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Biomedical subjects

S J Harris

Publications and source records attributed to S J Harris.

At least 91 records · Page 5Linked to original sources
PubMed1984

Assessment of acuity in human infants using face and grating stimuli.

In a variety of ocular disorders, square-wave gratings yield more optimistic estimates of visual acuity than more complex stimuli such as letters. However, for clinical vision testing of preverbal patients, square-wave gratings are usually employed in conjunction with preferential looking procedures. We developed a complex stimulus--a schematic face--for use in preferential looking procedures. Using the method of constant stimuli, the acuities of 1-, 3-, and 5-month-old infants with normal eyes were estimated using schematic faces and square-wave gratings. Within each age group, thresholds for face and grating stimuli were not significantly different, but psychometric functions obtained with faces were significantly steeper than those obtained with square-wave gratings. This suggests that complex stimuli such as the schematic face could yield more precise acuity estimates than gratings in some pediatric eye patients.

Age Factors↗
PubMed1983

The effect of aluminum on neuronal lipofuscin.

Adult white rats were injected over a period of 33 days with aluminum hydrochloride, while a control group, matched for age, sex and weight, received water injections only. At the end of that period, it was found that the group of rats which had received aluminum had lost weight. The animals were killed and an attempt was made to measure the amount of lipofuscin in hypoglossal neurones using fluorescence microscopy. The aluminum treated group did not have a greater level of autofluorescence, indicative of no increase in lipofuscin level in this group. However, a problem of method is described which might have led to the lack of a positive result.

Aluminum↗
PubMed1983

A rapid miniature thin layer chromatography system for analysis of prostaglandins and lipoxygenase products.

We have developed a miniature thin layer chromatography system for rapidly identifying the major arachidonate metabolites in a radiolabeled form elaborated by cells or tissues. This system separates the total spectrum of cyclooxygenase products and several of the most commonly found lipoxygenase pathway metabolites, while retaining the fine resolution of larger-scale and more time-consuming procedures. It requires less than one hour for extraction of metabolites, chromatography, and counting.

Animals↗
PubMed1981

Improved separation of motile sperm in asthenospermia and its application to artificial insemination homologous (AIH).

A method is described for the separation of motile sperm from semen by "migration' into a diluent, providing a large area of interface between the semen and the diluent and resulting in a good yield of motile sperm (58%), with a mean percentage of motility of 95%. The method provides a specimen free of seminal plasma and debris and suitable for intrauterine insemination in less than two hours. The motile fraction was used for AIH treatment of 20 couples with a mean of 4 years' infertility, where the female factor had been excluded and the male was asthenospermic. After a mean of six cycles, three pregnancies were achieved. Improvement of the percentage of motility alone did not, in this study, give a significant improvement in conception rates when compared with accepted cycles with the placebo.

Adult↗
PubMed1981

The energy dependence of W in argon/methane gas for 300 keV to 1.8 Me V protons.

As part of a programme related to neutron dosimetry, the variation of the average energy per ion pair, W, has been determined for protons within the energy range 300 keV to 1.8 MeV stopped in 90% argon-10% methane gas. A gridded ion chamber was used with pulse height analysis to measure ion yield. An increase of W with decreasing energy was observed below about 1 MeV with a reversal at 450 keV.

Argon↗
PubMed1981

Quantitative studies of the autofluorescence derived from neuronal lipofuscin.

The degree of accumulation of neuronal lipofuscin in the human brain can indicate the age of some neurones, may be correlated with certain disease processes and can be affected by drugs. The estimation of the volume of neuronal lipofuscin has usually employed relatively unreliable methods such as counting techniques or visual ratings, while the present paper describes and illustrates a method for measuring the intensity of the autofluorescence derived from neuronal lipofuscin. The relationship between autofluorescence intensity and amount of lipofuscin is discussed.

Aged↗
PubMed1980

Penetration of protective gloves as a route of intake for tritiated water and 125I-labelled sodium iodide solution.

Measurements have been made of the rate at which tritiated water and 125I-labelled sodium iodide solution penetrate various types of protective gloves, both isotopes being in common use in this form in universities and similar establishments. Diffusion coefficients relating to the glove materials are also determined. The health physics aspects are discussed and it is concluded that intakes by workers through intact gloves are not likely to be of major significance and can easily be minimised by the correct use and choice of glove.

Clothing↗
PubMed1978

Liver mixed function oxidases in chickens: induction by polychlorinated biphenyls and lack of induction by DDT.

Microsomal hydroxylase and demethylase activities were compared in livers from White Leghorn cockerels fed polychlorinated biphenyls (PCBs) containing 21 to 68% chlorine, or p,p'-DDT. The higher chlorinated PCBs, Aroclor 1254 and 1268, were potent inducers of hepatic enzyme activity while DDT did not induce these enzymes. Aroclor 1254 was the most potent inducer because feeding 5 ppm increased liver aminopyrine demethylase activity 1.5X but did not affect liver weight. Feeding 50 and 500 ppm of Aroclor 1254 and 1268 increased liver weight and demethylase activity per mg of protein. A differential response in the two enzymes occurred. Only 500 ppm of Aroclor 1268 increased hydroxylase activity. Aroclor 1242 had no effect on liver enzyme concentration but 50 and 500 ppm of Aroclor 1242 increased liver weights and consequently increased total enzyme activity. Our data demonstrated that in the avian species DDT and PCB did not have the same effect on hepatic microsomal enzyme activity.

Aniline Hydroxylase↗
PubMed1978

Embryotoxic effects of polybrominated biphenyls (PBB) in rats.

