The stress and workload of virtual reality training: the effects of presence, immersion and flow.

The present investigation evaluated the effects of virtual reality (VR) training on the performance, perceived workload and stress response to a live training exercise in a sample of Soldiers. We also examined the relationship between the perceptions of that same VR as measured by engagement, immersion, presence, flow, perceived utility and ease of use with the performance, workload and stress reported on the live training task. To a degree, these latter relationships were moderated by task performance, as measured by binary (Go/No-Go) ratings. Participants who reported positive VR experiences also tended to experience lower stress and lower workload when performing the live version of the task. Thus, VR training regimens may be efficacious for mitigating the stress and workload associated with criterion tasks, thereby reducing the ultimate likelihood of real-world performance failure. Practitioner Summary: VR provides opportunities for training in artificial worlds comprised of highly realistic features. Our virtual room clearing scenario facilitated the integration of Training and Readiness objectives and satisfied training doctrine obligations in a compelling engaging experience for both novice and experienced trainees.

Prospective study of telephone consultation and communication in pediatric infectious diseases.

BACKGROUND: Subspecialists are often called on to provide informal or "curbside" telephone consultation. There is limited documentation of the time spent on, content, nature and source of such consultations by pediatric infectious disease (PID) specialists. Nursing staff frequently assist physicians by triaging telephone calls. No previous studies have examined this aspect of their role in subspecialty practice. METHODS: We prospectively recorded all telephone calls to a newly established PID program for 1 year. Results were entered into a database and analyzed using the ABSTAT software. RESULTS: A total of 621 calls were received by the PID specialist and 1,260 by the PID nurse from March 1, 1999, through February 29, 2000. The mean number of calls per month was 51.8 +/- 24.8 for the physician and 105 +/- 43.3 for the nurse. The mean time spent per call was 9.6 +/- 5.9 min for the physician and 3.3 +/- 1.4 min for the nurse. A total of 103.5 h were spent directly on telephonic consultation/communication by the physician and 68.7 h by the nurse, respectively. Of the calls to the physician 78.6% came from other physicians, 51.5% being pediatricians in practice and 57% involving case management. Calls to the nurse were primarily from the laboratory (26.3%), with 93% regarding patients seen on the inpatient or outpatient service. CONCLUSIONS: Telephone consultation/communication is an integral and important part of a PID practice.

IGF-I but not the IGF-I variant long R(3)IGF-I increases serum IGFBP-3 in adolescent monkeys.

Previous work in rhesus monkeys has shown that both acute or chronic subcutaneous (s.c.) administration of insulin-like growth factor (IGF)-I elevates serum concentrations of IGF binding protein (IGFBP)-3. In order to determine whether an analog of IGF-I, which has a reduced affinity for the IGFBPs, has similar effects, a series of studies using adolescent female rhesus monkeys were conducted. In the first study, an s.c. injection of IGF-I (110 mg/kg;n = 6) significantly elevated serum IGFBP-3 concentrations through 7 h following treatment. In contrast, serum IGFBP-3 decreased throughout the day following an injection of Long R(3)IGF-I (110 mg/kg, s.c., n = 5). However, this decrease was not due to the analog treatment as serum IGFBP-3 also declined in a similar fashion in untreated females (n = 5) sampled on the same schedule. Serum GH levels were acutely suppressed by both IGFs but were not altered in untreated females. In the second study, serum IGFBP-3 were compared between untreated control females (n = 6) and females treated continuously by s.c. infusion with either Long R(3)IGF-I (120 mg/kg/day, s.c.;n = 5) or IGF-I (120 mg/kg/day, s.c.;n = 5) or IGF-I s.c.;n = 4). Serum IGFBP-3 was consistently elevated by IGF-I infusion, whereas levels in analog-treated monkeys were similar to those in control females. Although acute or chronic administration of Long R(3)IGF-I did not elevate serum IGFBP-3, chronic administration of the analog did not block the acute facilitating effects of IGF-I on serum IGFBP-3. The increase in serum IGFBP-3 following an acute injection of IGF-I (110 mg/kg, s.c.) was not significantly different between untreated females and females receiving a constant s.c. infusion of Long R(3)IGF-I. These data indicate either acutely or chronically administered IGF-I but not its analog Long R(3)IGF-I can elevate serum concentrations of IGFBP-3. Although the analog fails to increase serum IGFBP-3, it does not block the facilitating effects of IGF-I on concentrations of this IGFBP. Taken together, these data suggest that the increase in serum IGFBP-3 by exogenous IGF-I may not be a receptor mediated event but may be the result of IGF-I binding to IGFBP-3 and forming the binary and ternary complex, slowing IGFBP-3 degradation.

