Growth of Clostridium perfringens in cooked chili during cooling.

U.S. Department of Agriculture regulations require that brick chili be cooled from 48.9 degrees C to 4.4 degrees C within 2 h of cooking, but processors may not always be able to comply. Studies were conducted to evaluate the extent of bacterial multiplication resulting from outgrowth of germinated Clostridium perfringens spores experimentally inoculated into chili and incubated at various temperatures. Inoculated samples were heated (75 degrees C for 20 min) to activate spores, quickly equilibrated, and held at one of five desired temperatures for 6 h. No growth was observed for C. perfringens in samples held at 26.7 degrees C and below for 6 h, but growth was observed by 6 h in samples held at 32.2 degrees C and after 2 h in samples held at temperatures between 37.8 degrees C and 48.9 degrees C. Using isothermal growth data, we developed a simple model for predicting the growth of bacteria with time under exponential cooling conditions. The model predicts both the lag phase and the numbers of bacteria at specific times during the growth phase. It was developed by using isothermal growth data and tested by using temperature-varying growth data from experiments with spores of C. perfringens in chili. Actual data agreed closely with predicted results. The results should be useful for evaluating the hazard potential for growth of C. perfringens in chili.     

In vivo administration of purified human interleukin 2. II. Half life, immunologic effects, and expansion of peripheral lymphoid cells in vivo with recombinant IL 2

Purified recombinant human interleukin 2 (RIL 2) derived from E. coli containing the inserted gene encoding for IL 2 was administered to 20 patients with a variety of malignancies. Toxicity was dose related and included fever, chills, malaise, arthralgias, myalgias, and unexpectedly, weight gain related to marked fluid retention. All patients receiving more than 10(5) U/kg total cumulative dose developed evidence of fluid retention, and all patients requiring discontinuance of RIL 2 (11/20) received total doses of between 2.54 X 10(5) U/kg to 15.4 X 10(5) U/kg. The limiting dose with this preparation was 3000 U/kg/hr by continuous administration or 10(6) U/kg by bolus administration. IL 2 was rapidly cleared from the plasma, with a half life of 6.9 min, and a later delayed clearance was consistent with a two-compartment model, with slower release from the extravascular space back into the plasma compartment. A marked change in lymphoid cells in the periphery was noted with an early depletion of all lymphoid cells, followed by an expansion of such cells with continuous IL 2 administration. A twofold to 16-fold expansion of total lymphoid cells in the peripheral blood could be demonstrated. TAC+ cells representing up to 25% of the circulating peripheral blood mononuclear cells could be demonstrated with 3 wk of continuous RIL 2 administration. Interferon-gamma levels increased in patients treated with IL 2. Precursors of lymphokine-activated killer cells generated under standard conditions were depleted within 2 to 3 min after IL 2 administration, but repopulated the peripheral blood after 7 to 10 days of continuous IL 2 administration. No tumor regression was seen in any of the cancer patients treated with IL 2 alone.     

Compartmentation of glutamate metabolism in brain. Evidence for the existence of two different tricarboxylic acid cycles in brain

1. (14)C from [1-(14)C]glucose injected intraperitoneally into mice is incorporated into glutamate, aspartate and glutamine in the brain to a much greater extent than (14)C from [2-(14)C]glucose. This difference for [1-(14)C]glucose and [2-(14)C]glucose increases with time. The amount of (14)C in C-1 of glutamate increases steadily with time with both precursors. It is suggested that a large part of the glutamate and aspartate pools in brain are in close contact with intermediates of a fast-turning tricarboxylic acid cycle. 2. (14)C from [1-(14)C]acetate and [2-(14)C]acetate is incorporated to a much larger extent into glutamine than into glutamate. An examination of the time-course of (14)C incorporated into glutamine and glutamate reveals that glutamine is not formed from the glutamate pool, labelled extensively by glucose, but from a small glutamate pool. This small glutamate pool is not derived from an intermediate of a fast-turning tricarboxylic acid cycle. 3. It is proposed that two different tricarboxylic acid cycles exist in brain.     

