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Biomedical subjects

L Greenberg

Publications and source records attributed to L Greenberg.

At least 109 records · Page 6Linked to original sources
PubMed1969

The chick embryo neutralization test in the assay of meningococcal antibody. 1. Infection of the embryo with Neisseria meningitidis.

Present methods of controlling meningococcal cerebrospinal meningitis have failed to contain the disease. This has led to the search for effective vaccines and to the development of methods for assaying the potency of these vaccines, as well as for measuring the immune response of the individual. The feasibility of using the sero-protection test in embryonated eggs for the assay of meningococcal antibody has been investigated. The paper describes detailed investigations of the infectious process established by injecting Neisseria meningitidis by various challenge routes. Embryos, even 10-12 days old, showed high susceptibility to meningococci injected via the yolksac or chorioallantoic vein, and lesser susceptibility when injected via the intra-allantoic and chorioallantoic routes. The deaths of intravenously inoculated embryos coincided with the multiplication of the organisms and ensuing septicaemia. A study of the infection in embryos which had died, or were killed, 18-24 hours after inoculation showed a specific localization of the organisms in the brain.

Animals↗
PubMed1969

The chick embryo neutralization test in the assay of meningococcal antibody. 2. Response of the embryo to meningococcal endotoxin and to infection.

A previous report described the infection of the chick embryo with Neisseria meningitidis. Although death of embryos was preceded by multiplication of the organisms, the possibility exists that death is caused by the endotoxin contained in the inoculum or released by the bacteria lysing in vivo. A second important condition for the establishment of a satisfactory sero-protection test is that the embryo should act as a host and not merely as a growth medium for N. meningitidis.Results of tests with cortisone-treated embryos show that the pathogenic effect of live meningococcal challenge is mainly due to infection elicited by the meningococci and not to toxaemia. Also, the rate of clearance of meningococci from the blood of the embryo, increased by the addition of meningococcal immune serum, suggests that at this stage of embryonic development (12 days) the phagocytes are active in combating meningococcal infection.

Animals↗
PubMed1967

Circulating antibody response in BCG vaccination, tuberculous infection and sarcoidosis.

The bentonite flocculation test was used to differentiate antibodies formed by BCG vaccination from those produced by infections with virulent tubercle bacilli. Of 116 BCG-vaccinated nurses, only two (1.7%) showed antibody titres higher (1:128) than the threshold titre of 1:64 established for tuberculous patients.The bentonite test was also used to follow the course of infection in 54 patients with tuberculosis. A good correlation was found between the clinical course of the disease and O.T.-bentonite titres on repeated serological testing.Tuberculosis-like antibodies were demonstrated in sarcoidosis patients. These antibodies, however, are globulins (7S), in contrast to the macroglobulins (19S) found in tuberculous patients.

Antibody Formation↗
PubMed1967

Lysed BCG vaccines. 1. Observations on optimal conditions for BCG growth and lysis.

As a first step towards the production of a lysed BCG vaccine that would have reduced toxicity and allergenicity and yet be immunogenic, the growth and lysis of BCG bacilli under strictly controlled conditions have been studied.BCG grown in both Dubos and Aldridge liquid media showed an arithmetic linear growth, preceded by a very short logarithmic phase. This suggested that some of the cell population became metabolically inactive at a very early stage, possibly owing to suboptimal conditions of growth.Glycine, lysozyme and lithium chloride initiated lysis of BCG growth in the aforementioned media 24-48 hours after inoculation. After 2 weeks' incubation approximately 50% of the original BCG culture was lysed and the viable count had fallen 1000-fold. The autolytic pattern of BCG in a nitrogen-deficient, chemically defined Aldridge medium is also described.

BCG Vaccine↗
PubMed1967

A chemically defined protein-free liquid medium for the cultivation of some species of Neisseria.

Chemically defined, protein-free, liquid culture media are needed for research with pathogenic bacteria and for the preparation of vaccines from them. Variations in growth or yield of organisms should be due only to differences in strain, and the medium itself should have little or no antigenic properties or toxicity. The medium should maintain the integrity of the bacterial species fully and it is particularly important that the complete antigenic complement of the organism should remain unaltered. The medium should be inexpensive and simple to prepare. Such a medium for the cultivation of some species of Neisseria, known to be fastidious, is described.In this new medium all the criteria are satisfied, and its freedom from sensitizing proteins makes it of particular value for use in man. Results of safety tests of vaccines prepared from Neisseria gonorrhoeae and N. meningitidis grown in this medium were encouraging. It should also be useful in studies on the physiological characteristics of the individual species.

Bacteriological Techniques↗
PubMed1967

Lysed BCG vaccines. 2. The effect of lysis on the immunogenicity and allergenicity of BCG vaccines.

The authors have attempted to prepare lysed BCG vaccines retaining the protective antigens of the BCG cell wall and yet eliciting in experimental animals limited sensitivity to the tuberculin substances, the advantage sought being to retain the usefulness of the tuberculin following vaccination as an indicator of superinfection.Experimental vaccines were prepared by growing and lysing BCG in both Dubos and Aldridge liquid media with glycine, lysosyme and lithium chloride; vaccines were also prepared by autolysis in Aldridge nitrogen-deficient, chemically defined medium.Glycine, lysozyme and lithium chloride significantly reduced both the protective and allergenic properties of the lysates. The best protection was afforded by BCG cells autolysed in Aldridge medium. Treatment of the BCG autolysates with lysozyme alone did not affect the protective capability of the vaccines and almost completely eliminated the allergenicity. It is suggested that these BCG lysates contain metabolically inactive cells, which do not multiply in vitro but may still provide sufficient antigen in vivo to ensure protection.

Animals↗
PubMed1966

A study of tuberculosis antibodies by bentonite flocculation.

Bentonite particles sensitized with concentrated human Old Tuberculin were used for detection of circulating antibodies to M. tuberculosis in human sera.There was no sharp distinction between the titres of patients with active and inactive tuberculosis, but progressively higher antibody titres accompanied increased severity of infection. The sera of 95.3% of the patients studied had a titre of 1:8 or higher. This level was considered to be the minimal significant titre indicative of the presence of metabolically active bacilli in old and new lesions. Tuberculin-negative controls and syphilitic sera were negative. A common zone of incidence in the 1:8-1:32 range was found where differentiation between tuberculin-positive healthy people and patients with tuberculosis was not possible; however, titres of 1:64 or more were found only in tuberculous patients. The antibody under study is heat-labile.

Antibodies, Bacterial↗