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Biomedical subjects

C Walker

Publications and source records attributed to C Walker.

At least 415 records · Page 23Linked to original sources
PubMed1979

Refraction as a means of predicting squint or amblyopia in preschool siblings of children known to have these defects.

215 preschool siblings of children presenting with squint/amblyopia were screened by refraction after cycloplegia. The presence of +2.00 or more D of spherical hypermetropia in both eyes, or +1.00 or more D sphere or cylinder of anisometropia was significantly associated (P=0.0779%) with that child being identified 2+ years later as having either squint or amblyopia or both. Astigmatism of +1.50 or more D in either eye was significantly associated with anisometropia (P=0.000 0013%). If bilateral hypermetropia of +2.00 or more DS and/or +1.50 or more D of astigmatism in either eye had been taken as criteria for abnormality (ignoring anisometropia), there was a more significant association (P=0.0025%) between refraction and squint/amblyopia in these siblings. Such a child had 4 times more chance of having a visual defect than one who had no error of refraction when screened. These findings suggest that an environmental factor such as blurred vision may be relatively more important as a cause of squint/amblyopia than a genetically determined neurological abnormality.

Amblyopia↗
PubMed1979

Screening for refractive errors at age 1 year: a pilot study.

Cycloplegic refraction of 1-year-old children is technically possible and is acceptable to mothers as a method for screening children for visual defects. The range of refractions found in a sample of 186 1-year-old children is reported. Prediction of which children are significantly at risk for squint and/or amblyopia is possible on the basis of refractions at age 1 year according to the criteria selected for an 'abnormal' refraction. Bilateral hypermetropia and/or astigmatism or anisometropia at age 1 year was significantly (P less than 1 in 10 000) associated with a child eventually being found to have squint or amblyopia. Both the age of screening and criteria of abnormality will probably need modification. +2.50 or more D hypermetropia in any one meridian of either eye at age 1 year was even more significantly (P = 0.000 000 05%) associated with squint and/or amblyopia. The possibility that meridional hypermetropia could be the basic defect in squint and amblyopia is discussed.

Amblyopia↗
PubMed1979

Augmentation of lymphocyte surface immunogenicity following treatment with dimethyl-sulphoxide.

A mixed leucocyte culture is an in vitro tool for assessing differences in cell surface antigenicity between two cell populations. The MLC technique has been used to assess alterations in immunogenicity of rat lymphocytes, when exposed to the agent dimethyl-sulphoxide. Using four different rat strains, DMSO has been shown to be a surface-active agent that significantly increases the immunogenicity of both splenic and peripheral blood rat lymphocytes, as assessed by an increase in MLC reactivity. No augmentation of MLC reactivity is seen when syngeneic lymphocytes are used in the culture system as both effector and stimulator lymphocytes, thus confirming the immunological nature of the enhancement seen in allogeneic cultures.

Animals↗
PubMed1978

Ovarian hormonal responses to exercise.

The effects of exercise on estradiol, progesterone, follicle-stimulating hormones (FSH), and luteinizing hormone (LH) were studied in nine healthy females. Subjects were studied during light, heavy, and exhaustive exercise in the midfollicular and midluteal portions of their menstrual cycles. Resting hormone levels followed the expected pattern. Increases in estradiol and progesterone occurred at all intensities of exercise in the luteal phase but only in estradiol at exhaustion in the follicular phase. LH was unchanged with exercise in either phase and FSH increased in the follicular phase but not in the luteal phase. We conclude that exercise is a physiological stimulus to elevations in plasma estradiol, progesterone, and FSH, but not LH. The elevations are more marked in the luteal phase for the steroids and in the follicular phase for FSH. Increases in estradiol and progesterone are related to the intensity of exercise and appear to be independent of pituitary control.

Adult↗
PubMed1977

Characteristics of a short incubation model of scrapie in the golden hamster.

Repeated passage of the "Chandler" strain of scrapie in female golden hamsters using the intracerebral route of inoculation reduces the minimum incubation period to 60 days, about half of the minimum incubation period so far found in any of the mouse models of scrapie. The infectivity titres in brain in the clinical stage of the disease are considerably higher (greater than 8-0 -log10 LD50 i.c. units/0-05 g) than those found in mouse scrapie. The biological characteristics of this model of hamster scrapie are reported, including the effects on incubation period of route of inoculation, dose of agent, sex of hamster, ambient temperature (hibernation) and splenectomy. Some general and specific applications of this experimental model of scrapie are discussed.

Age Factors↗
PubMed1977

The monitoring of serum factors in patients with cancer.

Numerous changes occur in the sera of patients bearing malignant neoplasms. These changes may take the form of appearance of oncofetal proteins that are normally not detectable in non-cancer-bearing patients, or an alteration in the normally present serum constituents such as the serum proteins. Monitoring of these serum factors may be of considerable value in assessing the progress of cancer patients following treatment of their primary tumour. This paper reviews progress in this area to date and documents our early results with six non-specific serum factors (total protein, total protein hexose, total protein hexosamine, ceruloplasmin, alpha-1-antitrypsin, and haptoglobin), in 64 patients bearing a variety of malignant neoplasms in various stages of the disease. Present methods of postoperative assessment of cancer patients are inadequate for detecting early recurrence. Preliminary results indicate that the nonspecific serum factors that we are studying may be of considerable value for monitoring of cancer patients, and may also possibly serve as a diagnostic screen in high-risk groups.

Antigens, Neoplasm↗
PubMed1976

Isolation and characterization of temperature-sensitive mutants of Chinese hamster ovary cells after treatment with UV and x-irradiation.

The isolation of ten conditionally lethal temperature-sensitive mutants of the Chinese hamster ovary cell (CHO-Kl, pro-) by the BUdR-visible light selection procedure described. Treatment with radiation at doses known to cause single gene mutation in mammalian cells increases the mutation frequency by a factor of at least 14. These mutants will grow with normal plating efficiency at 34.5 degrees but will not grow at 39.5 degrees. Complementation analysis by two independent methods indicates that all mutants are recessive and allows the assignment of the mutants to six genetically independent complementation groups. Reversion analysis indicates that the TS-mutants are stable, spontaneous revertants arising at a frequency of less than 10(-6). Preliminary chromosome analysis revealed no systematic chromasomal abnormality in the mutants. Mitotic accumulation is used to study the generation time of the parental cells and representative mutants at 34.5 degrees and 39.5 degrees. The uses of these mutants for genetic analysis of mammalian cells in culture is discussed.

Cell Division↗