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Biomedical subjects

M White

Publications and source records attributed to M White.

At least 415 records · Page 23Linked to original sources
PubMed1981

The effect of the nature of the surround on the perceived lightness of grey bars within square-wave test gratings.

The perceived lightness of grey bars within grey-white and grey-black square-wave test gratings was measured in the presence of different surrounding regions (plain black, plain white, or black-white square-wave gratings). The results for the grey-white test gratings are explained in terms of three separate processes: (i) lightness contrast; (ii) lightness assimilation resulting from the limited ability of the visual system to deal with grating contrast at higher spatial frequencies; and (iii) lightness assimilation resulting from lateral inhibition between pattern detecting channels mediating the perception of the gratings in the test regions and the surrounds. The results for the grey-black test gratings were explained without reference to the third process. It is concluded that techniques involving lightness assimilation could provide investigators with a sensitive new method of investigating the specificities of the inhibitory interactions underlying pattern perception.

Discrimination Learning↗
PubMed1980

Mycosis fungoides associated with nodular sclerosing Hodgkin's disease: a case report.

The possibility of the transformation of mycosis fungoides into a lymphoma of another histologic type is problematic. Convincingly illustrated examples are not to be found in the literature. We report on a well-documented case of a man who developed nodular sclerosing Hodgkin's disease 15 years after first presenting with mycosis fungoides.

Adult↗
PubMed1980

Evidence for unequal crossing over within the mouse T/t complex.

The Tcp-1 gene located within the T/t complex on chromosome 17 of the mouse codes for a major cell surface-associated protein p63/6.9. Previously, we identified two structural alleles of this gene which specify alternate forms of the p63/6.9 protein. The Tcp-1b allele is associated with all wild-type chromosome 17; the Tcp-1a allele is found only with chromosome 17 carrying a complete t haplotype. Normal recombination along a major length of chromosome 17 is suppressed in mice that are heterozygous for any complete t haplotype. Suppression is not complete, however, and rare crossing over between wild-type and t haplotype chromatin does occur. In this report, 15 rare recombinant chromosomes have been analyzed for Tcp-1 alleles. The results indicate that in four independent events the Tcp-1b and Tcp-1a alleles have become associated in cis position in a single DNA molecule. Further genetic analysis provides support for the hypothesis that a significant nonhomology exists between the arrangement of DNA sequences on wild-type and t-carrying chromosome 17. This could account for both the suppression of normal recombination along the stretch of t chromatin and the frequent unequal crossing over when rare recombinational events do take place.

Alleles↗
PubMed1980

By the skin of your teeth.

Plaque Watchers is an organized community programme to educate, motivate and facilitate the acquisition of adequate personal oral health habits, particularly for children in schools. Working with other health providers and the help of industry, teachers, parents and the media, Project Supertooth resources (plaque tunnels, t-shirts, stickers, community service announcements in the media and oral health courses) should provide a significant step towards promoting dental health and prevention of dental disease in the community by controlling the 'skin of your teeth'.

Adolescent↗
PubMed1979

Errors in drug computations during newborn intensive care.

Medical personnel in a pediatric center were tested for their ability to correctly compute drug doses for sick newborns. One of every 12 doses computed by 95 registered nurses contained an error that would result in the administration of an amount that was ten times higher or lower than the dose ordered. The error rate was no different for experienced or inexperienced nurses. The test also included an evaluation of the nurse's ability to judge the appropriateness of the drug dose ordered for a specified infant. Experienced nurses tended to be more certain, although wrong, in their judgment when compared to inexperienced nurses. Eleven pediatricians, when given the same test, scored higher than the nurses but still made errors at the rate of one of every 26 computations attempted. Five registered pharmacists who were tested demonstrated far better computational skills than either the nursing or physician group.

Hospitals, Pediatric↗
PubMed1979

4q- syndrome.

To our knowledge, there have been three prior reports of patients found, with trypsin-Giemsa banding, to be monosomic for the terminal q segment of chromosome 4. Described herein is a fourth patient with this chromosome abnormality. Comparison of these four patients suggests a characteristic phenotype in the 4q- syndrome: cleft palate, satyr deformity of the pinnae, snub nose, retrognathia and micrognathia, hypertelorism, oropharyngeal hypothonia or upper airway obstruction, cardiac defect, clinodactyly of the fifth fingers with absence of a flexion crease, simian lines, displaced or clinodactylous toes, and mental retardation. In the three prior reports, the 4q- syndrome resulted from a de novo deletion. In the present case, the 4q monosomy was inherited from the father, who had a 4;20 translocation.

Abnormalities, Multiple↗
PubMed1979

Physostigmine: effects on fear or defense responses in the rat.

Previous research had shown that the anticholinergic drug, scopolamine, decreased innate defensive responses of rats to a live cat or mechanical robot, and that the effects of scopolamine were attributable to actions of the drug on the central nervous system. In the present research, the anticholinesterase, physostigmine, which increases central cholinergic activity, caused an increase in the defense responses of male hooded rats. Physostigmine caused significantly more freezing and significantly more suppression of feeding and suppression of time near the aversive stimulus (ROBOT). Dose-response curves showed a positive, linear relationship between dose (0.025, 0.05, 0.1 and 0.2 mg/kg) of physostigmine and defense responses. The present results could not be attributed to general response suppression since the effects of physostigmine were situation-specific, i.e., the drug had no significant effect on behavior in the non-aversive or NO ROBOT condition. The present results were taken as further evidence of the involvement of cholinergic activity in the mediation of defense responses. The effects of cholinergic and anticholinergic drugs on the observable defense response of freezing were thought to have important implications for the large literature relating these drugs and avoidance responding.

Aggression↗
PubMed1979

Amphetamine: effects on defensive flight or avoidance in the rat.

Treatment with a moderately high dose of amphetamine caused rats to retreat from a stimulus they would normally approach and explore (mechanical robot or live white rabbit). While saline-treated rats spent approximately equal amounts of time in the area of the apparatus near the stimulus, amphetamine-treated rats spent a high percentage of trial time in the area of the apparatus farthest from the stimulus. The drug effects were dose related (range: 1.75, 3.5 and 7.0 mg/kg) with higher avoidance time at higher doses, and significant linear trends accounting for much of the variance. The highest dose of amphetamine elicited response stereotypy. However, control conditions ruled out the possibility that the present results could be explained by competing motor responses of stereotypy or increased activity. Thus, apart from its actions on motor behavior, amphetamine treatment resulted in rats avoiding or retreating from an otherwise neutral stimulus.

Animals↗