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Biomedical subjects

M J Harris

Publications and source records attributed to M J Harris.

At least 163 records · Page 9Linked to original sources
PubMed1983

The lidgap defect in mice: update and hypotheses.

The open eye defect in the mouse can result from the action of mutant genes or of teratogens. Among the genetic forms, the lidgap series poses a particular challenge. The lidgap defect appears to be a complex genetic trait and may serve as a model for the genetic analysis of other genetically complex morphological defects in mammals. Extensive breeding data, together with data on the response of the trait to in utero treatment with cortisone, have been analyzed. The results lead us to propose a model involving a single major locus with a series of alleles of graded strength, hypomorphs. The ranking is lg greater than lgstn = lgSt greater than lgM1. The lg/lg genotype alone can be sufficient to produce the lidgap trait, but the "weaker" alleles require a second or even third locus acting in the same pathway. In addition, there is evidence that a recessive suppressor locus is present in the system. These hypotheses are testable and some experiments to develop them further are discussed.

Alleles↗
PubMed1983

Abnormal facial development in the mouse mutant first arch.

The first arch mutation in mice, far, causes specific severe craniofacial defects, different from those caused by other craniofacial mutations. The purpose of the present study was to define the facial defects in far homozygotes, to identify heterozygote expression, if any, and to investigate the embryogenesis of the defect. A genetic study and a developmental study were done. The genetic study showed that only far homozygotes, observed on day 18 of gestation, have cleft palate, pointed snout, and deficiency and disorganized pattern of maxillary vibrissae. Approximately 75% have open eye(s). In addition, only far homozygotes lack infraorbital vibrissa(e) (76%) or have facial skin tags (62%). Thus, the missing infraorbital vibrissa(e) and disturbed maxillary vibrissa pattern could be used to identify far/far embryos for developmental study. The developmental study showed that all of the defects observed in far homozygotes at birth can be accounted for by abnormalities present on day 12 of gestation. Both the palatal shelves and the vibrissal ridges are deficient and irregular. The maxillary branch of the trigeminal nerve is abnormal and associated with a streaming and swirling pattern of mesenchymal cells between vibrissae and palate. No aberrations in cell density are apparent on day 12. The primary defect in the far mutation is not known, but all of the defects derive specifically from the maxillary facial process, one portion of the first branchial arch.

Animals↗
PubMed1982

Eyelid growth and fusion in fetal mice. A scanning electron microscope study.

During the last phase of mammalian morphogenesis, between days 14 and 16 of gestation in the mouse, the fetal eyelids grow across the eye and become tightly fused with each other. This paper describes the surface pattern of fetal eyelids, revealed by the scanning electron microscope, during normal eyelid growth and fusion in the ICR/MI stock of mice. Fusion proceeds from both inner and outer canthi and progresses toward the middle of the gap. The first changes in cell shape and distribution occur at the inner canthus. On day 14, a large clump of rounded cells appears on the inner surface of the inner canthus. A day later, two clumps of rounded cells are positioned to either side of, i.e. above and below, the inner canthus. As fusion progresses, the diminishing gap fills with a profusion of rounded cells that are extruded, flattened, and sloughed off from the area of completed fusion. The profusion of rounded surface cells during eyelid growth and fusion appears to be a major characteristic in which the eyelid fusion process differs both from permanent fusions, such as the fusion of the neural tube, lip or palate, and from other temporary fusions, such as fusion of the digits to each other or of the pinnae to the scalp.

Animals↗
PubMed1981

Hemorrhagic complications of optic nerve drusen.

We found hemorrhages in 13 eyes of 57 patients with optic disk drusen. In seven eyes, the hemorrhages originated in peripapillary choroidal neovascular membranes. In the other six eyes, no neovascular membrane was present. Hemorrhages that occurred in the absence of choroidal new vessels caused no visual symptoms in any patient. All resolved without sequelae. Hemorrhages originating in choroidal neovascular membranes commonly caused visual symptoms; however, six of seven eyes retained visual acuities of 6/12 (20/40) or better without any therapy. Thus, despite potential submacular hemorrhage, we do not recommend routine photocoagulation for peripapillary choroidal neovascular membranes secondary to optic disk drusen.

Adult↗
PubMed1981

Ozone Sensitivity in Sweet Corn (Zea mays L.) Plants: A Possible Relationship to Water Balance.

Stomatal characteristics affecting gas exchange were compared in two sweet corn hybrids (var. Bonanza and Monarch Advance) which differ in foliar ozone sensitivity. No significant differences were observed in stomatal frequencies, guard cell lengths, or conductances to water vapor diffusion.When plant water status was compared, leaf-water potentials for the ozone-resistant cultivar, Bonanza, were lower. A comparison of the relationship between soil- and leaf-water potential indicated that the leaf-water potential of Bonanza was more sensitive to declines in soil-water potential. Additionally, a comparison of stomatal conductance to water vapor diffusion as soil moisture declined and following root detachment indicated that stomata of Bonanza were, likewise, more sensitive to increasing water stress. Data suggest that these differences are attributable to a greater shoot-to-root fresh weight ratio and higher resistance to water movement in the water-conducting tissues for Bonanza.Our observations suggest that root and water delivery system characteristics play a major contributory role in the determination of foliar ozone sensitivity in this species.

Journal Article↗
PubMed1981

Triploidy in 40 human spontaneous abortuses: assessment of phenotype in embryos.

Forty human spontaneous abortuses were identified as triploid, 34 by karyotype and 6 by DNA measurement. Of the 40, 26 were embryos of 5 to 7 weeks' developmental age, 6 were intact empty sacs, 4 were early growth-disorganized embryos, and 4 were fetuses. In an attempt to determine the extent to which embryonic phenotype reveals triploid karyotype, the phenotypes of the 26 triploid embryos were compared with those of the 40 embryos of known nontriploid karyotype identified in larger study of consecutive spontaneous abortuses. Each embryo was scored for presence or absence of each of 4 abnormal phenotypic features: retarded limb development, facial dysplasia, subectodermal hemorrhage, and cystic chorionic villi. Whereas this combination of features was found in a few abortuses with normal or trisomic karyotype, it was both common and most frequent with triploidy. Approximately half (12 of 22) of the triploid embryos had at least 3 of the features. Conversely, among assessable embryos of known karyotype, four fifths (12 of 15) of those with at least 3 of the 4 abnormal features were triploid. Thus, while not definitive, such phenotypic information can be used with caution in counseling for subsequent pregnancies.

Abnormalities, Multiple↗
PubMed1976

Paediatric communications with the post-partum patient.

Discussions with mothers during their puerperium allows the introduction of thoughts on child care and management to a captive audience at a highly receptive stage. Many mothers lack an understanding of the problems they are likely to face in the first months after delivery and are desperately afraid of "spoiling" their child. They are generally quite ignorant of the problems of feeding, "colic" and others. Discussion group counselling of the parents of babies treated in an intensive care nursery is of value for the parents and for the hospital staff. The mothers have problems of guilt and anxiety over their possible aetiological role, doubts about their ability to cope with an "abnormal" baby, and problems due to lack of contact with their baby.

Anxiety↗