Calcium metabolism in birds.

Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.     

Copper metabolism in experimental Border disease.

The proposal that hypocupraemia and hypocuprosis are characteristic manifestations of Border disease and of aetiological significance has been investigated. Mean plasma copper concentrations in 65 affected and 47 unaffected lambs were similar and in a controlled experiment, plasma and tissue copper concentrations tended to be higher in affected lambs than in controls. It is concluded that hypocupraemia and hypocuprosis are not consistent features of Border disease and thus have no aetiological significance.     

Erythrocyte metabolism in normal and glutathione-deficient sheep.

Glucose utilization and lactate formation in erythrocytes from normal and glutathione (GSH)-deficient sheep were similar. Significant differences were observed, however, between the 2 groups of sheep in the production of 14-CO2 from erythrocytes incubated with ascorbic acid or methylene blue, or both. The greater response of normal erythrocytes compared to erythrocytes deficient in GSH suggests that there are some metabolic differences in the pentose phosphate pathway (ppp) activity of the erythrocytes. The nature and site of these differences are, however, not known. When sheep were kept in a decompression chamber for 2 weeks and subjected to a simulated altitude of 7,000 m for 12 hours/day, the erythrocytes showed a four- to six-fold increase in the activity of the ppp.     

Therapy of diseases of ruminant intermediary metabolism.

Diseases of intermediary metabolism include ketosis and fatty liver of dairy cattle and pregnancy toxemia of ewes. These conditions occur when there is a failure of the homeostatic mechanisms regulating the mobilization of fats and the conservation of carbohydrates. The therapeutic approach is to reestablish the normal homeostatic patterns of fuel utilization. Suppression of excessive ketogenesis is the most important factor in reestablishing homeostasis. Ketogenesis can be suppressed by a number of therapeutic agents that act either by suppressing the mobilization of fatty acids or by inhibiting the transport of fatty acids into the hepatic mitochondria, the site at which fatty acids are converted to ketone bodies. Useful therapies include bolus glucose infusions, glucose precursors, and glucocorticoids.     

Methodologic studies on protein metabolism and bioenergetics of protein deposition in growing animals. 4. Energy metabolism in chickens in connection with measurement of parameters of protein metabolism

In connection with the measuring of parameters of the protein metabolism in parallel experiments, the energy metabolism of 6 chickens (origin Tetra B) in the live weight range between approximately 100 and 1,800 g was determined under conditions of restricted energy supply. 3 animals each received a feed mixture containing 20% (animal group 1) and 38% (animal group 2) crude protein. The amount of feed was daily increased by 1.5 g DM. The digestibility of energy and nitrogen was independent of the age. 66.3 +/- 3.3% and 64.0 +/- 5.0% resp. of the metabolisable energy were utilised for protein and fat retention. The energy maintenance requirement, determined at a live weight of 2,000 g, was independent of protein supply and averaged in the two animal groups 434 +/- 40 kJ metabolisable energy/kg live weight 0.75 . d. The result of multiple regression was, for the growth period investigated, an energy maintenance requirement of 403 +/- 32 kJ metabolisable energy/kg live weight 0.75 . d. 1.77 and 1.38 J metabolisable energy resp. were required for 1 J protein or fat retention. The energy requirement for protein retention was independent of the degree of protein supply. The results from the measuring of energy metabolism are discussed in connection with the kinetic parameters of protein metabolism ascertained in parallel experiments.     

Isolation and metabolism cage system for newborn pigs.

An isolation system was designed and constructed for isolating normal and infected newborn pigs. The system consisted of an outer cage fitted with a biological diffusion filter and a dunk bath entry system and an inner metabolism cage to contain the pig. When tested with S-13 bacteriophage, the isolation and metabolism cage system was at least 99% efficient in preventing the entry or escape of microorganism. A total of 267 Escherichia coli-infected newborn pigs have been isolated in these units, with no cross contaminations.     

The effect of phlebotomy on canine erythrocyte metabolism.

