Automatic Detection of Attention Shifts in Infancy: Eye Tracking in the Fixation Shift Paradigm

This study measured changes in switches of attention between 1 and 9 months of age in 67 typically developing infants. Remote eye-tracking (Tobii X120) was used to measure saccadic latencies, related to switches of fixation, as a measure of shifts of attention, from a central stimulus to a peripheral visual target, measured in the Fixation Shift Paradigm. Fixation shifts occur later if the central fixation stimulus stays visible when the peripheral target appears (competition condition), than if the central stimulus disappears as the peripheral target appears (non-competition condition). This difference decreases with age. Our results show significantly faster disengagement in infants over 4 months than in the younger group, and provide more precise measures of fixation shifts, than behavioural observation with the same paradigm. Reduced saccadic latencies in the course of a test session indicate a novel learning effect. The Fixation Shift Paradigm combined with remote eye-tracking measures showed improved temporal and spatial accuracy compared to direct observation by a trained observer, and allowed an increased number of trials in a short testing time. This makes it an infant-friendly non-invasive procedure, involving minimal observational training, suitable for use in future studies of clinical populations to detect early attentional abnormalities in the first few months of life.     

ΔF508 testing of the DNA bank of the Royal Manchester Children's Hospital

Summary Details of haplotype and ΔF508 status from various populations represented in the cystic fibrosis (CF) DNA bank of the Royal Manchester Children's Hospital are provided, together with information on the association of genotype and clinical status. Clinical details and DNA analyses from native English in the North-West and South-West of England (Bath), from Lancashire Pakistani families and from Afrikaans Namibian families are compared. A 78.5% incidence of ΔF508 has been found in English families. Compound heterozygotes with CF and only one ΔF508 gene have an increased likelihood of having milder disease, with lessPseudomonas isolated from sputum and relatively more showing either no regular respiratory pathogens or colonisation withStaphylococcus. There is also a relative increase in meconium ileus in these compound heterozygotes. The diagnosis of CF may be in doubt in some subjects negative for ΔF508. Some of the Bath families have unusual haplotypes for an English population and a compound heterozygote ΔF508/ΔI507 has been found. There is evidence from metD analysis of the founder effect in the Afrikaans Namibian families, who have a high ΔF508 incidence.     

Direct stimulation of monocyte release of interleukin 1 by mycobacterial protein antigens

We examined stimulation of monocyte (MN) release of interleukin 1 (IL 1) by soluble microbial products. MN from tuberculin skin test nonreactive donors incubated with PPD (100 micrograms/ml) released IL 1 activity of 80.5 +/- 33.9 U/ml (mean +/- SD, n = 6), similar to that induced by optimal concentrations of LPS (76.4 U/ml). OKT3-reactive cells were not required for this process. PPD-stimulated IL 1 release by MN did not appear to be due to endotoxin contamination, as 1) PPD contained 0.01% endotoxin, 2) MN incubated in LPS (0.1 micrograms/ml) produced 19.5 +/- 13.9 U/ml, significantly less than PPD (p = 0.03), and 3) addition of polymyxin B (12.5 micrograms/ml) abrogated IL 1 production in response to LPS (0.1 microgram/ml) but had no significant effect on PPD induction of IL 1. Antigen 5, a partially purified cytoplasmic antigen of Mycobacterium tuberculosis, had similar IL 1-inducing effects. Arabinogalactan (a mycobacterial polysaccharide), streptolysin O, and tetanus toxoid did not. Thus, mycobacterial protein antigens directly stimulate MN to release IL 1. This property may be central to the response of the naive host to mycobacterial infection and may play a pathophysiologic role in tuberculosis.     

There are two gene sequences for human apolipoprotein CI (apo CI) on chromosome 19, one of which is 4 kb from the gene for apo E

A cDNA probe corresponding to the mRNA sequence for apolipoprotein E (apo E) was used to screen two independently-constructed human genomic libraries. Two recombinants (lambda E-2, and lambda E2-1), isolated using the apo E cDNA probe, also contain part or all of the apo CI gene. Hybridisation studies using both apo E and apo CI cDNA probes show that these two genes are in the same orientation and separated by 4 kb.     

