Shannon M. Fernando

Myocyte Androgen Receptors Increase Metabolic Rate and Improve Body Composition by Reducing Fat Mass

Testosterone and other androgens are thought to increase lean body mass and reduce fat body mass in men by activating the androgen receptor. However, the clinical potential of androgens for improving body composition is hampered by our limited understanding of the tissues and cells that promote such changes. Here we show that selective overexpression of androgen receptor in muscle cells (myocytes) of transgenic male rats both increases lean mass percentage and reduces fat mass. Similar changes in body composition are observed in human skeletal actin promoter driving expression of androgen receptor (HSA-AR) transgenic mice and result from acute testosterone treatment of transgenic female HSA-AR rats. These shifts in body composition in HSA-AR transgenic male rats are associated with hypertrophy of type IIb myofibers and decreased size of adipocytes. Metabolic analyses of transgenic males show higher activity of mitochondrial enzymes in skeletal muscle and increased O(2) consumption by the rats. These results indicate that androgen signaling in myocytes not only increases muscle mass but also reduces fat body mass, likely via increases in oxidative metabolism.

Sexual Differentiation of the Spinal Nucleus of the Bulbocavernosus Is Not Mediated Solely by Androgen Receptors in Muscle Fibers

The spinal nucleus of the bulbocavernosus (SNB) neuromuscular system is a highly conserved and well-studied model of sexual differentiation of the vertebrate nervous system. Sexual differentiation of the SNB is currently thought to be mediated by the direct action of perinatal testosterone on androgen receptors (ARs) in the bulbocavernosus/levator ani muscles, with concomitant motoneuron rescue. This model has been proposed based on surgical and pharmacological manipulations of developing rats as well as from evidence that male rats with the testicular feminization mutation (Tfm), which is a loss of function AR mutation, have a feminine SNB phenotype. We examined whether genetically replacing AR in muscle fibers is sufficient to rescue the SNB phenotype of Tfm rats. Transgenic rats in which wild-type (WT) human AR is driven by a human skeletal actin promoter (HSA-AR) were crossed with Tfm rats. Resulting male HSA-AR/Tfm rats express WT AR exclusively in muscle and nonfunctional Tfm AR in other tissues. We then examined motoneuron and muscle morphology of the SNB neuromuscular system of WT and Tfm rats with and without the HSA-AR transgene. We observed feminine levator ani muscle size and SNB motoneuron number and size in Tfm males with or without the HSA-AR transgene. These results indicate that AR expression in skeletal muscle fibers is not sufficient to rescue the male phenotype of the SNB neuromuscular system and further suggest that AR in other cell types plays a critical role in sexual differentiation of this system.

Overexpression of Androgen Receptors in Target Musculature Confers Androgen Sensitivity to Motoneuron Dendrites

The dendritic arbors of spinal motoneurons are dynamically regulated by a variety of factors, and several lines of evidence indicate that trophic interactions with the target musculature are of central importance. In highly androgen-sensitive motoneuron populations, androgens are thought to regulate motoneuron dendrites through their action at the receptor-enriched target musculature. Using rats transgenically modified to overexpress androgen receptor (AR) in skeletal muscle, we directly tested the hypothesis that the enhanced expression of AR in the target musculature can underlie the androgenic regulation of motoneuron dendritic morphology. The morphology of motoneurons innervating the quadriceps muscle was examined in wild-type (WT) rats as well as in rats that had been transgenically modified to overexpress ARs in their skeletal musculature. Motoneurons innervating the vastus lateralis muscle of the quadriceps in gonadally intact male rats, and castrated males with or without androgen replacement, were labeled with cholera toxin-conjugated horseradish peroxidase, and dendritic arbors were reconstructed in three dimensions. In WT rats, quadriceps motoneuron dendrites were insensitive to hormonal manipulation. In contrast, quadriceps motoneuron dendrites in gonadally intact transgenic males were larger than those of WT males. Furthermore, overexpression of ARs in the quadriceps muscle resulted in androgen sensitivity in dendrites, with substantial reductions in dendritic length occurring after castration; this reduction was prevented with testosterone replacement. Thus, it appears that the androgen sensitivity of motoneuron dendrites is conferred indirectly via the enrichment of ARs in the musculature.

Subcellular effects of myocyte-specific androgen receptor overexpression in mice

Although androgen receptor (AR) within myocytes is thought to mediate many of the effects of testosterone and other androgens on skeletal muscle, little is known about the functions of AR within these cells. We, therefore, studied the ultrastructure of skeletal muscle of HSA-AR transgenic (Tg) mice that overexpress AR selectively in myocytes and exhibit neuromuscular atrophy. We examined male HSA-AR mice from two different founding lines: L78 (lower copy number and less severe phenotype) and L141 (higher copy number and more severe phenotype) and compared these to wild-type (Wt) brothers. We also examined testosterone-treated female mice from these two lines and compared them both to their Wt sisters and to vehicle-treated controls. Ultrastructural examination of extensor digitorum longus sections using transmission electron microscopy revealed remarkably disorganized myofibrils in male Tg and testosterone-treated female Tg mice. Quantification of ultrastructural pathology indicated reduced myofibril width, hypertrophic and hyperplastic intermyofibrillar mitochondria, and pronounced glycogen accumulation in HSA-AR males of both lines. Reduced myofibrillar width and increases in mitochondrial number, size, and volume density were also observed in testosterone-treated HSA-AR females, although glycogen accumulation was not observed. Structural abnormalities in mitochondria were also associated with increases in electron transport chain activity and systemic resting metabolic rate, indicative of hypermetabolism. We find that overexpression of AR in myocytes of HSA-AR mice results in alterations in myofibrils, mitochondria, and glycogen. Alterations in myofibrils and mitochondria appear to result from acute actions of testosterone, whereas those on glycogen do not. Pathology of myofibrils and/or mitochondria may, therefore, mediate in part the neuromuscular atrophy observed in HSA-AR mice.

