Biomedical subjects

E T Littledike

Publications and source records attributed to E T Littledike.

At least 37 records · Page 2Linked to original sources

PubMed1991

Efficiency of various cloned DNA probes for detection of bovine viral diarrhea viruses.

We have evaluated 24 cytopathic (CP) and 37 noncytopathic (NCP) strains of bovine viral diarrhea virus (BVDV) with a dot blot assay using four different genome segments of the NADL strain as hybridization probes (p80, p54, gp53, and gp62). The p80 and p54 probes hybridized to 23/24 (96%) and 22/24 (92%), respectively, of CP strains examined. In contrast, these same two probes only detected 16/37 (43%) and 5/37 (13%), respectively, of the NCP strains examined. The gp53 probe detected 18/24 (75%) and the gp62 probe detected 19/24 (79%) of the CP strains. In contrast, these latter two probes only detected 9/37 (24%) and 7/37 (20%), respectively, of NCP strains. This low detection rate of NCP strains suggests a need for developing a probe based on NCP sequences for identification of NCP strains.

Animals↗

PubMed1991

Serologic detection and practical consequences of antigenic diversity among bovine viral diarrhea viruses in a vaccinated herd.

Samples of sera were obtained from 5,725 cows in a semiclosed herd. In each of the preceding 7 years, the herd was vaccinated against bovine viral diarrhea (BVD) with killed virus. Neutralizing antibody tests were done on all samples of sera, using cytopathic virus, BVD-TGAC virus, that was antigenically distinct from the vaccine virus. Most samples of sera had high titers of neutralizing antibodies against BVD-TGAC virus. In 48 samples of sera, neutralizing antibodies were not detected against BVD-TGAC virus, but were detected against the vaccine virus. Neutralizing antibodies against selected noncytopathic BVD viruses were not detected in several samples of serum that had neutralizing antibodies against the vaccine virus and BVD-TGAC virus. Noncytopathic BVD virus was isolated from sera obtained from 3 cows less than 4 years old. Two cows were available for further testing, and persistent infection with BVD virus was confirmed in both cows. The BVD viruses isolated from those cows were not neutralized by several samples of sera. Immunoprecipitation of polypeptides induced by the vaccine virus was done with selected samples of serum. Two patterns of immuno-precipitated viral-induced polypeptides were identified. One pattern was consistent with exposure of cows with live virus. The other pattern was consistent with exposure of cows with only the killed virus vaccine.

Animals↗

PubMed1990

Measuring physiological responses of animals to environmental stressors using a microcomputer-based portable datalogger.

The microcomputer-based datalogger system described in this report provides excellent flexibility for accurate recording of signals from a variety of sensors at programmable intervals. The small size of the unit permits applications in many research situations in which physiological and microclimate records are required from unrestrained animals. Data presented from two experiments with cattle with ad libitum access to feed demonstrate the utility of the system. The high resolution and frequent measurements illustrate the fine detail of thermoregulatory responses of cattle (as represented by tympanic temperature) to sequential moderate and hot environments, the association of feeding activities with tympanic temperature at moderate conditions, and the disruptions in thermoregulatory function and feeding activities in hot conditions. A comparison of four anatomical sites (two internal, two sub-dermal) for measuring body temperature also illustrates shortcomings in using sub-dermal measures to reflect responses to dynamic ambient environments.

Animals↗

PubMed1988

Use of 24-F-1,25-dihydroxyvitamin D3 to prevent parturient paresis in dairy cows.

