These same low levels have been associated with primary hypersomnia in general in mouse studies. “Mice with systemic carnitine deficiency exhibit a higher frequency of fragmented wakefulness and rapid eye movement (REM) sleep, and reduced locomotor activity.” Administration of acetyl-L-carnitine was shown to improve these symptoms in mice. A subsequent human trial found that people with narcolepsy given L-carnitine spent less total time in daytime sleep than people who were given a placebo. Animal models
Animal studies try to mimic the disorder in humans by either modifying the Hypocretin/Orexin receptors or by eliminating this peptide. An orexin deficit caused by the degeneration of hypothalamic neurons is suggested to be one of the causes of narcolepsy. More recent clinical studies on both animals and humans have also revealed that hypocretin is involved in other functions beside regulation of wakefulness and sleep. These functions include autonomic regulation, emotional processing, reward learning behaviour or energy homeostasis. In studies where the concentration of the hypocretin was measured under different circumstances, it was observed that the hypocretin levels increased with the positive emotion, anger or social interaction but stayed low during sleep or during pain experience.The most reliable and valid animal models developed are the canine (narcoleptic dogs) and the rodent (orexin-deficient mice) ones which helped investigating the narcolepsy and set the focus on the role of orexin in this disorder. Dog models
Dogs, as well as other species like cats or horses, can also exhibit spontaneous narcolepsy with similar symptoms as the ones reported in humans.
The rash is said to "stain", changing color from red to dark brown, before disappearing. Overall, measles usually resolves after about three weeks.People who have been vaccinated against measles but have incomplete protective immunity may experience a form of modified measles. Modified measles is characterized by a prolonged incubation period, milder, and less characteristic symptoms (sparse and discrete rash of short duration). Complications
Complications of measles are relatively common, ranging from mild ones such as diarrhea to serious ones such as pneumonia (either direct viral pneumonia or secondary bacterial pneumonia), laryngotracheobronchitis (croup) (either direct viral laryngotracheobronchitis or secondary bacterial bronchitis), otitis media, acute brain inflammation (and very rarely subacute sclerosing panencephalitis), and corneal ulceration (leading to corneal scarring).In addition, measles can suppress the immune system for weeks to months, and this can contribute to bacterial superinfections such as otitis media and bacterial pneumonia. Two months after recovery there is a 11–73% decrease in the number of antibodies against other bacteria and viruses.The death rate in the 1920s was around 30% for measles pneumonia. People who are at high risk for complications are infants and children aged less than 5 years; adults aged over 20 years; pregnant women; people with compromised immune systems, such as from leukemia, HIV infection or innate immunodeficiency; and those who are malnourished or have vitamin A deficiency. Complications are usually more severe in adults. Between 1987 and 2000, the case fatality rate across the United States was three deaths per 1,000 cases attributable to measles, or 0.3%.