Publications by authors named "Symonds H"

77 Publications

The choleretic effect of menbutone and clanobutin sodium in steers.

Authors:
H W Symonds

Vet Rec 1982 May;110(18):423-5

Adult steers were given either clanobutin or menbutone intravenously and the effects on bile flow measured. Doses of 4.3 g of clanobutin or 3.0 g of menbutone had no effect on bile flow. However, when bile flow was previously reduced by reducing the total bile salts in the enterohepatic circulation both compounds were potent choleretics, increasing the volume of bile flow up to four-fold.
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http://dx.doi.org/10.1136/vr.110.18.423DOI Listing
May 1982

Surgical procedure for modifying the duodenum in cattle to measure bile flow and the diurnal variation in biliary manganese, iron, copper and zinc excretion.

Res Vet Sci 1982 Jan;32(1):6-11

A surgical procedure is described for modifying the duodenum of cattle so that bile can be sampled and its rate of flow measured for long periods. In 12 steers, aged three months to three years and weighing between 50 and 650 kg, bile flow ranged from 2 to 12 ml per minute, the rate of flow increasing with bodyweight. The rate of flow expressed as ml per minute per 100 kg bodyweight decreased as bodyweight increased, the regression equation being in (ml per minute per 10 kg) = 1.65-0.0022 x where x = bodyweight (kg), r = 0.871. The mean concentrations of copper, iron, manganese and zinc in bile were 8.2, 6.2, 17.1 and 3.3 mumol per litre respectively. The concentration of iron was the least variable between the steers. The average total cholate concentration was 100 mmol per litre and total solids ranged from 5.4 to 7.2 per cent. Diurnal patterns in bile flow and trace element excretion were measured in four adult steers during a period of 38.5 hours. Although the rate of excretion of iron, zinc and copper and bile flow varied throughout the period, changes could not be associated with feeding or time of day. The concentration of manganese in bile and its excretion rate varied in a reproducible manner which may be related to feeding activity. The mean output of the four trace elements in bile from the four steers during 24 hours was, copper 37.7 mumol, iron 68.0 mumol, manganese 80.3 mumol and zinc 59.6 mumol.
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January 1982

The excretion of selenium in bile and urine of steers: the influence of form and amount of Se salt.

Br J Nutr 1981 Nov;46(3):487-93

1. The excretion of 75Se and stable Se in bile and urine was measured in four steers during 6 h after intravenous injections of 75Se as either selenite or selenate containing either 5 or 5000 microgram carrier Se. 2. When 5000 microgram Se were given, the rate of urinary excretion and plasma clearance of 75SE was similar for both salts. Approximately 23% was excreted in urine and plasma clearance was triexponential, the mean half-life (t 1/2) of the successive components, alpha, beta, and gamma, being 2.3, 15-2 and 465 min respectively. The amount of 75Se excreted in bile was small; 1.94% of the 75SeO3(2-) and 0.86% of the 75SeO4(2-) dose. 3. When 5 microgram Se were given the plasma clearance of 75Se was initially biexponential but the entry of 75Se-labelled protein from the liver caused an increase in plasma radioactivity after 30-40 min. The effect was most marked after 5 microgram 75SeO3(2-) when plasma 75Se radioactivity returned to 69% of the activity present at 2 min. Values for t 1/2 of the two components of clearance for 75SEO4(2-) were respectively alpha 2.6 and 2.5 min, and beta 15.9 and 36.6 min. Similar amounts of 75Se appeared in bile (0.2% of the dose) after injection of either salt but much less 75Se was excreted in urine after 75SeO3(2-) (6%) than after 75SeO4(2-) (17%). 4. At low dosage rates (5 microgram) Se is more readily incorporated into tissues from SeO3(2-) than from SeO4(2-).
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http://dx.doi.org/10.1079/bjn19810057DOI Listing
November 1981

The maximum capacity of the liver of the adult dairy cow to metabolize ammonia.