Forty-one aged Jersey cows were fed a high Ca diet prior to parturition to predispose them to parturient paresis. Twenty-one of the cows were treated with 24-F-1,25-dihydroxyvitamin D3, a synthetic analogue of 1,25-dihydroxyvitamin D3, 7 d before the expected parturition. Treated cows received either 100 micrograms (n = 7) or 150 micrograms (n = 14) of 24-F-1,25-dihydroxyvitamin D3, intramuscularly at 7-d intervals until the cow calved. Incidence of parturient paresis among untreated animals was 85% (17/20). Injections of 100 micrograms of 24-F-1,25-dihydroxyvitamin D3 reduced the incidence of parturient paresis to 43% (3/7), whereas 150 micrograms injections of 24-F-1,25-dihydroxyvitamin D3 reduced the incidence of parturient paresis to 29% (4/14). Plasma concentrations of hydroxyproline were not elevated prior to parturition in 24-F-1,25-dihydroxyvitamin D3-treated cows, indicating that treatment did not stimulate bone resorption and that the ability of 24-F-1,25-dihydroxyvitamin D3 to prevent parturient paresis likely resides in its ability to stimulate intestinal Ca absorption prior to parturition. Further, cows treated with 24-F-1,25-dihydroxyvitamin D3 that developed parturient paresis had lower than normal plasma concentrations of 1,25-dihydroxyvitamin D, indicating that 24-F-1,25-dihydroxyvitamin D3 treatment impairs the metabolism of 25-hydroxyvitamin D in response to hypocalcemia. These data suggest that injection of 24-F-1,25-dihydroxyvitamin D3, delivered at 7-d intervals prior to parturition, can effectively reduce incidence of parturient paresis in dairy cows.

Animals↗

PubMed1987

Interactions of calcium, phosphorus, magnesium and vitamin D that influence their status in domestic meat animals.

Known and possible interactions between Ca, P, Mg, parathyroid hormone (PTH), calcitonin (CT), vitamin D and its metabolites, and interactions of each of these with other factors plus complexities and possible variations between and within domestic animal species, such as age, sex, physiologic state (i.e., pregnancy, lactation and growth) and diet, make Ca, P and Mg metabolism extremely dynamic and complex. Many advances have been made in understanding these interactions and how each of these factors is controlled, secreted or metabolized within the body. Some interactions among these factors are discussed in detail, mostly with a view to understanding mechanisms by which homeostasis of Ca, P and Mg is maintained. Also, three of the major diseases of mineral metabolism of cattle (milk fever, grass tetany and wheat pasture poisoning) provide excellent models to study the complex soil, plant and animal interrelationships among Ca, P, Mg and the factors that influence and control the ultimate utilization of these minerals in animals. These diseases are used to illustrate some of the interactions among many of the factors that influence Ca, Mg and P metabolism in domestic animals.

Animals↗

PubMed1986

Intracellular location of unoccupied 1,25-dihydroxyvitamin D receptors: a nuclear-cytoplasmic equilibrium.

In order to investigate the subcellular distribution of unoccupied 1,25-dihydroxyvitamin D3 receptors, highly purified cytoplasts and nucleoplasts were prepared from two kidney cell lines (PK1 and MDBK). This was accomplished utilizing the technique of enucleation by cytochalasin B and density gradient centrifugation. Unoccupied 1,25-dihydroxyvitamin D3 receptors were found in both the nuclear and cytosolic compartments, with approximately 70% of the receptors localized in the cytoplasm. When cells were pretreated with 1,25-[3H]dihydroxyvitamin D, prior to enucleation, it was found that 90% of the receptor-hormone complex was associated with nucleoplasts, thus demonstrating that cytochalasin B treatment does not alter the high-affinity association of the receptor-hormone complex with the nucleus. The ratio of unoccupied receptor/protein was found to be the same in whole cells, cytoplasts, and nucleoplasts for both cell types. The ratio of unoccupied receptor/DNA was highest in cytoplasts and lowest in nucleoplasts. Taken together, these data indicate that the unoccupied 1,25-dihydroxyvitamin D receptor is generally associated with cell proteins and not specifically associated with cell DNA. We therefore propose, at least for these cells, that the unoccupied 1,25-dihydroxyvitamin D receptor exists in equilibrium between the nuclear and cytosolic compartments of the whole cell, and receptor-hormone binding shifts this equilibrium to favor nuclear localization.

Animals↗

PubMed1986

Bone resorption, renal function and mineral status in cows treated with 1,25-dihydroxycholecalciferol and its 24-fluoro analogues.

