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B Tartakovsky

Publications and source records attributed to B Tartakovsky.

At least 55 records · Page 3Linked to original sources
PubMed1988

Antigen-tuftsin conjugate signals interleukin-1 synthesis and secretion.

The immunoglobulin heavy chain derived tetrapeptide, tuftsin (Thr-Lys-Pro-Arg), known for its phagocytosis-stimulating activity, was found to augment the antigen-presenting capacity of macrophages in culture, when applied simultaneously with antigen. Injection of antigens or antigens admixed with tuftsin had no immunogenic effect in vivo. On the other hand, antigen-tuftsin covalent conjugates, injected in aqueous solution intramuscularly or intravenously, significantly augmented antibody production. Studying the mechanism underlying these immunogenic effects, we demonstrate that tuftsin, when applied to macrophages together with, or conjugated to, antigens, signals de novo synthesis of mRNA encoding for interleukin-1 (IL-1), and induces secretion of IL-1 from the cells. We suggest that triggering the immunogenic processes by tuftsin conjugates is a consequence of up-regulation of IL-1 synthesis and secretion.

Animals↗
PubMed1986

T cell clone producing an IL 1-like activity after stimulation by antigen-presenting B cells.

We have analyzed the involvement of IL 1 in a cellular interaction during which murine B cells serve as antigen-presenting cells for a T cell clone (D10.G4.1). This T cell clone was chosen for study because it is highly dependent on exogenous IL 1 for concanavalin A (or anti-receptor antibody)-induced proliferation. We observed that B cells presented either self I-Ak plus nominal antigen or allogeneic I-Ab, and consequently induced proliferation of this T cell clone without any requirement for exogenous IL 1. After an overnight co-culture with allogenic B cells, we detected an IL 1-like activity in lysates of the cell mixture, but were unable to detect a similar activity in the culture medium. This IL 1-like activity was induced in a MHC-restricted manner. We determined that this intracellular IL 1-like activity was derived from the D10.G4.1-responding T cells, rather than from the antigen-presenting B cells. Moreover, we were unable to detect an IL 1-like activity in murine B cells after a variety of stimuli including LPS, anti-Ig, activated T cell supernatants, or combinations of these stimuli. Hybridization of cytoplasmic RNA with an oligonucleotide probe for human IL 1-alpha confirmed the T cell source of the biological activity. The IL 1-like factor derived from the cell culture mixture lysate showed two broad peaks of activity after gel filtration, one in the 10,000 to 20,000 dalton range and the second in the 35,000 to 45,000 dalton range. This first description of IL 1 activity produced by a T cell may introduce a new element to the early events leading to T cell activation and proliferation.

Animals↗
PubMed1983

Splenic B cells function as immunogenic antigen-presenting cells for the induction of effector T cells.

Previous studies performed in our laboratory have revealed that an ordered, sequential, tricellular interaction is obligatory for the antigen-driven induction of a specific effector memory T cell. Thus, it was found that antigen-pulsed peritoneal macrophages signal, in spleen cells, the generation of antigen-specific initiator lymphocytes. These lymphocytes, following injection to syngeneic recipients, recruit, in the draining lymph nodes, "virgin" antigen-reactive T lymphocytes. Although the nature of the first and last cell in the interacting sequence was well characterized, the identity of the intermediary initiator splenic cell was obscure. Studies were carried out to characterize the nature of the splenic initiator cells. It was found that spleen cells from nu/nu, adult thymectomized and neonatal thymectomized, or spleen cells from normal donors which had been subjected to cytolysis using anti-Thy-1.2 antibodies in the presence of complement, did generate, following interaction with keyhole limpet hemocyanin (KLH)-fed macrophages, specific initiator cells. Carrageenan impairment of spleen macrophages did not affect the generation of initiator cells, nor did the depletion of dendritic cells from the spleen. On the other hand highly enriched B cell, but not highly enriched T cell populations, when seeded on KLH-pulsed macrophages, generated antigen-specific initiators, which, in vivo, recruited antigen-reactive T cells. It thus appeared that B lymphocytes can function as intermediary obligatory antigen-presenting cells and actively transfer immunogenic signals from peritoneal antigen-presenting cells to T lymphocytes. These findings may therefore suggest that antigen-specific B cells do not function solely as antibody-producing cells, but, once activated by macrophages, may control the induction and differentiation of some antigen-reactive T cell subsets. Thus, one can view the B cell as an important regulatory cell of both cellular and humoral immune functions. The significance of this observation with regard to Ir gene control at the level of B lymphocytes is discussed.

