Plasma indicators of muscle damage in a model of nutritional myopathy in weaner sheep

SUMMARY Subclinical nutritional myopathy was induced in 5-month-old sheep by feeding them a diet low in vitamin E and selenium. Subsequently clinical myopathy was induced by dosing with protected polyunsaturated fatty acids. Plasma activities of creatine kinase (CK), pyruvate kinase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase and aldolase, enzymes of muscle origin, all remained above their reference ranges in clinically affected sheep, but fluctuated widely. Similar fluctuations occurred in subclinically affected animals, resulting in some activities being within the reference ranges and some above, at different times. Plasma malondialdehyde, an indicator of lipid peroxidation, proved of no diagnostic value. Terminal plasma CK activities were significantly correlated with microscopic damage in the vastus lateralis (VL), but not the vastus intermedius (VI) or the tensor fascia lata (TFL) muscles. AST was the most highly correlated with damage in VI and VL. In two clinically affected sheep successfully treated with an oral dose of α-tocopherol actetate all enzymes decreased steadily to within their reference ranges, at rates probably related to their plasma half-lives. These results suggest that measurement of plasma CK activity would be useful in monitoring recovery of treated sheep.     

Cerebral dopamine, apomorphine and oral activity in the neonatal pig

Neonatal piglets in which oral stimulation associated with feeding was reduced by intragastric tube feeding displayed an increase in stereotyped snout rubbing, licking and chewing behaviour. An investigation of a possible neurochemical basis for this behaviour was made by using sensitive radioenzymatic and micro-fluorimetric assays to estimate the concentrations of the catecholamines and of the dopamine metabolites homovanillic acid (HVA) and 3,4-dihydroxyphenyl-acetic acid (DOPAC) in different brain regions. These observations revealed that the increased non-nutritive oral activity of such piglets did not appear to be caused by an increased release of dopamine in the brain, since it was not associated with increases in the concentrations of the acidic metabolites of dopamine in either the caudate nucleus, the putamen, the nucleus accumbens, the olfactory tubercle, the hypothalamus, or the substantia nigra. The only neurochemical changes observed were small decreases in the concentration of HVA in the putamen and the nucleus accumbens. A lack of effect on catecholamine concentrations in any of the six brain regions examined suggested that the environmental manipulation caused no changes in the development of catecholamine-containing nerve endings.
Subcutaneous injection of apomorphine was found to increase the non-nutritive oral activity of piglets. Apparent conditioning effects of the environment on apomorphine-induced stereotyped behaviour however, prevented any satisfactory testing of possible changes in cerebral dopamine receptor sensitivity following reduced oral stimulation.     

Population dynamics and stock status of cobia,Rachycentron canadum,caught in Australian recreational and commercial coastal fisheries

Abstract Age and growth of Rachycentron canadum (L.) was studied in northern and eastern Australia to provide data for a preliminary assessment of the stock and to explore possible fisheries management strategies using minimum legal lengths. Fish collected from commercial and recreational fisheries ranged in size and weight from 125 to 1633 mm fork length (FL) and 0.031 to 55 kg respectively. Annual growth increments in sectioned otoliths formed by November–December. Estimated ages ranged from 0 to 7 yr for both genders. Longevity was estimated to be at least 13 yr. Von Bertalanffy growth function parameters were L = 1160 mm FL, K = 0.63 yr^?1 and t₀ = ?0.21 yr^?1. Rachycentron canadum reach 600 mm FL in their first year and over 1000 mm FL in 3 years. Natural and total mortalities were estimated at 0.35 yr^?1 and 0.85 yr^?1, respectively. Populations of R. canadum may be vulnerable to growth overfishing under the current minimum legal length of 750 mm total length (TL) in Queensland waters. An increase in minimum legal length to 850 mm TL is recommended.     

Stratospheric fallout of strontium-89 and barium-140

A series of nuclear test explosions which occurred in the fall of 1958 caused a very large increase of Sr(89) and Ba(140) in the stratosphere. The Ba(140)/Sr(89) ratio in the stratosphere, and hence in the troposphere, has decreased steadily since then with a half-life of approximately 17 days.     

Muscle enzymes in the diagnosis of ovine weaner nutritional myopathy

SUMMARY The diagnostic performance of plasma tests for muscle enzymes was measured in sheep from flocks affected by clinical and sub-clinical nutritional myopathy. Parallel combinations of tests for creatine kinase (CK), alanine amino transferase (ALT), aspartate amino transferase (AST) and lactate dehydrogenase had higher diagnostic sensitivity than CK alone. The enzymes ALT and AST showed the highest correlation with the degree of muscle damage. A parallel combination of tests for plasma CK and ALT as well as tests for plasma α-tocopherol and red cell glutathione peroxidase are recommended for the diagnosis of nutritional myopathy and a decision on the appropriate treatment. The number of false negative results based on a diagnosis from the microscopic examination of single muscles was higher than for the parallel combination of tests. The number of false negatives was highest for the vastus intermedius and lowest for the tensor fascia lata. Diagnosis using a panel of blood tests has the advantages of overcoming problems of inadequate muscle sampling, a larger number of sheep in the flock can be tested and a more rapid diagnosis can be obtained.