Factors influencing the potential mobility and bioavailability of exchangeable ammonium ion in dried lake sediments

Abstract

The effect of drying temperature and oxidation on the level of exchangeable ammonium ion found in sediments has been examined using samples collected from along a polluted creek and from shallow lake bays. The sediments were dried at temperatures between 20°C and 100°C (either in air or under a nitrogen atmosphere), and the ammonium ion content was extracted into 0.1 M KCl prior to analysis using an ion selective electrode. Exposure to air during the drying stage usually resulted in lower ammonium values, while increasing the drying temperature altered the amount of displaceable (i.e. available) ammonium ion extracted, generally in an upward direction. The amount detected (5–25 μ g^?1) varied between sites, and surface sediment values differed from the 10–50 cm core material results. The pH of the extracts varied with the drying temperature used, indicating that the heating process promoted some chemical changes in the test samples. The study has demonstrated that in nutrient level surveys, the analytical data produced can depend greatly on the sample preparation procedure selected. It also indicated the type of changes which could occur when dredged sediments are land dumped.     

Binding specificity of monoclonal antibodies towards fragments of human growth hormone produced by plasmin digestion

To help define the immunological epitopes on human growth hormone (hGH), interaction of fragments of the hormone with 7 monoclonal antibodies (McAbs) was studied. Plasmin-digested hGH, containing two peptides (hGH1-134 and hGH141-191) joined by a disulphide bond, bound to each McAb with affinity similar to that of intact hGH. The purified C-terminal fragment, hGH141-191, showed low affinity for each McAb. The N-terminal fragment, hGH1-134, bound with quite high affinity to 2 McAbs (EB1 and EB3) but not to the other 5. We conclude that residues 1-134 of hGH contain the epitope to which McAbs EB1 and EB3 bind.     

Method for detecting viruses in aerosols

A simple method with poliovirus as the model was developed for recovering human enteric viruses from aerosols. Filterite filters (pore size, 0.45 micron; Filterite Corp., Timonium, Md.) moistened with glycine buffer (pH 3.5) were used for adsorbing the aerosolized virus. No virus passed the filter, even with air flow rates of 100 liters/min. Virus recovery from the filter was achieved by rapid elution with 800 ml of glycine buffer, pH 10. The virus in the primary eluate was reconcentrated by adjusting the pH to 3.5, adding AlCl3 to 0.0005 M, collecting the virus on a 0.25-micron-pore Filerite disk (diameter, 25 mm) and and eluting with 6 ml of buffer, pH 10. With this method, virus could be detected regularly in aerosols produced by flushing when 3 X 10(8) PFU of poliovirus were present in the toilet bowl. Poliovirus-containing fecal material from two of four infants who had recently received oral polio vaccine also yielded virus in the aerosols when feces containing 2.4 X 10(7) to 4.5 X 10(7) PFU of virus had been added to the toilet bowl. Persons infected with a variety of natural enteric viruses are known to excrete this amount of virus in their daily stools.     

Iodinated bovine prolactin. Characterization and binding to mammary gland cells.

Iodinated bovine prolactin (2.6 iodine atoms/molecule; labelled with a trace of 125I to give a specific activity of 0.041 muCi/mg) was prepared by the chloramine T method. It was active in two bioassays (pigeon crop sac and dispersed mouse mammary cell), though somewhat less active than the unmodified hormone. In an immunoassay, iodinated prolactin was more effective than the unmodified hormone at displacing 125I-prolactin from antibody. High specific activity 125I-prolactin (1 iodine atom/molecule; 70 muCi/microgram) was used for autoradiographic studies on the binding of prolactin to mouse mammary cells. In vivo the labelled hormone found in the mammary gland was associated with membranes of mammary epithelial cells and with alveolar lumen contents. In vitro 125I-prolactin was shown to bind to dispersed mouse mammary epithelial cells.