The mechanisms of adaptation for muscle fascicle length changes with exercise: Implications for spastic muscle.

We are proposing optimal training conditions that can lead to an increase in the number of serial sarcomeres (SSN) and muscle fascicle length (FL) in spastic muscles. Therapeutic interventions for increasing FL in clinical populations with neurological origin, in whom relative shortness of muscle fascicles contributed to the presentation of symptoms such as spasticity, contracture, and limited functional abilities, do not generally meet these conditions, and therefore, result in less than satisfactory outcomes. Based on a review of literature, we argue that protocols of exercise interventions that led to sarcomerogenesis, and increases in SSN and FL in healthy animal and human models satisfied three criteria: 1) all involved eccentric exercise at appropriately high velocity; 2) resulted in positive strain of muscle fascicles; and 3) momentary deactivation in the stretched muscle. Accordingly, to increase FL in spastic muscles, new exercise protocols in which the three presumed criteria are satisfied, must be developed, and long-term muscle architectural and functional adaptations to such trainings must be examined.

Obesity and addiction: can a complication of surgery help us understand the connection?

Obesity is a multifactorial, chronic disease that has proven difficult to treat. An increased understanding of aetiological mechanisms is critical to the development of more effective obesity prevention and treatment strategies. A growing body of empirical evidence has demonstrated parallels between obesity, overeating and substance abuse, including shared behavioural, psychological and neurophysiological factors implicated in the excessive intake of both food and substances of abuse. Several different lines of research have recently emerged that hold the potential to shed light on the connection between obesity, food reward and addiction, with studies examining changes in alcohol use/misuse after weight loss surgery providing a particularly interesting perspective on these interrelationships. However, these lines of investigation have proceeded in relative isolation, and relevant research findings have yet to be integrated in a synthesized, comprehensive manner. To provide an opportunity to achieve such a synthesis, a scientific symposium was convened at the Radcliffe Institute in Cambridge, Massachusetts. Invited participants were researchers working in diverse domains related to the intersection between obesity and addiction. Extensive discussion was generated suggesting novel research directions. In this article, we summarize and synthesize the symposium participants' ongoing research in this area, incorporating additional relevant research holding potential clues regarding the connections between obesity, weight loss surgery and addiction.

Patterned feeding induces neuroendocrine, behavioral and genetic changes that promote palatable food intake.

BACKGROUND: Selection of a healthy diet is the cornerstone for treating obesity and metabolic disease. Unfortunately, the majority of diets fail leading to weight regain and in some cases, pathological feeding behavior. We hypothesize that alternating bouts of caloric overconsumption and caloric restriction, behavioral manifestations of dieting induce neuroendocrine, behavioral and genetic changes that promote future bouts of palatable food intake. METHODS: To test this hypothesis, we subjected male Long-Evans rats to a high-fat diet (HFD) feeding paradigm that induced a pattern of caloric overconsumption and caloric restriction. Under these conditions we measured operant responding for sucrose, pre-meal ghrelin secretion, the effects of peripheral ghrelin blockade on patterned feeding, HFD intake in an aversive environment and mRNA expression of the ghrelin receptor, orexin, orexin-1 and 2 receptors, and FTO in the medial prefrontal cortex, lateral hypothalamus and ventral tegmental area. RESULTS: Rats subjected to this feeding regimen displayed increased ghrelin levels prior to HFD exposure and blockade of this response attenuated patterned feeding behavior. In addition, patterned feeding promoted enhanced motivation for sucrose, diminished extinction of this response and increased HFD intake in an aversive environment. The neuroendocrine and behavioral changes correlated with increased hypothalamic expression of the ghrelin receptor and FTO. CONCLUSION: Collectively, these data indicate that patterns of feeding that include caloric overconsumption and caloric restriction induce neuroendocrine and neurobiological changes that signify an enhanced drive for palatable food.

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility.

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility's diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built-in calorimeters give in situ measurements of the x-ray environment along the sample lines of sight. The measured accuracy of sample responses as well as planned modifications to the XTRRA cassette is discussed.

A Langmuir probe diagnostic for time-of-flight measurements of transient plasmas produced by high-energy laser ablation.

We discuss here the development of a Langmuir probe (LP) diagnostic to examine high-density, high-temperature inhomogeneous plasmas such as those that can be created at the University of Rochester's Laboratory for Laser Energetics OMEGA facility. We have configured our diagnostic to examine the velocity of the plasma expanding from the target. We observe velocities of approximately 16-17 cm/µs, with individual LP currents displaying complex structures, perhaps due to the multiple atomic species and ionization states that exist.

