Dry Rehydratable Film Method for Enumerating Confirmed Escherichia coli in Poultry, Meats, and Seafood: Collaborative Study

A rehydratable dry-film plating method for Escherichia coli, the Petrifilm E. coli/Coliform (EC) Count Plate in foods, has been compared with the AOAC INTERNATIONAL most probable number (MPN) method. Eleven laboratories participated in the collaborative study. Three E. coli levels in 8 samples each of frozen raw ground turkey, frozen raw ground beef, and frozen cooked fish were tested in duplicate. Mean log counts for the Petri film plate procedure were not significantly different from those for the MPN procedure for cooked fish samples inoculated with low or high inocula levels, for samples of raw turkey inoculated at medium level, and for beef inoculated at low, medium, and high levels. Repeatability and reproducibility vari ances of the Petrifilm EC Plate method recorded at 24 h were as good as or better than those of the MPN method. The dry rehydratable film method for enumerating confirmed E. coli in poultry, meats, and seafood has been adopted first action by AOAC INTERNATIONAL.

Altered sensitivity to a quaternary ammonium sanitizer in stressed Listeria innocua

Chemical sanitizers are commonly used to inactivate Listeria monocytogenes and other Listeria species that persist in food-processing environments after cleaning. In this study, Listeria innocua cultures were exposed to acid, heat, cold, and starvation stress and then assessed for sensitivity to the quaternary ammonium compound cetrimide. Unstressed and stressed cultures were exposed to cetrimide for 3 min, neutralized, and plated on tryptic soy agar with yeast extract to determine the percentage of survivors. Relative to controls, L. innocua exposed to acid and starvation conditions was less sensitive to cetrimide, whereas heat and cold stress increased cetrimide sensitivity (P < 0.05). The diminished sensitivity of acid- and starvation-stressed L. innocua to cetrimide suggests that these stressors might increase the persistence of this organism within food-manufacturing facilities. In contrast, enhanced L. innocua sensitivity to cetrimide following heat and cold stress suggests that these interventions might increase sanitation efficacy.

Phenotypic and functional comparison of cultures of marrow-derived mesenchymal stem cells (MSCs) and stromal cells

Mesenchymal stem cells (MSCs) are a population of pluripotent cells within the bone marrow microenvironment defined by their ability to differentiate into cells of the osteogenic, chondrogenic, tendonogenic, adipogenic, and myogenic lineages. We have developed methodologies to isolate and culture-expand MSCs from human bone marrow, and in this study, we examined the MSC's role as a stromal cell precursor capable of supporting hematopoietic differentiation in vitro. We examined the morphology, phenotype, and in vitro function of cultures of MSCs and traditional marrow-derived stromal cells (MDSCs) from the same marrow sample. MSCs are morphologically distinct from MDSC cultures, and flow cytometric analyses show that MSCs are a homogeneous cell population devoid of hematopoietic cells. RT-PCR analysis of cytokine and growth factor mRNA in MSCs and MDSCs revealed a very similar pattern of mRNAs including IL-6, -7, -8, -11, -12, -14, and -15, M-CSF, Flt-3 ligand, and SCF. Steady-state levels of IL-11 and IL-12 mRNA were found to be greater in MSCs. Addition of IL-1alpha induced steady-state levels of G-CSF and GM-CSF mRNA in both cell preparations. In contrast, IL-1alpha induced IL-1alpha and LIF mRNA levels only in MSCs, further emphasizing phenotypic differences between MSCs and MDSCs. In long-term bone marrow culture (LTBMC), MSCs maintained the hematopoietic differentiation of CD34+ hematopoietic progenitor cells. Together, these data suggest that MSCs represent an important cellular component of the bone marrow microenvironment.

