Extensive multiple test centre evaluation of the VecTest malaria antigen panel assay

To determine which species and populations of Anopheles transmit malaria in any given situation, immunological assays for malaria sporozoite antigen can replace traditional microscopical examination of freshly dissected Anopheles. We developed a wicking assay for use with mosquitoes that identifies the presence or absence of specific peptide epitopes of circumsporozoite (CS) protein of Plasmodium falciparum and two strains of Plasmodium vivax (variants 210 and 247). The resulting assay (VecTest(TM) Malaria) is a rapid, one-step procedure using a 'dipstick' test strip capable of detecting and distinguishing between P. falciparum and P. vivax infections in mosquitoes. The objective of the present study was to test the efficacy, sensitivity, stability and field-user acceptability of this wicking dipstick assay. In collaboration with 16 test centres world-wide, we evaluated more than 40 000 units of this assay, comparing it to the standard CS ELISA. The 'VecTest(TM) Malaria' was found to show 92% sensitivity and 98.1% specificity, with 97.8% accuracy overall. In accelerated storage tests, the dipsticks remained stable for >15 weeks in dry conditions up to 45degreesC and in humid conditions up to 37degreesC. Evidently, this quick and easy dipstick test performs at an acceptable level of reliability and offers practical advantages for field workers needing to make rapid surveys of malaria vectors.

E-cadherin homophilic ligation directly signals through Rac and phosphatidylinositol 3-kinase to regulate adhesive contacts

Classical cadherins mediate cell recognition and cohesion in many tissues of the body. It is increasingly apparent that dynamic cadherin contacts play key roles during morphogenesis and that a range of cell signals are activated as cells form contacts with one another. It has been difficult, however, to determine whether these signals represent direct downstream consequences of cadherin ligation or are juxtacrine signals that are activated when cadherin adhesion brings cell surfaces together but are not direct downstream targets of cadherin signaling. In this study, we used a functional cadherin ligand (hE/Fc) to directly test whether E-cadherin ligation regulates phosphatidylinositol 3-kinase (PI 3-kinase) and Rac signaling. We report that homophilic cadherin ligation recruits Rae to nascent adhesive contacts and specifically stimulates Rae signaling. Adhesion to hE/Fc also recruits PI 3-kinase to the cadherin complex, leading to the production of phosphatidylinositol 3,4,5-trisphosphate in nascent cadherin contacts. Rae activation involved an early phase, which was PI 3-kinase-independent, and a later amplification phase, which was inhibited by wortmannin. PI 3-kinase and Rae activity were necessary for productive adhesive contacts to form following initial homophilic ligation. We conclude that E-cadherin is a cellular receptor that is activated upon homophilic ligation to signal through PI 3-kinase and Rae. We propose that a key function of these cadherin-activated signals is to control adhesive contacts, probably via regulation of the actin cytoskeleton, which ultimately serves to mediate adhesive cell-cell recognition.

Identification of T cell epitopes on the 33-kDa fragment of Plasmodium yoelii merozoite surface protein 1 and their antibody-independent protective role in immunity to blood stage malarial

Merozoite surface protein 1 (MSP1) of malaria parasites undergoes proteolytic processing at least twice before invasion into a new RBC. The 42-kDa fragment, a product of primary processing, is cleaved by proteolytic enzymes giving rise to MSP1(33), which is shed from the merozoite surface, and MSP1(19), which is the only fragment carried into a new RBC. In this study, we have identified T cell epitopes on MSP1(33) of Plasmodium yoelii and have examined their function in immunity to blood stage malaria. Peptides 20 aa in length, spanning the length of MSP1(33) and overlapping each other by 10 aa, were analyzed for their ability to induce T cell proliferation in immunized BALB/c and C57BL/6 mice. Multiple epitopes were recognized by these two strains of mice. Effector functions of the dominant epitopes were then investigated. Peptides Cm15 and Cm21 were of particular interest as they were able to induce effector T cells capable of delaying growth of lethal P. yoelii YM following adoptive transfer into immuno-deficient mice without inducing detectable Ab responses. Homologs of these epitopes could be candidates for inclusion in a subunit vaccine.

