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Biomedical subjects

S Harvey

Publications and source records attributed to S Harvey.

At least 307 records · Page 17Linked to original sources
PubMed1980

Somatostatin stimulates glucagon secretion in ducks.

In normal fasting ducks, a somatostatin infusion (800 ng/kg/min for 30 min) elicited a prompt inhibition of insulin secretion, plasma levels falling from 140 +/- 20 to 20 +/- 6 pg Eq/ml as observed in mammals.--However plasma glucagon-like-immunoreactivity shown to be decreased in mammals by somatostatin was sharply increased from a mean basal level of 1.46 +/- 0.13 ng Eq/ml to 6.61 +/- 0.77 ng Eq/ml. This effect was not mediated via inhibition of growth hormone secretion since it was also observed in hypophysectomised ducks. Despite the fall in plasma insulin and rise in GLI observed with somatostatin infusion in intact birds, plasma glucose concentrations were lower than with control saline infusion.

Animals↗
PubMed1980

Circulating growth hormone and prolactin concentrations in turkeys and chickens infected with Histomonas meleagridis.

1. Histomonas meleagridis was inoculated into young chickens and turkeys and the effect of the infection (blackhead) on circulating growth hormone (GH) and prolactin concentrations determined. 2. During the course of the infection in turkeys there was a marked increase in plasma GH concentration which correlated with the severity of the disease, as judged by liver and caecal characteristics. The infection was less severe in chickens and no correlation between plasma GH and the degree of infection was observed. 3. The concentration of plasma prolactin was increased in the chicken, but not in the turkey, during the invasive period of infection.

Animals↗
PubMed1980

The effect of an injection of corticotrophin on plasma concentrations of corticosterone, growth hormone and prolactin in two strains of domestic fowl.

1. Three-week-old Light Sussex (LS) and Rhode Island Red (RIR) chicks were injected with long-acting corticotrophin (ACTH: 30 IU/kg) and the plasma concentrations of corticosterone, growth hormone (GH) and prolactin were determined over a 6-h period. Plasma concentrations of corticosterone and growth hormone were also measured after an injection of corticosterone (500 microgram/kg). 2. The resting plasma concentration of corticosterone in LS was less than that in RIR birds. The increase elicited by ACTH was smaller in LS but, since it was maintained for longer, the plasma corticosterone response was at least 18% larger than that in RIR birds. 3. Plasma GH concentration was decreased after an injection of ACTH in both strains but the decrease lasted longer in the LS chicks. 4. Plasma prolactin concentration was unaffected by ACTH. 5. After intra-abdominal injection of corticosterone, plasma GH concentration was depressed in both strains. It is concluded that ACTH-induced depression of plasma GH and growth is mediated by corticosterone.

Adrenocorticotropic Hormone↗
PubMed1980

Growth and the plasma concentrations of growth hormone and prolactin in chicks: effects of "environmental enrichment", sex and strain.

1. The effects of including novel objects in the environment ("environmental enrichment") on body-weight gain, relative body-weight gain, gain: food ratio, plasma growth hormone (GH) and prolactin concentrations in male and female broiler and layer chicks was investigated. 2. Environmental enrichment improved body-weight gain, relative body-weight gain and gain : food ratio but had no effect on circulating GH or prolactin concentrations. 3. Weight gain and gain : food ratio were greater in the broilers than in the layer chicks, while plasma GH and prolactin (females only) concentrations were less. 4. There were no sex differences in weight gain and relative weight gain but gain : food ratio was significantly greater in females than in males. In both strains plasma GH concentrations were higher in male than in female broilers.

Animals↗
PubMed1980

Respiratory systems and cytochromes in Campylobacter fetus subsp. intestinalis.

Cell suspensions of Campylobacter fetus subsp. intestinalis grown microaerophilically in complex media consumed oxygen in the presence of formate, succinate, and DL-lactate, and membranes had the corresponding dehydrogenase activities. The cells and membranes also had ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine oxidase activity which was cyanide sensitive. The fumarate reductase activity in the membranes was inhibited by p-chloromercuriphenylsulfonate, and this enzyme was probably responsible for the succinate dehydrogenase activity. Cytochrome c was predominant in the membranes, and a major proportion of this pigment exhibited a carbon monoxide-binding spectrum. Approximately 60% of the total membrane cytochrome c, measured with dithionite as the reductant, was also reduced by ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine. A similar proportion of the membrane cytochrome c was reduced by succinate under anaerobic conditions, whereas formate reduced more than 90% of the total cytochrome under these conditions. 2-Heptyl-4-hydroxyquinoline-N-oxide inhibited reduction of cytochrome c with succinate, and the reduced spectrum of cytochrome b became evident. The inhibitor delayed reduction of cytochrome c with formate, but the final level of reduction was unaffected. We conclude that the respiratory chain includes low- and high-potential forms of cytochromes c and b; the carbon monoxide-binding form of cytochrome c might function as a terminal oxidase.

