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Biomedical subjects

F B Gordon

Publications and source records attributed to F B Gordon.

At least 19 recordsLinked to original sources
PubMed1975

Effect of exposure to hyperoxic, hypobaric, and hyperbaric environments on concentrations of selected and aerobic and anaerobic fecal flora of mice.

Alterations in selected aerobic and anaerobic fecal microflora of the mouse were determined during exposure to hyperoxic and normoxic hypo- and hyperbaric environments. Examination of fecal cultures obtained during exposure for 6 weeks to either 60 or 77% oxygen concentration 1 atmosphere absolute revealed little alteration in the aerobic or anaerobic flora. There appeared to be only a retardation in the reduction of the Klebsiella-Enterobacter flora which normally occurs after weaning. During exposure to hypobaric environments (100% O-2, 0.2 atmosphere absolute), significant alterations in concentrations of Escherichia coli, slow lactose fermenters, Klebsiella-Enterobacter, and enterococci were found in some instances. All alterations were toward increased concentrations. Variations in concentrations of different colony types of obligately anaerobic gram-positive (anGPR) and gram-negative (anGNR) rods cultured during the same experiments also occurred. One colony type of anGPR appeared to decrease while a second type increased in numbers. Concentrations of three colony types of anGNR were generally, but not always, increased. During hyperbaric exposure (2.8% O-2, 7.5 atmospheres absolute), increased concentrations of Klebsiella-Enterobacter, E. coli, slow lactose fermenters and enterococci were also noted. Changes in numbers of both colony types of anGPR, when occurring, were in the direction of lower numbers. Alteration in numbers of anGNR were in both directions but were more frequent in the direction of higher numbers. After return to normal air for 4 weeks of either hypo- or hyperbaric exposure, fecal concentrations of all organisms tended to revert toward control values with the exception of the anGPR which remained in lower concentrations after termination of the hyperbaric exposure. These observations indicate that, despite the great variation in the fecal flora among individual mice, it is possible to discover the effects induced by altered gaseous environments.

Aerobiosis↗
PubMed1972

Effect of ionizing irradiation on susceptibility of McCoy cell cultures to Chlamydia trachomatis.

The effect of graded doses of irradiation (cobalt-60) on the morphology of McCoy cells was analyzed, and 4,000 to 5,000 r was selected as a satisfactory dose for production of giant cells. The susceptibility of radiation-induced giant cells to chlamydial infection was compared with that of nonirradiated cells by using three strains of Chlamydia trachomatis and one of C. psittaci. Monolayers of giant cells were more susceptible than normal McCoy cells as indicated by (i) greater numbers of inclusions (four- to eightfold) per unit area of monolayer, (ii) larger inclusions (fourfold greater in area), (iii) higher infective titers (1 log or more greater) of harvested cells, and (iv) greater ease of promoting a second cycle of growth. Graded doses of irradiation were applied also to mouse fibroblast (L) cells, and a similar increase in susceptibility to chlamydial infection was noted. It is concluded that giant cells produced by irradiation possess advantages over nonirradiated cells in culture for growth of Chlamydia.

Animals↗
PubMed1971

Ultrastructural analysis of the effects of penicillin and chlortetracycline on the development of a genital tract Chlamydia.

The developmental cycle of a genital tract Chlamydia (MRC-1/G) growing in irradiated monkey kidney cell monolayers was analyzed by electron microscopy. Growth was essentially similar to that of C. psittaci and ocular isolates of C. trachomatis. Penicillin (50 units/ml) interfered with the growth cycle by producing greatly enlarged initial bodies which sometimes measured 3 mum instead of the normal 1 to 1.3 mum in diameter. In contrast to penicillin, chlortetracycline (10 mug/ml) did not grossly distort morphology of the initial body but had a definite inhibitory effect on the formation of elementary bodies depending upon the time postinfection the antibiotic was added. If added 24 hr or later postinfection, typical inclusions containing elementary bodies were formed. When administered 18 hr postinfection, the transition of initial bodies to elementary bodies was prevented, and the inclusion was much smaller when examined at 48 hr in comparison to a control without chlortetracycline. Addition of the drug at 6 or 12 hr postinfection resulted in very small inclusions which contained only one or two chlamydiae of an initial body type. It was not possible to detect chlamydiae when chlortetracycline was added immediately after adsorption (0 hr), and cells were examined by light and electron microscopy at 48 hr.

Journal Article↗
PubMed1971

Effect of Interferon and Interferon Inducers on Infections with a Nonviral Intracellular Microorganism, Rickettsia akari.