Relationship between cranio-cervical flexion range of motion and pressure change during the cranio-cervical flexion test

The purpose of this study was to quantify the sagittal angular displacement of the head (cranio-cervical flexion) for the five incremental stages of the cranio-cervical flexion test (CCFT). Range of cranio-cervical flexion during the CCFT was measured using a digital imaging method in 20 healthy volunteer subjects. The intra- and inter-rater reliability of the digital imaging technique for the assessment of this movement were also examined. The results of this study demonstrated a linear relationship between the incremental pressure targets of the CCFT and the percentages of full range cranio-cervical flexion range of motion (ROM) measured in the supine lying position of the test using a digital imaging technique. A mean of 22.9% full range cranio-cervical flexion was used to reach the first pressure target of the CCFT followed by linear increments up to 76.6% for the last stage of the test. An increasing amount of cranio-cervical flexion ROM was used to achieve the five successive stages of the CCFT reflecting an increasing contractile demand on the deep cervical flexor muscles. Excellent inter-rater (ICC = 0.994) and intra-rater reliability (ICC = 0.988-0.998) were demonstrated for the angular measurements using this digital imaging technique. (C) 2003 Elsevier Science Ltd. All rights reserved.

Assessing childrens competence in computer interactions: Preliminary reliability and validity of the test of mouse proficiency

The Test of Mouse Proficiency (TOMP) was developed to assist occupational therapists and education professionals assess computer mouse competency skills in children from preschool to upper primary (elementary) school age. The preliminary reliability and validity of TOMP are reported in this paper. Methods used to examine the internal consistency, test-retest reliability, and criterion- and construct-related validity of the test are elaborated. In the continuing process of test refinement, these preliminary studies support to varying degrees the reliability and validity of TOMP. Recommendations for further validation of the assessment are discussed along with indications for potential clinical application.

Antibody-dependent enhancement of Murray Valley encephalitis virus virulence in mice

Enhancement of flavivirus infection in vitro in the presence of subneutralizing concentrations of homologous or heterologous antiserum has been well described. However, the importance of this phenomenon in the enhancement of flavivirus infection in vivo has not been established. In order to study antibody- mediated enhancement of flavivirus infection in vivo, we investigated the effect of passive immunization of mice with Japanese encephalitis virus (JE) antiserum on the outcome of infection with Murray Valley encephalitis virus (MVE). We show that prior treatment of mice with subneutralizing concentrations of heterologous JE antiserum resulted in an increase in viraemia titres and in mortality following challenge with wild-type MVE. Our findings support the hypothesis that subneutralizing concentrations of antibody may enhance flavivirus infection and virulence in vivo. These findings are of potential importance for the design of JE vaccination programs in geographic areas in which MVE co-circulates. Should subneutralizing concentrations of antibody remain in the population following JE vaccination, it is possible that enhanced disease may be observed during MVE epidemics.

Ultraviolet signals in birds are special

Recent behavioural experiments have shown that birds use ultraviolet (UV)-reflective and fluorescent plumage as cues in mate choice. It remains controversial, however, whether such UV signals play a special role in sexual communication, or whether they are part of general plumage coloration. We use a comparative approach to test for a general association between sexual signalling and either UV-reflective or fluorescent plumage. Among the species surveyed, 72% have UV colours and there is a significant positive association between UV reflectance and courtship displays. Among parrots (Psittaciformes), 68% of surveyed species have fluorescent plumage, and again there is a strong positive association between courtship displays and fluorescence. These associations are not artefacts of the plumage used in courtship displays, being generally more 'colourful' because there is no association between display and colours lacking UV reflectance or fluorescence. Equally, these associations are not phylogenetic artefacts because all results remain unchanged when families or genera, rather than species, are used as independent data points. We also find that, in parrots, fluorescent plumage is usually found adjacent to UV-reflective plumage. Using a simple visual model to examine one parrot, the budgerigar Melopsittacus undulatus, we show that the juxtaposition of UV-reflective and fluorescent plumage leads to a 25-fold increase in chromatic contrast to the budgerigar's visual system. Taken together, these results suggest that signals based on UV contrast are of special importance in the context of active sexual displays. We review briefly six hypotheses on why this may be the case: suitability for short-range signalling; high contrast with backgrounds; invisibility to predators; exploitation of pre-existing sensory biases; advertisement of feather structure; and amplification of behavioural signals.

Climate of fear in organisational settings: Construct definition, measurement and a test of theory

This paper reports a study that explored a new construct: climate of fear. We hypothesised that climate of fear would vary across work sites within organisations, but not across organisations. This is in contrast a to measures of organisational culture, which were expected to vary both within and across organisations. To test our hypotheses, we developed a new 13-item measure of perceived fear in organisations and tested it in 20 sites across two organisations (N = 209). Culture variables measured were innovative leadership culture, and communication culture. Results were that climate of fear did vary across sites in both organisations, while differences across organisations were not significant, as we anticipated. Organisational culture, however, varied between the organisations, and within one of the organisations. The climate of fear scale exhibited acceptable psychometric properties.