Hands-on defibrillation and electrocardiogram artefact filtering technology increases chest compression fraction and decreases peri-shock pause duration in a simulation model of cardiac arrest.

BACKGROUND Reducing pauses during cardiopulmonary resuscitation (CPR) compressions result in better outcomes in cardiac arrest. Artefact filtering technology (AFT) gives rescuers the opportunity to visualize the underlying electrocardiogram (ECG) rhythm during chest compressions, and reduces the pauses that occur before and after delivering a shock. We conducted a simulation study to measure the reduction of peri-shock pause and impact on chest compression fraction (CCF) through AFT. METHODS In a simulator setting, participants were given a standardized cardiac arrest scenario and were randomly assigned to perform CPR/defibrillation using the protocol from one of three experimental arms: 1) Standard of Care (pauses for rhythm analysis and shock delivery); 2) AFT (no pauses for rhythm analysis, but a pause for defibrillation); or 3) AFT with hands-on defibrillation (no pauses for rhythm analysis or defibrillation). The primary outcomes were CCF and peri-shock pause duration, with secondary outcomes of pre- and post-shock pause duration. RESULTS AFT with hands-on defibrillation was found to have the highest CCF (86.4%), as compared to AFT alone (83.8%, p<0.001), and both groups significantly improved CCF in comparison with the Standard of Care (76.7%, p<0.001). AFT with hands-on defibrillation was associated with a reduced peri-shock pause (2.6 seconds) as compared to AFT alone (5.3 seconds, p<0.001), and the Standard of Care (7.4 seconds, p<0.001). CONCLUSIONS In this cardiac arrest model, AFT results in a greater CCF by reducing peri-shock pause duration. There is also a small but detectable improvement in CCF with the addition of hands-on defibrillation.

Analysis of bystander CPR quality during out-of-hospital cardiac arrest using data derived from automated external defibrillators

BACKGROUND Little is known regarding the quality of cardiopulmonary resuscitation (CPR) performed by bystanders in out-of-hospital cardiac arrest (OHCA). We sought to determine quality of bystander CPR provided during OHCA using CPR quality data stored by Automated External Defibrillators (AEDs). METHODS We used the Resuscitation Outcomes Consortium database to identify OHCA cases of presumed cardiac etiology where an AED was utilized. We then matched AED data to each case identified. AED data was analyzed using manufacturer software in order to determine overall measures of bystander CPR quality, changes in bystander CPR quality over time, and adherence to existing 2010 Resuscitation Quality Guidelines. RESULTS 100 cases of OHCA of presumed cardiac etiology involving bystander CPR and with corresponding AED data. Mean age was 62.3 years, and 75% were male. Bystanders demonstrated high-quality CPR over all minutes of resuscitation, with a chest compression fraction of 76%, a compression depth of 5.3 cm, and a compression rate of 111.2 compressions/min. Mean perishock pause was 26.8 s. Adherence rates to 2010 Resuscitation Guidelines for compression rate and depth were found to be 66% and 55%, respectively. CPR quality was lowest in the first minute, resulting from increased delay to rhythm analysis (mean 40.7 s). In cases involving shock delivery, latency from initiation of AED to shock delivery was 59.2 s. CONCLUSIONS We found that bystanders perform high-quality CPR, with strong adherence rates to existing Resuscitation Guidelines. High-quality CPR is maintained over the first five minutes of resuscitation, but was lowest in the first minute.

Outcomes and Costs of Patients Admitted to the Intensive Care Unit Due to Accidental or Intentional Poisoning

Introduction: Acute poisoning represents a major cause of morbidity and mortality, and many of these patients are admitted to the intensive care unit (ICU). However, little is known regarding ICU costs of acute poisoning. Methods: This was a retrospective matched database analysis of patients admitted to the ICU with acute poisoning from 2011 to 2014. It was performed in 2 ICUs within a single tertiary care hospital system. All patient information, outcomes, and costs were stored in the hospital data warehouse. Control patients were defined as randomly selected age-, sex-, severity index-, and comorbidity index-matched nonpoisoned ICU patients (1:4 matching ratio). Results: A total of 8452 critically ill patients were admitted during the study period, of whom 277 had a diagnosis of acute poisoning. The mean age was 44.5 years, and the most common xenobiotics implicated were sedative hypnotics (20.2%), antidepressants (15.2%), and opioids (10.5%). Of these, 73.6% of poisonings were deemed intentional. In-hospital mortality of poisoned patients was 5.1%, compared to 11.1% for control patients (P < .01). The median ICU length of stay (LOS) for poisoned patients was 3.0 days, compared with 4.0 days for control patients (P < .01). The mean total cost for poisoned patients was CAD

Use of the low-frequency/high-frequency ratio of heart rate variability to predict short-term deterioration in emergency department patients with sepsis

18 958. Control patients had a significantly higher mean total cost of CAD

Impact of nighttime Rapid Response Team activation on outcomes of hospitalized patients with acute deterioration

60 628 (P < .01). The xenobiotics associated with the highest costs were acetaminophen (CAD

Sepsis-3 Septic Shock Criteria and Associated Mortality Among Infected Hospitalized Patients Assessed by a Rapid Response Team

18 585), toxic alcohols (CAD