Phenotypic and functional comparison of cultures of marrow-derived mesenchymal stem cells (MSCs) and stromal cells

Mesenchymal stem cells (MSCs) are a population of pluripotent cells within the bone marrow microenvironment defined by their ability to differentiate into cells of the osteogenic, chondrogenic, tendonogenic, adipogenic, and myogenic lineages. We have developed methodologies to isolate and culture-expand MSCs from human bone marrow, and in this study, we examined the MSC's role as a stromal cell precursor capable of supporting hematopoietic differentiation in vitro. We examined the morphology, phenotype, and in vitro function of cultures of MSCs and traditional marrow-derived stromal cells (MDSCs) from the same marrow sample. MSCs are morphologically distinct from MDSC cultures, and flow cytometric analyses show that MSCs are a homogeneous cell population devoid of hematopoietic cells. RT-PCR analysis of cytokine and growth factor mRNA in MSCs and MDSCs revealed a very similar pattern of mRNAs including IL-6, -7, -8, -11, -12, -14, and -15, M-CSF, Flt-3 ligand, and SCF. Steady-state levels of IL-11 and IL-12 mRNA were found to be greater in MSCs. Addition of IL-1alpha induced steady-state levels of G-CSF and GM-CSF mRNA in both cell preparations. In contrast, IL-1alpha induced IL-1alpha and LIF mRNA levels only in MSCs, further emphasizing phenotypic differences between MSCs and MDSCs. In long-term bone marrow culture (LTBMC), MSCs maintained the hematopoietic differentiation of CD34+ hematopoietic progenitor cells. Together, these data suggest that MSCs represent an important cellular component of the bone marrow microenvironment.

CD40-mediated stimulation contributes to lymphocyte proliferation, antibody production, eosinophilia, and mastocytosis during an in vivo type 2 response, but is not required for T cell IL-4 production

CD40/CD40 ligand interactions are required for the development of T cell-dependent Ab responses in vivo. The role of these cell surface molecules in contributing to T cell cytokine production and the development of effector populations other than B cells and T cells is, however, less well defined. We have examined the in vivo effects of blocking CD40/CD40 ligand interactions on the type 2 mucosal immune response that follows oral inoculation of mice with the nematode parasite, Heligmosomoides polygyrus. Administration of anti-gp39 (CD40L) mAb (MR1) blocked H. polygyrus-induced elevations in serum IgG1 levels and inhibited elevations in blood eosinophils and mucosal mast cells at day 14 after inoculation. Anti-gp39 mAb markedly inhibited B cell blastogenesis 8 days after H. polygyrus inoculation but did not inhibit elevations in B cell class II MHC expression. Maximal elevations in B7-2 expression required signaling through both CD40 and the IL-4R. Elevations in T cell cytokine gene expression and elevations in the number of IL-4-secreting cells were unaffected by treatment with anti-gp39 mAb, although IL-4 production was inhibited by anti-IL-4R mAb. These results suggest that CD40/CD40L interactions are not required to activate T cells to produce cytokines but are required for the activation and proliferation of other effector cells associated with the type 2 response.

CD40-mediated stimulation contributes to lymphocyte proliferation, antibody production, eosinophilia, and mastocytosis during an in vivo type 2 response, but is not required for T cell IL-4 production

CD40/CD40 ligand interactions are required for the development of T cell-dependent Ab responses in vivo. The role of these cell surface molecules in contributing to T cell cytokine production and the development of effector populations other than B cells and T cells is, however, less well defined. We have examined the in vivo effects of blocking CD40/CD40 ligand interactions on the type 2 mucosal immune response that follows oral inoculation of mice with the nematode parasite, Heligmosomoides polygyrus. Administration of anti-gp39 (CD40L) mAb (MR1) blocked H. polygyrus-induced elevations in serum IgG1 levels and inhibited elevations in blood eosinophils and mucosal mast cells at day 14 after inoculation. Anti-gp39 mAb markedly inhibited B cell blastogenesis 8 days after H. polygyrus inoculation but did not inhibit elevations in B cell class II MHC expression. Maximal elevations in B7-2 expression required signaling through both CD40 and the IL-4R. Elevations in T cell cytokine gene expression and elevations in the number of IL-4-secreting cells were unaffected by treatment with anti-gp39 mAb, although IL-4 production was inhibited by anti-IL-4R mAb. These results suggest that CD40/CD40L interactions are not required to activate T cells to produce cytokines but are required for the activation and proliferation of other effector cells associated with the type 2 response.