Aging per se does not influence glucose homeostasis - In vivo and in vitro evidence

OBJECTIVE - To assess the effect of age on glucose metabolism by examining 1) glucose metabolism in young and middle-aged subjects when total or regional adiposity is taken into account and 2) in vitro glucose transport in adipose tissue explants from young and middle-aged women paired for total and abdominal adiposity. RESEARCH DESIGN AND METHODS - Study 1: body composition, subcutaneous abdominal and visceral adipose tissue areas, and fasting and oral glucose-stimulated glucose and insulin were measured in 84 young and 81 middle-aged men and in 110 young and 91 middle-aged women. Study 2: glucose uptake in subcutaneous abdominal and visceral adipose tissue explants were measured in eight young and eight middle-aged women. RESULTS - Study 1: young and middle-aged men showed similar subcutaneous abdominal tissue area, whereas fat mass and visceral adipose tissue were greater in middle-aged than in young men (P < 0.01). Fat mass and subcutaneous and visceral adipose tissue areas were greater in middle-aged as compared with young women (P < 0.01). Fasting plasma glucose and the glucose response to an oral glucose tolerance test were significantly higher in middle-aged than in young men and women (P < 0.001). Statistical control for visceral adipose tissue area eliminated the difference seen in glucose response in men and women. Study 2: glucose transport in subcutaneous and omental adipose tissue did not differ between young and middle-aged women. CONCLUSIONS - 1) Visceral obesity, more than age per se, correlates with glucose intolerance in middle-aged subjects; 2) aging does not influence in vitro adipose tissue glucose uptake.

New fluorescence parameters for monitoring photosynthesis in plants - 1. The effect of illumination on the fluorescence parameters of the JIP-test

Chlorophyll fluorescence measurements have a wide range of applications from basic understanding of photosynthesis functioning to plant environmental stress responses and direct assessments of plant health. The measured signal is the fluorescence intensity (expressed in relative units) and the most meaningful data are derived from the time dependent increase in fluorescence intensity achieved upon application of continuous bright light to a previously dark adapted sample. The fluorescence response changes over time and is termed the Kautsky curve or chlorophyll fluorescence transient. Recently, Strasser and Strasser (1995) formulated a group of fluorescence parameters, called the JIP-test, that quantify the stepwise flow of energy through Photosystem II, using input data from the fluorescence transient. The purpose of this study was to establish relationships between the biochemical reactions occurring in PS II and specific JIP-test parameters. This was approached using isolated systems that facilitated the addition of modifying agents, a PS II electron transport inhibitor, an electron acceptor and an uncoupler, whose effects on PS II activity are well documented in the literature. The alteration to PS II activity caused by each of these compounds could then be monitored through the JIP-test parameters and compared and contrasted with the literature. The known alteration in PS II activity of Chenopodium album atrazine resistant and sensitive biotypes was also used to gauge the effectiveness and sensitivity of the JIP-test. The information gained from the in vitro study was successfully applied to an in situ study. This is the first in a series of four papers. It shows that the trapping parameters of the JIP-test were most affected by illumination and that the reduction in trapping had a run-on effect to inhibit electron transport. When irradiance exposure proceeded to photoinhibition, the electron transport probability parameter was greatly reduced and dissipation significantly increased. These results illustrate the advantage of monitoring a number of fluorescence parameters over the use of just one, which is often the case when the F-V/F-M ratio is used.

Epitope map for a growth hormone receptor agonist monoclonal antibody, MAb 263

Monoclonal antibody (MAb) 263 is a widely used monoclonal antibody that recognizes the extracellular domain (ECD) of the GH receptor. It has been shown to act as a GH agonist both in vitro and in vivo, and we report here that it must be divalent to exert its effect on the full-length receptor. To understand the mechanism of its agonist action, we have determined the precise epitope for this antibody using a novel random PCR mutagenesis approach together with expression screening in yeast. A library of 5200 clones of rabbit GH receptor ECD mutants were screened both with MAb 263 and with an anticarboxy-tag antibody to verify complete ECD expression. Sequencing for clones that expressed complete ECD but were not MAb 263 positive identified 20 epitope residues distributed in a discontinuous manner throughout the ECD. The major part of the epitope, as revealed after mapping onto the crystal structure model of the ECD molecule, was located on the side and upper portion of domain 1, particularly within the D - E strand disulfide loop 79 - 96. Molecular dynamics docking of an antibody of the same isotype as MAb 263 was used to dock the bivalent antibody to the 1528-Angstrom(2) epitope and to visualize the likely consequences of MAb binding. The minimized model enables the antibody to grasp two receptors in a pincer-like movement from opposite sides, facilitating alignment of the receptor dimerization domains in a manner similar to, but not identical with, GH.