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Biomedical subjects

S Harvey

Publications and source records attributed to S Harvey.

At least 289 records · Page 16Linked to original sources
PubMed1982

Urokinase-like plasminogen activators of unusually high molecular weight secreted by a cell line derived from a human lung cancer case.

The HPL-SK-1 cell line derived from the pleural exudate of a lung cancer patient has been shown to secrete plasminogen activators of very high molecular weights (greater than or equal to 2 and 1 million), as shown by gel filtration on Sepharose 6B or CL-6B. The size of these activators could not be reduced by chromatography in buffers containing 2% sodium dodecyl sulfate, 8 M urea, or 1 M KSCN. Goat anti-urokinase antibody inhibited these activators only partially. Trypsin digestion of the 2 million-dalton species yielded several active fragments including one of the size of urokinase, 55,000 daltons. These large activators could be purified only by a double antibody immunoadsorption technique which consisted of the formation of a soluble immune complex between the activators and goat anti-urokinase IgG, followed by the adsorption of this complex to rabbit anti-goat IgG coupled to Affi-Gel 10. The eluted activators were purified 50-fold (2 million daltons) and 130-fold (1 million daltons), respectively. Reduction of the two largest species in the presence of sodium dodecyl sulfate resulted in the appearance of smaller molecular weight active fragments of differing size, indicating that these activators are disulfide-linked oligomers. Among the fragments of the 2 million-dalton species was found a 10,000-dalton enzyme which had lost activator and antigenic specificity and retained only a non-specific protease activity. A similar fragment was also isolated from reduced, purified 55,000-dalton urinary urokinase.

Antigen-Antibody Complex↗
PubMed1982

Influence of ingested petroleum on the reproductive performance and pituitary-gonadal axis of domestic ducks (Anas platyrhynchols).

1. The chronic ingestion of a sublethal dose (5%) of dietary North Sea crude oil delayed the onset of lay in adult Khaki Campbell ducks transferred from a short (8L:16D) to long day (16L:8D) photoperiod and greatly reduced the rate of oviposition and quality (weight and shell thickness) of the eggs subsequently laid. 2. Refeeding the oil-fed birds with the uncontaminated control diet stimulated the rate of egg production and improved egg quality, but in both cases not to the level in the controls. 3. Food intake and the plasma calcium level in the petroleum-fed birds were reduced, but these effects are unlikely to be causally responsible for the adverse effects of petroleum on avian reproduction. 4. Gonadotrophic (luteinizing hormone, LH) hormone secretion in the oil fed birds was not suppressed and the impairment of reproductive performance was not due to low plasma LH levels. 5. The reduced rate of lay in the oil-fed birds was accompanied by low gonadal steroid (progesterone) levels. The detrimental effects of oil and reproduction may be due to direct or indirect effects on the ovary or shell gland.

Animals↗
PubMed1982

Adrenocortical responses of ducks to treadmill exercise.

The influence of treadmill exercise on corticosterone secretion has been determined in domestic ducks. In birds unused to such exercise the concentrations of plasma corticosterone were markedly increased (greater than fourfold) after 15 or 30 min of treadmill exercise (1.1 km/h at 3 degrees grade) and the level remained high (between 30 and 40 ng/ml) throughout 90 min of exercise. This increase in corticosterone secretion accompanied a similar increase in colon temperature and was independent of the plasma glucose level. After exercise the corticosterone concentration declined to the pretreatment level within 60 min of recovery. In birds used to the exercise the corticosterone response to a standard (30 min) period of exercise was diminished (by 77.6%) in comparison with untrained birds and was no greater than the response (1.7-fold) in stationary control birds after handling and bleeding. The diminution of the corticosterone response to exercise may be due to the trained birds becoming fitter and better able to perform the work involved.

Adrenal Cortex↗
PubMed1981

Changes in somatomedin-like activity and growth hormone concentrations in the plasma of the domestic fowl (Gallus domesticus).