Br J Nutr 1981 Nov;46(3):481-6

1. Three adult dairy cows were fitted with cannulas in a mesenteric, portal, hepatic and jugular vein and a carotid artery. They received infusions of step-wise increasing amounts of ammonia as ammonium acetate via a mesenteric vein until NH 3 intoxication occurred. Sodium acetate was used in control infusions. The maximum rate of uptake of NH3 by the liver and the concentrations of glucose, urea, lactate, acetate and bilirubin in blood were measured. 2. During the infusions of ammonium acetate the liver extracted almost all the NH3 present in the portal vein until an infusion rate of approximately 15.0 mmol/min was reached. The maximum capacity of the liver to remove NH3 during its first pass was on average 1.84 mmol/min per kg wet weight. The cows became intoxicated when arterial plasma ammonia concentrations reached 0.8 mmol/l. Concentrations of NH3 in jugular venous blood were between 66 and 74% of those in the carotid.
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http://dx.doi.org/10.1079/bjn19810056DOI Listing
November 1981

The maximum capacity of the bovine liver to excrete manganese in bile, and the effects of a manganese load on the rate of excretion of copper, iron and zinc in bile.

Br J Nutr 1981 May;45(3):605-11

1. The maximum capacity of the bovine liver to excrete manganese in bile was determined in three Friesian-cross steers surgically prepared to allow bile flow-rate to be measured and samples collected. Plasma Mn concentrations were increased by infusing manganese chloride solutions into a jugular vein and the biliary excretion rates of Mn, copper, zinc and iron were measured. 2. The maximum capacity of the liver to excrete Mn in bile was exceeded at an infusion rate of approximately 4000 microgram Mn/min, and at this rate there was a significant decrease in the concentration of Cu, Fe and Zn in bile. The maximum concentration (mean +/- SE) of Mn in bile was 193 +/- 19 microgram/ml, and the maximum excretion rate (mean +/- SE) was 1210 +/- 130 microgram/min for three animals. There was no reduction in bile flow or evidence of live damage as a result of the infusions.
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http://dx.doi.org/10.1079/bjn19810138DOI Listing
May 1981

Selenium metabolism in the dairy cow: the influence of the liver and the effect of the form of Se salt.

Br J Nutr 1981 Jan;45(1):117-25

1. Six adult Friesian cows were given 75Se as either 75SeO32- or 75SeO42- intravenously. Five of the cows had cannulas in an hepatic vein, the portal vein and one carotid artery to enable the uptake of 75Se by the liver to be measured. Radioactive balance studies were carried out on two of the cows given 75SeO32- and two given 75SeO42-. A seventh cow was given an oral dose of 75Se-labelled barley and the excretion of 75Se in faeces, urine and milk was measured for 14 d. 2. After the injection of 75SeO32- plasma 75Se concentration decreased during the first 30 min with a mean half-life (t 1/2) of 15.6 min. From 30 to 60 min after dosing the concentration of radioactivity increased to reach approximately 50% of the level present 2 min after dosing. Following the injection of 75SeO42- the 75Se was cleared with a mean t 1/2 of 28.5 min during the first 30 min and plasma radioactivity increased only slightly during the next 30 min. 3. during the phase of rapid clearance of 75Se after the injection of 75SeO32- the hepatic venous 75Se concentration was approximately 5% lower than portal venous 75Se concentration. During the period when plasma 75Se activity was increasing the activity in hepatic venous plasma was 3% greater than portal activity. Of the 75Se cleared from plasma after injecting 75SeO32- 40% was calculated to be removed by the liver. 4. After intravenous dosing with 75SeO32- or 75SeO42- approximately 9.5 and 17.0% respectively of the dose injected was excreted in faeces and 10% in urine within 14 d. Almost three times as much 75Se was excreted in urine and 3.5 times as much in faeces during the first 24 h after dosing with 75SeO42- as after 75SeO32-.
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http://dx.doi.org/10.1079/bjn19810084DOI Listing
January 1981

Net hepatic and splanchnic metabolism of lactate, pyruvate and propionate in dairy cows in vivo in relation to lactation and nutrient supply.

