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Biomedical subjects

L K Vaughn

Publications and source records attributed to L K Vaughn.

24 records · Page 2Linked to original sources
PubMed1979

Sensitivity of hypothalamic sites to salicylate and prostaglandin.

This study was designed to determine the dose of salicylate necessary to produce substantial antipyresis, and to determine the relationship between the response to salicylate and prostaglandin infused into the same region of the preoptic area of the rabbit. The effect of preoptic infusions of three doses of sodium salicylate, or a control solution, on the fever produced by an intravenous injection of endogenous pyrogen was measured. The pyrogenic response to prostaglandin E1 injected into the same preoptic sites in the same rabbits was also monitored. The results showed that the 50 microgram/microL per hour dose of salicylate did not produce significant antipyresis but that the 100 and 200 microgram/microL per hour doses did. The results also showed a significant correlation between the magnitude of fever produced by prostaglandin E1 and the magnitude of antipyresis produced by sodium salicylate at a particular site. Those sites at which infusion of salicylate produced the most effective antipyresis were also the ones at which prostaglandin E1 produced the largest fevers.

Animals↗
PubMed1979

Blood pressure in unanesthetized bacterially infected rabbits: effects of antipyretic drug therapy.

It has previously been determined that an intraperitoneal infusion of a combination of antipyretic-anti-inflammatory drugs, sodium salicylate and acetaminophen, increases the survival rate of rabbits injected with Pasteurella multocida, a gram-negative bacterium. To determine whether the increased survival rate was attributable to antihypotensive effects of the drug therapy, aortic arch blood pressure was measured continuously in unanesthetized rabbits before and after an injection of bacteria. The results of this investigation revealed that the injection of bacteria produced a fall in mean arterial pressure of 13 mm Hg in both drug- and saline-infused rabbits. These results exclude the possibility that the increased survival rate of rabbits injected with P. multocida, when infused with sodium salicylate and acetaminophen is attributable to the prevention in the fall in mean arterial pressure.

Acetaminophen↗
PubMed1978

Imparied thermoregulation in pregnant rabbits at term.

Pregnant and nonpregnant female rabbits were placed in hot (33 degrees C) and cold (3 degrees C) environments and their core temperatures measured. Pregnant rabbits during the 3 days before giving birth were less able to maintain normal body temperatures in thermally adverse environments than were nonpregnant rabbits. This alteration in thermoregulatory ability may permit an environmental temperature change that is not dangerous to nonpregnant rabbits to be potentially harmful or lethal to both mother and offspring.

Animals↗
PubMed1978

Fever and survival in rabbits infected with Pasteurella multocida.

1. Fever and survival rate of New Zealand white rabbits, injected with two doses of live Pasteurella multocida, were compared to determine if the relation between fever and survival observed in reptiles is also seen in a mammal. Since it is known that fever is beneficial in infected reptiles, our experiments were viewed as an initial step in the investigation of a similar potentially beneficial effect in mammals.2. There was a statistically significant correlation between the fever magnitude and survival. As fever increased up to 2.25 degrees C, the survival rate increased. Fevers above this level were associated with a decreased survival rate.3. Antipyretic drugs were administered to half the rabbits. The drugs were ineffective in reducing the fevers produced by injections of large doses of bacteria. Rabbits infused with antipyretics had a decreased mortality rate. The decreased mortality rate may be due to some action of the drugs other than their antipyretic effect.4. In vitro growth of P. multocida at normal (39 degrees C) and febrile (42 degrees C) temperatures was not significantly different. This suggests that the increased survival rate associated with higher fevers was not due to a direct inhibition of the growth of the bacteria by the increased temperature. It may be due to an enhancement of some aspect of the rabbits' immunological defences.5. It remains to be determined whether fever causes a higher survival rate or whether fever is only correlated with survival rate.

Animals↗
PubMedDate not supplied

Antipyresis: its effect on mortality rate of bacterially infected rabbits.

The effect of an antipyretic drug administered directly into the preoptic-anterior hypothalamus was measured in order to investigate the role of fever on mortality of bacterially infected mammals. New Zealand white rabbits (Oryctolagus cuniculus) were injected intravenously with Pasteurella multocida and either sodium salicylate or a control solution was infused directly into the preoptic-anterior hypothalamus. Both groups developed fevers, but the fever of the rabbits infused with the antipyretic was reduced by 50% during the initial stage of infection. Hypothalamic sodium salicylate infusions produced a lower average fever than control infusions over an initial 5 hour period of infection, reducing average 5 hour fevers from 1.56 degrees C to 0.72 degrees C. All of the infected rabbits infused with sodium salicylate died whereas only 29% of the infected control rabbits died. Rabbits receiving sodium salicylate alone did not die. The increased mortality could possibly be the result of a fulminating infection caused by rapidly multiplying bacteria during the initial, attenuated phase of the febrile course in the salicylate-treated rabbits.

Animals↗