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Biomedical subjects

A N Rowan

Publications and source records attributed to A N Rowan.

13 recordsLinked to original sources
PubMed1990

Refinement of animal research technique and validity of research data.

Refinement of research techniques using animals will lead to less animal distress and, at the same time, will usually lead to higher quality and more robust data. For example, acclimation of laboratory animals to handling and experimental procedures will produce not only an animal that is easier to handle but also one that reacts to the experimental stimulus rather than to the handler. Even when the animal is acclimated to handling, handling or anesthesia can cause marked changes to commonly measured biological parameters such as serum hormone and tissue metabolite levels. Standard animal housing systems are also stressful to the animals. One research report, for example, found that mice in conventional facilities had plasma corticosterone values of 150-500 ng/ml compared to values below 35 ng/ml from mice kept in special "low-stress" housing. However, assessment of stress in animal research is not easy and few technicians or research scientists are good judges of moderate stress. Investigators in the United Kingdom have recently published a report on a new technique that might allow more objective assessment of discomfort in laboratory rats and mice. The amount of exploratory behavior in treated and control animals can be used for developing a Disturbance Index (DI). The DI is a measure of the extent to which a procedure or treatment causes a departure from normal behavior. The initial data using the DI indicate that it could be a promising approach for assessing animal well-being (or the lack of it).

Animal Husbandry↗
PubMed1979

Changes in the contents of adenine nucleotides and intermediates of glycolysis and the citric acid cycle in flight muscle of the locust upon flight and their relationship to the control of the cycle.

1. The contents of some intermediates of glycolysis, the citric acid cycle and adenine nucleotides have been measured in the freeze-clamped locust flight muscle at rest and after 10s and 3min flight. The contents of glucose 6-phosphate, pyruvate, alanine and especially fructose bisphosphate and triose phosphates increased markedly upon flight. The content of acetyl-CoA is decreased after 3min flight whereas that of acetylcarnitine is decreased markedly after 10s flight, but returns towards the resting value after 3min flight. The content of citrate is markedly decreased after both 10s and 3min flight, whereas that of isocitrate is changed very little after 10s and is increased by 50% after 3min. The content of oxaloacetate is very low in insect flight muscle and hence it was measured by a sensitive radiochemical assay. The content of oxaloacetate increased about 2-fold after 3min flight. A similar change was observed in the content of malate. The content of ATP decreased about 15%, whereas those of ADP and AMP increased about 2-fold after 3min flight. 2. Calculations based on O(2) uptake of the intact insect indicate that the rate of the citric acid cycle must be increased >100-fold during flight. Consequently, if citrate synthase catalyses a non-equilibrium reaction, the activity of the enzyme must increase >100-fold during flight. However, changes in the concentrations of possible regulators of citrate synthase, oxaloacetate, acetyl-CoA and citrate (which is an allosteric inhibitor), are not sufficient to account for this change in activity. It is concluded that there may be much larger changes in the free concentration of oxaloacetate than are indicated by the changes in the total content of this metabolite or that other unknown factors must play an additional role in the regulation of citrate synthase activity. 3. The increased content of oxaloacetate could be produced via pyruvate carboxylase, which may be stimulated during the early stages of flight by the increased concentration of pyruvate. 4. The decreases in the concentrations of citrate and alpha-oxoglutarate indicate that isocitrate dehydrogenase and oxoglutarate dehydrogenase may be stimulated by factors other than their pathway substrates during the early stages of flight. 5. Calculated mitochondrial and cytosolic NAD(+)/NADH ratios are both increased upon flight. The change in the mitochondrial ratio indicates the importance of the intramitochondrial ATP/ADP concentration ratio in the regulation of the rate of electron transfer in this muscle.

Adenine Nucleotides↗
PubMed1978

Partial purification and some properties of pyruvate carboxylase from the flight muscle of the locust (Schistocerca gregaria).

A procedure is described for the partial purification of pyruvate carboxylase (pyruvate:CO2 ligase (ADP-forming), EC 6.4.1.1) from the flight muscle of the locust (Schistocerca gregaria). Characterisation of the kinetic properties of this enzyme indicates that it is activated by acetyl-CoA, is insensitive to inhibition by di- and tricarboxylic acids and exhibits an apparent Km for HCO3-(16 mM) which differs by an order of magnitude from that observed for other pyruvate carboxylases. It is suggested that activation of this locust flight muscle pyruvate carboxylase during the rest leads to flight transition may result from increases in the concentrations of pyruvate and HCO3- under these conditions.

Flight, Animal↗
PubMed1978

Trends in the use of nonhuman primates in biomedical programmes.

Recent surveys of the use of primates in biomedical laboratories indicate that the demand, especially for imported animals, is declining. Reasons for this trend are not clear, although restrictions on export by countries of origin undoubtedly have a significant effect. More precise survey techniques and terminology would aid comparisons and help to identify the factors involved in changes in demand.

Animals↗