Pregnant Sprague Dawley rats were given 0, 0.25, 0.5, 1, 5, and 10 mg of a commercial polybrominated biphenyl, FireMaster BP-6 (PBB), in olive oil by gavage each day from days 7 through 15 of pregnancy. Laboratory chow and water were given ad libitum. Treatment with PBB had no significant effect on body weight gain, food and water consumption, and urine production. The mothers were killed on day 20, and the only significant effect observed was an increased liver weight of those given 1, 5, and 10 mg PBB. Spleen, kidney, ovarian, gravid uterine, and perirenal fat pad weights were similar to those of control mothers. PBB had no significant effect on number of live/dead fetuses, crown-rump length or fetal weight. No grossly malformed fetuses were observed in PBB-treated mothers. The effects of PBB transfer from mothers to nursing pups was studied by reciprocal exchange of pups between control mothers and mothers treated with 10 mg PBB. When the pups were 21 days old, they were weaned and fed control chow. The following four combinations of prenatal-postnatal exposure were studied: control-control (C:C); control-PBB (C:PBB); PBB-control (PBB:C); and PBB-PBB. Although the birth weights of pups from PBB-treated mothers were similar to those of the controls, body weights of 60-day-old males exposed prenatally and postnatally (PBB:C, C:PBB, and PBB:PBB) were less (p less than 0.05) than those of the controls (C:C). The weights of the perirenal fat pads of male and female pups exposed to PBB were less (p less than 0.05) than the control. Liver weights, on a body weight basis, were higher in male and female pups exposed to PBB. Vaginal openings were delayed; the percentages of 36-day-old pups with open vaginas were 50 (C:C), 38 (PBB:C), 28 (C:PBB), and 30 (PBB:PBB).

Animals↗
PubMed1977

A technique for evaluating the stability of figures in a figure-ground pattern.

A technique is described which uses a reversible word-figure for studying effects of experimental variables on the stability of figures. In a reversible word-figure black on white inter-letter spaces represent "nonsense" forms which are usually perceived first. In this study the latency of reversal to the white on black word-configuration is taken as an index of the stability of the perceptual construction involving the black nonsense forms. The results show that pre-exposure of the nonsense forms increases their stability. Either labelling the forms or attempting to memorize them increases stability somewhat more than merely rating them for "aesthetic appeal."

Discrimination, Psychological↗
PubMed1976

Antibody response and reduction in bursa of Fabricius and spleen weights of progeny of chickens fed PCBs.

In Experiment 1, polychlorinated biphenyls (Aroclors 1016, 1232, 1242, 1248, and 1254) were fed ad libitum to White Leghorn chickens at dietary levels of 5, 10, and 20 p.p.m. for 8 weeks. Hatchability of eggs from hens fed 10 and 20 p.p.m. of Aroclors 1232, 1242, and 1248 was reduced. The weights of the spleen and bursa of Fabricius of day-old chicks from hens fed 10 p.p.m. of Aroclors 1242 and 1248 or 20 p.p.m. of Aroclors 1232, 1242, 1248, and 1254 were less than those of control chicks. Body weights were similar to those of controls at hatching, but the 3 week weight gains of progeny from hens fed 20 p.p.m. Aroclors 1242 and 1248 were less than gains of control progeny. After replacement of the PCB diet with uncontaminated feed, hatchability improved within 2 weeks and by 8 weeks was similar to the hens were fed uncontaminated feed. In Experiment 2, hens were fed 10 p.p.m. 1248 ad libitum for 8 weeks. The progeny bursa weights were reduced, but the treatment did not interfere with interfere with antibody production. PCB treatment had no effect on antibody production after primary or secondary challenges with Brucella abortus. However, after the primary challenge, bursectomized birds of both the control and PCB groups produced significantly fewer antibodies than the nonbursectomized birds. Differential accumulations of the polychlorinated biphenyls occurred in the effs. Chlorinated biphenyls with relative retention times less than that of DDE accumulated to less than one-half of the dietary concentration whereas chlorinated biphenyls with retention times greater than that of DDE accumulated in the eff to a concentration equivalent to the dietary concentration.

Animals↗
PubMed1975

Effects of polychlorinated biphenyls and terphenyls and polybrominated biphenyls on pentobarbital sleeping times of Japanese quail.

Polychlorinated biphenyls (Aroclor 1221, 1232, 1242, 1248, 1254, 1260, 1262, and 1268), polychlorinated terphenyls (Aroclor 5460), a mixture of polychlorinated biphenyls and terphenyls (Aroclor 4465) and polybrominated biphenyls (BP-6) were administered in a single dose, 100 mg/kg body weight injected orally, to mature male and female Japanese quail. Two hr after Aroclor treatment, pentobarbital sleeping times were prolonged (2 to 3 times control) in both male and female quail. Twenty-four hr after treatment, sleeping times were similar to those of controls. However, 48 hr after treatment with Aroclor 1248 through Arolcor 5460 and with BP-6, sleeping times of males were only 1/2 those of controls, whereas after treatment with Aroclor 1221, 1232 and 1242, sleeping times were similar to those of controls. The reduction in sleeping times of male quail 48 hr after administration of PCBs was correlated with the percentage of chlorine in the PCB with greater reductions in male than female quail. The response after three days ad libitum feeding of 300 ppm of each substance was the same as the response 48 hr after a single oral injection. Although very few birds died from the toxicity of the Aroclors and BP-6, mortality was greatly increased during anesthesia when the pentobarbital was administered two hr after single oral dosing.

Animals↗