Complete Genome Sequences of Virus Strains Isolated from Bottle A of the South African Live Attenuated Bluetongue Virus Vaccine.

This is a report of the complete genome sequences of plaque-selected isolates of five virus strains included in bottle A of the South African Onderstepoort Biological Products commercial live attenuated bluetongue virus vaccine.

Cerebral protein synthesis in the ovine fetus near term with amino acid infusion and insulin-induced hypoaminoacidemia.

BACKGROUND: Studies during early development have shown that the precursor availability of amino acids directly affects protein synthesis both at the whole-body level and for select organ tissues, although this has not been studied for the brain. OBJECTIVE: We utilized a mixed amino acid infusate and an insulin euglycemic clamp technique in the ovine fetus near term, with increases and decreases in circulating amino acid levels of ∼30 to 40% on average, and determined the impact on cerebral protein synthesis. METHODS: Fetal sheep received a 6-hour infusion of Primene® 10% (amino acid infusate group) or a co-infusion of insulin and 10% dextrose (insulin/dextrose infusate group) together with a continuous infusion of L-[1-(13)C]-leucine. Measurements were obtained for fetal plasma leucine enrichment at steady-state and brain tissue intracellular free and protein-bound leucine enrichment at necropsy, followed by the determination of cerebral protein fractional synthetic rates (FSR). RESULTS: Protein FSR for the cerebral cortex averaged ∼58 and ∼39%/day when using the intracellular free and plasma enrichment values for the precursor pool measurements, respectively, providing for maximal and minimal FSR values, and with little difference between the amino acid and insulin/dextrose groups, although significantly higher than respective values for the cerebellum. CONCLUSION: Accordingly, there was no evidence of a differential effect of increases versus decreases in circulating amino acids on cerebral protein synthesis as studied, which may be attributed to the saturable nature of the blood-brain barrier transporters for amino acids.

Induced hyper and hypo amino acidemia in the ovine fetus near term: effects on electrocortical activity.

Amino acid infusate (Primene) and insulin euglycemic (insulin + 10% dextrose) clamp techniques were used in the ovine fetus near term and the impact on the incidence of low-voltage and high-voltage electrocortical (ECOG) activities was determined. Fetal sheep were studied over a 2-hour control period and a subsequent 6-hour experimental period.With the Primene infusion, the basic and neutral amino acids were increased by 43% and 25%, respectively, whereas the acidic amino acids showed little change. With the insulin/dextrose infusion, the basic and neutral amino acids decreased by 48% and 30%, respectively, whereas the acidic amino acids were again little changed. A small fall in arterial oxygen saturation and an increase in fetal heart rate for both groups can be attributed to an insulin-mediated increase in fetal metabolic rate. Despite the moderate increases and decreases in circulating amino acid levels, there was no significant change in the mean percent time or duration of fetal ECOG activities for either study group.

Effects of antenatal glucocorticoids on cerebral protein synthesis in the preterm ovine fetus.

OBJECTIVE: Although antenatal glucocorticoids have well-known benefits for infants who are born preterm by the enhancement of pulmonary maturation, adverse effects on brain growth and development have been reported in several animal-based studies. We have used the chronically catheterized ovine fetus to determine the effects of synthetic glucocorticoids that are administered at doses used clinically on cerebral protein synthesis during early brain development using [13C]-leucine tracer method. STUDY DESIGN: Chronically instrumented pregnant sheep at 0.85 gestation received 2 intramuscular injections of betamethasone at 170 microg/kg maternal weight or saline 24 hours apart together with a continuous infusion of L-[1-(13)C]-leucine to the fetus on the second day of experimentation. Measurements were obtained for fetal plasma leucine enrichment at steady-state and brain tissue intracellular free and protein-bound leucine enrichment at necropsy, followed by the determination of cerebral protein fractional synthetic rates (FSRs). A coefficient of variation was determined for plasma and tissue enrichment measurements to assess the inherent methodologic variance with the use of [13C]-leucine tracer technology. RESULTS: The cerebral protein FSR averaged approximately 112% per day and approximately 35% per day when the intracellular free and plasma enrichment values were used for the precursor pool measurements, respectively, providing for maximal and minimal FSR values. There were no differences between cortical and cerebellar tissues nor between the saline control and the betamethasone animal groups. The coefficient of variation for the plasma-enrichment values averaged approximately 2%; the coefficient of variation for the tissue enrichment values averaged approximately 10%, with an inverse relationship between the [13C]-leucine enrichment values and the coefficient of variation values. CONCLUSION: Although cerebral FSR values for the preterm ovine fetus are high and indicate high rates of protein synthesis and degradation, we found no evidence that these are altered by betamethasone as used clinically and thereby do not account for the reported structural alterations in the brain after a single-course of antenatal glucocorticoids.