Reliability of a history of previous varicella infection in adults.

CONTEXT: Apparent second episodes of varicella are reported in immunocompetent hosts, but laboratory confirmation of prior immune status has rarely been possible. OBJECTIVE: To evaluate adult patients with varicella who claimed to have had previous varicella to determine whether they had true second episodes or primary cases with inaccurate clinical histories. DESIGN: Adult subjects with varicella who enrolled in an antiviral treatment trial were interviewed about a history of varicella. The clinical course of varicella was documented prospectively in all subjects. Serum samples that predated the acute illness were obtained from the US Navy's central serum storage facility for subjects who reported a previous episode of varicella. These stored samples were tested in parallel by enzyme-linked immunosorbent assay, latex agglutination, and Western blot for IgG antibodies to varicella-zoster virus (VZV). PARTICIPANTS: Twenty military personnel with varicella and a history of the disease. SETTING: A military hospital in San Diego, Calif. MAIN OUTCOME MEASURE: Presence or absence of antibodies to VZV. RESULTS: Twenty (10.8%) of 184 adults with serologically confirmed acute varicella reported a prior history of varicella. The clinical course of these 20 patients did not differ from those with no history of varicella. Serum samples that had been collected a mean of 12.4 months (median, 12 months; range, 3 days to 34 months) before the incident episode were available for 19 subjects. All 19 serum samples lacked IgG antibodies to VZV. CONCLUSION: A history of previous varicella infection in adults with varicella may not be reliable. True second episodes of varicella are probably rare in immunocompetent adults.

Treatment of adult varicella with sorivudine: a randomized, placebo-controlled trial.

The antiviral and clinical efficacy of sorivudine in adults with varicella was evaluated in a double-blind, placebo-controlled randomized trial. A total of 186 patients were hospitalized for isolation and treatment within 96 h of rash onset. The diagnosis of varicella was confirmed in 184 patients with paired sera. Patients were randomly assigned to receive 10 or 40 mg of sorivudine or an identical placebo once a day for 5 days. Treatment with 40 mg of sorivudine (compared with placebo) shortened the mean time to 100% crusting from 6.6 to 5.8 days (P = .004) and reduced the mean days that new lesion formed from 3.9 to 3.1 (P = .014). Mean days of cutaneous viral shedding were reduced from 3.3 in the placebo group to 2.6 in the 40-mg sorivudine group (P = .002). The effectiveness of therapy was not affected by the duration of rash before initiation of therapy. Sorivudine is a promising new agent for the treatment of varicella-zoster virus infections.

Detection of varicella-zoster virus DNA in air samples from hospital rooms.

Varicella-zoster virus (VZV) is a highly contagious infectious agent that causes outbreaks in institutional settings. Transmission of VZV is felt to occur following direct contact with an infected individual and by aerosol spread. To document the aerosolization of VZV, a polymerase chain reaction (PCR) assay was used to detect VZV DNA in air samples obtained from hospital rooms of patients with active VZV infection. VZV DNA was detected in 64 (82%) of 78 air samples from rooms housing patients with active varicella and 9(70%) of 13 samples from rooms of patients with herpes zoster. VZV was detected 1.2-5.5 m from patients' beds and for 1-6 days following onset of rash. On some occasions, VZV DNA could be detected outside the hospital isolation rooms housing patients. This PCR-based method allows the detection and semiquantitation of VZV aerosolization and can be a useful tool for monitoring efforts to control VZV aerosols in the environment.

Effect of adding cognitively demanding tasks on soccer skill performance.

The effect of adding cognitively demanding elements to the performance of a real-world motor task in which functional interference among the elements in performance existed was investigated across level of expertise. The primary task involved running as quickly as possible through a 15.25-m slalom course. Two secondary tasks were used, dribbling of a soccer ball and identification of geometric shapes projected on a screen located at the end of the slalom course. 4 novice, 5 intermediate, and 5 expert female soccer players served as subjects and performed three trials each of three experimental conditions: running through the slalom course, running through the slalom course while dribbling a soccer ball, and running through the slalom course while dribbling a soccer ball and identifying geometric shapes. Analysis of variance using a 3 (experimental condition) x 3 (level of expertise) design gave significant main effects and a significant interaction. The latter indicated that, although the addition of cognitively demanding elements caused a decrement in performance, the amount of decrement decreased as level of expertise increased. It was concluded that structural interference between elements of performance decreased the positive effect of automation of one element on dual task performance.