Animals↗
PubMed1983

Sex-associated differences in the immune response against fetal major histocompatibility antigens. II. Association of the female IgG1 with H-2K-encoded alloantigens.

Alloantibodies against the H-2b haplotype were produced in C3HeB female and male parental mice in response to transplantation of F1 fetal tissue (bones). In testing IgG1 and IgG2 antibodies by means of the FACS II we found striking sex-associated differences in the isotypes produced: female mice produced much more IgG1 than male mice, although they produced comparable amounts of IgG2. Using protein-A-sepharose-purified fractions of IgG1 and IgG2, raised in the parental females we found the specificity of this extra IgG1 to be directed against the H-2Kb private determinants, in contrast to the IgG2 which was found to be specific for H-2Kb, H-2Db and I-Ab subregion alloantigens. The relevance of the association between H-2K alloantigens and IgG1, in context of the fetal-maternal relationship is discussed.

Animals↗
PubMed1983

Alterations in major histocompatibility complex phenotypes of mouse cloned T10 sarcoma cells: association with shifts from nonmetastatic to metastatic cells.

The T10 sarcoma, induced in a (C57BL/6J X C3HeB/-FeJ)F1 (H-2b X H-2k) mouse, grows locally (L-T10) and generates spontaneous lung metastases (M-T10). L-T10 cells were found to express the H-2b haplotype, whereas M-T10 expressed both the H-2b and H-2k haplotypes. Most L-T10 cloned cells expressed the H-2b haplotype and were not metastatic. The minority expressed both H-2k and H-2b and were metastatic. Serial transplantations of H-2k-negative clones always ended in spontaneous expression of the H-2k haplotype concomitantly with the acquisition of metastatic potency. The expressed H-2k seemed to be associated with the metastatic properties inasmuch as an H-2b-positive--H-2k-negative clone, which had lost the expressed H-2b and was temporarily H-2 negative, remained nonmetastatic until reexpression of the two haplotypes occurred. Serial transfers of H-2k-positive clones resulted in the maintenance of the expressed H-2k haplotype and the retention of metastatic capacity. A shift toward increased metastatic capacity correlated with H-2k expression occurred during serial transfers of every clone tested. Expression of major histocompatibility complex components, rather than their loss, may potentiate the metastatic capacity of tumor cells.

Animals↗
PubMed1981

Sex-associated differences in the immune response against fetal major histocompatibility antigens.

Alloantibodies against H-2b and H-2k haplotypes were produced in C57BL/6J and C3H female and male mice in response to transplantation of F1 fetal tissue (bone) or adult F1 cells (spleen). Testing IgG1 and IgG2 antibodies by means of the fluorescence-activated cell sorter (FACS II), we found no differences between males and females in the isotype content of antisera produced against spleen cells from adult donors. In contrast, striking sex-associated differences were found in the isotypes produced against fetal allografts: females produced much more IgG1 than males, although they produced comparable amounts of IgG2. Hence, it appears that females differ from males in their humoral alloreactivity against major histocompatibility complex (MHC) gene products expressed on fetal cells. Such MHC antigens expressed on fetal tissues seem to generate different immune signals than the MHC antigens expressed on adult cells. These observations might be of relevance to the biological role played by the IgG1 alloantibodies produced during pregnancy against the MHC alloantigens of the fetus.

Animals↗
PubMed1980

Serological detection of H-2K- and H-2D-gene products. I. Principal difference between T and B lymphocytes in expression of H-2D-encoded alloantigens.

Using the fluorescence-activated cell sorter (FACS II), we have analyzed the expression of H-2K- and H-2D-gene products on the membrane of various cellular components of the murine immune system. Using this serological technique we show a basic difference between T and B lymphocytes. Whereas all cellular components analyzed--hydrocortisone-resistant thymocytes, splenic T and B lymphocytes, macrophages and bone-marrow cells--expressed H-2K-subregion-encoded alloantigens at a high density, it seems that the high density expression of H-2D-encoded alloantigens is restricted mainly to B cells and to macrophages. Hydrocortisone-resistant thymocytes, splenic T lymphocytes and bone-marrow cells, on the other hand, showed significant expression of the H-2D alloantigens only at low membrane density. These results, then, provide evidence for the existence of an imbalance in serologically detectable expression of H-2K- and H-2D-region-gene products on the cell membrane of various cells comprising the murine immune system.

Animals↗
PubMed1979

Segregation of human peripheral blood lymphocytes according to their affinity for insolubilized histamine. Principal differences between males and females.

