The effects of allopurinol, uric acid, and inosine administration on xanthine oxidoreductase activity and uric acid concentrations in broilers.

The purpose of these studies was to determine the effects of uric acid (UA) and inosine administration on xanthine oxidoreductase activity in broilers. In experiment one, 25 broilers were assigned to 5 treatment groups: control, AL (25 mg of allopurinol/kg of body mass), AR (AL for 2 wk followed by allopurinol withdrawal over wk 3), UAF (AL plus 6.25 g of UA sodium salt/kg of feed), and UAI (AL plus 120 mg of UA sodium salt injected daily). The UA administration had no effect on plasma concentration of UA (P > 0.05), and all allopurinol-treated birds had lower (P < 0.05) UA levels than controls. The UA concentrations were restored in both plasma and kidney of AR birds at wk 3, but liver UA concentrations remained lower. Whereas xanthine oxidoreductase (XOR) activity in the liver (LXOR) was reduced (P < 0.05) by allopurinol treatment, XOR activity in the kidney (KXOR) was not affected (P = 0.05). In experiment two, 3 groups of 5 birds each were fed 0 (control), 0.6 M inosine/kg of feed (INO), or INO plus 50 mg of allopurinol/kg of body mass (INOAL). The INOAL birds showed lower total LXOR activity, but KXOR activity was not affected. Both INO and INOAL birds had higher plasma and kidney UA concentrations than controls. The results suggest that regulation of UA production is tissue dependent.

Upscaling the synthesis of biodegradable multiblock copolymers capable of a shape-memory effect.

Thermoplastic, phase-segregated multiblock copolymers (MBC) with shape-memory capability consisting of poly(ε-caprolactone) (PCL) switching segments and poly(p-dioxanone) (PDO) or poly(ω-pentadecalactone) (PPD) hard segments were prepared on a scale of several kilograms following a newly developed upscaling procedure. Dihydroxytelechelic poly(ether)esters were coupled by an aliphatic diisocyanate gaining products of sufficiently high molecular weights. The obtained biodegradable MBC exhibited good elastic properties and a shape-memory effect (SME) with a switching temperature (T (sw)) around body temperature. The yield of the synthesis could be improved and reaction time reduced, while mechanical and shape-memory properties were not affected. These multifunctional materials, which are now available in a larger scale have a high application potential as smart implant materials especially for minimally invasive surgery.

Effects of allopurinol on uric acid concentrations, xanthine oxidoreductase activity and oxidative stress in broiler chickens.

The purpose of this study was to determine the effects of allopurinol (AL) on xanthine oxidoreductase (XOR) activity and uric acid (UA) levels in chickens. Thirty 5-week-old broilers were divided into three groups and fed 0 (control), 25 (AL25) or 50 (AL50) mg AL per kg of body mass for 5 weeks. Chicks were weighed twice weekly and leukocyte oxidative activity (LOA) and plasma purine levels were determined weekly in five birds per group. Chicks were sacrificed after 2 or 5 weeks, and samples from tissues were taken for analysis of XOR activity. Plasma UA concentrations were lower (P<0.001) and xanthine and hypoxanthine concentrations were greater (P<0.001) in AL25 and AL50 birds compared to controls, whereas no differences (P=0.904) were detected in allantoin concentrations. By week 5, body mass was reduced (P<0.001) to 84.0 and 65.1% of that in controls for AL25 and AL50 broilers, respectively, and LOA was 4.1 times greater (P<0.05) in AL25 compared to control birds. Liver XOR activity was increased by 1.1 and 1.2 times in AL25 and AL50 birds, but there was no change (P>0.05) in XOR activity in the pancreas and intestine. These results suggest that AL effect on XOR activity is tissue dependent.

Haemorrhage and adrenocortical activity in the fowl (Gallus domesticus).

Plasma aldosterone concentrations were markedly elevated in chickens by the removal of 10-30% of their total blood volume. This aldosterone response to haemorrhage was delayed and of reduced magnitude in birds pretreated for 48 hr with dexamethasone (100 micrograms/kg every 12 hr), in which the basal aldosterone level was also suppressed. Corticosterone concentrations were elevated in both haemorrhaged and nonhaemorrhaged birds, although these responses were completely abolished by dexamethasone pretreatment, which also reduced the basal corticosterone concentration. Prolactin concentrations were unaffected by haemorrhage. These results demonstrate that haemorrhage specifically affects adrenocortical function by increasing aldosterone release and suggests that factors other than the pituitary-adrenal axis are responsible for this stimulation of secretion.

Dietary sodium and adrenocortical activity in ducks (Anas platyrhynchos) and chickens (Gallus domesticus).

