Highly efficient induction of protective immunity by a vaccinia virus vector defective in late gene expression.

Vaccinia viruses defective in the essential gene coding for the enzyme uracil DNA glycosylase (UDG) do not undergo DNA replication and do not express late genes in wild-type cells. A UDG-deficient vaccinia virus vector carrying the tick-borne encephalitis (TBE) virus prM/E gene, termed vD4-prME, was constructed, and its potential as a vaccine vector was evaluated. High-level expression of the prM/E antigens could be demonstrated in infected complementing cells, and moderate levels were found under noncomplementing conditions. The vD4-prME vector was used to vaccinate mice; animals receiving single vaccination doses as low as 10(4) PFU were fully protected against challenge with high doses of virulent TBE virus. Single vaccination doses of 10(3) PFU were sufficient to induce significant neutralizing antibody titers. With the corresponding replicating virus, doses at least 10-fold higher were needed to achieve protection. The data indicate that late gene expression of the vaccine vector is not required for successful vaccination; early vaccinia virus gene expression induces a potent protective immune response. The new vaccinia virus-based defective vectors are therefore promising live vaccines for prophylaxis and cancer immunotherapy.

Temporary increase of plasma epinephrine affects stress responses 24 h later.

The impact of temporary (24 h) implantation of epinephrine tables on catecholamine responses to handling and immobilization 24 h later was investigated in rats. Free plasma epinephrine responded with an increase to both types of stress (77% and 326%, respectively) while controls showed a weaker response to immobilization. The basal level of free plasma norepinephrine was reduced (46% vs. controls) after epinephrine pretreatment, but neither handling nor immobilization had a specific effect on this parameter. In contrast, the basal level of free plasma dopamine was increased after epinephrine pretreatment (183%); however, as with free norepinephrine, there was no specific effect of handling or immobilization. Conjugated plasma epinephrine was significantly lowered after epinephrine pretreatment (44% vs. controls). It did not respond specifically to handling or immobilization except for a stronger response after 20 min of immobilization. Conjugated norepinephrine showed no specific response, but increased nonspecifically after extended immobilization. Conjugated dopamine was lowered (30%-48%) in the E-treated group and did not respond to stress at any time. Thus, a temporary elevation of free plasma epinephrine affected, differentially, basal levels and stress responses of free and conjugated catecholamines 24 h later.

Detection and evaluation of persisting stress-induced hormonal disturbances by a post stress provocation test in humans.

Eighteen healthy army officers were subjected after prolonged rest to exhaustive ergometric work for about 15 minutes. Before and afterwards blood was taken from the cannulated antecubital vein for determination of free and sulfoconjugated catecholamines, cortisol, glucose, and white blood cell count. One week later, the same procedure was repeated with the same subjects with the difference that the probands underwent about 2.5 hours of difficult mountain climbing and a subsequent rest of 1.5 hours before ergometry. The most important results were: 1) total and bound fractions of catecholamines showed some significant differences between the first and second ergometry due to the previous mountain climbing stress; 2) serum cortisol did not increase after the first ergometry but did so significantly after the second ergometry due to the previous stress; low cortisol is not always indicative of the absence of stress; 3) the absolute number of white blood cells increased in both situations, correlated significantly with the severity of the stress and the individual increases were more person than situation specific and; 4) blood glucose remained unaffected in both situations. We conclude that a previous stress experience can affect a second stress response and that such a post stress provocation test can uncover persistent hormonal alterations. This procedure may be useful for the evaluation of inaccessible stress situations from subsequent stress measures.

Critical comments on the classic concept of hypoglycemia induced epinephrine secretion.

Our experiments showed that a continuous chronic administration of norepinephrine (NE) to rats for 20 h by means of subcutaneously implantable retard tablets, led to a highly significant epinephrine(E) depletion of the adrenal medulla during normoglycemia. The rise of free plasma NE was accompanied by increased free plasma E values at 12 hours. At this time the liver contents of glycogen and free intracellular glucose showed their most pronounced decrease. At 12 and 20 hours both liver glycogen and medullar E values were very low. To check a possible causal relationship between those two events another experiment was performed in which the breakdown of liver glycogen should be inhibited. NE treated rats were force fed with 50% glucose solution 9 h after tablet implantation. This resulted in only mild glycogen depletion, which was no more able to trigger E liberation from the medulla. Therefore we conclude that pronounced liver glycogen depletion possesses a triggering ability for medullar E output by which hypoglycemia could be prevented.

Norepinephrine triggers medullar epinephrine depletion during normoglycemia.

Our experiments did show that chronic 12 hours administration of norepinephrine (NE) to rats by means of subcutaneously implantable retard tablets, led to a highly significant epinephrine (E) depletion of the adrenal medulla during normoglycemia. The expected rise of free plasma NE at 6 and 12 hours was accompanied by increased free plasma E values at 12 hours. At this very time point the liver contents of glycogen and free intracellular glucose showed their most pronounced decrease. Since at 12 hours both liver glycogen and medullar E values were at their lowest, a second experiment was performed to examine a possible causal relationship. In order to curb the breakdown of liver glycogen, rats were force fed with 50% glucose solution 9 hours after NE tablet implantation. Glucose feeding not only caused a much less pronounced liver glycogen fall at 12 hours, but, at the same time also prevented E depletion of the adrenal medulla. These observations suggested that rapid fall of liver glycogen and/or liver intracellular free glucose might be the trigger for medullar E depletion, even before hypoglycemia.