PubMed Health⌕ Search

Biomedical subjects

C Reuben

Publications and source records attributed to C Reuben.

11 recordsLinked to original sources
PubMed1999

Differences in morbidity measures and risk factor identification using multiple data sources: the case of stroke.

BACKGROUND: Epidemiologic studies utilise medical information from a variety of sources. These include subject or proxy interviews, medical records, death certificates and administrative records. Since the choice of data source may affect the validity of study results, it is important to understand the effect of different case-ascertainment methodologies on estimates of risk. METHODS: The NHANES I Epidemiologic Follow-up Study (NHEFS) contains several sources of information that can be used to define case status. In this report we investigate whether the use of seven different algorithms for case ascertainment, each based on different combinations of data sources, results in substantive differences in the estimates of incidence rates and relative risks associated with selected, documented, risk factors for stroke. RESULTS: The seven different models of case identification gave very different estimates of stroke incidence. However, the characteristics of the cases defined by the models, except for cases identified by death certificate only, were remarkably similar. There was also remarkable similarity in relative risks obtained from six of the seven models. The model using only death certificate information generally produced higher relative risk estimates. CONCLUSIONS: Despite wide variations in the estimates of incidence, characteristics of the cases using different case definition were remarkably similar, as were the risks associated with stroke incidence. The main difference occurred when cases were identified from the death certificate only. These results furnish some evidence that analyses based on self report can provide valid, useful information.

Adult↗
PubMed1988

Induction by an immunogenic immunomodulating agent of nonspecific T cell suppression of lymphocyte responsiveness in MLR but not of antibody production.

Spleen cells derived from BALB/c mice that had been repeatedly immunized with the methanol extraction residue (MER) fraction of tubercle bacilli exhibited a depressed capacity to act as responder cells in allogeneic and syngeneic mixed lymphocyte reactions (MLR). Previously reported studies revealed that such spleen cells are also defective in the in vitro generation of antibodies. In order to determine the nature of the cells responsible for the depressed MLR reactivity, purified populations of splenic macrophages, B lymphocytes, T lymphocytes originating from normal and from MER-immunized mice, and cell culture supernatants were added to MLR mixtures consisting of normal mouse splenocytes. Macrophages originating from MER-immunized mice and their culture supernatants exerted a significantly higher suppressive effect on MLR than that of corresponding preparations from normal mice. Splenic T cells originating from MER-immunized mice and their supernatants also significantly suppressed the MLR response. However, the same T cell populations that were inhibitory in MLR failed to suppress the in vitro generation of antibodies against sheep red blood cells in the presence of either MER or 2-mercaptoethanol. These and previously reported findings indicate that a nonspecific immunomodulating agent, MER, can, under certain conditions of treatment, elicit the induction of nonspecific suppressor T cells for MLR but not for antibody production, and, accordingly, can inhibit cellular and humoral immunological responsiveness by different mechanisms.

Adjuvants, Immunologic↗
PubMed1987

Chromosome aberrations and sister chromatid exchanges in Chinese hamster ovary cells: evaluations of 108 chemicals.

Results from the testing of 108 coded chemicals in Chinese hamster ovary (CHO) cells for the induction of chromosome aberrations and sister chromatid exchanges (SCEs) are presented. All chemicals were tested with and without exogenous metabolic activation, using protocols designed to allow testing up to toxic doses. Cell harvest times could also be extended if chemical-induced cell cycle delay was seen. Chromosome aberrations were induced by 43 of the chemicals, and 66 induced SCEs; 37 of the chemicals were positive for both endpoints.

Animals↗
PubMed1985

Effects of the methanol extraction residue (MER) tubercle bacillus fraction on the production of antibodies in vitro. III. Consequence of prior sensitization to MER.

Mice repeatedly immunized with the methanol extraction residue fraction of tubercle bacilli (MER) in incomplete Freund's adjuvant produced high titers of circulating antibodies against MER, as assessed by the enzyme-linked immunosorbent assay (ELISA) method. Spleen cells derived from these animals failed to respond to the usual nonspecific immunopotentiating influence of MER on the primary production of antibodies (generation of specific plaque-forming cells) in vitro to sheep red blood cells. The defect was expressed by B lymphocytes and splenic macrophages, but not by splenic T lymphocytes or peritoneal exudate macrophagic cells. Impaired responsiveness by spleen cells from MER-immunized animals to nonspecific immunostimulation was also expressed with regard to another, unrelated biological response modifier, lipopolysaccharide. There was no impairment of responsiveness to polyclonal mitogenic stimulation. Possible mechanisms of the effects described are discussed.

Adjuvants, Immunologic↗
PubMed1984

Effects of the methanol extract residue (MER) tubercle bacillus fraction on the production of antibodies in vitro. II. Effects on macrophage and lymphocyte populations.