The effect of mouse interferon (IF) on the multiplication of Rickettsia akari in homologous (L-929) cell cultures and the effect of IF inducers on R. akari infection in mice were investigated. There was a reduction in the proportion of cells containing rickettsiae in IF-treated cultures and in the yield of rickettsiae from these cultures, as compared with those from infected cultures without IF. Trypsin treatment and heating for 1 hr at 65 C destroyed this antirickettsial activity of the IF preparation, whereas ultracentrifugation (105,000 x g for 90 min) and acidification at pH 2.0 did not affect it. There was no evidence that mouse IF inactivated R. akari directly, nor did it have an inhibitory effect on multiplication of R. akari in heterologous chick embryo cell or monkey kidney cell cultures. Susceptibility of R. akari to the action of IF was about 16 times less than that of Chlamydia trachomatis and 256 times less than the susceptibility of vesicular stomatitis virus. Mice were not protected from infection with R. akari by intraperitoneal injection with IF inducers, Newcastle disease virus (10(8.3) plaque-forming units/0.2 ml) or polyriboinosinic acid-polyribocytidylic acid complex (poly I:C, 200 mug/0.2 ml), within 24 hr before or 24 hr after intraperitoneal challenge. The yields of R. akari harvested from the spleens, livers, and peritoneal washings of infected mice treated with IF inducers were similar to those of infected control mice. Titers of IF in peritoneal washings of treated mice, taken 6 hr after administration of Newcastle disease virus or 9 hr after injection of poly I:C, were 1,024 or 320 units/ml, respectively.

Journal Article↗
PubMed1971

Effect of Interferon and Interferon Inducers on Infections with a Nonviral Intracellular Microorganism, Chlamydia trachomatis.

The effect of mouse interferon (IF) on the multiplication of Chlamydia trachomatis (strain MRC-1/G) in homologous (L-929) cell cultures and the effect of the IF inducers Newcastle disease virus (NDV) and polyriboinosinic acid-polyribocytidylic acid complex (poly I:C) on the experimental infection of mice with aerosolized C. trachomatis (strain MoPn) were investigated. Treatment of infected cell cultures with IF reduced the number of cells containing chlamydial inclusions and depressed the yield of chlamydiae as determined by titrations for infectivity. Growth of chlamydiae was reduced when cultures were exposed to IF 6 or 18 hr before infection, and slight reduction of the yield was also detectable in cell cultures treated with IF at early intervals (0 or 4 hr) after chlamydial infection. No effect of IF on penetration of chlamydiae into mouse cells was observed, whether phagocytic cells from peritoneal washings or L-929 cells were used, indicating that the inhibitory effect of IF occurs after chlamydiae enter the host cell. Additional evidence was obtained that a significant effect of IF occurs at an early stage in maturation of the intracellular chlamydiae. In mice exposed repeatedly to NDV aerosols and challenged with aerosolized MoPn 8 hr after the first exposure to NDV, mortality was delayed by 2 to 3 days and lung consolidation was slightly reduced at 3 days after infection. Yields of chlamydiae from lung pools of NDV-treated mice, taken at 3, 6, and 9 days after challenge, were not significantly different from those of controls. Similar results were obtained when mice were challenged with MoPn 8 hr after intranasal injection with 100 mug of poly I:C or 24 hr after intravenous injection with 200 mug of poly I:C. In contrast, administration of 0.2 ml of NDV (10(8.3) plaque-forming units) intravenously 10 hr before or 24 hr after challenge with MoPn accelerated mortality of mice by 2 to 3 days. In all experiments, detectable levels of IF in sera or 20% lung suspensions were found only up to 48 to 72 hr after exposure of mice to IF inducers.

Journal Article↗
PubMed1971

Enhancement of phagocytosis by interferon-containing preparations.

Exposure of mononuclear cells from the mouse peritoneal cavity to interferon (IF)-containing mouse sera enhanced phagocytosis of colloidal carbon particles by the cells. The same effect was observed when the cells were exposed to IF-containing cell culture harvest free of serum. The magnitude of this effect of IF-containing preparations paralleled the titer of IF and was not related to the dilution of various IF-containing serum specimens tested. The factor responsible for the enhancing effect was stable at pH 2, inactivated by trypsin, and nonsedimentable at 105,000 x g. Heating at 60 C for 1 hr destroyed it, and its kinetics of heat inactivation paralleled that of the antiviral activity of IF. A period of incubation of phagocytic cells with IF-containing serum was necessary before a maximum level of enhancement was reached, and once established was not removable by repeated washing of cells. The kinetics of the production of the enhancing factor in mice injected with Newcastle disease virus was essentially identical to that of the simultaneous production of IF as measured by antiviral activity. Contrary to the effect of mouse IF preparations, human IF preparation did not enhance the activity of mouse phagocytes. It appears, therefore, that the phagocytosis-enhancing factor falls within the present definition of IF.

Animals↗