The relative potencies of 1,25-dihydroxycholecalciferol, 24-F-1,25-dihydroxycholecalciferol, and 24,24-F2-1,25-dihydroxycholecalciferol at three doses (25, 100 or 400 micrograms) were assessed in nonlactating Jersey cows. The 24,24-F2-1,25-dihydroxycholecalciferol induced a significantly greater hypercalcemia and hyperphosphatemia than did 1,25-dihydroxycholecalciferol. The 24-F-1,25-dihydroxycholecalciferol was intermediate in its hypercalcemic and hyperphosphatemic potency. Urinary hydroxyproline excretion rate and plasma hydroxyproline concentration were not significantly increased by treatment with any of the compounds. This indicates that these compounds did not stimulate bone resorption in nonlactating, nongravid cows. Renal function was significantly impaired in cows that received a 400-micrograms dose of any compound. There was a severe reduction in glomerular filtration rate (up to 42%) and urine specific gravity. Renal function was most severely affected in cows treated with 24,24-F2-dihydroxycholecalciferol and was evident even at the 100-micrograms dosage level.

Animals↗

PubMed1986

Vitamin D3 and D3 metabolites in young goats fed varying amounts of calcium and vitamin D3.

Twenty-four male goats, 2 to 4 wk of age, were allotted to four dietary treatments in a 2 X 2 factorial design and, for 20 wk, were fed a milk diet at 12.5% body weight. Treatments varied in amounts of supplemental calcium and vitamin D3. Daily allowances per kilogram body weight were: 9.4 IU vitamin D3 (basal), 9.4 IU vitamin D3 plus 406 mg calcium carbonate (basal plus Ca), 940 IU vitamin D3 (basal plus D3), and 940 IU vitamin D3 plus 406 mg calcium carbonate (basal plus Ca plus D3). At the end of wk 7, a corn supplement was added to all diets at 1% body weight daily. Addition of vitamin D3 to the diet resulted in a dramatic increase in plasma concentrations of vitamin D3. Goats in the basal plus D3 and basal plus Ca plus D3 groups had nearly 100 X greater concentrations of vitamin D3 than goats in the basal and basal plus Ca groups. When greater amounts of vitamin D3 were fed, dietary calcium interacted to decrease plasma vitamin D3 concentrations. Plasma concentrations of 25-hydroxyvitamin D3 were unaffected by additional dietary calcium but were increased by dietary vitamin D3, increasing sixfold to seven-fold in the basal plus D3 and basal plus Ca plus D3 groups. Supplemental calcium resulted in decreased plasma 1,25-dihydroxyvitamin D3. No signs of vitamin D toxicity were noted. The physiological responses reported implicate the goat as a potential animal model for vitamin D research in dairy cattle.

Animals↗

PubMed1986

Sequential sampling and analysis of renal hydroxylase activities of cattle given 1 alpha-hydroxyvitamin D3.

A new method was developed for sequential sampling of bovine renal cortex. This method results in minimum hemorrhage and adhesions and provides sufficient renal cortex tissue for assay of 25-hydroxyvitamin D 1 alpha-, 24-, and 23-hydroxylase activities. Application of this procedure in calves and pregnant cows treated with 1 alpha-hydroxyvitamin D3 is described. The success of these experiments suggests these techniques could be used to follow enzyme activities that control crucial aspects of vitamin D metabolism in normal peripartum cows and cows with milk fever or other diseases of mineral metabolism.

Animals↗

PubMed1986

Effect of synthetic bovine parathyroid hormone in dairy cows: prevention of hypocalcemic parturient paresis.