Requirement of CTLA-4 counter receptors for IL-4 but not IL-10 elevations during a primary systemic in vivo immune response

The CD28/CTLA-4 costimulatory signal is required for TCR-mediated T cell activation resulting in increased IL-2 production in vitro, but its role in IL-4 production is unclear and few studies have examined the function of CTLA-4/CD28 in the in vivo immune response. We have examined the in vivo effects of blocking the interaction of B7 with its ligands, CTLA-4 and CD28, in an IL-4 dominant in vivo immune response to goat anti-mouse IgD. This response is characterized by elevations in serum Igs preceded by elevations in IL-2 and the Th2 cytokines: IL-4, IL-9, and IL-10. The fusion protein CTLA4-Ig administered during the in vivo immune response to goat anti-mouse IgD caused an inhibition in elevations of IL-2, IL-4, and IL-9 gene expression at both day 3 and day 6 after immunization. In contrast, IL-10 cytokine gene expression as late as day 6 after immunization was not decreased. Cell sorting analysis demonstrated that TCR-alpha beta +, CD4+ T cells were the primary source of the elevated IL-10, suggesting that T cell activation leading to IL-10 gene expression may not require CTLA-4 ligand interactions. Similarly CTLA4-Ig completely blocked elevations in the number of IL-4- but not IL-10-secreting cells, as measured by ELISPOT, in both unsorted splenic cells and sorted CD4+, TCR-alpha beta+ T cells. In situ staining of spleen sections also showed inhibition of IL-4-producing cells. These results suggest that, with the notable exception of IL-10, interaction, of B7 with its ligands is required for elevated Th2 cytokine gene expression and secretion during a primary systemic IL-4-dominant response.

Requirement of CTLA-4 counter receptors for IL-4 but not IL-10 elevations during a primary systemic in vivo immune response

The CD28/CTLA-4 costimulatory signal is required for TCR-mediated T cell activation resulting in increased IL-2 production in vitro, but its role in IL-4 production is unclear and few studies have examined the function of CTLA-4/CD28 in the in vivo immune response. We have examined the in vivo effects of blocking the interaction of B7 with its ligands, CTLA-4 and CD28, in an IL-4 dominant in vivo immune response to goat anti-mouse IgD. This response is characterized by elevations in serum Igs preceded by elevations in IL-2 and the Th2 cytokines: IL-4, IL-9, and IL-10. The fusion protein CTLA4-Ig administered during the in vivo immune response to goat anti-mouse IgD caused an inhibition in elevations of IL-2, IL-4, and IL-9 gene expression at both day 3 and day 6 after immunization. In contrast, IL-10 cytokine gene expression as late as day 6 after immunization was not decreased. Cell sorting analysis demonstrated that TCR-alpha beta +, CD4+ T cells were the primary source of the elevated IL-10, suggesting that T cell activation leading to IL-10 gene expression may not require CTLA-4 ligand interactions. Similarly CTLA4-Ig completely blocked elevations in the number of IL-4- but not IL-10-secreting cells, as measured by ELISPOT, in both unsorted splenic cells and sorted CD4+, TCR-alpha beta+ T cells. In situ staining of spleen sections also showed inhibition of IL-4-producing cells. These results suggest that, with the notable exception of IL-10, interaction, of B7 with its ligands is required for elevated Th2 cytokine gene expression and secretion during a primary systemic IL-4-dominant response.

CTLA-4 ligands are required to induce an in vivo interleukin 4 response to a gastrointestinal nematode parasite

