goes back thousands of years. However, it has increased to alarming proportions in the last four decades and has created a serious problem in the world of sport, spreading many ramifications (Donohoe and Johnson, 1986). A broad array of pharmacological agents are employed to enhance athletic performance (i.e. doping). The most notorious of these drugs have been anabolic-androgenic steroids (AS). Abuse of AS by athletes constitutes just one aspect of doping of athletes (Wilson, 1988). AS are a group of synthetic steroid compounds that are structurally related to the natural male sex hormone testosterone (Murad and Haynes, 1985). Testosterone was isolated in 1935 and its metabolic effects elucidated shortly after. In 1939, Boje suggested that the use of male sex hormones might enhance athletic performance (Yesalis, et al. 1989).peer-reviewe

The heme-hemopexin scavenging system is active in the brain, and associates with outcome after subarachnoid hemorrhage

Background and Purpose – Long-term outcome after subarachnoid hemorrhage (SAH) is potentially linked to cytotoxic heme. Free heme is bound by hemopexin (Hpx) and rapidly scavenged by CD91. We hypothesized that heme scavenging in the brain would be associated with outcome after haemorrhage. Methods - Using cerebrospinal fluid (CSF) and tissue from SAH patients and control individuals, the activity of the intracranial CD91-Hpx system was examined using enzyme-linked immunoassays, ultra-high performance liquid chromatography and immunohistochemistry. Results - In control individuals, CSF Hpx was mainly synthesized intrathecally. After SAH, CSF Hpx was high in one-third of cases, and these patients had a higher probability of delayed cerebral ischaemia and poorer neurological outcome. The intracranial CD91-Hpx system was active after SAH since CD91 positively correlated with iron deposition in brain tissue. Heme-Hpx uptake saturated rapidly after SAH, since bound heme accumulated early in the CSF. When the blood-brain barrier was compromised following SAH, serum Hpx level was lower, suggesting heme transfer to the circulation for peripheral CD91 scavenging. Conclusions - The CD91-heme-Hpx scavenging system is important after SAH and merits further study as a potential prognostic marker and therapeutic target

Unusual case of intracranial dural AV fistula presenting with acute myelopathy

We present a case of intracranial arteriovenous fistula with perimedullary venous drainage presenting with acute myelopathy, which is an unusual presentation of this uncommon condition. Subsequent catheter angiogram defined the arterial feeders from the meningohypophyseal trunk and petrosal branch of the middle meningeal artery. The patient was successfully embolised, resulting in complete obliteration of the fistula, and significant resolution of brainstem and cervical cord changes along with clinical improvement

Searching for Dark Matter at the LHC with a Mono-Z

We investigate a mono-Z process as a potential dark matter search strategy at the LHC. In this channel a single Z boson recoils against missing transverse momentum, attributed to dark matter particles, $\chi$, which escape the detector. This search strategy is related, and complementary to, monojet and monophoton searches. For illustrative purposes we consider the process $q\bar{q} -> \chi\chi Z$ in a toy dark matter model, where the Z boson is emitted from either the initial state quarks, or from the internal propagator. Among the signatures of this process will be a pair of muons with high pT that reconstruct to the invariant mass of the Z, and large amounts of missing transverse energy. Being a purely electroweak signal, QCD and other Standard Model backgrounds are relatively easily removed with modest selection cuts. We compare the signal to Standard Model backgrounds and demonstrate that, even for conservative cuts, there exist regions of parameter space where the signal may be clearly visible above background in future LHC data, allowing either new discovery potential or the possibility of supplementing information about the dark sector beyond that available from other observable channels.Comment: 11 pages, 13 figure

Chronologic and dental ages of Maltese schoolchildren : a pilot study

Objectives: Dental ageing systems are useful for forensic, research and clinical purposes. As no data exists relating to the dental development of the Maltese population, we set up a pilot study to initiate formation of a set of tables pertaining to the dental development of Maltese schoolchildren. Methods: Panoramic radiographic records of 120 patients aged 11 to 14 years were sequentially collected from the records kept at the School Dental Clinic, Floriana and St Luke’s Hospital. These records were matched for age and sex. The calcification of the teeth was graded according to Nolla (1960) and the results obtained compared to Nolla’s tables to determine how closely the Maltese population conforms to these tables. Results: We found no significant difference between the estimated (dental) age and the chronological age of male schoolchildren. A significant difference existed for female schoolchildren. The dental age of the female schoolchildren was delayed when compared to that of male schoolchildren. Conclusion: Nolla’s tables require to be adjusted to take into account the variation in dental development of the Maltese population. Maltese schoolgirls exhibit slower dental development when compared to the figures given in the literature.peer-reviewe

