Evaluation of potential toxicity of smoke from controlled burns of furnished rooms - effect of flame retardancy.

It has been reported that incorporation of fire retardants into home furnishings and electronics increases the toxicity of smoke produced during combustion in house fires. Studies have been limited to exercises in analytical chemistry but the biological effects of emissions, particularly regarding chronic toxicity, have not been investigated. The combustion of furnishings with and without chemical flame retardants (FR) regarding (1) ignition resistance and fire progression, (2) chemical composition of smoke (analytical chemistry), and (3) toxicity was compared.

Adverse Outcome Pathway for Antimicrobial Quaternary Ammonium Compounds.

Quaternary ammonium compounds (QACs) or quats are a large class of antimicrobial chemicals used in households and institutions as sanitizers and disinfectants. These chemicals are utilized as food processing sanitizers, algicides, in the process of water treatment, and preservatives in cosmetics. The aim of this study was to determine an Adverse Outcome Pathway (AOP) whereby two widely used QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC), may result in respiratory tract and gastrointestinal tract effects.

Post-market surveillance of consumer products: Framework for adverse event management.

Analysis of spontaneous reports of adverse events is an important source of information that can be used to improve consumer products. Various agencies have adverse event reporting requirements and many companies collect such data directly from consumers. Nonetheless, a universal framework is absent that identifies and evaluates spontaneously reported adverse events, and, most important, assesses the potential association between exposure and adverse events.

Subchronic toxicology of tetrabromobisphenol A in rats.

Tetrabromobisphenol A (TBBPA) is used to protect a wide range of electrical and electronic equipment, consumer electronics and office and communication equipment from catching fire. TBBPA reacts covalently with other monomers becoming an integral part of the cross-linked molecular structure. This study was conducted to evaluate the subchronic toxicity of TBBPA administered by gavage daily for 13 weeks at 0, 100, 300, and 1000 mg/kg/day in male and female CD® rats.

Evaluation of the utility of the lifetime mouse bioassay in the identification of cancer hazards for humans.

Limited testing resources, the need to limit animal use, and the demand for better knowledge about carcinogenic hazards require that the carcinogenicity testing paradigm based on lifetime cancer bioassays in rats and mice should be as efficient and reliable as possible. We have therefore reevaluated the rodent bioassay, particularly for nongenotoxic chemicals and conducted a rigorous examination of the 710 substances listed in the Carcinogenic Potency Database (CPDB) that were tested in both mice and rats. The CPDB is a web-based database that provides access to the literature and the results of 6540 bioassays on 1547 chemicals that have been published in the general literature through 2001 and by the National Cancer Institute/National Toxicology Program through 2004.

Toxicologic significance of histologic change in the larynx of the rat following inhalation exposure: a critical review.

The larynx is a site in the respiratory tract of animals that often shows a response to inhaled substances. In many cases, the most sensitive endpoint in repeated dose inhalation studies is squamous metaplasia (often of minimal severity) of the larynx. The U.

The efficient bovine insulin presentation capacity of bone marrow-derived macrophages activated by granulocyte-macrophage colony-stimulating factor correlates with a high level of intracellular reducing thiols.

Bone marrow-derived macrophages (BMM phi) were shown before to function as antigen-presenting cells. We show here, that the antigen presentation capacity of BMM phi depends on the nature of the antigen and is differently regulated by the lymphokines interferon-gamma (IFN-gamma) and granulocyte/macrophage-colony-stimulating factor (GM-CSF). When bovine insulin (BI) was employed as antigen, only BMM phi treated with GM-CSF (GM-CSF-M phi) were efficient presenters, but when presentation of the antigens ovalbumin and conalbumin was tested, IFN-gamma-pulsed BMM phi (IFN-gamma-M phi) proved superior to GM-CSF-M phi.

Antigenically activated helper T cells are required as stimulator cells for optimal activation of cytotoxic T lymphocytes under conditions of limiting helper factors.

This paper deals with the question of how antigenically activated helper cells interact with cytotoxic T-lymphocyte (CTL) precursor cells in an environment where helper factor is limiting. Experiments in culture systems with limiting concentrations of helper factor indicated that the (optimal) activation of CTL required antigenically activated helper T cells as stimulator cells. These experiments were performed partly in macrocultures which contained prostaglandin E2 (PGE2) and partly in microcultures with small numbers of responder cells and without additional helper factors.

