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.

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.

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.

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.

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.

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.

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.

Studies on the mechanism and reversal of the phospholipase-A2 inactivation of D-glucose uptake by isolated human erythrocyte membranes

The mechanism underlying the inactivation of the stereospecific uptake of D-glucose by isolated human-erythrocyte membranes following digestion with phospholipase A2 (Kahlenberg, A. &Banjo, B. (1972) J. Biol. Chem 247, 1156–1160) was investigated. This inactivation was not accompanied by any significant change in the uptake of L-glucose. The decrease in D-glucose uptake following limited (25–30%) cleavage of membrane phospholipids by phospholipase A2 was characterized by a twofold increase in the apparent dissociation constant of the D-glucose–membrane complex and a 34% decrease in the membrane's maximum capacity for D-glucose uptake. These effects of phospholipase A2 were completely reversed upon removal of the membrane-bound phospholipid byproducts (fatty acids and lysophospholipids) by washing the membranes with defatted bovine-serum albumin. Oleic acid and various lysophosphatides added to albumin-washed, phospholipase A2-treated membranes in amounts formed by the enzyme treatment produced negligible inhibition of D-glucose uptake. With more extensive phospholipase A2 digestion of membrane phospholipids, defatted bovine-serum albumin did not restore D-glucose uptake despite the removal of the phospholipid by-products formed.In addition to the inactivation of D-glucose uptake, limited enzyme treatment transforms the appearance of the membranes collected by centrifugation from opaque white to transparent and gelatinous. Both of these effects of phospholipase A2 are completely reversed upon incubation of the membranes at pH 5.5 for 2 h at 37 °C without loss of any of the membrane lysophosphatides and fatty acids formed by the enzyme treatment. It is suggested that this pH- and temperature-dependent restoration of D-glucose uptake is due to a conformational change resulting in the relocation of the membrane D-glucose-binding sites into a functional environment.These results indicate that the inactivation of D-glucose uptake by phospholipase A2, which was not accompanied by any change in L-glucose uptake, occurs by two different mechanisms. With limited hydrolysis of membrane phospholipids, one or both of the resulting phospholipid by-products reversibly inhibit the uptake of D-glucose by decreasing the affinity of the membrane for D-glucose and by masking a portion of the total available D-glucose-binding sites. However, upon extensive cleavage of phospholipids in the hydrophobic region of the membrane, there is an apparently irreversible disorganization of the membrane D-glucose-binding component. This might be due to destruction of vital phospholipids and/or a disturbance of the interactions between the lipid and protein components of the membrane.

Evidence for an asymmetric distribution of phospholipids in the human erythrocyte membrane

The changes in phospholipid composition of the inner (cytoplasmic) surface of the human erythrocyte membrane resulting from the digestion of sealed inside-out vesicles with phospholipases A2 and C were determined. Virtually all of the phosphatidylethanolamine and phosphatidylserine and 30–40% of the phosphatidylcholine and sphingomyelin of inside-out vesicles were found to be accessible to enzyme hydrolysis. In contrast, all of the above phospholipids of unsealed ghosts were susceptible to phospholipolytic digestion. These results are a direct demonstration of an asymmetric distribution of phospholipids in the human erythrocyte membrane.

Bilateral choroidal metastases from "adenoma" of the bronchus

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Effect of estrogen antibodies on pregnancy in the rat

Treatment of pregnant rats with small amounts of non-specific estrogen antibodies did not inhibit pregnancy but increased the percent males in the litter. Administration of specific antibodies to estradiol immediately following mating prevented pregnancy in all animals, while administration at mid-pregnancy caused only some reduction in the number of pregnant animals. Administration of specific estriol antibody had no effect following mating but caused nearly total resorption of fetuses at mid gestation.

Luminescence, Electron Paramagnetic Resonance, and Optical Properties of Lunar Material

Dust samples have been found to luminesce weakly under proton excitation, but not under ultraviolet. Damage, recovery, and heating effects have been investigated. Chips of breccia show luminescence, from white inclusions only, under ultraviolet and protons. Some rock chips show general luminescence, mainly from plagioclase. No natural or excited thermoluminescence has been found for dust or chips. The electron paramagnetic resonance spectrum shows the same broad Fe(3+) dipole resonance for dust and for some chips; other chips show no response. The polarization characteristics of dust are found to be identical to those of the Sea of Tranquillity, independently of proton damage. Chips show characteristics unlike any part of the lunar surface.