Use of optical fibres for multi-parameter monitoring in electrical AC machines

This paper describes a new approach to multi-parameter monitoring for electrical AC machines. It is demonstrated that speed, torque and temperature can be measured using optical fibres incorporating sensors in the form of fibre Bragg gratings (FBGs) distributed around the machine. One fibre can incorporate several FBGs and hence provide several measurements. Experimental results showing speed, torque, direction of rotation, stator housing vibration and temperature measured using the FBG method are presented and validated against measurements obtained from conventional sensors. The results show that the optical fibre based approach allows multiple parameters to be monitored accurately and simultaneously with only a fraction of the usual monitoring equipment required. Another advantage of the proposed method is the EMI immunity naturally provided by optical solutions. The presented measurement technique can also offer a new alternative approach to sensorless control

The contribution of explicit processes to reinforcement-based motor learning

Despite increasing interest in the role of reward in motor learning, the underlying mechanisms remain ill defined. In particular, the contribution of explicit processes to reward-based motor learning is unclear. To address this, we examined subjects’ ( n = 30) ability to learn to compensate for a gradually introduced 25° visuomotor rotation with only reward-based feedback (binary success/failure). Only two-thirds of subjects ( n = 20) were successful at the maximum angle. The remaining subjects initially followed the rotation but after a variable number of trials began to reach at an insufficiently large angle and subsequently returned to near-baseline performance ( n = 10). Furthermore, those who were successful accomplished this via a large explicit component, evidenced by a reduction in reach angle when they were asked to remove any strategy they employed. However, both groups displayed a small degree of remaining retention even after the removal of this explicit component. All subjects made greater and more variable changes in reach angle after incorrect (unrewarded) trials. However, subjects who failed to learn showed decreased sensitivity to errors, even in the initial period in which they followed the rotation, a pattern previously found in parkinsonian patients. In a second experiment, the addition of a secondary mental rotation task completely abolished learning ( n = 10), while a control group replicated the results of the first experiment ( n = 10). These results emphasize a pivotal role of explicit processes during reinforcement-based motor learning, and the susceptibility of this form of learning to disruption has important implications for its potential therapeutic benefits. NEW &amp; NOTEWORTHY We demonstrate that learning a visuomotor rotation with only reward-based feedback is principally accomplished via the development of a large explicit component. Furthermore, this form of learning is susceptible to disruption with a secondary task. The results suggest that future experiments utilizing reward-based feedback should aim to dissect the roles of implicit and explicit reinforcement learning systems. Therapeutic motor learning approaches based on reward should be aware of the sensitivity to disruption. </jats:p

W/Z Bremsstrahlung as the Dominant Annihilation Channel for Dark Matter, Revisited

We revisit the calculation of electroweak bremsstrahlung contributions to dark matter annihilation. Dark matter annihilation to leptons is necessarily accompanied by electroweak radiative corrections, in which a $W$ or $Z$ boson is also radiated. Significantly, while many dark matter models feature a helicity suppressed annihilation rate to fermions, bremsstrahlung process can remove this helicity suppression such that the branching ratios Br($\ell \nu W$), Br($\ell^+\ell^-Z$), and Br($\bar\nu \nu Z$) dominate over Br($\ell^+\ell^-$) and Br($\bar\nu \nu$). We find this is most significant in the limit where the dark matter mass is nearly degenerate with the mass of the boson which mediates the annihilation process. Electroweak bremsstrahlung has important phenomenological consequences both for the magnitude of the total dark matter annihilation cross section and for the character of the astrophysical signals for indirect detection. Given that the $W$ and $Z$ gauge bosons decay dominantly via hadronic channels, it is impossible to produce final state leptons without accompanying protons, antiprotons, and gamma rays.Comment: 8 pages, 6 figures; replaced to match published versio

Sex differences in predictors and regional patterns of brain age gap estimates

The brain-age-gap estimate (brainAGE) quantifies the difference between chronological age and age predicted by applying machine-learning models to neuroimaging data and is considered a biomarker of brain health. Understanding sex differences in brainAGE is a significant step toward precision medicine. Global and local brainAGE (G-brainAGE and L-brainAGE, respectively) were computed by applying machine learning algorithms to brain structural magnetic resonance imaging data from 1113 healthy young adults (54.45% females; age range: 22–37 years) participating in the Human Connectome Project. Sex differences were determined in G-brainAGE and L-brainAGE. Random forest regression was used to determine sex-specific associations between G-brainAGE and non-imaging measures pertaining to sociodemographic characteristics and mental, physical, and cognitive functions. L-brainAGE showed sex-specific differences; in females, compared to males, L-brainAGE was higher in the cerebellum and brainstem and lower in the prefrontal cortex and insula. Although sex differences in G-brainAGE were minimal, associations between G-brainAGE and non-imaging measures differed between sexes with the exception of poor sleep quality, which was common to both. While univariate relationships were small, the most important predictor of higher G-brainAGE was self-identification as non-white in males and systolic blood pressure in females. The results demonstrate the value of applying sex-specific analyses and machine learning methods to advance our understanding of sex-related differences in factors that influence the rate of brain aging and provide a foundation for targeted interventions