The costimulatory signal provided to T cells through CTLA-4-ligand interactions is required for T cell activation resulting in increased interleukin 2 (IL-2) production in vitro, but its role in the production of IL-4 and other cytokines is unclear and few in vivo studies have been performed to confirm results of in vitro experiments. We have examined the in vivo effects of blocking CTLA-4 ligands on the T helper cell 2 (Th2)-associated mucosal immune response that follows oral infection of mice with the nematode parasite, Heligmosomoides polygyrus. CTLA-4Ig administration inhibited H. polygyrus-induced increases in mesenteric lymph node (MLN) B cell major histocompatibility complex class II expression and size and T cell-derived IL-4 gene expression. In addition, CTLA-4 immunoglobulin (Ig) partially blocked increased IL-3, IL-5, and IL-9 cytokine gene expression in Peyer's patch (PP) and MLN 8 d after primary inoculation of mice with the parasite. Increases in the number of IL-4- but not IL-5-secreting cells were also inhibited by CTLA-4Ig. H. polygyrus-induced elevations in serum IgE levels but not blood eosinophils, were markedly inhibited by CTLA-4Ig. These results suggest that stimulation of CD28 and/or CTLA-4 is required for T cell priming leading to IL-4 cytokine production, B cell activation, and IgE secretion during a Th2-like, mucosal immune response to a nematode parasite.

The gene encoding the cellulase (Avicelase) Cel1 from Streptomyces reticuli and analysis of protein domains

Streptomyces reticuli produces an unusual cellulase (Avicelase), with an apparent molecular weight of 82 kDa, which is solely sufficient to degrade crystalline cellulose. During cultivation the processing of the Avicelase to a truncated enzyme (42 kDa) and an inactive protein (40 kDa) correlated with the occurrence of an extracellular protease. After its purification this 36 kDa protease cleaved the S. reticuli Avicelase in vitro in the same manner. Using antibodies raised against the Avicelase and its truncated form (42 kDa) and gene libraries of S. reticuli DNA in the Escherichia coli phage vectors lambda gt11 and Charon 35, the Avicelase gene (cel1) was identified. Further subcloning and DNA-sequencing revealed a G+C rich (72%) reading frame of 2238 bp encoding a protein of 746 amino acids. The transcriptional start site was mapped about 180 bp upstream from the GTG start codon. A signal sequence of 29 amino acids was identified by aligning the deduced amino acids with the characterized N-terminus of the 82 kDa Avicelase. Comparison of the N-terminal amino acids from the purified proteins with the amino acid sequence derived from the Avicelase gene revealed that the truncated enzyme (42 kDa) corresponds to the C-terminal region whereas the inactive proteolytically derived protein (40 kDa) represents the N-terminal part of the 82 kDa Avicelase. Comparisons with amino acid sequences deduced from known cellulase genes indicated the presence of three putative protein domains: (i) an N-terminal part showing significant similarity with a repeat region of endoglucanase C from Cellulomonas fimi, recently shown to be a cellulose-binding domain; (ii) an adjoining region sharing homology with the N-terminal domains with unknown function of endoglucanase A from Pseudomonas fluorescens, endoglucanase D from Clostridium thermocellum and a cellodextrinase from Butyrivibrio fibrisolvens, and (iii) a C-terminal catalytic domain belonging to cellulase family E.

Methyl isocyanate: reproductive and developmental toxicology studies in Swiss mice

Studies were conducted in Swiss (CD-1) mice to evaluate the potential of inhaled vapors of methyl isocyanate (MIC) to affect reproduction and development. Inhaled MIC at concentrations of 0, 1, or 3 ppm, 6 hr per day during days 14 through 17 of gestation caused a significant increase in the number of dead fetuses at birth and caused a significant decrease in neonatal survival during lactation. In contrast, exposure of male and female mice to 1 or 3 ppm given 6 hr per day for 4 consecutive days had no effect on reproduction during mating trials conducted 1, 8, and 17 weeks after the exposure period. Similarly, there was no evidence of a dominant lethal effect in exposed male mice.

Micromorphology and Surface Characteristics of Lunar Dust and Breccia

Although nothing of direct biologic interest was observed in the sample studied, small shaped glass particles and glazed pits resemble objects which elsewhere have been described as fossils. These features, although nonbiological, do bear on processes of lunar weathering and outgassing. The glazed pits are impact features. Fusion of their surfaces released gases. Electron microscopy of the glasses, pits, and angular microfractured mineral grains indicates a prevalence of destructive weathering processes-thermal expansion and contraction, abrasion by by-passing particles, and, of course, impact. ous at room temperature.