Metabolism and the Circadian Clock Converge.

Metabolism and the circadian clock converge.

Filed under: Eating Disorders

Physiol Rev. 2013 Jan; 93(1): 107-35
Eckel-Mahan K, Sassone-Corsi P

Circadian rhythms occur in almost all species and control vital aspects of our physiology, from sleeping and waking to neurotransmitter secretion and cellular metabolism. Epidemiological studies from recent decades have supported a unique role for circadian rhythm in metabolism. As evidenced by individuals working night or rotating shifts, but also by rodent models of circadian arrhythmia, disruption of the circadian cycle is strongly associated with metabolic imbalance. Some genetically engineered mouse models of circadian rhythmicity are obese and show hallmark signs of the metabolic syndrome. Whether these phenotypes are due to the loss of distinct circadian clock genes within a specific tissue versus the disruption of rhythmic physiological activities (such as eating and sleeping) remains a cynosure within the fields of chronobiology and metabolism. Becoming more apparent is that from metabolites to transcription factors, the circadian clock interfaces with metabolism in numerous ways that are essential for maintaining metabolic homeostasis.
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Developmental outcome in Pierre Robin sequence: A longitudinal and prospective study of a consecutive series of severe phenotypes.

Filed under: Eating Disorders

Am J Med Genet A. 2013 Jan 9;
Thouvenin B, Djadi-Prat J, Chalouhi C, Pierrot S, Lyonnet S, Couly G, Abadie V

Pierre Robin sequence (PRS) is a congenital condition with a heterogeneous and imprecise developmental prognosis. We conducted a longitudinal prospective study analyzing the long-term developmental outcome of a consecutive series of 39 children with PRS who had an a priori good prognosis (isolated PRS or PRS associated with a Stickler syndrome) but severe neonatal disorders (respiratory and feeding difficulties). Psychomotor and cognitive levels, speech, and eating behavior were assessed at 15 months of age and 3 and 6 years of age; 24 of the oldest children were interviewed at age 11 or 12 years. Results were analyzed by diagnosis, extent of respiratory and feeding disorders, and treatment modalities. Cognitive scores were within normal ranges and increased over time, from 90.5 at 15 months of age to 109.1 at 6 years. The 24 oldest children were enrolled in the appropriate junior high school grade at the normal age. For children 15 months of age, language scores were below the average, as were scores for vocabulary at 3 years for half of the patients. At 6 years, children’s speech showed persistent rhinolalia, which was mild (47%), moderate (11%), or major (11%). At 15 months of age, 74% of the children had satisfactory eating behavior, and 15% had serious difficulties. At 3 and 6 years, 18% and 6% of the children, respectively, had eating problems. Treatment modalities had no significant effect on long-term outcome. Global developmental quotient scores were lower but not significantly for children with an associated Stickler syndrome than those with isolated PRS. Children with isolated PRS showed good prognosis. © 2013 Wiley Periodicals, Inc.
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Magnetic Resonance Imaging Volumetry for Noninvasive Measures of Phenotypic Flexibility during Digestion in Burmese Pythons.

Filed under: Eating Disorders

Physiol Biochem Zool. 2013 Jan; 86(1): 149-58
Hansen K, Pedersen PB, Pedersen M, Wang T

Abstract Pythons are renowned for the profound phenotypical flexibility of their visceral organs in response to ingestion of large meals following prolonged fasting. Traditionally, the phenotypic changes are studied by determining organ mass of snakes killed at different times during digestion. Here we evaluate the use of magnetic resonance imaging (MRI) for in vivo measurements of the visceral organs in fasting and digesting snakes. Twelve snakes were MRI scanned immediately before the organs were removed and weighed to provide direct comparison of the two methods. Both methods provided similar estimates for the mass of liver, gallbladder, and pancreas, whereas MRI overestimated the size of the heart and small intestine, probably because blood and digesta contributed to the volume determined by MRI. The correlations were used to derive wet organ mass from MRI-based volumes to evaluate the mass development through repeated MRI scans of five digesting snakes. MRI was performed at fasting and 24, 48, 72, 132, and 500 h after eating a meal corresponding to 25% of body mass. This observation period revealed a reversible volume upregulation of the visceral organs, supporting the view that successive MRI facilitates in vivo investigations of structural changes accompanied by digestion.
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Mechanisms and causes of wear in tooth enamel: implications for hominin diets.

Filed under: Eating Disorders

J R Soc Interface. 2013; 10(80): 20120923
Lucas PW, Omar R, Al-Fadhalah K, Almusallam AS, Henry AG, Michael S, Thai LA, Watzke J, Strait DS, Atkins AG

The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss.
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Caloric Restriction Enhances Fear Extinction Learning in Mice.

Filed under: Eating Disorders

Neuropsychopharmacology. 2013 Jan 3;
Riddle MC, McKenna MC, Yoon YJ, Pattwell SS, Santos PM, Casey BJ, Glatt CE

Fear extinction learning, the ability to reassess a learned cue of danger as safe when it no longer predicts aversive events, is often dysregulated in anxiety disorders. Selective serotonin reuptake inhibitors (SSRI’s) enhance neural plasticity and their ability to enhance fear extinction learning may explain their anxiolytic properties. Caloric restriction (CR) has SSRI-like effects on neural plasticity and anxiety-related behavior. We implemented CR in mice to determine its effects on conditioned fear responses. Wild type and serotonin transporter (SERT) knockout mice underwent CR for seven days leading to significant weight loss. Mice were then tested for cued fear learning and anxiety-related behavior. CR markedly enhanced fear extinction learning and its retention in adolescent female mice and adults of both sexes. These effects of CR were absent in SERT knockout mice. Moreover, CR phenocopied behavioral and molecular effects of chronic fluoxetine but there was no additive effect of CR in fluoxetine-treated mice. These results demonstrate that CR enhances fear extinction learning through a SERT-dependent mechanism. These results may have implications for eating disorders such as anorexia nervosa (AN), in which there is a high prevalence of anxiety prior to the onset of dietary restriction and support proposals that in AN CR is a motivated effort to control dysregulated fear responses and elevated anxiety.Neuropsychopharmacology accepted article preview online, 3 January 2013; doi:10.1038/npp.2012.268.
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