Continuous s.c. infusion rather than twice-daily injections of IGF-I more effectively increases serum IGF binding protein-3 in female monkeys.

OBJECTIVE: In order to better understand how the IGF-I axis is affected by exogenous IGF-I, this study compared the effects of a constant s.c. infusion of IGF-I with that of twice-daily injections of IGF-I in young adult female rhesus monkeys. Clinical studies suggest that circulating concentrations of insulin-like growth factor binding protein-3 (IGFBP-3) are decreased or unaffected by IGF-I administration, whereas acute increases in IGF-I may increase serum IGFBP-1. However, studies in monkeys indicate that acute or continuous infusion of IGF-I effectively increases serum IGFBP-3. DESIGN AND METHODS: Female monkeys were studied for 5 days with no IGF-I supplementation (baseline) and for 5 days of IGF-I treatment by either constant infusion (120 microg/kg per day s.c., n = 5) or twice-daily injections of IGF-I (60 microg/kg per injection s.c., n = 5). Serum samples were collected daily at 0800 h and at 0800, 0900, 1100, 1500, and 2000 h on days 1 and 4 for each condition. Samples were assayed for IGF-I, IGFBPs-1 and -3, insulin, and glucose. RESULTS: Serum IGF-I was consistently increased above baseline within 24 h of the initiation of constant infusion, but was delayed until the second day of treatment in the injection group. Serum IGFBP-3 followed the pattern of IGF-I, with concentrations increased by day 1 during constant infusion and by day 2 during intermittent injections. Although both treatments effectively increased serum IGFBP-3, the increase was greater during constant infusion (31% above baseline) compared with injection (17%). Immunoblotting revealed that the constant infusion of IGF-I resulted in quantitatively more lower-molecular-mass fragments of IGFBP-3 than were observed during baseline or intermittent injections. Size-exclusion chromatography and ultrafiltration indicated that most IGFBP-3 was found in the ternary complex, with a greater percentage found in the ternary complex during baseline (90%) than during constant infusion (86%) or intermittent injections of IGF-I (87%). In contrast, serum concentrations of IGFBP-1 were increased on day 1 of both treatments, but declined towards baseline values as treatment progressed. Serum concentrations of insulin and glucose were unaffected by either mode of IGF-I treatment. Serum concentrations of IGF-I and IGFBP-3 were increased within 3h of the injection, before declining towards the pre-injection level. In contrast, the daily pattern of serum hormone concentrations was similar between the baseline condition and during constant infusion of IGF-I. Although higher during the treatment phase, serum IGF-I and IGFBP-3 concentrations decreased significantly from 0800 h until the afternoon meal, reaching a nadir in the evening before increasing again the next morning. Serum insulin decreased also after the morning meal and increased significantly immediately after the afternoon meal. Although serum IGFBP-1 also decreased initially after the morning meal, concentrations reached a peak before the afternoon meal as serum insulin reached its nadir. CONCLUSION: The results of the present analysis indicate that the constant infusion of IGF-I more effectively sustains serum concentrations of IGF-I and IGFBP-3 than do twice-daily injections. Although the percentage of IGF-I and IGFBP-3 in the ternary complex was similar during both treatments, the constant infusion regimen produced lower-molecular-mass fragments of IGFBP-3. In addition, serum IGF-I and IGFBP-3 appeared to be regulated diurnally, even during IGF-I infusion, whereas IGFBP-1 and insulin were affected by the timing of food intake. Taken together, these data suggest that, in the monkey, IGFBP-3 is regulated by factors in addition to GH, and that IGF-I can affect its own bioavailability by increasing circulating concentrations of IGFBP-3.

7-alkylidenecephalosporin esters as inhibitors of human leukocyte elastase.

A series of 7-alkylidenecephalosporins and 7-vinylidenecephalosporins, as their benzhydryl esters, have been tested as inhibitors of both porcine pancreatic elastase and human leukocyte elastase. Selected 7-alkylidenecephalosporin esters are found to be potent inhibitors of HLE. One category of new inhibitors is the 7-(haloalkylidene)cephalosporins. In contrast to previously reported cephalosporin-based elastase inhibitors, these haloalkylidene cephems show optimum inhibitory activity as sulfides, rather than as sulfones. They are efficient and irreversible inhibitors. A second class of active compounds is represented by the benzhydryl ester 7-(cyanomethylidene)cephalosporin sulfone. In contrast to the activity of these new inhibitors, the benzhydryl ester of the mechanism-based beta-lactamase inhibitor, 7-[(2'-pyridyl)methylidene]-cephalosporin sulfone showed little inhibitory activity as an elastase inhibitor. 7-Vinylidenecephalosporins were also relatively poor inhibitors, although the terminally unsubstituted allene sulfide showed activity as an inhibitor of PPE. A modeling analysis suggests the 7-alkylidene substituents can be readily accommodated in the S1 pocket. A potential mechanism of inhibition is proposed.