The effect of the methanol extract residue (MER) fraction of BCG tubercle bacilli on the generation of primary antibody responsiveness in vitro to sheep red blood cells (SRBC) was ascertained in cell reconstitution experiments, employing enriched populations of mouse macrophages and of T and B lymphocytes. In each of the antibody generation cultures one or another of the cell fractions had been exposed to MER, either by treatment of the donor animals or by preincubation with the agent for 48 hr in vitro. In some experiments, supernatants of MER-preincubated cells were employed in place of the cells. Macrophages and T cells that had been exposed to MER in vivo or in vitro and their supernatants demonstrated a markedly greater effect than nonexposed cells in the generation of direct specific plaque-forming cells (PFC) upon antigenic stimulation of the cultures with SRBC. In contrast, PFC production was not stimulated in B-lymphocyte populations that had been in contact with the agent.

Adjuvants, Immunologic↗
PubMed1980

In vitro studies on the effect of anti-lymphocyte serum on the humoral immune response.

The effect of ALS (I), a heterologous anti-lymphocyte serum prepared against lymph node cells from rats pre-immunised with sheep erythrocytes (SRBC), on plaque forming cells (PFC) to SRBC was studied in vitro. ALS (I) reduced the number of both IgM and IgG PFC when complement was included in the reaction. This ability of ALS (I) to inhibit PFCs in vitro was absorbed out by the IgG fraction of anti-SRBC serum. Thus ALS (I) was thought to possess and anti-idiotypic antibody directed against B-cells at a later stage of differentiation.

Absorption↗
PubMed1979

Suppression of secondary immune response by antilymphocyte serum: time relationship between immunization and administration of antilymphocyte serum.

The effect of antilymphocyte serum (ALS) on the secondary humoral immune response to sheep erythrocytes (SRBC) in rats was studied by the Jerne plaque assay technique. Its effect was also studied on the delayed hypersensitivity (DH) response to SRBC by the foot pad swelling test. ALS(N), which was prepared against lymphocytes from normal rats, had no effect on the secondary humoral and cellular response or on the primary cellular response, when administered postantigenically. ALS(I), which was raised against lymph node cells from SRBC immunized rats produced significant immunosuppression of the secondary response to SRBC when administered either before or after the antigenic injections. In the case of DH, ALS(I) behaved just like ALS(N) having no effect on the secondary response and suppressing the primary only when administered prior to the antigen.

Animals↗
PubMed1979

Specific suppression of delayed hypersensitivity response to sheep erythrocytes by heterologous anti-lymphocyte serum.

The development of a heterologous anti-lymphocyte serum (ALS) capable of specifically suppressing the delayed hypersensitivity (DH) response is reported. This ALS, termed ALS(CMI), was prepared against lymph node cells from rats which had been immunized against sheep erythrocytes (SRBC) following treatment with cyclophosphamide which is known to enhance the DH response and suppress the humoral immune response. The effect of ALS(CMI) on the primary DH response to SRBC using the footpad swelling test was studied. Its effect on the primary humoral immune response to SRBC was also studied using the Jerne plaque assay technique. ALS(CMI) suppressed the humoral antibody response to SRBC and the DH response to a third party antigen only when administered before the antigen, having no effect when administered post-antigenically. On the other hand, ALS(CMI) significantly suppressed the primary DH response to SRBC when administered either before or after the antigen.

Animals↗
PubMed1978

Suppression of primary immune response by heterologous anti-lymphocyte sera.

The effect of anti-lymphocyte serum (ALS) on the primary immune response to sheep erythrocytes (SRBC) in rats was studied by the Jerne Plaque technique. ALS against normal rat lymph node cells, ALS(N) suppressed the immune response to SRBC when administered before the antigen and had no effect on the immune response when administered either with or after the antigen. ALS(I), which was produced against lymph node cells from SRBC immunized rats, produced significant immunosuppression when administered either before or after the antigen.

Animals↗
PubMedDate not supplied

Immunological reactivity to a mycobacterial fraction is associated with nonspecific suppression of immunological responsiveness in vivo.

Previously reported studies revealed that spleen cells from BALB/c mice immunized against a methanol extraction residue (MER) fraction of tubercle bacilli are defective in the in vitro generation of antibodies to SRBC and in allogeneic responsiveness against C57BL spleen cells. We now show that mice repeatedly immunized with MER also exhibit a depressed capacity to respond to antigenic stimulation in vivo. Thus mice repeatedly injected with MER were impaired in their ability to react to antigenic stimulation by SRBC and by C57BL spleen cells. Impairment in the response to SRBC immunization was expressed at the level of delayed-type hypersensitivity (DTH) as well as of antibody production. The response of MER hyperimmunized mice to contact sensitization with dinitrofluorobenzene (DNFB) was not impaired, but the lymph node cells of DNFB-sensitized animals had a depressed ability to respond to in vitro stimulation by the monovalent hapten dinitrobenzene sulfonate (DNBS). The present findings indicate that extensive exposure to an immunogenic immunomodulating mycobacterial fraction can lead to a depressed responsiveness to unrelated antigenic stimulation.

Animals↗