Enzyme activity declines with erythrocyte age in most mammals. To test this concept in the dog, we decreased the PCV to less than 20 by phlebotomy. The erythrocytes were restored rapidly (1.57 per cent per day). The resulting decline in the mean erythrocyte age was accompanied by increased activity by most of the erythrocyte enzymes studied. Enzymes with lower initial enzymatic activity (hexokinase, pyruvate kinase, 6-phosphogluconate dehydrogenase and glutathione reductase) increased proportionally more than those with higher initial activity (lactate dehydrogenase, 3-phosphoglycerate kinase, glyceraldehyde-3-dehydrogenase and glucose-6-dehydrogenase). Among species, increases in enzyme activity after phlebotomy appear to be related to each species' life span. Most of the metabolites increased concomitantly with the highest reticulocyte period. Diphosphoglycerate concentrations did not change significantly during the experiment.     

Hormonal regulation and calcium metabolism in the rabbit.

Calcium is an important mineral in homeostasis in all vertebrate animals. It is the most abundant mineral in the body, and is the major component of bones and teeth. In addition, calcium is involved in various vital physiologic processes, including blood coagulation, muscle contraction, membrane permeability, nerve conduction, enzyme activity, and hormone release. Calcium metabolism in the rabbit differs in several respects from that of most mammals. This article discusses calcium metabolism and its hormonal regulation in the rabbit, as compared with normal calcium metabolism in other mammalian species. Medical disorders associated with this unique metabolism are introduced briefly.     

Hepatic drug metabolism and adverse hepatic drug reactions.

Drugs and other chemicals are usually metabolized in the liver in the drug-metabolizing enzyme system. The metabolites sometimes bind with cellular macromolecules and injure the cell directly or serve as new antigens to create immunologic injury in a delayed fashion. The immediate or toxic injury is dose-dependent, predictable and zonal in the liver lobule, usually in the central region. Carbon tetrachloride intoxication and acetaminophen overdose are examples of injury resulting from microsomal metabolism. Other injuries related to microsomal metabolism are those produced by vinyl chloride in polymerization plant workers and by methotrexate in psoriatics or leukemic children. Most adverse drug reactions affecting the liver and producing jaundice are unpredictable, delayed in onset, and only hypothetically related to microsomal metabolism in some instances. The two main types are cholestasis and viral-hepatitis-like. The former may be in a pure form, in which case it may be partly dose-dependent, or in a form mixed with hepatitis. Many drugs produce cholestasis in a small percentage of persons, and because the reaction is benign, albeit prolonged at times, such drugs continue to be used. The viral-hepatitis-like reaction involves few drugs and affects few persons, but can be fatal. The recognition that chronic hepatitis can be caused by drugs such as oxyphenisatin, alpha-methyldopa, and isoniazid has added a new dimension to the clinical problem of adverse drug reactions, which may extend to widely used and commonly available agents like aspirin.     

The energy metabolism of growing swine in the body weight range of 10-50 kg. 2. Nitrogen and energy metabolism

Investigations were carried out about nitrogen and energy metabolism feeding rations with 17-24 and 44-47% crude protein content on maintenance and growing level to castrated male hybrid pigs of line 150. In growing periods the N deposition amounted to 10 g/animal.d (15 kg live weight), 18 g/animal.d (30 kg LW) and 21 g/animal.d (greater than 40 kg LW) on lower protein feeding level. In experiments with higher protein feeding level the corresponding results were 17, 22 and 22 g N deposition/animal.d. The partial utilization of metabolizable energy for deposition amounted to 70% for the rations with 17-24% protein content and to 59% for the rations with 44-47% protein content, without correlation to the animals development and the alternation in the protein feeding level. The results of regression analysis about maintenance requirement were 814, 775 and 806 kJ metabolizable energy/kg LW0.62.d in trials feeding rations with 17-24% crude protein content as well as 764, 846 and 818 kJ metabolizable energy/kg LW0,62.d in trials feeding rations with 44-47% crude protein content. 1,5-1,8 MJ metabolizable energy were used per MJ protein energy deposition and 1,3-1,4 MJ per MJ fat energy deposition respectively. The energy deposition per kg live weight gain amounted to values between 9 (10 kg LW) and 18 MJ (60 kg LW).