Intravenous infusion of synthetic bovine parathyroid hormone for 96 h increased 1,25-dihydroxyvitamin D, Mg, Ca, and hydroxyproline in plasma of pregnant cows within 16, 24, 48, and 72 h, respectively. Plasma Ca concentration was maximal at the end of the 96-h infusion (15.1 mg/100 ml). Plasma concentration of 1,25-dihydroxyvitamin D at 96 h was twice that before parathyroid hormone infusion, indicating that parathyroid hormone stimulated 1,25-dihydroxyvitamin D production in the presence of hypercalcemia. The urinary excretion of hydroxyproline indicated that at least 48 h of parathyroid hormone stimulation was required to stimulate bone resorption in the pregnant cow. Eight periparturient cows were on a high Ca diet prepartum. Four cows were treated with intravenous parathyroid hormone prior to parturition. Four cows were untreated. All four untreated cows developed parturient paresis. None of the cows treated with parathyroid hormone developed parturient paresis. However, two cows that received parathyroid hormone for less than 24 h prior to parturition became hypocalcemic, but not recumbent. Plasma Ca concentrations remained within normal limits in the two other cows that received greater than 60 h parathyroid hormone infusion prior to parturition. We conclude that exogenous parathyroid hormone (1-34) can prevent parturient paresis if administered at least 60 h prior to parturition.

Animals↗

PubMed1986

Effects of dietary calcium, vitamin D3, and corn supplementation on growth performance and mineral metabolism in young goats fed whole milk diets.

Twenty-four male goats, approximately 2 to 4 wk of age, were allotted to four dietary treatments in a 2 X 2 factorial design and were fed a basal milk diet at 12.5% body weight for 20 wk. Vitamin D3 was added to the milk in two different amounts with and without supplemental CaCO3. At the end of wk 7, corn was added to all diets at 1% body weight. Over 20 wk, average daily gain was unaltered by addition of Ca or vitamin D3 to the diet. When corn was added to the diet, gains increased from 48 to 180 g/d. Plasma Ca concentrations were not affected by dietary treatment. Supplemental Ca decreased plasma Mg concentrations. Corn supplementation curtailed a depression in plasma Mg and seemed to prevent a whole milk-induced hypomagnesemia. Fecal excretion of all minerals measured was increased in goats fed supplemental Ca. Dietary Ca increased urinary Ca but decreased urinary Mg. Percentage of apparent absorption of Ca, Mg, and total ash was lower in Ca-supplemented goats, as was apparent retention of Ca and Mg. The physiological responses reported suggest the goat as a potential research model for mineral metabolism studies in other ruminants.

Animals↗

PubMed1985

Dietary calcium and vitamin D: risk factors in the development of atherosclerosis in young goats.

Effects of supplemental dietary calcium and vitamin D on lipid distribution and aortic mineralization were examined in young goats. Twenty-four goats, 2-4 wk of age, were allotted one of four dietary treatments for a 20-wk period and fed a basal milk diet (Basal), a calcium-supplemented diet (Basal + Ca), a cholecalciferol-enriched diet (Basal + D3) or a diet with both calcium and cholecalciferol (Basal + Ca + D3). Goats in the Basal + Ca group had plasma cholesterol concentrations that were 16.6% of those of the Basal group. Percentage absorption and fecal excretion of total lipids were unaffected by dietary treatment. Generally, total lipid and cholesterol concentrations were unaltered in liver, other viscera and carcass tissues. Dietary cholecalciferol increased concentrations of cholesterol and total lipid in aortas, whereas dietary calcium decreased total lipids in aortas. Concentrations of calcium, magnesium and total ash were increased in aortas by dietary treatment, with a marked increase observed in the Basal + Ca + D3 group. Sudan IV and gross calcium staining in aortas revealed both lipid and mineral deposition that confirmed composition data. A high intake of vitamin D accompanied by excessive intake of calcium seems to accelerate the development of atherosclerosis. Supplemental calcium with normal amounts of vitamin D, however, is hypocholesterolemic and seems protective against the atherogenic process.

Animals↗

PubMed1985

Effect of dietary phosphorus levels on porcine renal 25-hydroxyvitamin D-1 alpha- and 24R-hydroxylase activities and plasma 1,25-dihydroxyvitamin D3 concentration.

