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Biomedical subjects

D E ROGERS

Publications and source records attributed to D E ROGERS.

At least 37 records · Page 2Linked to original sources
PubMed1958

Studies on bacteriemia. IV. Alterations in rabbit mortality associated with aging of a culture of Escherichia coli.

Rabbits given an intravenous injection of an 18 to 24 hour broth culture of E. coli commonly died within 28 hours. The injection of a 4 hour broth culture of the same strain of E. coli containing equal numbers of living bacilli produced only an occasional death. Initial clearance rates and subsequent bacteriemias were similar in animals receiving either culture. Study of changes in circulating leukocytes or the temperature response to washed bacterial cells or culture filtrates failed to reveal obvious differences in host response to young or old cultures. It was found that both living bacterial cells and some substance or substances present in culture filtrates were required to produce subsequent death. The injection of whole old cultures containing both these factors produced hypothermia instead of the endotoxin type fever response which followed the injection of whole young cultures. Subsequent experiments revealed that this hypothermia appeared to be secondary to a period of transient but profound shock which occurred soon after the injection in rabbits receiving old cultures. No significant alterations in arterial pressure accompanied injections of young cultures. Evidence is presented which suggests that this period of hypotension rendered animals more likely to die with a persisting bacteriemia tolerated without event by non-shocked animals. The mechanisms which operate to increase mortality during the post shock period are as yet unclarified.

Aging↗
PubMed1957

Studies on bacteriemia. III. The blood stream clearance of Escherichia coli in rabbits.

Large numbers of E. coli were rapidly removed from the blood stream of rabbits at rates which initially paralleled the removal of similar numbers of staphylococci. Splanchnic tissues removed approximately two-thirds of the circulating bacilli in transit through the liver and spleen. In contrast to the cessation of splanchnic trapping noted 20 to 40 minutes following the injection of staphylococci, splanchnic trapping of E. coli continued unchanged for 3 to 5 hours unless the splanchnic tissues were dearly reseeding the blood stream. This resulted in the continued disappearance of E. coli over a 60 to 90 minute period, and differed from the constant bacteriemia maintained beyond 20 minutes after the injection of staphylococci. Some of the differences in the initial clearance of these two microorganisms appeared to relate to differences in host leukocyte-bacterium relationships. In vitro studies indicated that E. coli were rapidly killed following ingestion by rabbit polymorphonuclear leukocytes. Staphylococci survive such ingestion. The injection of E. coli was followed by a prolonged granulocytopenia with evidence of sequestration of granulocytes within the pulmonary vascular bed. The injection of staphylococci was followed by a transient leukopenia, with rapid return of granulocytes to the circulation (15). It appears probable that E. coli ingested by sequestered leukocytes are destroyed within the cell, and that leukocytes do not reenter the circulation containing living E. coli. Such intraleukocytic residence in the blood stream has been shown to be of possible importance in the maintenance of staphylococcal bacteriemia (14). An increasing E. coli bacteriemia occurred rapidly after the initial clearance period, indicating that many sequestered bacilli remained viable. Increasing bacteriemia also occurs 3 to 5 hours after the injection of staphylococci. The bacterial or host cell mechanisms which allow this secondary resurgence of bacterial populations are currently under investigation.

Animals↗
PubMed1957

Studies on bacteriemia. II. Further observations on the granulocytopenia induced by the intravenous injection of Staphylococci.

Intravenous injection of staphylococci produced a marked, transient granulocytopenia inrabbits. Leukopenia was rapidly followed by return of polymorphonuclear leukocytes to the peripheral blood, and normal circulating granulocyte levels were reestablished within 20 to 40 minutes. Differential arterio-venous leukocyte studies showed that polymorphonuclear leukocytes were trapped within the pulmonary vascular bed and, less constantly, in the splanchnic viscera during the initial 10 to 20 minutes following the injection of staphylococci. Granulocytes were subsequently found in larger numbers in blood leaving the lungs and splanchnic tissues, suggesting that entrapped polymorphonuclear leukocytes rapidly reentered the blood stream. This sequence of changes in circulating granulocytes was not significantly altered by splenectomy or the administration of cortisone. It has previously been shown that virtually all staphylococci in the blood stream are found within circulating polymorphonuclear leukocytes 10 to 40 minutes after the injection of culture (9). It is during this period that granulocytes return to the blood stream in large numbers. These observations suggest that staphylococci are phagocyted by polymorphonuclear leucocytes temporarily sequestered in the lungs and splanchnic viscera. It appears probable that some sequestered granulocytes containing living staphylococci subsequently return to the circulation. Such intraleukocytic staphylococci are believed to play a role in the maintenance of bacteriemia.

Agranulocytosis↗