Modelling of congenital nystagmus waveforms produced by saccadic system abnormalities.

Models of the mechanisms of normal eye movements are typically described in terms of the block diagrams which are used in control theory. An alternative approach to understanding the mechanisms of normal eye movements involves describing the eye movement behaviour in terms of smooth changes in state variables. The latter approach captures the burst cell firing against motor error (difference between target gaze angle and current gaze angle) phase plane behaviour which is found experimentally and facilitates the modelling of variations in burst cell behaviour. A novel explanation of several types of congenital nystagmus waveforms is given in terms of a saccadic termination abnormality.

Rotavirus infection in normal nursery: epidemic and surveillance.

Human rotavirus (HRV) epidemics have not been reported in normal full-term newborn nurseries in the US. This report describes an epidemic from April 27 to May 6, 1982 in which 23 infants were infected. Diagnosis was confirmed with Rotazyme (Abbott) in 82% (23/28) of the neonates screened. Five were asymptomatic; in the remaining 18 cases, the symptoms were usually mild and self-limited. Transient shedding of the virus was found in 8% (4/52) of personnel screened, and only one of them was symptomatic. Control measures included the following: strict cohorting, closure of transitional nursery, enteric precautions and wiping of horizontal surfaces with 95% ethyl alcohol which has been shown to be an effective virucidal agent for rotavirus in laboratories. Follow-up in 80 of 108 contact neonates born during the epidemic showed only two mildly symptomatic cases after discharge. During an 11-month period of surveillance, 33% of neonates (1,688/5,054) born at Cook County Hospital were screened for excretion of virus in stools; only 3.6% of infants (61/1,688) were positive by Rotazyme and none were symptomatic. This report suggests that strict measures are helpful in control of HRV epidemic gastroenteritis and asymptomatic shedding need not be as high as the previously reported incidence of 40% to 50%.