Results of studies on the effect of dietary P deprivation on pig renal 1 alpha- and 24-hydroxylase activities and on concentrations of plasma alkaline phosphatase, Ca, P and vitamin D metabolites are presented. Renal 1 alpha-hydroxylase activity was increased six- to eightfold and plasma 1,25-dihydroxyvitamin D3 concentration increased two- to threefold in pigs fed a low P diet (.085% P) compared with pigs fed a control diet (.6% P). In contrast, renal 24-hydroxylase activity and plasma 25-hydroxyvitamin D concentration did not differ between diet groups. Plasma alkaline phosphatase activity was two to four times higher in pigs fed the low P diet compared with pigs fed the control diet. The rate of gain by pigs fed the low P diet was less than pigs fed the control diet. The low P diet was associated with a prolonged elevation of renal 1 alpha-hydroxylase activity in spite of the presence of a pronounced hypercalcemia.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

PubMed1985

Effects of dietary vitamin D3 on concentrations of vitamin D and its metabolites in blood plasma and milk of dairy cows.

To determine the effect of supplemental dietary vitamin D3 on concentration of vitamin D and its metabolites in milk, 20 Holstein cows were assigned to four groups and fed either 0, 10,000, 50,000, or 250,000 IU of vitamin D3/d beginning approximately 2 wk prepartum and continuing through wk 12 of lactation. Samples of blood plasma and milk were assayed for concentrations of vitamin D, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D. Only the daily dosage of 250,000 IU caused significant increases of concentrations of vitamin D or 25-hydroxyvitamin D in plasma. Concentrations of vitamin D and 25-hydroxyvitamin D in milk were approximately equal and averaged .2 ng/ml. Little 1,25-dihydroxyvitamin D and no 24,25-dihydroxyvitamin D could be detected in milk from any of the four treatment groups. Cows fed 250,000 IU of vitamin D3/d produced milk containing 54 IU of vitamin D activity per liter, whereas unsupplemented cows produced milk containing 17 IU/L. Oral supplementation with up to 250,000 IU of vitamin D3/d does not increase effectively vitamin D activity of milk.

24,25-Dihydroxyvitamin D 3↗

PubMed1985

Suppression of mitogenic response of bovine lymphocytes during experimental ketosis in calves.

Experimental ketosis was induced by feeding calves a diet containing 1,3 butanediol for 9 or 10 days. Blood beta-hydroxybutyrate was significantly (P less than 0.05) elevated during clinical ketosis. The mitogenic response of the lymphocytes collected during ketosis was significantly (P less than 0.01) suppressed, and the suppression persisted for 2 weeks. During ketosis, all calves fed a 1,3 butanediol diet had clinical signs of an upper respiratory tract infection. Possible relationships between the suppressed function of lymphocytes, the increased concentration of 1,3 butanediol, and the increased susceptibility of the calves to infections during ketosis were considered.

3-Hydroxybutyric Acid↗

PubMed1984

25-Hydroxyvitamin D 1 alpha- and 24-hydroxylase activities in pig kidney homogenates: effect of vitamin D deficiency.

A method was developed for simultaneous assay of 25-hydroxyvitamin D 1 alpha- and 24-hydroxylase in pig kidney homogenates. The products of these enzymes, 1,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol, were extracted from the in vitro incubation mixtures, isolated and purified by gel filtration and high-performance liquid chromatography, identified by ultraviolet absorption spectrometry, and high performance liquid chromatography with a second solvent system and quantified relative to authentic standards with a 254-nm detector system. Assay conditions included 12.5 microM substrate (25-hydroxycholecalciferol) concentration and an incubation time of 15 minutes at 37 degrees C, which was on the linear portion of time curves for both enzymes. Maximum enzyme velocity was 1548 pmol/minute per gram kidney tissue for 1 alpha-hydroxylase and 286 pmol/minute per gram kidney tissue for 24-hydroxylase. The apparent Km for pig kidney 25-hydroxyvitamin D 1 alpha-hydroxylase (1 alpha-hydroxylase) was 445 nM and for 25-hydroxyvitamin D 24-hydroxylase (24-hydroxylase) was 833 nM. We also demonstrated the use of this assay in pigs fed a semisynthetic diet with or without vitamin D. Pigs fed vitamin D-deficient diet had a 5- to 10-fold increase in 1 alpha-hydroxylase activity, severe hypocalcemia, low plasma, 1,25-dihydroxycholecalciferol, very low plasma (undetectable) 24,25-dihydroxycholecalciferol concentration, and no detectable 24-hydroxylase activity compared to those fed the vitamin D-replete diet.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

PubMed1984

Effect of sow vitamin D status at parturition on the vitamin D status of neonatal piglets.