Immature chickens and ducks were maintained on synthetic diets containing normal (0.4%), low (0.018%), or high (1.9%) sodium for 8 days, with freshwater available ad libitum. Food intake was similar in both species regardless of the diet but weight gain was depressed in birds fed the low-sodium diet. In both species the circulating aldosterone concentration was increased within 24 hr of dietary sodium depletion, although maximal levels were not attained until after 5 days. The magnitude of adrenocorticotrophin (ACTH)-induced aldosterone secretion was also increased in sodium-deprived chickens and ducks. The basal aldosterone level was slightly suppressed by excess dietary sodium, which blunted the aldosterone response to exogenous ACTH. The transfer of chickens and ducks from low- to high-sodium regimes reduced the aldosterone levels (within 24 hr) to those in their respective controls. The transfer of birds from high- to low-sodium diets resulted in a prompt increase in the aldosterone concentration, although of reduced magnitude when compared with control birds transferred to low sodium. In both species alterations in the dietary sodium content had no effect on basal or ACTH-induced corticosterone secretion. The plasma prolactin levels in chickens were also unrelated to their sodium status. These results suggest that homeostatic adaptations in electrolyte balance during sodium depletion or excess are principally mediated by alterations in aldosterone secretion.

Thyroid and adrenal responses of ducks (Anas platyrhynchos) during saline adaptation.

Fresh water-reared Aylesbury ducklings were given 0.1 or 0.2 M NaCl drinking water and variations in the plasma concentrations of thyroxine (T4), triiodothyronine (T3), corticosterone, and aldosterone were determined. Within 24 hr of being transferred to 0.2 M NaCl the corticosterone concentration was increased, whereas the levels of plasma T3 and aldosterone were reduced. The increase in corticosterone secretion persisted for at least 7 days, but the T3 and aldosterone concentrations had returned to control levels within 5 days. The concentrations of plasma aldosterone and T3 were similarly affected in birds transferred to 0.1 M NaCl, although corticosterone levels increased only after the birds were maintained on 0.1 M NaCl for 7 days. Plasma concentrations of T4 were increased in 1- to 2-week-old (but not 7-week-old) birds 7 days after their transfer to 0.1 and 0.2 M NaCl. In birds maintained on saline for 6 weeks the basal concentration of each hormone was not significantly different from that in fresh water-reared controls. When saline-reared birds were returned to freshwater conditions the plasma aldosterone and T3 concentrations were increased over a 5-day period. Transfer to saline consistently reduced body weight and food intake, whereas the transfer of saline-reared birds to fresh water stimulated body weight gain. Consequently, although these endocrine responses during saltwater adaptation might be expected to minimise the loss of body reserves and to facilitate the extra renal excretion of sodium, these alterations in endocrine function may be partly due to salt water-induced changes in food intake.

Localization of cells producting thyroid stimulating hormone in the pituitary gland of the domestic drake.

Cells binding anti-bovine TASH beta serum were found exclusively in the rostral lobe of the adenohypophysis of the drake using the peroxidase-antiperoxidase complex unlabelled antibody method. The specificity of the binding of the anti-serum to TSH cells was established by relating the morphology and relative abundance of immunochemically stained cells to the TSH content of the adenohypophysis after experimentally altering the activity of the pituitary-thyroid axis. The TSH activity of the adenohypophysis was assessed indirectly, by the weight of the thyroid glands, and directly, by bioassay. As determined by bioassay, the TSH content of the rostral lobe of the adenohypophysis was much greater than that of the caudal lobe. Compared with control drakes, immunochemically stained cells in birds fed a goitrogen, methimazole, seemed to be enlarged and were closer together, while the stained cells in drakes injected with thyroxine were shrunken and less intensely stained. The TSH content of the adenohypophysis was increased in drakes fed methimazole. Castration did not alter the TSH content of the adenohypophysis or change the morphology of immunochemically stained cells. These observations suggest that in the drake: 1) anti-bovine TSH beta serum binds specifically to TSH cells; 2) the TSH cells occur in the rostral and not in the caudal lobe of the adenohypophysis; and 3) the activity of TSH cells is not inhibited by the feedback effects of gonadal steroids.

The effect of hypothalamic lesions on thyroid-stimulating hormone concentration in the chicken pituitary.

Studies of thyroid activity following hypothalamic lesions have provided indirect evidence of TSH influence on the pars distalis of birds. The present study examined the influence of hypothalamic lesions on TSH assays of the rostral and caudal lobes of the pars distalis. Lesions of the septomesencephalic tract increased TSH levels in the rostral lobe but had no influence on the caudal lobe. Lesions of the supraoptic or ventrolateral nuclei neither stimulated nor depressed TSH in either lobe of the pars distalis.