Biomedical subjects

A G Krieger

Publications and source records attributed to A G Krieger.

4 recordsLinked to original sources

PubMed1995

Mixed-field neutrons and gamma photons induce different changes in ileal bacteria and correlated sepsis in mice.

High doses of radiation induce septicaemia, from bacterial translocation, and death in animals. Mice were exposed to either comparable lethal (LD90/30) or sublethal (LD0/30) doses of mixed-field [n/(n + y) = 0.67] or pure 60Co gamma-photon radiation. The relative biological effectiveness of these comparable doses of radiation was 1.82, determined by probit analysis. Mice given a lethal dose of mixed-field radiation developed a significant (p < 0.01), 10(9)-fold increase in Gram-negative facultative bacteria in their ilea over values in control mice. In contrast, mice given a lethal dose of gamma-photon radiation developed a significant (p < 0.01) increase in only Gram-positive bacteria in their ilea, while the number of Gram-negative bacteria remained near values in control mice. Data correlated with bacteria that were isolated and identified from the livers of mice that were given comparable lethal doses (LD99/30) of mixed-field or gamma-photon radiation. In sublethally irradiated mice, fluctuation in the total number of bacteria was detected in their ilea during the first week following irradiation, after which the number approximated the value in control mice. This difference in the predominant facultative bacteria in ilea resulting from different qualities of radiation has important implications for the treatment of septicaemic-irradiated hosts.

Animals↗

PubMed1980

Gonococci-human polymorphonuclear leukocyte interactions: metabolic studies associated with attachment and ingestion.

Utilizing monolayers of human polymorphonuclear leukocytes, optimal conditions for attachment and ingestion of Neisseria gonorrhoeae were determined. Both attachment and ingestion were optimal at 36 degrees C when a bacteria-leukocyte ratio of 100:1 was employed. After 30 min of incubation, log-phase viable type 2 gonococci were attached to 90% of leukocytes, whereas log-phase viable type 4 gonococci were ingested by 80 to 90% of cells. Respiratory inhibitors had no effect on attachment or ingestion, whereas glycolytic inhibitors blocked ingestion but did not affect attachment of gonocci to the leukocyte surface. Inhibition was dose dependent and partially reversible. The oxidative metabolism of leukocytes with gonococci attached or ingested was also examined. Attachment of log-phase type 2 gonococci stimulated a minimal increase in glucose oxidation and oxygen consumption by leukocytes in contrast to marked increases by leukocytes that had ingested viable type 4 or heat-killed typed 2 organisms. These results demonstrate that attachment of log-phase type 2 gonococci to the surface membrane does not stimulate significant leukocyte oxidative metabolism nor initiate the phagocytic process.

Glucose↗

PubMed1978

The species of viridans streptococci associated with microbial endocarditis: incidence and antimicrobial susceptibility.

Streptococcal endocarditis has been well recognized for decades and over the years investigators at The New York Hospital have defined many of the diagnostic and therapeutic modalities currently employed in patients with this disease. In this study, speciation of the viridans streptococci has provided new insights into the relative frequency and antimicrobial susceptibility patterns of these organisms. Indeed, recent studies also suggest that S. milleri endocarditis is associated with a high incidence of suppurative complications and that patients with S. bovis endocarditis may have a significant incidence of underlying but asymptomatic lower gastrointestinal malignancies. Further studies correlating viridans streptococcal species with other clinical and laboratory parameters of endocarditis should provide additional insights into this disease.

Culture Media↗

PubMedDate not supplied

Viridans streptococcal endocarditis: the role of various species, including pyridoxal-dependent streptococci.

The viridans streptococci are a heterogeneous group of organisms frequently associated with microbial endocarditis. Isolates from consecutive patients with endocarditis due to viridans streptococci who were seen at The New York Hospital from 1944 to 1955 and from 1970 to 1978 were speciated, and the relative frequencies and patterns of sus ceptibility to penicillin were determined. Vitamin B6-dependent streptococci, classified as Streptococcus mitior, accounted for 5%-6% of microbial endocarditis in both time periods. Since these nutritional variants require the active forms of vitamin B6 for growth in routein media, they can be responsible for culture-negative endocarditis. Media must be supplemented with either pyridoxal hydrochloride or pyridoxamine dihydrochloride (the active forms of vitamin B6) for isolation, identification, and subsequent testing of susceptibility to antimirobial agents. Pyridoxine hydrochloride does not support the growth of these organisms in vitro.

Endocarditis, Bacterial↗