Biochem J 1980 Jan;186(1):47-57

1. Circulating concentrations of glucose, propionate, lactate and pyruvate, and net exchange of these compounds across the liver and gut, were measured in lactating and non-lactating dairy cows (a) in the normal fed state, (b) before, during and after intravenous infusion of an aqueous solution of glucose, propionate or lactate (lactating cows only) in fed animals, and (c) before and during 6 days of food deprivation. 2. In the normal fed state, gut output of propionate, hepatic output of glucose and hepatic uptake of lactate were all higher in the lactating group. There was a net uptake of pyruvate across the liver in the lactating cows and a net output in the non-lactating cows. In the lactating cows there was a net uptake of lactate and pyruvate by the splanchnic bed (i.e. gut and liver combined). 3. In the lactating cows, the glucose and propionate infusions had the following effects: decrease in net hepatic uptake of lactate; a switch in pyruvate exchange across the liver from uptake to output; suppression of uptake of lactate and pyruvate by the splanchnic bed; increase in the magnitude of the liver (propionate uptake)/(glucose output) ratio. Lactate infusion did not affect hepatic propionate uptake. 4. Food deprivation increased hepatic extraction of lactate and pyruvate and decreased the liver (propionate uptake)/(glucose output) ratio in both groups. 5. It is concluded that mechanisms exist to ensure an inverse relationship between the availability to the cow of glucose or propionate and utilization by the splanchnic bed of endogenously derived lactate and pyruvate.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1161502PMC
http://dx.doi.org/10.1042/bj1860047DOI Listing
January 1980

The half-life of glutamate dehydrogenase in plasma of dry and lactating dairy cows.

Res Vet Sci 1979 Sep;27(2):267-8

The clearance of glutamate dehydrogenase from plasma was measured weekly for three weeks in three dry and three lactating cows. The clearance was exponential with a mean clearance constant of 0.0488/j and means (+/- SE) half-life of 14.2 (+/- 0.77) h. There were variations among cows and among measurements in the same cow but there was no difference between the mean half-lives of GDH in lactating and dry cows. Because of the long half-life the small variations among individual cows are unlikely to affect the interpretation of increased plasma GDH activity.
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September 1979

Differences between lactating and non-lactating dairy cows in concentration and secretion rate of insulin.

Biochem J 1979 May;180(2):281-9

1. Four parameters of insulin metabolism were compared in catheterized lactating and non-lactating Friesian x Ayrshire dairy cows. 2. The four parameters, i.e. arterial and portal-venous concentrations of insulin, and pancreatic output and hepatic uptake of insulin, were approx. 2-, 3-, 3- and 5-fold higher respectively in the non-lactating cows than in the lactating cows in the normal fed state. Statistical significance was not achieved for the differences in magnitude in the case of the latter two parameters, however. 3. All four parameters increased significantly about 4-fold when non-lactating cows were infused intravenously with glucose for 48 h at a rate of 4.2 mmol/min. The parameters also increased in the lactating cows during glucose infusion, but the values reached were substantially lower than in the non-lactating cows and the increases were not statistically significant. 4. Arterial insulin concentrations doubled in the non-lactating cows during a 3 h infusion of propionate into a mesenteric vein, but remained unaltered in the lactating cows. 5. Differences in insulin concentration and output between the lactating and non-lactating cows were not consistently related to differences in either glucose concentration or glucose-entry rate. Arterial propionate concentrations were similar in both groups of cows at all times. 6. It is concluded that in the dairy cow, insulin secretion in response to an insulinotropic agent is diminished during lactation.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1161051PMC
http://dx.doi.org/10.1042/bj1800281DOI Listing
May 1979

Effects of food deprivation on ketonaemia, ketogenesis and hepatic intermediary metabolism in the non-lactating dairy cow.

