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Biomedical subjects

R Blair

Publications and source records attributed to R Blair.

At least 145 records · Page 8Linked to original sources
PubMed1981

Morphine conditioned taste aversion reversed by periaqueductal gray lesions.

The role of the periaqueductal gray (PAG) in morphine conditioned taste aversion (CTA) was studied using male Wistar rats as subjects. Following the presentation of a novel saccharin solution, animals with or without a lesion of the PAG were intraperitoneally injected with either morphine, lithium, ethanol or fenfluramine. As evident by the amount of saccharin solution consumed on a subsequent presentation, a PAG lesion reversed a morphine CTA but not CTAs produced by the other drugs used. The results suggest that the PAG may in part mediate morphine CTA.

Animals↗
PubMed1980

Opiate receptors may mediate the suppressive but not the excitatory action of ACTH on motor activity in rats.

Subcutaneous injections of adrenocorticotropin (ACTH) or of the opiate antagonist naltrexone produced a one (2.0 mg/kg) dpressed, whereas smaller doses of ACTH (50 micrograms/kg) and of naltrexone (0.125 and 0.25 mg/kg) stimulated motor activity in the open field test. Furthermore, naltrexone at a dose level that had no effect on motor activity blocked the suppressive effect of the high doses of ACTH but had no effect on the stimulating effect of the intermediate dose of ACTH. Finally, chronic naltrexone administration resulted in enhanced sensitivity to the suppressive but not to the stimulating effect of ACTH on motor activity. It is argued that opiate receptors may play a selective role in the effect of ACTH on motor activity. Such receptors may mediate the supressive effect of high doses of ACTH whereas other, naltrexone insensitive receptor systems may mediate the stimulating effect of ACTH on activity functions.

Adrenocorticotropic Hormone↗
PubMed1980

Heroin, but not levorphanol, produces explosive motor behavior in naloxone-treated rats.

Intraventricular infusions of heroin (an opiate) or levorphanol (an opioid) in rats produced rigidity but not explosive motor behavior (EMB). When preceded by an IP injection of naloxone, infusions of heroin but not levorphanol produced EMB. The results suggest that naloxone-antagonized effects of opiates mask EMB and that certain opioids do not induce EMB.

Animals↗
PubMed1978

Assimilation theory, attentive fields, and the Müller-Lyer illusion.

The assimilation theory of geometric illusions was employed to predict changes in the outgoing and ingoing forms of the Mûller-Lyer illusions as a function of attentive field size. It was found that the theory predicted correctly the form of the function relating amount of illusion and size of attentive field only for the outgoing Müller-Lyer. For the ingoing illusion the prediction was opposite to the empirically obtained results. The findings are seen as additional evidence for the untenability of a unitary theory, such as assimilation theory, for both versions of the Müller-Lyer illusion as they fail to account for substantial difference between them.

Female↗
PubMed1976

The use of growth and liver aspartate aminotransferase to assess the effect of source of non-essential nitrogen on pyridoxine depletion, repletion and requirements of chicks.

1. Two experiments were carried out to study the relationship between growth, liver aspartate aminotransferase (Asp AT) and dietary pyridoxine to determine the pyridoxine requirement of chicks fed on diets containing crystalline essential amino acids with glutamic acid (GA) or diammonium citrate (DAHC) as the non-essential nitrogen source. 2. In one experiment purified diets containing isolated soy-protein with 0 or 3 mg pyridoxine/kg were used. The deficient chicks were significantly lighter, coverted food less efficiently and liver Asp AT activity was decreased. When deficient chicks were offered an adequate diet performance improved and Asp AT activity rapidly increased. 3. In the second experiment diets containing crystalline amino acids GA or DAHC combined with 0, 1 or 3 mg pyridoxine/kg (GA: 0, GA: 1, GA: 3, DAHC: 1, DAHC:3) were used. Growth rates of chicks fed on GA: 1 and GA: 3 were similar, whereas chicks fed on DAHC: 1 were significantly lighter than those given DAHC: 3. The growth data indicated a pyridoxine requirement for chicks fed on the GA diets of not more than 1mg/kg and of more than 1 mg/kg in those fed on diets containing DAHC. Asp AT activity varied significantly with dietary content of pyridoxine but not with the nitrogen source. When Asp AT activity was used to assess pyridoxine requirements, there was nof difference between chicks fed on GA or DAHC diets.