Radiochromic film measurement of spatial uniformity for a laser generated x-ray environment.

An existing x-ray source application (XRSA) test cassette was modified to hold multiple x-ray filter materials followed by two radiochromic film types (FWT-60 and HD-810 Gafchromic® film) to qualitatively characterize the spectral-spatial uniformity over the XRSA sample field of view. Multiple sets of film were examined and nominal set was determined. These initial, qualitative measurements suggest a low-energy regime (E < 3 keV) spatial anisotropy and spatial isotropy at higher energies (E > 3 keV).

GOAT induced ghrelin acylation regulates hedonic feeding.

Ghrelin is an orexigenic hormone that regulates homeostatic and reward-related feeding behavior. Recent evidence indicates that acylation of ghrelin by the gut enzyme ghrelin O-acyl transferase (GOAT) is necessary to render ghrelin maximally active within its target tissues. Here we tested the hypothesis that GOAT activity modulates food motivation and food hedonics using behavioral pharmacology and mutant mice deficient for GOAT and the ghrelin receptor (GHSR). We evaluated operant responding following pharmacological administration of acyl-ghrelin and assessed the necessity of endogenous GOAT activity for operant responding in GOAT and GHSR-null mice. Hedonic-based feeding behavior also was examined in GOAT-KO and GHSR-null mice using a "Dessert Effect" protocol in which the intake of a palatable high fat diet "dessert" was assessed in calorically-sated mice. Pharmacological administration of acyl-ghrelin augmented operant responding; notably, this effect was dependent on intact GHSR signaling. GOAT-KO mice displayed attenuated operant responding and decreased hedonic feeding relative to controls. These behavioral results correlated with decreased expression of the orexin-1 receptor in reward-related brain regions in GOAT-KO mice. In summary, the ability of ghrelin to stimulate food motivation is dependent on intact GHSR signaling and modified by endogenous GOAT activity. Furthermore, GOAT activity is required for hedonic feeding behavior, an effect potentially mediated by forebrain orexin signaling. These data highlight the significance of the GOAT-ghrelin system for the mediation of food motivation and hedonic feeding.

Orexin signaling in the paraventricular thalamic nucleus modulates mesolimbic dopamine and hedonic feeding in the rat.

Data from our laboratory indicate that the orexin system is involved in the regulation of both conditioned and unconditioned responding for palatable foods. Anticipation of food rewards activates orexin receptor containing neurons within the paraventricular nucleus of the thalamus (PVT). The PVT regulates mesolimbic dopamine neurochemistry through direct connections with the nucleus accumbens and modulates the processing of cognitive-emotional information, suggesting that the PVT may represent a unique brain region with the capacity to mediate orexinergic effects on brain dopamine and behavior. Here, we tested the hypothesis that PVT orexin signaling mediates mesolimbic dopamine and reward-based feeding. To do this we used a behavioral pharmacological approach in tandem with central genetic manipulation of the orexin-1 receptor in the PVT. Data from these studies indicate that orexin-A action in the PVT increases dopamine levels in the nucleus accumbens. In addition, endogenous orexin signaling in the PVT mediates locomotor activity and hedonic feeding responses. Together these data highlight the PVT as a critical site capable of mediating orexin action on brain dopamine and reward-based feeding.

The role of orexin-A in food motivation, reward-based feeding behavior and food-induced neuronal activation in rats.

Consumption beyond homeostatic needs, referred to here as reward-based feeding behavior, is a central contributor to the current obesity epidemic worldwide. Importantly, reward-based feeding can be driven by palatability, the taste and texture of the food, as well as cues associated with the consumption of palatable foods. The hypothalamic orexin system regulates both diet preference and anticipation of food rewards making it a likely target to modulate reward-based feeding behavior. In the current manuscript we hypothesized that orexin signaling mediates food-motivated behaviors and reward-based feeding behavior. We further hypothesized that orexin neurons and targets of the orexin system become activated in response to cues associated with the consumption of palatable food. Data from these studies suggest that orexin signaling promotes progressive ratio responding for palatable foods while blockade of orexin signaling attenuates reward-based feeding of a high fat diet. In addition, cues linked to the consumption of chocolate, or the receipt of a daily meal, activate the orexin system and its target regions differentially. Collectively, these data suggest that orexin signaling mediates reward-based feeding behavior and, within specific target regions, may regulate cue-induced overconsumption of palatable foods.