Inhibition of a primary DNA-synthesis response by trinitrobenzosulfonate (TNBS)-activated suppressor cells; characterization of the inhibitory cells.

Repeated intravenous injections of high doses of trinitrobenzosulfonate (TNBS) or dinitrobenzosulfonate (DNBS) activate suppressor cells which inhibit the in vivo activation of a primary DNA synthesis response against trinitrochlorobenzene (TNCB) and dinitrochlorobenzene (DNCB), respectively, almost completely and the delayed type hypersensitivity (DH) response only partially. When tested on the DNA-synthesis response, the suppressor cells show excellent specificity with little cross reactivity of TNBS (or DNBS) induced suppressor cells for DNCB- (or TNCB-) specific responses. TNBS- and DNBS-specific suppressor activity is found in spleen cells, mesenteric lymph nodes and peripheral lymph nodes.

Surface carbohydrate composition of murine thymocytes and of lymph node cells from normal and athymic (nude) mice.

Surface glycoproteins (papain digests) have been isolated from lymph node cells of normal mice which contain mainly T cells, and from lymph node cells of nude (athymic) mice, which essentially represent B cells. Gaschromatographic analysis revealed that the glycoproteins from the lymph node cells of the euthymic mice contain less galactose than the glycoproteins from lymph node cells of the athymic mice, but contain still more galactose than glycoproteins from thymocytes. Lymph node cells from both sources contain about equal amounts of neuraminic acid, while thymocytes contain slightly less sialic acid.

"Early T cells" and "late T cells"; suggestive evidence for two T cell lineages with separate developmental pathways.

Peripheral lymphocytes from mice have been analyzed by a combination of cell electrophoresis and size distribution analysis and the data have been processed with a computer into two-dimensional distribution patterns (fingerprints). The fingerprints of lymph node cells revealed the existence of at least three major classes of small lymphocytes. Cells with similar physical properties were found in the spleen and thoracic duct lymph.

The antigen-inexperienced thymic suppressor cells: a class of lymphocytes in the young chicken thymus that inhibits antibody production and cell-mediated immune responses.

Transfer of thymus cells from young chickens in combination with a light whole body irradiation (360 R) was found to suppress the rejection of skin grafts across strong histocompatibility (B) differences. On the average, the suppressed animals also showed decreased serum hemagglutinin titers against erythrocytes of the skin donor strain and a decreased graft-versus-host (GvH) reactivity against embryos of this strain. The thymic suppressor cells can be obtained from animals that have not experienced the antigen under test.

Suppressor cells in the embryonic thymus mediate allograft tolerance.

Thymus cells from non-immunized young chickens suppress the allograft rejection in lightly irradiated syngeneic or allogeneic recipients and mediate longlasting skingraft survival in a significant proportion of recipients across a strong histocompatibility difference. Suppressive activity of this kind is already found in the embryonic thymus and is therefore believed to mediate also self tolerance and neonatal allograft tolerance.

Immunosuppressive effect of syngeneic thymus cells on allograft rejection.

Transfer of thymus cells from young chickens to syngeneic recipients suppresses the allograft rejection between strains differing at the major histocompatibility (B) locus. Thymus cell transfer in combination with a light whole body irradiation (360 R) prolongs significantly the mean rejection time of skin allografts and leads in a proportion of recipients to long-lasting graft survival (greater than 200 days). Three weeks after the cell transfer, the suppression appears to be antigen specific, as judged by the normal reactivity against third-party skin grafts.

Surface carbohydrate composition of different types of chicken lymphocytes.

A simple and quick procedure was used to analyse the carbohydrate composition of surface glycoproteins from chicken lymphocytes. The procedure included papain digestion of the cells, a two-step purification of the supernatant material and a sugar analysis by gaschromatography. The method made it possible to analyse samples of about 10(9) lymphocytes.

Lymphocyte subpopulations in the thymus.

The thymus of mice and chickens contains at least four discrete populations of lymphoid cells: Two distinct cortical populations of small lymphocytes (early and late population), a hydrocortisone resistant and presumably medullary population of small lymphocytes, and a population of medium sized lymphocytes (prolymphocytes) (see Table I and Figure 3). These four cell types were identified with preparative cell separation techniques (e.g.