Totipotent hematopoietic stem cells: normal self-renewal and differentiation after transplantation between mouse fetuses

Successful engraftment of mouse fetal liver cells in early fetal recipients, after microinjection via the placental circulation, is attributable to seeding of the recipient's liver by a cell type that is ancestral to both the myeloid and lymphoid definitive lineages and is capable of sustained self-renewal and differentiation for more than 2 years. This primitive cell is therefore the normal totipotent hematopoietic stem cell (THSC). The use of a large series of mutant anemic recipients with decreasing severity of an endogenous stem-cell defect (W/W, Wv/Wv, Wf/Wf, Wv/+), and therefore of graded selective advantage to normal donor cells, has revealed that engraftment entails marginal numbers of cells--probably individual ones--in the least afflicted hosts. Thus the observed progressive and coordinate shift toward donor-strain erythrocytes, granulocytes and B and T lymphocytes, over time, indicates THSC expansion to form a larger stem-cell pool and normally regulated differentiation of cells from the pool. This transplant system allows allogeneic combinations with impunity and therefore provides many novel experimental possibilities for investigating THSC normal development, genetic abnormalities or neoplastic potential in relation to the intact developmental succession of hematopoietic tissue environments in vivo.     

Cellular mechanisms of the antitumor activity of recombinant IL-6 in mice.

The systemic administration of human rIL-6 to mice resulted in the regression of established, 3-day pulmonary micrometastases from two weakly immunogenic tumors, but not from a nonimmunogenic tumor, in the absence of observable toxicity. Although IL-6 alone failed to have a significant therapeutic impact on advanced, 10-day pulmonary macrometastases from weakly immunogenic tumors, substantial cure rates of mice could be achieved when this cytokine was combined with cyclophosphamide. Histologic analysis of the lungs of mice receiving IL-6 revealed infiltration with lymphoid cells during the regression of pulmonary nodules from a weakly immunogenic tumor. IL-6-mediated tumor regression could be abrogated after selective in vivo depletion of either CD4 or CD8 T cell subsets by the systemic administration of specific mAb. In vivo generation of tumor-specific CTL, but not of lymphokine-activated killer cells, was detected in the lungs of IL-6-treated mice during regression of pulmonary metastases. Collectively, these findings demonstrate a role for IL-6 in the treatment of established solid tumors that have the capacity to elicit T cell responses in the host. Differences in host cellular mechanisms involved in tumor regression mediated by immunotherapy using IL-6 vs IL-2 are discussed.     

Jugular plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha in prepubertal beef heifers treated with progestogen then challenged with oxytocin.

Prepubertal Angus crossbred heifers (n = 24) between 8 and 10 mo of age were used to determine if progestogen treatment would enhance jugular concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) after oxytocin (OT) injections. Heifers were stratified by age and weight and allotted to randomized treatments in a 2 x 2 factorial arrangement. Heifers were treated with either a norgestomet (NOR) implant (6 mg) for 9 d or no implant (0 mg; BLK). On d 8 of NOR treatment, jugular veins were catheterized and, on d 9, blood samples were collected every 15 min for 165 min. The first four samples were used to determine basal PGFM concentrations (an indirect measure of uterine PGF2 alpha release). After collection of the fourth sample, either OT (100 IU) or saline (0 IU; SAL) was injected via the jugular catheter. After the 165-min sample was collected, NOR implants were removed. Beginning 48 h after implant removal, a second 165- min blood sampling period was initiated. Average progesterone concentrations were less than 1 ng/ml during both bleeding periods. Within treatment, PGFM concentrations were similar between the first and second sampling periods; therefore, data within treatment were combined. Basal PGFM concentrations were higher (P < .01) in NOR-treated than in BLK heifers. Oxytocin did not increase PGFM concentrations in BLK-OT heifers; however, a marked increase in PGFM was detected in the NOR-OT heifers in response to oxytocin. Average PGFM concentration was greatest (P < .0001) in NOR-OT heifers, and PGFM profiles differed (P < .0001) between NOR-OT and each of the other treatment groups. Results from this study indicate that NOR increases basal PGFM and may "condition" the uterus to respond to OT in prepubertal heifers.     

<Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> inhibits <Emphasis Type="Italic">in-vitro Candida</Emphasis> biofilm development

Background  

Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.