An attempt was made to investigate the possible existence of differences in the composition of peripheral blood lymphocytes between males and females. Using affinity chromatography of human peripheral mononuclear cells on insolubilized histamine together with staining by fluoresceinated histamine-rabbit serum albumin (HRSA) we revealed that males possess a significantly higher proportion of mononuclear cells which bind to HRSA. These results are also reflected in sex-related differences in proliferative responses of the HRSA-non-adherent mononuclear cell population to T cell-dependent mitogens antigens and allogeneic mononuclear cells.

Animals↗
PubMedDate not supplied

Application of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process.

This work examined the use of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process. Experiments were carried out in a laboratory-scale anaerobic digestor fed with either synthetic or agricultural (cheese factory) wastewater. An in-line fiber optic probe installed in the external recirculation loop of the reactor was used to acquire fluorescence spectra with an interval of 5-10 min. The spectra were compared with analytical measurements taken at the same time to develop regression models, which were then used to predict concentrations of chemical oxygen demand, volatile fatty acids, and other key process parameters. A comparison of partial least squares (PLS), nonlinear principal components regression, and step-wise regression models on an independent set of data showed that the PLS model gave the best prediction accuracy.

Bacteria, Anaerobic↗
PubMedDate not supplied

Application of a variable structure model in observation and control of an anaerobic digestor.

In this work, a variable structure model (VSM) of an anaerobic digestion process was developed. The anaerobic biodegradation process was described by four nonlinear submodels representing methanogenic, chemical oxygen demand overload, acidogenic, and hydrogen-inhibited states of the anaerobic process. At any instant, process dynamics was modeled only by one of the submodels, while the others were considered trailing. The choice of a leading submodel was handled by a knowledge-based system, which analyzed available process variables, such as off-gas composition and reactor pH. The feasibility of the proposed method was demonstrated both by using the VSM to predict the outputs of a comprehensive process model, and the experimental results obtained in a pilot scale anaerobic fixed-bed bioreactor.

Algorithms↗
PubMedDate not supplied

Evaluation of multiwavelength culture fluorescence for monitoring the aroma compound 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) production.

Fluorescence spectra of a 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) fermentation culture broth were combined with measurable process variables for off-line and on-line process monitoring. Culture broth fluorescence in UV and visible ranges was acquired by a fiber optic LCD array spectrometer. Process dynamics was followed on-line using a fiber optic probe attached to an external recirculation loop of the bioreactor. Partial least squares and stepwise regression methods were used to correlate measurable process parameters with the components of the fluorescence spectra. Both methods provided adequate approximation of yeast density, HEMF, glucose, and ethanol concentrations from fluorescence spectra. HEMF production was observed during the oxido-reductive growth phase when there was a lack of measurable oxygen in the culture broth and an excess of glucose. The addition of glucose resulted in the rapid production of HEMF and other metabolite intermediates such as ethanol, acetate, and glycerol.

Cell Count↗
PubMedDate not supplied

A comparison of air and hydrogen peroxide oxygenated microbial fuel cell reactors.

In this study, a two-compartment continuous flow microbial fuel cell (MFC) reactor was used to compare the efficiencies of cathode oxygenation by air and by hydrogen peroxide. The MFC reactor had neither a proton-selective membrane nor an electron transfer mediator. At startup, the cathodic compartment was continuously aerated and the anodic compartment was fed with a glucose solution. An increase of electrical power generation from 0.008 to 7.2 mW m(-2) of anode surface with a steady-state potential of 215-225 mV was observed within a period of 12 days. The performance of the air-oxygenated MFC reactor progressively declined over time because of biofilm proliferation in the cathodic compartment. Oxygenation of the cathodic compartment using 300 mL d(-1) of 0.3% hydrogen peroxide solution resulted in a power density of up to 22 mW m(-2) (68.2 mA m(-2)) of anode surface at a potential of 340-350 mV. The use of H2O2 for oxygenation was found to improve the long-term stability of the MFC reactor.

Air↗
PubMedDate not supplied

Application of scanning fluorometry for monitoring of a fermentation process.

Conventional observation of a fermentation process by using NAD(P)H-dependent fluorescence provides a mean for cell monitoring, but its practical application has been very limited due to many factors that affect culture fluorescence. In this work we studied correlation of scanning fluorometry signals with various process variables and with cell metabolic states and showed that scanning fluorometry is more informative than conventional NAD(P)H-dependent fluorescence. A stepwise multiple-regression procedure has been used to select meaningful signals from the whole spectrum, and we found that with three or four components of the excitation-emission plane the process variables can be portrayed with a rather good accuracy. The approach is demonstrated on the examples of wild-type or recombinant Escherichia coli and Saccharomyces cerevisiae fermentations.

Anti-Bacterial Agents↗