Campylobacter↗
PubMed1980

Effect of oral contraceptive cycle on dry socket (localized alveolar osteitis).

Use of oral contraceptives was associated with a significant increase in the frequency of dry socket after extraction of mandibular third molars. The probability of dry socket increases with the estrogen dose in the oral contraceptive. The risk of dry socket associated with oral contraceptives can be minimized by performing extractions during days 23 through 28 of the tablet cycle.

Contraceptives, Oral↗
PubMed1980

Influence of stress on the secretion of corticosterone in the duck (Anas platyrhynchos).

The influence of stress on the secretion of corticosterone has been investigated by radioimmunoassay in domestic ducks (Anas platyrhynchos) of 6-8 weeks of age. Intravenous and i.m. injections of synthetic ACTH (Synacthen, 25 i.u./bird and Synacthen Depot, 100 i.u./bird respectively) markedly increased (2.7- to 10-fold) basal concentrations of corticosterone in plasma (3-6 ng/ml) in comparison with those in birds injected with 0.9% saline (1 ml/bird). Maximum levels of 30-40 ng/ml plasma were reached after 30 min and 5 h respectivley. Increased levels of corticosterone in plasma were also seen within 5 min of i.v. administration of saline and remained as high as those in birds treated with Synacthen for at least 20 min after injection. Blood sampling (from the brachial vein) was, by itself, sufficient to increase levels of corticosterone in plasma; a large (twofold) rise being observed as soon as 1 min after initial handling and bleeding, with concentrations of 30-40 ng/ml being found in birds bled 15 times during a period of 14 min. However, in a flock of birds, the alarm created in unhandled birds while others were being bled had no effect on concentrations of corticosterone in plasma. Deprivation of food or water for 24 h also enhanced levels of corticosterone in plasma, as did 24 h of adaptation to 0.2 M-NaCl drinking water. These results have demonstrated the lability of the secretion of corticosterone in response to stress and demonstrated its usefulness as a physiological indicator of stress in ducks.

Adrenocorticotropic Hormone↗
PubMed1980

The effect of Escherichia coli endotoxins on the concentrations of corticosterone and growth hormone in the plasma of the domestic fowl.

The intravenous injection of chickens aged six to 11 weeks with Escherichia coli endotoxins (serogroups O111 and O78) produced a large increase in the plasma corticosterone concentration which was maximal (five to 10-fold) after 1 h and still evident after 8 h. It did not vary with the dose over the range 0.1 to 2 mg/kg and was smaller than that produced by adrenocorticotrophic hormone (ACTH) (20 iu/kg). A decrease in growth hormone concentration was detected between 1 and 2 h after endotoxin administration in six- to seven-week-old birds, this change being opposite to that which occurs in man.

Adrenocorticotropic Hormone↗
PubMed1979

In vitro stimulation of chicken pituitary growth hormone and prolactin secretion by chicken hypothalamic extract.

The effect of an acid extract of chicken hypothalami on the in vitro secretion of prolactin and growth hormone (GH) by dispersed chicken pituitary cells has been investigated. Both prolactin and GH release were stimulated in a dose related manner in the presence of the hypothalamic extract (HE). Somatostatin had no effect on the basal or HE stimulated release of prolactin although it did inhibit the HE induced release of GH.

Animals↗
PubMed1979

Growth hormone and prolactin secretion in growing domestic fowl: influence of sex and breed.

Plasma growth hormone (GH) and prolactin concentrations were measured between 1 and 24 weeks of age in both sexes of a laying strain of chickens and from 1 to 9 weeks of age in broiler cockerels. 2. GH and prolactin concentrations were highest in young birds and higher in males than in females. 3. In both sexes GH and prolactin concentrations were correlated inversely with age and body weight and positively with relative weight gain. 4. Differences in growth rate between broilers and layers were related to differences in blood GH concentrations. 5. Water deprivation for periods of 6, 12, 18 or 24 h increases plasma prolactin markedly but did not affect GH secretion significantly.

Age Factors↗
PubMed1979

Variations in plasma prolactin, thyroid hormones, gonadal steroids and growth hormone in turkeys during the induction of egg laying and moult by different photoperiods.

1. Concentrations of prolactin, growth hormone, testosterone, progesterone, thyroxine and triiodothyronine were measured in the blood plasma of female turkeys during successive periods of egg laying, a decline in lay, a moult induced by a short photoperiod (6 light: 18 dark) and a resumption of egg laying induced by a long photoperiod (16L:8D). 2. Concentrations of prolactin, growth hormone, testosterone and progesterone were higher in laying birds than in birds which were moulting or not laying. 3. The concentration of testosterone, but not of the other hormones studied, increased significantly during the period of profuse moult. 4. Concentrations of the thyroid hormones did not change with the varying physiological condition of the birds. However, the concentration of thyroxine was depressed by the long photoperiod.

Animals↗