Biochem J 1979 Jan;178(1):35-44

1. The aim of this work was to investigate why non-lactating dairy cows are less susceptible to the development of ketonaemia during food deprivation than are dairy cows in early lactation. 2. The first experiment (Expt. A) consisted of determining the effect of 6 days of food deprivation on the concentrations of ketone bodies, and of metabolites related to the regulation of ketogenesis, in jugular blood and liver of non-lactating cows. 3. During the food deprivation, blood ketone-body concentrations rose significantly, but to a value that was only 16% of that achieved in lactating cows deprived of food for 6 days [Baird, Heitzman & Hibbitt (1972) Biochem. J. 128, 1311--1318]. 4. In the liver, food deprivation caused: a rise in ketone-body concentrations; a fall in the concentration of glycogen and of various intermediates of the Embden-Meyerhof pathway and the tricarboxylic acid cycle; an increase in cytoplasmic reduction; a decrease in the [total NAD+]/[total NADH] ratio; a decrease in energy charge. These changes were all qualitatively similar to those previously observed in the livers of the food-deprived lactating cows. 5. There appeared therefore to be a discrepancy in the food-deprived non-lactating cows between the absence of marked ketonaemia and the occurrence of metabolic changes within the liver suggesting increased hepatic ketogenesis. This discrepancy was partially resolved in Expt. B by the observation in two catheterized non-lactating cows that, although there was a 2-fold increase in hepatic ketogenesis during 6 days of food deprivation, ketogenesis from the splanchnic bed as a whole (i.e. gut and liver combined) declined slightly owing to cessation of gut ketogenesis.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1186478PMC
http://dx.doi.org/10.1042/bj1780035DOI Listing
January 1979

The absorption of dietary manganese by dairy cows.

Res Vet Sci 1978 May;24(3):366-9

Additional manganese, sufficient to increase the dietary concentration to approximately 1000 mg/kg, was administered to one cow for four and another for seven days. Manganese concentrations in portal and mesenteric plasma were increased by a mean of 3.9 microgram/litre above the concentration in systemic plasma. This increment is equivalent to the absorption of 0.54 per cent of the administered manganese. The cow which received manganese for seven days showed after six days larger increases in systemic plasma manganese concentration which may indicate a toxic effect of excess manganese upon the liver.
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May 1978

The effect of litter size on placental blood flow and placental calcium transfer in the multifoetate guinea-pig.

Br J Nutr 1978 Mar;39(2):347-56

1. Placental blood flow rate and calcium transfer rate were measured at 61 d of pregnancy in guinea-pigs carrying between one and eight foetuses. 2. Placental blood flow rate was significantly correlated with foetal weight. Ca transfer rate was related to placental size. Irrespective of litter size the mean amount of Ca transferred across a placenta was between 0.22 and 0.34 mg/h per g placental tissue. 3. It was concluded that there was a limit to the rate of transfer which was produced by a combination of limitations in placental blood flow rate, maternal plasma Ca concentration and placental tissue transfer capacity.
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http://dx.doi.org/10.1079/bjn19780044DOI Listing
March 1978

The effect of xylazine and xylazine followed by insulin on blood glucose and insulin in the dairy cow.

Vet Rec 1978 Jan;102(2):27-9

The effect of xylazine and xylazine followed 20 minutes later by insulin upon glucose metabolism and plasma insulin concentrations was examined in three cows. After doses of 0.18 mg per kg xylazine given intramuscularly (IM) or 0.15 mg per kg given intravenously (IV) hepatic glucose production increased, plasma insulin concentrations decreased to 25 to 33 per cent of control values, and there was a prolonged hyperglycaemia. When 200 units of soluble insulin were given 20 minutes after similar doses of xylazine there was a rapid fall in blood glucose and a reduction in the rate of glucose production by the liver. Xylazine-induced hyperglycaemia arose from a combination of increased hepatic glucose production and reduced plasma insulin concentrations. Peripheral tissues were still responsive to insulin and when adequate insulin was available blood glucose concentrations rapidly decreased.
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http://dx.doi.org/10.1136/vr.102.2.27DOI Listing
January 1978

Pathogenesis of fatty liver in fasted cows.

Proc Nutr Soc 1977 May;36(1):41A

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May 1977

The effect of xylazine upon hepatic glucose production and blood flow rate in the lactating dairy cow.

Authors:
H W Symonds

Vet Rec 1976 Sep;99(12):234-6

The effect of xylazine (Rompun) upon hepatic glucose production and blood flow rate was measured in two cows. Doses of 0-16 or 0-18 mg/kg bodyweight increased blood glucose concentrations by 200 per cent and hepatic glucose production by 400 per cent. Maximum blood glucose concentrations were reached approximately 40 minutes after dosing and did not start to fall until 185 minutes. Concentrations were near normal 24 hours after dosing. The increase in hepatic glucose production was greatest 20 minutes after dosing and production had returned to control rates 150 minutes after dosing. Visceral glucose utilisation was also increased. Blood flow rates in the hepatic and portal veins were reduced to 50 to 60 per cent of their predosing values. It is concluded that the prolonged hyperglycaemia which persists beyond 150 minutes is produced either by continued glucose production from sites other than liver and viscera or by reduced utilisation of the blood glucose by peripheral tissue.
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http://dx.doi.org/10.1136/vr.99.12.234DOI Listing
September 1976

Macromolecular components of genital tract fluids from the sheep.