The memory representation of motor skills: a test of schema theory.

Currently, a popular model for the central representation of motor skills is embodied in Schmidt's schema theory of discrete motor skill learning (Schmidt, 1975). Two experiments are reported here that contrast predictions from a schema abstraction model that is the basis for schema theory with those from an exemplar-based model of motor skill memory representation. In both experiments, subjects performed 300 trials per day of three variations of a three-segment timing task over 4 days of acquisition. The subjects then either immediately transferred to four novel variations of the same task (Experiment 1) that varied in degree of similarity to the exemplars experienced during acquisition; or performed two novel and two previously produced exemplars, following 24-h and 1-week retention intervals (Experiment 2). The results indicated that novel task transfer was not affected by the degree of similarity between the acquisition and transfer exemplars, and that there was no advantage for a previously produced exemplar over a novel exemplar after either a 24-hr or 1 week retention interval. Also, in both experiments, a consistent pattern of bias in responding was noted for novel task transfer and retention. These results are indicative of a schema abstraction model of memory representation for motor skills.

Detection of varicella-zoster virus DNA in the oropharynx and blood of patients with varicella.

The polymerase chain reaction (PCR) was used to detect varicella-zoster virus (VZV) DNA in respiratory epithelial cells and in peripheral blood leukocytes from adults with varicella. VZV DNA was detected in oropharyngeal epithelium in 62% of patients early in the course of varicella; the amount of VZV DNA declined with time and was detectable in only 22% of patients for greater than 6 days. VZV DNA was also detected in peripheral blood leukocytes in 74% of patients early in disease and was detected in both polymorphonuclear and mononuclear leukocytes. PCR demonstrated the presence of VZV DNA in the oropharynx and blood of most patients during varicella, in contrast to the ability to detect VZV in these tissues by viral culture.

A note on schema and exemplar approaches to motor skill representation in memory.

Given the need for a memory representation of well-learned motor skills, a common assumption in motor behavior is that this knowledge is stored in a central, abstracted form. Active production of motor skills has not been used in experimental designs that have provided empirical support for this view of representation, however. Much of the faith in centralized, abstracted forms of memory representation for motor skills is due to the popularity of Schmidt's schema theory, which has adapted the prototype abstraction model from category learning research to the representation of motor skills. Since schema theory was proposed, however, an alternative view that seriously questions the preeminence of the prototype abstraction model for the central representation of knowledge has arisen in the category learning literature. This particular view, termed the specific exemplar model, has led a number of researchers in cognition to develop mixed models that involve both prototypic abstraction and specific exemplar elements. This note, then, identifies what can be perceived as a gap in the empirical knowledge base in motor behavior and discusses the possibility of using the debate about representation for category learning as a stimulus for initiating a similar investigation into the representation of motor skills. A hypothetical specific exemplar model for the memory representation of motor skills is outlined, and possible empirical comparisons between this model and the schema abstraction model are suggested.

Preparation and control of rapid, multisegmented responses in simple and choice environments.

Research investigating the preparation and control of rapid, multisegmented responses typically has assumed complete programming of the response occurring prior to movement initiation and has made use of a simple reaction time (RT) paradigm. A notable exception is Rosenbaum's work which proposed the Hierarchical Editor (HED) model that is specifically directed toward the control of movements in the choice environment. The purposes of this study were to investigate the assumption of complete programming prior to movement initiation and to compare predictions of the HED model with other programming models. Three experiments are reported in which subjects were required to tap either one, two, or three plates as rapidly as possible in either a simple or choice RT situation. The results were very consistent in these experiments even with several modifications in apparatus and methodology. Of particular interest were effects of movement complexity on RT and movement time (MT) for the first and second segments of the movement (M1 and M2). Choice RT (CRT) results consistently showed no increases in RT as the number of movement segments increased but showed significant increases in M1. For simple RT situations, however, there were small but consistent increases in RT as well as increases in M1 with increases in the number of movement parts. For both CRT and SRT results, small but nonsignificant increases were noted for M2. These results provide evidence for incomplete programming prior to response initiation. Although the SRT data can be accommodated by Henry's theory, the HED model appears to offer the best overall fit for the results.