The plasma concentrations of calcium, phosphorus, vitamin D, and vitamin D metabolites were determined in cholecalciferol-treated sows and untreated sows at parturition and their piglets (at birth and at 10 days of age) to determine the relationship between sow vitamin D status and neonatal piglet vitamin D status. At birth, there was a high degree of correlation between sow and piglet plasma concentrations of 25-hydroxycholecalciferol (r = 0.944), 24,25-dihydroxycholecalciferol (r = 0.895), and 25,26-dihydroxycholecalciferol (r = 0.737). Neonatal piglet plasma 1,25-dihydroxyvitamin D was low (42.0 +/- 10.2 pg/ml) and was not correlated with maternal plasma 1,25-dihydroxyvitamin D (r = 0.022). Neonatal plasma calcium and phosphorus were significantly correlated (P less than 0.05) with maternal plasma 1,25-dihydroxyvitamin D (r = 0.515 and 0.581, respectively). Parenteral cholecalciferol treatment of sows before parturition proved an effective means of supplementing young piglets with cholecalciferol (via the sow's milk) and its more polar metabolites via placental transport. However, it had no significant effect on either the plasma mineral or 1,25-dihydroxyvitamin D status of the sow or young piglet.

Aging↗

PubMed1984

Infusions of parathyroid hormone in ruminants: hypercalcemia and reduced plasma 1,25-dihydroxyvitamin D concentrations.

The relationship between infused synthetic bovine PTH-(1-34) and plasma concentrations of minerals and vitamin D metabolites was studied in eight calves (150-230 kg) and two thyroparathyroidectomized goats. Calves were infused iv with saline for 15-20 h. Then, calves were infused with one of three types of solution for an additional 35-h period. Three of the eight calves received 3 ng/kg X min (group H), three received 0.75 ng/kg X min (group L), and the remaining two calves received control saline over a 33-h period (group C). Blood samples were taken every 4-6 h. Plasma calcium, phosphorus, hydroxyproline, and 1,25-dihydroxyvitamin D [1,25-(OH)2D] remained relatively constant in control calves. PTH infusions into calves in group H resulted in an increase in plasma calcium from 2.4 to a plateau of 3.0 mmol/liter. PTH infusion caused no change in plasma phosphorus, but increased urinary excretion of phosphorus. Infusion of PTH caused a moderate increase in urinary calcium excretion, followed by pronounced calciuria after PTH withdrawal. Plasma concentrations of 1,25-(OH)2D decreased from about 30 pg/ml at the start of infusion to undetectable levels (less than 5 pg/ml) at the end of the infusion and for 30 h thereafter. Similar, but less pronounced, changes in plasma calcium and 1,25-(OH)2D concentration were observed in group L. Hypocalcemia and hypophosphatemia developed in the two lactating goats after thyroparathyroidectomy, and plasma 1,25-(OH)2D concentrations were decreased. PTH infusion (3 ng/kg X min) corrected the hypocalcemia and hypophosphatemia and markedly raised plasma 1,25-(OH)2D concentrations. When calcium chloride was infused in addition to PTH, the resulting hypercalcemia (3 mmol/liter) was associated with a marked reduction in plasma 1,25-(OH)2D. We conclude that the concentration of calcium in plasma has the major regulatory role on plasma 1,25-(OH)2D concentrations in ruminant species when potentially conflicting signals, such as hypercalcemia and high PTH concentrations, are present simultaneously.

Animals↗