J Reprod Fertil 1976 Sep;48(1):99-107

The proteins and glycosidases in the luminal fluid from the genital tract of ewes at different stages of the oestrous cycle and early pregnancy were studied. Most of the proteins in oviducal fluid and uterine fluid were serum proteins, but an increased amount of a glycoprotein excluded from Sephadex G-200 was detected in oviducal fluid at oestrus. Small amounts of uterine-specific proteins were detected in uterine fluid by polyacrylamide gel electrophoresis and isoelectric focusing. The number of these varied according to the stage of pregnancy. The activities of several glycosidases were elevated in uterine fluid when compared with serum; beta-N-acetylgalactosaminidase and beta-N-acetylglucosamindase were particularly active. Ovine cervical mucus was shown to contain an epithelial glycoprotein which had a composition similar to that of the glycoproteins isolated from human and bovine cervical mucus.
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http://dx.doi.org/10.1530/jrf.0.0480099DOI Listing
September 1976

Manganese metabolism in cows and goats.

Biochim Biophys Acta 1976 Aug;444(1):1-10

When 54MnCl2 was incubated with fresh bovine or caprine serum for 20 h and the serum subjected to electrophoresis at pH 9.5, the 54Mn bound to transferrin and alpha2-macroglobulin in proportions which varied with the temperature of incubation and the temperature of electrophoresis. Between 0 and 37 degrees C, the higher the temperature of incubation the larger the proportion bound to transferrin and the lower the proportion bound to alpha2-macroglobulin. The temperature at which electrophoresis was performed had little effect on the proportion of 54Mn bound to transferrin, but increasing temperature reduced the proportion of 54Mn bound to alpha2-macroglobulin. Mn2+ did not bind to purified transferrin in vitro in the absence of an oxidising agent. In the presence of permanganate, Mn3+ was formed and chelated by transferrin at physiological pH. In fresh serum this oxidation step may be performed by ceruloplasmin or molecular oxygen. Mn2+ was bound reversibly to alpha2-macroglobulin but this protein played no part in the oxidation of divalent manganese and had no effect on the protein binding of trivalent manganese. Manganese in the divalent state, either free as Mn2+ or bound to alpha2-macroglobulin, is removed from blood plasma very efficiently by the liver. However, the manganic-transferrin complex normally found in circulation is not rapidly removed from plasma. The liver can remove large amounts of excess manganous manganese which it presumably excretes; the small essential fraction of the manganese absorbed is oxidised to the trivalent state and bound to transferrin.
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http://dx.doi.org/10.1016/0304-4165(76)90218-xDOI Listing
August 1976

Proteins in the luminal fluid from the bovine oviduct.

J Reprod Fertil 1975 Nov;45(2):301-13

Oviducal fluid was collected by cannulation from four cows and by irrigation from fifteen slaughtered cows. The proteins in the fluid were examined by polyacrylamide gel electrophoresis at pH 4-5 and pH 8-9, isoelectric focusing on polyacrylamide, immunodiffusion, immunoelectrophoresis, affinity chromatography and gel filtration. The macromolecular components found were mainly serum proteins but small amounts of other proteins were detected in oestrous and dioestrous samples by electrophoresis at pH 8-9 following fractionation of the fluid by gel filtration or affinity chromatography. Small amounts of cathodically migrating proteins were detected directly by electrophoresis at pH 4-5 in dioestrous samples but not in oestrous samples. Determination of glycosidase activities revealed that the levels at oestrus were similar to the levels detected in serum. At dioestrus, the activities of B-N-acetylgalactosaminidase and beta-N-acetylglucosaminidase were elevated.
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http://dx.doi.org/10.1530/jrf.0.0450301DOI Listing
November 1975
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