The amplitude of nocturnal melatonin concentrations is not decreased by oestradiol and does not alter reproductive function in adolescent or adult female rhesus monkeys.

Nocturnal concentrations of melatonin in serum decline significantly with advancing pubertal development in both children and non-human primates and elevated levels may be associated with anovulation in adults. Three studies, using female rhesus monkeys, were performed to determine whether (1) the decline in nocturnal melatonin concentrations in adolescents was due to maturational increases in serum oestradiol, (2) the experimental elevation in nocturnal melatonin would delay the normal progression of puberty in post-menarchial monkeys, and (3) the experimental elevation in nocturnal melatonin would disrupt normal ovulatory function in adults. In experiment 1, juvenile female rhesus monkeys, housed indoors in a fixed photoperiod (12 h light:12 h darkness), were assigned randomly to one of two treatment groups: ovariectomized with no replacement therapy (control; n = 4) or ovariectomized with oestradiol replacement therapy maintaining oestradiol at approximately 90 pmol/l (treated; n = 8). Twenty-four hour as well as daytime serum samples were collected from 19 to 35 months of age. Nocturnal melatonin concentrations declined significantly in all females with advancing chronological age and this change was unaffected by oestradiol treatment. The decline in nocturnal melatonin concentrations occurred, on average, 2.0 +/- 0.2 months after the initial rise in serum LH in control females and 6.0 +/- 0.8 months in treated females. Furthermore, this decline in night-time melatonin was not related to significant developmental changes in body weight. In experiment 2, control (n = 6) and melatonin-treated (treated; n = 6) adolescent female monkeys were studied from -30 to +105 days from menarche. Beginning at 45 days following menarche, treated females received 30 days of nocturnal melatonin infusion to elevate levels to prepubertal values. Developmental changes in perineal swelling and coloration as well as serum oestradiol and insulin-like growth factor-I (IGF-I) were compared with values observed during the 45-day pretreatment and 30-day post-treatment conditions as well as with those observed in control females. Despite a significant elevation in nightly melatonin levels for the 30-day period in treated females, developmental changes in oestradiol, IGF-I, and perineal coloration and swelling were not different compared with the control females. In experiment 3, adult females were given melatonin nightly beginning on the first day of menses following an ovulatory cycle and treatment was continued for 45 days or until the next menstruation occurred. Melatonin was elevated to supraphysiological levels every night throughout the treatment period.(ABSTRACT TRUNCATED AT 400 WORDS)

Bizarre imagery, interference, and distinctiveness.

Previous studies have shown that bizarre and common images produce equivalent levels of recall in unmixed-list designs. Using unmixed lists, we tested the view that bizarre images would be less susceptible than common images to common sources of interference. In all experiments, subjects imaged a list of either bizarre or common sentences and then performed some kind of interfering task before recalling the initial list of sentences. Experiment 1 showed that bizarre images were better accessed than common images after imaging an intervening list of common sentences. Also, components of common images tended to be better recalled than those of bizarre images after imaging an intervening list of bizarre sentences. Experiments 2a and 2b showed that interfering tasks consisting of studying lists of common concrete nouns did not differentially affect memory for bizarre and common images. In Experiment 3, labeling and imaging an interfering list of common pictures produced higher recall of bizarre images. Generally, bizarre images appeared to be less susceptible than common images to interference from certain types of common encodings. Importantly, the superior recall of bizarre images was always due to greater image (sentence) access, whereas higher recall of common images was associated with greater recovery of the image (sentence) constituents. Explanation of the precise pattern of results requires consideration of the distinctive properties of bizarre images.

Booster effect in delayed hypersensitivity skin testing.

After a pilot study had suggested that a drug augmented delayed hypersensitivity, we conducted a control study in which 19 normal volunteers had the same skin test battery applied as in the pilot study, on two occasions one month apart with no intervening treatment. No change was observed in delayed hypersensitivity response to PPD, Candida, or tetanus antigens. However, a significant decrease in response to mumps antigen was observed, and there was a marked "booster" or augmented response to SKSD antigen. These observations have implications for studies of immunomodulation and the mechanism of action of delayed hypersensitivity response.

Failure of cimetidine as an immunomodulator in cancer patients and normal subjects.

Our pilot study of cimetidine as an immunomodulator in cancer patients showed no effect at clinically used doses on total blood, neutrophil, lymphocyte, or monocyte count, quantitative immunoglobulin, percentage of E-rosetting cells, phytohemagglutinin responses or delayed hypersensitivity responsiveness. We concluded that in clinically used doses, cimetidine produces no significant immunomodulation either in vivo or in vitro.