Variations to immunoreactive growth hormone (GH) and bioassayable somatomedin-like activity (SLA) were determined in the plasma of the domestic fowl. The plasma concentrations of SLA (potency relative to a pooled serum standard) and GH were both inversely age-related in growing cockerels (Thornber 909) between 3 and 20 weeks of age (SLA, r = 0.454; P less than 0.01, GH, r = 0.548; P less than 0.01) and directly related to each other (r = 0.54; P less than 0.01). In immature birds maintained on a photoperiod of 16 h light, 8 h darkness, plasma concentrations of SLA were highest during the first hour of darkness (1.19 +/- 0.18 units/ ml (u/ml) mean +/- S.E.M., n = 6) and significantly lower 1 h after dawn (0.78 +/- 0.07 u/ml n = 6). No diurnal variations in plasma concentrations of GH were observed. Deprivation of food in two strains of chickens (Thornber 909 and broiler) significantly reduced plasma concentrations of SLA in both strains and increased plasma concentrations of GH in the Thornber strain. Re-feeding fasted Thornber chickens caused the plasma concentrations of SLA and GH to return to normal within 24 h but had no effect in broilers. Deprivation of water, which also reduces food intake, for 12, 18 and 24 h markedly reduced plasma concentrations of SLA but had no effect on plasma GH concentration in Thornber cockerels.

Aging↗
PubMed1981

Effect of synthetic thyrotrophin-releasing hormone and its analogues on growth hormone secretion in the domestic fowl (Gallus domesticus).

Variations in plasma growth hormone (GH) concentrations following iv or sc administration of synthetic thyrotrophin-releasing hormone (TRH, Pyr-His-Pro-NH2) have been followed in immature and adult domestic fowl. TRH markedly stimulated GH secretion in newly hatched (1 and 2 day old) chicks and in 6-week-old cockerels but in adult male or female birds of two strains had very little effect, if any. Intravenous injection of 4 TRH analogues (Pyr-His-Mep-NH2, Pyr-Meh-Mep-NH2, Pyr-Meh-Mep-NH and Pyr-Meh-Pro-NH2) were also potent GH secretagogues in 6-week-old birds. The stimulatory effect of TRH or the TRH-analogues on GH secretion was not dose-related.

Age Factors↗
PubMed1981

Serum concentrations of prolactin, luteinizing hormone, growth hormone, corticosterone, progesterone, testosterone and oestradiol in relation to broodiness in domestic turkeys (Meleagris gallopavo).

Variations in concentrations of LH, GH, prolactin, corticosterone, oestradiol, testosterone and progesterone in serum were followed over a 24 h period (14 h light:10 h darkness) in laying and broody turkeys and in turkeys suspected of becoming broody (pre-broody hens). In laying hens marked variations in LH and gonadal steroid levels were observed in relation to the ovulatory cycle of the bird. These patterns of hormone secretion were not seen in either group of broody birds. Levels of GH in serum were very variable and showed no correlation with the egg-laying or light:darkness cycle and the concentrations did not differ between the respective physiological states. A nocturnal increase in the concentration of corticosterone in serum was observed in all three groups of turkeys and the concentration was occasionally higher in the pre-broody and broody birds than in the laying hens. The serum prolactin concentration in each group was also very variable and showed no obvious relationship with the ovulatory or photoperiodic cycle. The mean circulating prolactin concentration throughout the 24 h period did not differ significantly between the groups. These results suggest that broodiness in the domestic turkey is not initiated or maintained by enhanced prolactin secretion.

Animals↗
PubMed1981

Concentrations of pituitary, gonadal and adrenal hormones in serum of laying and broody white rock hens (Gallus domesticus).

Diurnal variations in circulating concentrations of LH, GH, prolactin, corticosterone, oestradiol, progesterone and testosterone were followed in laying and broody White Rock domestic fowl. Throughout the 24 h study prolactin concentrations in serum were consistently (two- to fourfold) higher in broody than in laying birds, in which the prolactin level varied with the light:darkness or ovulatory cycles. Concentrations of GH in serum tended to be lower in broody birds but in both groups were very variable and showed no obvious relationship with either the lighting or ovulatory cycles. Broodiness was also characterized by low LH and gonadal steroid levels and by the absence of preovulatory peaks in the serum concentrations of these hormones. A diurnal rhythm in corticosterone was observed in both the laying and broody birds, with high levels during the period of darkness. Corticosterone concentrations were markedly higher in the broody birds than in laying birds during most of the 24 h study. No diurnal rhythm in the blood haematocrit level was observed in either group, although the level was generally lower in broody birds. This difference, however, was insufficient to account for the lower LH and gonadal steroid levels in the broody birds. The results suggest that prolactin is involved in the initiation or maintenance of broodiness in the fowl and the possibility of an antigonadal role for the hormone is discussed.