Dominant rats are natural risk takers and display increased motivation for food reward.

Risk-taking behavior is a vital aspect mediating the formation of social structure in animals. Here, we utilized the visible burrow system (VBS), a model in which rats form dominance hierarchies, to test the hypothesis that dominant rats in the VBS are natural risk takers and display an increased motivational state after VBS exposure. In particular, we predicted that dominant rats would have attenuated anxiety-like behavior and augmented acquisition of operant responding for food reward relative to subordinate and controls. We further hypothesized that these behaviors would correlate with elevated mesocortical orexin signaling. Prior to burrow exposure, male Long-Evans rats were tested on the elevated plus maze (EPM), and subsequently exposed to the VBS for seven consecutive days. At the conclusion of burrow exposure body weight and plasma corticosterone were used to confirm social rank within each colony. Interestingly, rats that went on to become dominant in the VBS spent significantly more time in the open arms of the EPM prior to burrow exposure and displayed increased operant responding for food reward. This effect was present over a range of reinforcement schedules and also persisted for up to 1 month following VBS exposure. Moreover, dominant rats displayed increased orexin receptor mRNA in the medial prefrontal cortex (mPFC) relative to subordinate and control rats. These data support previous findings from our group and are consistent with the hypothesis that risk-taking behavior may precede dominance formation in social hierarchies.

Experimental reproduction of a spiking mortality syndrome of turkeys.

Two-day-old turkey poults were inoculated with either a chicken embryo homogenate used previously to produce spiking mortality syndrome in chickens (the "Oakwood Agent") or an intestine-pancreas homogenate collected from field turkeys with the syndrome known as spiking mortality of turkeys. Twelve days postinoculation, the mean plasma insulinlike growth factor-1 (IGF-1) level and mean body weights were significantly depressed, and the mean plasma growth hormone level was significantly elevated, in the poults receiving the turkey-derived homogenate (P < or = 0.0003), as was previously reported in chickens with spiking mortality syndrome. The depression in plasma IGF-1 levels may explain the runting seen in poults that survive spiking mortality of turkeys in the field. Following a 4-hr fast and a brief cool water spraying, poults exhibited clinical signs indistinguishable from those of chicks with spiking mortality syndrome. However, plasma glucose levels in the affected poults were within the normal range, unlike chickens with spiking mortality syndrome. Immunohistochemistry on formalin-fixed intestines, ceca, and bursae produced positive staining using an arenavirus antibody in epithelial cells of poults inoculated with the turkey homogenate and those inoculated with the Oakwood Agent. Tissues of uninoculated controls were negative. Poults inoculated with the Oakwood Agent did not show noticeable disease.

Experimental reproduction of hypoglycemia-spiking mortality syndrome in broiler chickens with the use of homogenized brains containing arenaviruslike particles.

Severe hypoglycemia-spiking mortality syndrome was experimentally reproduced in broiler chicks. Inoculum was homogenized brains from 28-day-old commercial broiler chicks with central nervous system signs (50% [v/v] in phosphate-buffered saline with 2% fetal calf serum). Oral inoculations of 1.2 ml of the homogenate were given at 1 day of age to broiler chicks (n = 15). Fourteen days later, chicks were fasted and stressed with a 2-sec cool water spray. Six chicks (40%) developed clinical signs of spiking mortality syndrome and were severely hypoglycemic. Uninoculated control chicks (n = 15) from the same hatch, also fasted and stressed simultaneously, were unaffected. Examination of a banded fraction produced from the inoculum with the use of transmission electron microscopy with negative staining revealed viruslike particles indistinguishable from arenavirus particles stained and examined simultaneously. Avian encephalomyelitis virus was isolated by one of three laboratories attempting virus isolation with the use of embryonating chicken eggs.

Experimental reproduction of severe hypoglycemia and spiking mortality syndrome using field-derived and embryo-passaged preparations.

