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Biomedical subjects

R F Schell

Publications and source records attributed to R F Schell.

At least 127 records · Page 7Linked to original sources
PubMed1979

Endemic syphilis: passive transfer of resistance with serum and cells in hamsters.

Serum or spleen cells from hamsters immune to infection with Treponema pallidum strain Bosnia A conferred partial protection against syphilitic infection by the same strain on recipient hamsters. Cutaneous lesions did not develop, and in the lymph nodes the average weight and number of treponemes detected were significantly lower than in normal and control hamsters. Treatment of the immune spleen cells with antithymocyte serum and complement abolished their ability to transfer resistance. This is the first direct evidence that thymus-derived cells are involved in resistance to syphilitic infection.

Animals↗
PubMed1979

Effects of Fildes enrichment on antibiotic susceptibility testing of Haemophilus influenzae in the Autobac.

The results of this investigation showed that the Autobac could be used to determine the susceptibility of Haemophilus influenzae to ampicillin, chloramphenicol, and tetracycline when eugonic broth was supplemented with 1.5% Fildes enrichment. An excellent correlation was obtained between the susceptibilities as determined by the agar dilution minimal inhibitory concentration method and the Autobac. For ampicillin all H. influenzae isolates with minimal inhibitory concentrations of </=1 mug/ml had light scattering indexes of >/=0.60. Those isolates with minimal inhibitory concentrations of >/=4 mug/ml had light scattering indexes of </=0.49. For chloramphenicol and tetracycline all isolates had minimal inhibitory concentrations of </=1 mug/ml and light scattering indexes of >/=0.71.

Ampicillin↗
PubMed1979

Inability of immune cells treated with anti-thymocyte serum to confer on hamsters resistance to cutaneous infection with Treponema pertenue.

The mechanism by which hamsters acquire resistance to yaws or frambesia is poorly understood. This investigation has shown that immune lymphoid cells (spleen and lymph node) could confer on hamsters resistance to infection with Treponema pertenue. Treatment of these immune cells with a specific antithymocyte serum (ATS) inhibited the transfer of resistance. Twenty-one days after infection, recipients of immune cells treated with ATS had cutaneous lesions, in contrast to recipients of immune cells treated with normal rabbit serum. Treatment of immune cells with ATS, however, did not completely abolish resistance to treponemal infection. The weight and number of treponemes in the lymph nodes of recipients were significantly lower than those infused with normal cells treated with ATS or normal rabbit serum. The specificity of the ATS was demonstrated by its failure to inhibit functional antibody-producing cells and its high cytotoxic activity for thymocytes. These results present direct evidence that ATS-sensitive cells are involved in resistance to frambesial infection.

Animals↗
PubMed1979

Ability of enriched immune T cells to confer resistance in hamsters to infection with Treponema pertenue.

This investigation presents the first direct evidence that T cells are involved in resistance to challenge with Treponema pertenue. Enriched T cells from immune hamsters were obtained by sequential filtration through glass and nylon-wool columns. This procedure removed the majority of functional antibody-producing and immunoglobulin-bearing cells. The fractionated cell suspensions were less responsive to stimulation by phytohemagglutinin, lipopolysaccharide, and dextran sulfate, but they were enriched with antithymocyte-sensitive cells and were more responsive to stimulation with concanavalin A. Hamsters receiving fractionated or unfractionated immune cells had no cutaneous lesions 21 days after infection and had significantly lower lymph node weights and fewer treponemes per node than hamsters that received fractionated or unfractionated normal cells. Resistance was transferred with immune cell suspension enriched in T cells despite an absence of anamnestic antibody response to specific treponemal antigens.

Animals↗
PubMed1979

Recovery of Haemophilus influenzae from twenty-three blood culture media.

Haemophilus influenzae is an important agent of bacteremia and has fastidious growth requirements. The purpose of this investigation was to determine the ability of commercial blood culture media to support the growth of this fastidious microorganism. Twenty-three types of blood culture media were inoculated with individual suspensions of eight strains of H. influenzae in the presence or absence of an erythrocyte-serum mixture. The rates of recovery of the H. influenzae strains from the various types of blood culture media were compared. The results demonstrated that the type of medium, the manufacturer, the erythrocyte-serum mixture, and the strain of H. influenzae influenced the recovery rates of H. influenzae. Optimal recovery of the strains of H. influenzae was obtained from brain heart infustion blood culture medium (GIBCO). Trypic soy broth (GIBCO) and supplemental peptone of Becton, Dickinson and Co. also were found to be superior to the remaining types of media tested for the recovery of H. influenzae.

Blood↗
PubMed1979

Use of CB hamsters in the study of Treponema pertenue.

The CB/Ss LAK strain of inbred hamster was used as a model for studies of infection with Treponema pertenue and of acquired resistance to it. When infected, this strain developed cutaneous lesions which lasted for six to seven months, even in the presence of peak titres of antitreponemal antibody. The rate of appearance and resolution of these lesions varied with the size of the inoculum. The infected hamsters' inguinal lymph nodes increased significantly in weight and teemed with treponemes for several weeks. Animals infected for eight or 10 weeks obtained quick resolution of their lesions by treatment with penicillin and were thereafter resistant to reinfection.