Animals↗
PubMed1981

Diminution of thyrotrophin releasing hormone-induced growth hormone secretion in adult domestic fowl (Gallus domesticus).

Age-related changes in the response of GH to administration of thyrotrophin releasing hormone (TRH) have been investigated in the domestic fowl. In two strains of chicken the i.v. administration of TRH (10 microgram/kg) to 4-week-old male and female birds markedly increased (greater than 100 ng/ml) the plasma GH concentration within 10 min of treatment and the concentration remained higher than the pretreatment level for at least a further 20 min. Saline (0.9%) administration had no effect on GH secretion in comparable groups of control birds. The same dose of TRH had no effect on plasma GH concentrations in adult (greater than 24-week-old) laying hens or cockerels. The administration of TRH at doses of 0.1-100 microgram/kg (i.v.) or 0.39-50 microgram/bird (s.c.) also had very little, if any, effect on GH secretion in laying hens. In laying hens slight increases (10-20 ng/ml, P less than 0.05) inthe plasma concentrations of GH were observed in one experiment 60 min after the s.c. injection of 100 microgram TRH, and in another 60, 90 and 120 min after the serial s.c. injection of TRH (100 microgram/bird) every 30 min over a 150 min period. The poor GH response to TRH of the adults to TRH stimulation was not due to high circulating concentrations of endogenous gonadal steroids, as surgical gonadectomy had no effect on the GH response to TRH. These results suggest maturational differences in the control of GH secretion in the fowl.

Age Factors↗
PubMed1981

Inhibition of growth hormone release by prostaglandins in immature domestic fowl (Gallus domesticus).

The effect of prostaglandin (PG) E1, PGE2 and PGF2 alpha on GH secretion has been assessed in immature domestic fowl. The intravenous or subcutaneous administration of PGE1 and PGE2 (at a dose of approximately 200 microgram/kg) to 2-, 6- and 8-week-old cockerels consistently lowered plasma GH concentrations. This inhibition in GH secretion was observed for at least 40 min after administration of PGE1 and PGE2. The same dose of PGF2 alpha suppressed plasma GH levels in 2- and 6- week-old birds but the magnitude and duration of this response was less than that induced by PGE1 and PGE2. At this dose, administration of PGE1 and PGE2 resulted in overt signs of distress (e.g. gaping, panting, eye closure and postural instability) within 5-10 min of injection and the birds appeared to be sedated thereafter. Prostaglandin F2 alpha and lower doses of PGE1 and PGE2 did not have any apparent effect on behavior. These results suggest that prostaglandins inhibit GH secretion in birds although this may reflect a non-specific stress response.

Alprostadil↗
PubMed1981

Influence of insulin and glucagon on secretion of growth hormone in growing ducks (Anas platyrhynchos).

An inverse age-related pattern of GH secretion has been identified in immature ducks between 2 and 9 weeks of age, the plasma level of GH falling progressively from 30-40 ng/ml at 2 weeks of age to the adult level (less than 10 ng/ml) by 9 weeks of age. This decrease in GH secretion was not accompanied by any age-related changes in the concentrations of plasma immunoreactive insulin of glucagon-like immunoreactivity or in plasma glucose or free fatty acid level. In 4- to 6-week-old ducklings the intravenous infusion of insulin (2.5 or 10 mu./kg per min for 30 min) and glucagon (0.1 or 0.5 micrograms/kg per min for 30 min) induced some inhibition of GH secretion, independently of changes in blood glucose level. These results suggest that although insulin and especially glucagon have direct effects on GH secretion in the duck, maturational differences in pancreatic function are unlikely to be causally related to the decrease in GH secretion during growth.

Aging↗