The clinical signs, enteritis, weight depression, and hypoglycemia of spiking mortality syndrome were experimentally reproduced in broiler breeders and broiler chicks. Inocula included 1) virus-like particles from intestines of chicks with spiking mortality syndrome that had been banded in a discontinuous Renograffin gradient, 2) homogenized darkling beetles collected from litter of farms where spiking mortality syndrome had occurred repeatedly, and 3) homogenized embryos which had been inoculated with the Renograffin-banded material. Arkansas variant infectious bronchitis virus and arenavirus-like particles were identified in the inocula. Serology on samples from surviving chicks suggested the presence of an avian encephalomyelitis virus in one of the inocula. One-day-old (n = 172) and 2.5-day-old (n = 30) chicks were inoculated orally, and some were also injected intraperitoneally or subcutaneously, with 0.5 ml of the inocula. Twelve to fourteen days postinoculation, chicks were fasted for 4-6 hours, then briefly stressed with a cool water spray. Within 1.5 hours, inoculated chicks began dying with severe hypoglycemia and clinical signs of spiking mortality syndrome. Body weights were significantly depressed. Uninoculated controls (n = 130) from the same hatches, also fasted and stressed, were unaffected clinically and were not hypoglycemic. One group (n = 52) of inoculated chicks exposed to a controlled lighting program was unaffected clinically, had significantly higher mean plasma glucose levels, and had significantly less body weight depression than chicks exposed to continuous lighting. We concluded that exposure to controlled amounts of light/darkness can ameliorate much of the hypoglycemia, mortality, and runting-stunting associated with spiking mortality syndrome of chickens. The significance of the viruses and virus-like particles detected in the inocula is currently under investigation.

Markedly reduced pancreatic glucagon levels in broiler chickens with spiking mortality syndrome.

Pancreata from 19 hypoglycemic field broilers with spiking mortality syndrome and 19 clinically normal field broilers with normal blood glucose levels were collected and quick-frozen in liquid nitrogen immediately after the chicks were bled and killed. All chicks were 16 days old and were of the same genetic cross. Pancreata were weighed, and acid-alcohol extractions were made on each specimen. Radioimmunoassays for glucagon levels were made on each extract. Mean pancreatic glucagon content of the hypoglycemic chicks was depressed 14-fold (93.1%) compared with that of the non-hypoglycemic group. There was a close correlation between plasma glucose levels and pancreatic glucagon levels (P = 0.0001).

Hypoglycemia, enteritis, and spiking mortality in Georgia broiler chickens: experimental reproduction in broiler breeder chicks.

The clinical signs, hypoglycemia, and mortality of "spiking mortality syndrome" were experimentally reproduced. Seven groups of day-old male primary broiler breeder chicks were orally inoculated with tissue and/or fecal-urate homogenates taken from field broilers with spiking mortality syndrome and from field broilers with enteritis and/or runting-stunting syndrome. All homogenates used as inocula were shown by transmission electron microscopy and negative staining to contain arenavirus-like particles. Inocula produced from field broilers with spiking mortality syndrome contained the highest numbers of the arena-virus-like particles and produced the highest percentage of hypoglycemic chicks 13-15 days postinoculation after a 5-to-9-hour fast. These homogenates also produced the most significant differences in mean plasma growth hormone and insulin-like growth factor-1 levels. The significance of the arenavirus-like particles is unknown but is currently being investigated.

Mouse ethanol-inducible cytochrome P-450 (P450IIE1). Characterization of cDNA clones and testosterone induction in kidney tissue.

A mouse cDNA clone for the ethanol-inducible cytochrome P-450 (P450IIE1) was obtained by screening a liver cDNA library with an oligonucleotide representing a consensus sequence found in the orthologous rat, human, and rabbit sequences. The protein sequence deduced from the cDNA sequence had an identity of 93% to rat, 81% to rabbit, and 76% to human orthologous sequences. The highest levels of P450IIE1 mRNA were found in liver of both sexes, and male kidney. Developmentally, C57BL/6 female liver P450IIE1 mRNA was detectable 1 day postpartum and reached steady-state levels in animals approximately 16-20 days of age. Kidney and adrenal gland P450IIE1 mRNA was found to be induced 25-50-fold and 4-fold by testosterone treatment, respectively, and the level in both tissues reached maximum levels between 12 h and 2 days after treatment. Nuclear run-on experiments demonstrated that testosterone treatment for 24-48 h resulted in a slight transcriptional activation of the P450IIE1 gene in the kidney. However, the increase in transcription rate was far below the increase in mRNA level, suggesting that much of the induction occurs by posttranscriptional mechanisms. This process requires the androgen receptor since mutant Tfm mice lacking receptor are not inducible.

Virus isolation accuracy: an evaluation of eight laboratories involved in poultry diagnostics.

A study was undertaken to evaluate the accuracy of diagnostic laboratories at isolation of common avian viral pathogens. Fourteen "unknown" samples were submitted to eight laboratories in seven states. All positive and negative samples were guaranteed pure by SPAFAS. Virus-isolation results were erroneous in many cases. Based on this study, it appears that protocol for virus isolation of avian pathogens should be standardized throughout the United States.