PubMed Health⌕ Search

Biomedical subjects

M Mackay

Publications and source records attributed to M Mackay.

At least 55 records · Page 3Linked to original sources
PubMed1991

Visual curve tracing properties.

Subjects decided whether 2 dots were on the same curve or 2 different curves, and the curvature of the curves or the proximity of other (distractor) curves to the target curve was varied. Response time increased as the arc length of the curve connecting the 2 dots increased, suggesting that the curve was traced to perform the task. Tracing rate was faster for low- than high-curvature contours and was increasingly slower as distractor contours were increasingly proximal to the traced curve. Proximity results were predicted by a model in which response time depends on the ratio of the distance between the dots and the distance between adjacent lines. Curve tracing operations used to integrate information along contours are sensitive to several properties of the contours. The implications of the sensitivity of tracing operations to these curve properties are discussed.

Adult↗
PubMed1991

Isolation and characterisation of clones from the Caco-2 cell line displaying increased taurocholic acid transport.

The Caco-2 cell line has been cloned by the limiting dilution technique. Clones and reclones have been tested for growth characteristics, transepithelial electrical resistance, ability to transport taurocholic acid specifically and morphological homogeneity. Although clones have similar growth patterns to the parental population they display a variety of electrophysiological, biochemical and morphological characteristics. One clone, clone 40, has been characterised in detail and shown to transport significantly higher amounts of taurocholic acid. Moreover, this clone displays morphological homogeneity and is stable with respect to this parameter over an extended time period.

Adenocarcinoma↗
PubMed1990

Illness vs prevention.

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed1988

Informed consent.

Explore the source record for details and available documents.

Informed Consent↗
PubMed1988

Major surface antigen p190 of Plasmodium falciparum: detection of common epitopes present in a variety of plasmodia isolates.

Plasmodium falciparum merozoites are covered with polymorphic proteins that are processed from a 190 kd (p190) precursor protein. These are candidates for an antimalarial vaccine. We cloned and expressed a number of DNA fragments, comprising almost the entire p190 gene of the K1 isolate, in Escherichia coli. Pooled human endemic-area sera and rabbit antibodies raised against p190 protein isolated from K1 parasites react with only a limited number of the recombinant proteins. From these studies we could select two antigenic polypeptides containing conserved amino acid stretches of the otherwise highly polymorphic protein. Rabbits and mice injected with the purified recombinant proteins produce antibodies reacting differentially with various isolates of P. falciparum. We obtained antibodies detecting all isolates tested and a monoclonal antibody specific for isolates containing a K1 type allele of the p190 gene.

Amino Acid Sequence↗
PubMed1987

Drug addicts and AIDS.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Allelic dimorphism in a surface antigen gene of the malaria parasite Plasmodium falciparum.

Merozoites of the malaria parasite Plasmodium falciparum carry surface proteins processed from a precursor termed p190 or p195. Polymorphism has been reported in this protein. Since the protein is a candidate for a malaria vaccine, it is important to understand the nature of this polymorphism. We have determined the complete nucleotide sequence of the p190 gene from the MAD20 strain (a Papua New Guinea isolate). Comparisons of the gene with that from other strains of P. falciparum allowed us to study the genetic basis of the antigen's polymorphism. The gene consists of sequences distributed in variable blocks, which are separated by conserved or semi-conserved sequences. Variable sequences occur both in regions that code for tripeptide repeats and in regions with no apparent repeats. Interestingly, according to the present data, variable sequences are not widely polymorphic but fall into two distinct types. We argue that the p190 protein is encoded by dimorphic alleles capable of limited genetic exchange and present evidence at the nucleotide level documenting intragenic recombination in Plasmodium.

Alleles↗
PubMed1987

A signal detection procedure eliminates priming biases in dichotic listening.

Dichotic digit names were presented to normal right-handed adults in two experiments, the first of which used a standard free report procedure and the second of which used a signal detection procedure. Prior to each test, a priming bias was generated by having subjects monitor either the left or right ear for 30 selective listening trials. The expected priming effect was found in Experiment 1: ear asymmetry and order of report were altered according to the ear previously monitored. In contrast, no priming effect was observed with the signal detection procedure used in Experiment 2. There was a right-ear advantage in sensitivity irrespective of the ear previously monitored. The findings suggest that priming biases act by altering the order in which multiple stimuli are processed and reported.

Adolescent↗
PubMed1986

Biomechanical analysis of drop and countermovement jumps.

For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle joints. In addition, electromyograms were recorded from five muscles in the lower extremity. The results obtained for DJ appeared to depend on jumping style. In a subgroup of subjects making a movement of large amplitude (i.e. bending their hips and knees considerably before pushing off) the push-off phase of DJ closely resembled that of CMJ. In a subgroup of subjects making a movement of small amplitude, however, the duration of the push-off phase was shorter, values for moments and mean power output at the knees and ankles were larger, and the mean EMG activity of m. gastrocnemius was higher in DJ than in CMJ. The findings are attributed to the influences of the rapid pre-stretch of knee extensors and plantar flexors after touch-down in DJ. In both subgroups, larger peak resultant reaction forces were found at the knee and ankle joints, and larger peak forces were calculated for the Achilles tendon in DJ than in CMJ.

Adult↗
PubMed1986

Characterisation of a repetitive DNA sequence from the malaria parasite, Plasmodium falciparum.

A repetitive DNA fragment cloned from the malaria parasite, Plasmodium falciparum, has been analysed. It contains a 21 base pair sequence which occurs in multiple tandem repeats. Two clusters of the same repeat are found in opposite orientations on the same DNA fragment. The repetitive DNA provides an additional way to distinguish between different strains of parasite by hybridisation to genomic blots and may serve as a species-specific probe for diagnosis.

Animals↗