Astrocyte expression of the Drosophila TNF-alpha homologue, Eiger, regulates sleep in flies.

Sleep contributes to cognitive functioning and is sufficient to alter brain morphology and function. However, mechanisms underlying sleep regulation remain poorly understood. In mammals, tumor necrosis factor-alpha (TNFα) is known to regulate sleep, and cytokine expression may represent an evolutionarily ancient mechanism in sleep regulation. Here we show that the Drosophila TNFα homologue, Eiger, mediates sleep in flies. We show that knockdown of Eiger in astrocytes, but not in neurons, significantly reduces sleep duration, and total loss-of-function reduces the homeostatic response to sleep loss. In addition, we show that neuronal, but not astrocyte, expression of the TNFα receptor superfamily member, Wengen, is necessary for sleep deprivation-induced homeostatic response and for mediating increases in sleep in response to human TNFα. These data identify a novel astrocyte-to-neuron signaling mechanism in the regulation of sleep homeostasis and show that the Drosophila cytokine, Eiger, represents an evolutionarily conserved mechanism of sleep regulation across phylogeny.

Prognostic factors in canine exocrine pancreatic insufficiency: prolonged survival is likely if clinical remission is achieved.

BACKGROUND: Response to therapy in canine exocrine pancreatic insufficiency (EPI) varies considerably, making it difficult to determine prognosis for individual patients. HYPOTHESIS: Response to initial treatment (RIT) and survival are affected by signalment, clinical variables, and therapeutic regimen employed. ANIMALS: Client-owned dogs diagnosed with EPI between 1990 and 2002 were included in this study. METHODS: The study comprised a retrospective, questionnaire-based review. RESULTS: One hundred seventy-eight completed questionnaires were returned. RIT was good in 60% of treated dogs, partial in 17%, and poor in 23%. On univariate analysis, dogs that received antibiotics (P = .037) or had high serum folate concentration (P = .037) had a poorer RIT. On multivariate analysis, there were no strong predictors of good RIT. Nineteen percent of treated dogs were euthanized within 1 year, but overall median survival time for treated dogs was 1919 days. No clear benefit of changing to a fat-restricted diet could be demonstrated, but marked hypocobalaminemia (< 100 ng/L) was associated with shorter survival (P = .012). Use of uncoated pancreatic enzyme supplements, antibacterials, or H2 antagonists was not associated with longer survival. Breed, sex, age at diagnosis ( < or = 4 years or > 4 years), and clinical signs at diagnosis also made no difference. CONCLUSIONS AND CLINICAL IMPORTANCE: Long-term prognosis in canine EPI is favorable for dogs that survive the initial treatment period. Although there are few predictors of good RIT or long-term survival, severe cobalamin deficiency is associated with shorter survival. Therefore, parenteral cobalamin supplementation should be considered when hypocobalaminemia is documented.

Breed associations for canine exocrine pancreatic insufficiency.

BACKGROUND: Knowledge of breed associations is valuable to clinicians and researchers investigating diseases with a genetic basis. HYPOTHESIS: Among symptomatic dogs tested for exocrine pancreatic insufficiency (EPI) by canine trypsin-like immunoreactivity (cTLI) assay, EPI is common in certain breeds and rare in others. Some breeds may be overrepresented or underrepresented in the population of dogs with EPI. Pathogenesis of EPI may be different among breeds. ANIMALS: Client-owned dogs with clinical signs, tested for EPI by radioimmunoassay of serum cTLI, were used. METHODS: In this retrospective study, results of 13,069 cTLI assays were reviewed. RESULTS: An association with EPI was found in Chows, Cavalier King Charles Spaniels (CKCS), Rough-Coated Collies (RCC), and German Shepherd Dogs (GSD) (all P < .001). Chows (median, 16 months) were younger at diagnosis than CKCS (median, 72 months, P < .001), but not significantly different from GSD (median, 36 months, P = .10) or RCC (median, 36 months, P = .16). GSD (P < .001) and RCC (P = .015) were younger at diagnosis than CKCS. Boxers (P < .001), Golden Retrievers (P < .001), Labrador Retrievers (P < .001), Rottweilers (P = .022), and Weimaraners (P = .002) were underrepresented in the population with EPI. CONCLUSIONS AND CLINICAL IMPLICATIONS: An association with EPI in Chows has not previously been reported. In breeds with early-onset EPI, immune-mediated mechanisms are possible or the disease may be congenital. When EPI manifests later, as in CKCS, pathogenesis is likely different (eg, secondary to chronic pancreatitis). Underrepresentation of certain breeds among dogs with EPI has not previously been recognized and may imply the existence of breed-specific mechanisms that protect pancreatic tissue from injury.