Animal Feed↗
PubMed1976

Responses of laying hens to a low-protein diet supplemented with essential amino acids, L-glutamic acid and/or intact protein.

1. Three sequential experiments, each lasting 8 weeks, were carried out on 576 singly-caged light hybrids. 2. In experiment 1 egg production was 84% using a conventional control diet, 61% with a basal low-protein diet, and 79% with the basal diet supplemented with 10 essential amino acids+L-glutamic acid (GA). 3. In experiment 2 supplementation with lysine and methionine (L+M) alone increased egg production significantly from 54 to 72%, compared with 83% with the conventional diet. 4. In experiment 3 egg production was 55% with the basal diet, 71% with the basal diet+L+M, 75% with a diet containing 141 g protein/kg+L+M, and 73% with the conventional diet. 5. In all three experiments supplementation with GA alone either gave no significant response or a depression in production. 6. Daily intakes of 1-24 g nitrogen as non-essential amino acids and 13 to 14 g total crude protein per bird resulted in good egg production. Supplementation of the basal diet with L+M resulted in a daily intake of 413 mg methionine/bird day which was considered adequate, and a daily intake of 710 mg lysine which was considered slightly inadequate.

Amino Acids, Essential↗
PubMed1976

The involvement of biotin in preventing the fatty liver and kidney syndrome in chicks.

Three experiments were carried out to investigate the involvement of vitamins in the fatty liver and kidney syndrome. The compounds studied, singly and in combination, were thiamin, riboflavin, nicotinic acid, pyridoxine, pantothenic acid, biotin, folic acid vitamin B12, ascorbic acid, choline and inositol and of these, only biotin prevented the syndrome. The minimum levels of supplemental dietary biotin required to prevent mortality varied from 0-05 to 0-15 mg/kg, depending on the diet. These levels were higher than the amounts required for maximum liveweight.

Animal Feed↗
PubMed1976

The involvement of further nutritional factors in the fatty liver and kidney syndrome in chicks.

Supplementing chick diets causing fatty liver and kidney syndrome (FLKS) with a wide range of minerals or with antibiotics did not affect mortality significantly but supplements of isolated soy protein or a mixture of crystalline amino acids were both equally effective in reducing mortality. Biotin supplementation of the parent flock diet subsequent mortality among the progeny by 30 per cent. Data on the age-distribution of the syndrome and the general conclusions from a whole series of experiments are presented.

Age Factors↗
PubMed1975

The involvement of dietary fat and vitamins, stress, litter and starvation on the incidence of the fatty liver and kidney syndrome in chicks.

Dietary and environmental factors involved in the fatty liver and kidney syndrome (FLKS) were studied. Addition of maize oil, tallow or olive oil isoenergetically at the expense of starch to the standard highmortality diet reduced mortality from 19 to 7 per cent. Supplementation of the standard diet with a mixture of vitamins reduced mortality to 1 per cent whereas supplementation with thiamin alone reduced it to 11 per cent. Mortality was 53 per cent higher among females than males. At 25 days of age mortality was 94 per cent higher among birds that had been subjected to repeated stressing. Withdrawal of food on day 36 resulted in a marked increase in mortality.

Animal Feed↗
PubMed1975

The effect of dietary fat and protein levels, form and cereal type on fatty liver and kidney syndrome in chicks.

A total of 4200 day-old Ross I broiler chicks were subjected to an ambient temperature 2 to 3C degrees higher than normal and were fed various diets to determine the effects of dietary factors and sex on mortality from fatty liver and kidney syndrome (FLKS). In a first experiment mortality was not significantly influenced by cereal type (barley or wheat) but was influenced significantly by fat content of the diet. In a second experiment mortality was increased significantly with a low protein diet and with a pelleted one compared with a mash diet. In both experiments mortality was signigicantly higher in females than in males. High levels of protein and fat in the diet had a protective influence on mortality but the results, especially with pelleted diets, suggested that some other nutrient(s) might be involved in the syndrome.

Animal Feed↗