Animals↗
PubMed1978

Passive transfer of resistance to frambesial infection in hamsters.

The immune mechanism by which hamsters acquire resistance to infection with Treponema pertenue, the causative agent of frambesia, or yaws, has not been elucidated. Serum or cells (spleen or lymph node) obtained from hamsters resistant to frambesial infection were transferred to normal syngenic recipients, who are subsequently infected with T. pertenue. The following parameters were used to measure the ability of immune serum of cells to confer resistance on recipient hamsters to frambesial infection: inhibition of the development of cutaneous lesions, decreased weight, and number of treponemes in the inguinal lymph nodes. This investigation demonstrated that immune serum conferred protection on recipient hamsters infected with T. pertenue. Discontinuation of the administration of immune serum (18 days after frambesial infection) did not result in the development of cutaneous lesions. Since the inguinal lymph nodes contained a sizeable number of treponemes (2.6 X 10(5)), immune serum failed to prevent frambesial infection. Recipients of immune spleen or lymph node cells initially developed frambesial lesions 9 days after infection. The frambesial lesions began to resolve 12 to 14 days after infection and by day 21 had completely regressed. These results illustrated that humoral factors and cells are involved in resistance of the hamster to frambesial infection.

Animals↗
PubMed1978

Evaluation of twenty-three blood culture media.

Several investigators have evaluated clinically a variety of commercially available blood culture media. No agreement has been reached as to which of these media is optimal for detection of bacteremia. The purpose of this study was to determine the rate of recovery of microorganisms from various blood culture media. A total of 23 blood culture media were inoculated with 7 to 15 microorganisms per bottle in the presence or absence of an erythrocyte-serum mixture. The results demonstrated that blood culture media differed in their ability to support the growth of microorganisms. At 4 days after inoculation, only 10 of the 23 blood culture media supported the growth of 91% (10 of the 11) or more of the test microorganisms. The recovery rate of microorganisms depended not only upon the type of medium but also upon the manufacturer of the type of blood culture medium. The addition of an erythrocyte-serum mixture to the blood culture media did not influence the difference in the recovery rate of microorganisms among media and the same type of medium prepared by different manufacturers. The majority (15 of the 23) of the blood culture media supplemented with the erythrocyte-serum mixture failed to support the growth of 91% or more of the test microorganisms at 4 days after inoculation. These results have demonstrated that blood culture media need to be improved. Better quality control measures should also be implemented to evaluate commercial blood culture media.

Bacteria↗
PubMed1976

Immunologic mechanisms of infectious syphilis.

We believe that humoral and cellular immunity both are involved in the response of the host to infection with T. pallidum. A complex interaction between stimulation and suppression of cell-mediated immunity may be involved. This interaction may explain the unusual clinical course in which secondary syphilis waxes and wanes before culminating in immunity.

Animals↗
PubMed1975

Lymphocyte transformation in syphilis: an in vitro correlate of immune suppression in vivo?

Suppression of cellular immunity during primary and secondary infection may explain, in part, the unusual clinical evolution of syphilis. We have previously shown that lymphocytes from normal subjects undergo blastic transformation when exposed in vitro to Treponema refringens. This response was suppressed in patients with syphilis. the suppression being unrelated to serum factors. In the present paper we studied lymphocyte response in vitro to T. refringens, T. reiter, and T. pallidum as well as to monilia and trychophytins. The response to these antigens was suppressed in patients with syphilis although the response to phytohemagglutinin. pokeweed mitogen, and streptolysin was normal. These data support the hypothesis that human infection with T. pallidum is followed by a complex interaction between cellular and humoral immunity, the former being suppressed in primary and secondary stages.

Antigens, Bacterial↗
PubMed1975

New evidence for the non-infectivity of Treponema pallidum for mice.

We have recently shown that syphilitic rabbits are resistant to challenge with Listeria monocytogenes. This resistance was thought to reflect stimulation of cell-mediated immunity by active infection with Treponema pallidum. We now report data which show that the growth of Listeria was not suppressed in mice inoculated with T. pallidum. Re-inoculation with T, pallidum or with a large dose of an avirulent treponeme also failed to suppress the growth of Listeria. These results contrast with those obtained in rabbits and provide additional evidence that T. pallidum is not infective for the mouse.

Animals↗
PubMed1974

In vitro lymphocyte response to Treponema refringens im human syphilis.

The response of lymphocytes from patients with syphilis and normal subjects was studied in vitro by using phytohemagglutinin (PHA), pokeweed mitogen (PWM), streptolysin O (SLO), and a preparation of Treponema refringens. Normal lymphocytes exhibited a dose-response curve to treponemes. Although lymphocytes from patients with primary and secondary syphilis responded normally to PHA and PWM, their response to SLO was suppressed and they failed to show significant stimulation by treponemes. Serum from syphilitic patients did not affect normal lymphocytes, and culturing lymphocytes from patients with syphilis in normal serum did not restore their responsiveness. Six to 10 weeks after syphilitic patients had been treated, the degree of stimulation by treponemes was the same as for normal subjects. These data give indirect support to the hypothesis that immunological suppression occurs during active infection with T. pallidum.

Antigens, Bacterial↗