Donor-type activated natural killer cells promote marrow engraftment and B cell development during allogeneic bone marrow transplantation.

Purified NK cells were obtained from mice with severe combined immune deficiency and were activated with human IL-2 (hrIL-2) in vitro to determine if, once activated, these cells could be transferred with compatible bone marrow cells (BMC) and promote marrow engraftment in irradiated allogeneic recipients. After culture with hrIL-2, these cells maintained a phenotypic and lytic spectrum consistent with a pure population of activated NK cells. These activated NK cells were then adoptively transferred with the donor BMC and rhIL-2 into lethally irradiated allogeneic hosts. The addition of NK cells with the BMC allowed for more rapid hematopoietic engraftment as determined through short term studies, and greater donor-derived chimerism with accelerated reconstitution of the B cell population as determined with long term analysis. No evidence of graft-vs-host disease was detected in the recipients receiving the activated NK cells with allogeneic T cell replete BMC and hrIL-2. The mechanism by which the transferred NK cells improved BMC engraftment was at least partly through the abrogation of the host effector cell's ability to mediate resistance to the marrow graft. Thus, the administration of donor-type activated NK cells with BMC and hrIL-2 may significantly augment hematopoietic engraftment and immune reconstitution in the clinical setting of allogeneic BMT without giving rise to graft-vs-host disease.     

Comparative response of nestling European starlings and red-winged blackbirds to an oral administration of either dimethoate or chlorpyrifos.

Red-winged blackbird (Agelaius phoeniceus; blackbird) and European starling (Sturnus vulgaris; starling) nestlings were dosed with either 2.0 mg/kg body mass chlorpyrifos, 50.0 mg/kg body mass dimethoate, or a propylene glycol carrier in situ. Four growth measurements (body mass, culmen, tarsus, wing) were recorded from nestlings to determine if these organophosphorus compounds caused perturbations in development at sublethal concentrations. Blackbird nestlings were more sensitive to chlorpyrifos than starling nestlings were more sensitive to dimethoate than blackbird nestlings. This was in contrast to reported adult LD50 values where the reverse was true. Blackbird nestlings were more tolerant of a substantially higher concentration of dimethoate than the adult LD50. The sensitivity of starling nestlings to dimethoate was similar to adults. In contrast, juveniles of both species were more sensitive to chlorpyrifos than adults. After the initial 24 hr, surviving nestlings dosed with either chemical recovered and continued their development. Exposure to dimethoate caused significant depression in starling body mass during the initial 24 hr period. Survivors obtain body mass equal to controls within 48 hr post dosing. The research presented here demonstrates that the simple supposition that passerine nestlings are typically more sensitive to toxins than adults does not always hold true. It also indicates that sensitivity relationships among adults do not necessarily apply to their nestlings.     

Praziquantel: The enigmatic antiparasitic

Praziquantel (PZQ), a pyrazinoisoquinoline, was introduced as a novel anthelmintic in 1975. PZQ is currently the drug of choice for the treatment of a wide range of both veterinary and human trematode and cestode infections, including human schistosomiasis. Current estimates suggest that 150 million humans are infected with schistosomes, and it is expected that PZQ will play the lead role in chemotherapeutic control of those infections. Despite the time that has passed since its introduction and its obvious importance in global health care, it is not yet understood why PZQ is so selective and effective. The target molecules for PZQ have not been defined, nor are the sites of its effects within the parasites known. Here, Tim Day, James Bennett and Ralph Pax summarize some of the progress that has been made toward reaching these objectives in recent years.     

A general model for the interaction of foreign molecules with lipid membranes: drugs and anaesthetics

A general microscopic interaction model is proposed to describe the changes in the physical properties of phospholipid bilayer membranes due to foreign molecules which, to different degrees, partition between the membrane phases and the aqueous environment. The model is a multi-state lattice model for the main phase transition of lipid bilayers and the foreign molecules are assumed to intercalate as interstitials in the lattice. By varying the model parameters, the diversity in the thermodynamic properties of the model is explored using computer-simulation techniques which faithfully take account of the thermal fluctuations. The calculations are performed in both the canonical and the grand canonical ensembles corresponding to the cases where the concentration of foreign molecules in the membrane is either fixed or varies as the external conditions are changed. A classification of the diverse thermal behaviour, specifically with regard to the phase diagram, the specific heat, the density fluctuations, and the partition coefficient, is suggested with a view to rationalizing a large body of experimental measurements of the effects of different foreign molecules on membrane properties. The range of foreign molecules considered includes compounds as diverse as volatile general anaesthetics like halothane, cocaine-derived local anaesthetics like procaine, calcium-channel blocking drugs like verapamil, antidepressants like chlorpromazine, and anti-cancer agents like adriamycin.     

Estrogen-stimulation of postconfluent cell accumulation and foci formation of human MCF-7 breast cancer cells

Foci, nodules of cellular overgrowth, that appear after confluence are an in vitro characteristic of malignant transformation. A well-studied in vitro model of estrogen-dependent tumors is the MCF-7 cell line, derived from a pleural metastasis of a human breast adenocarcinoma. We report that cultivation of MCF-7 cells, using routine methods, results in extensive estrogen-stimulated postconfluent cell accumulation characterized by discrete three-dimensional arrays. Side view Nomarski optical sections revealed these to be principally multicellular foci with occasional domes and pseudoacinar vacuoles. This effect on MCF-7 cell growth occurs in media containing fetal bovine serum but not with calf serum or charcoal-dextran-treated fetal bovine serum unless supplemented with estrogens. Foci formation starts 5-6 days after confluence, and the number of foci generated is a function of the concentration of added estrogens. Foci formation is suppressed by the antiestrogens Tamoxifen and LY 156758. Addition of progesterone, testosterone, or dexamethasone had little or no effect, while various estrogens (ethinyl estradiol, diethylstilbestrol, and moxestrol) induced foci development. Clones derived from single cells of the initial MCF-7 population revealed a wide variance in estrogen-induced foci formation, demonstrating heterogeneity of this tumor cell line. The postconfluent cell growth of the estrogen receptor-deficient cell line, MDA-MB-231, contrasted with MCF-7 by developing an extensive multilayer morphology devoid of discrete structures. The tumorigenic potential of the MCF-7 cells used in our experiments was confirmed by their estrogen-dependent growth in immunosuppressed male BDF1 mice. These data suggest an estrogen receptor-based mechanism for the development of multicellular foci during postconfluent growth of MCF-7 cells. After confluence, foci, in contrast to the quiescent surrounding monolayer, retain proliferating cells. Focus formation, therefore, reflects the heterogeneous responsiveness of these cells to estrogens and should provide a model permitting in vitro comparisons between the progenitor cells of multicellular foci and the monolayer population.     

The mechanisms of preterm labour; the interaction between amnion cells and leukocytes in the metabolism of arachidonic acid

Chorioamnionitis is frequently associated with preterm labour. We have used a cell culture model system to examine the effects of leukocytes upon the metabolism of endogenous arachidonic acid from within amnion cells. We have demonstrated that activated leukocytes release substances which increase the overall release and metabolism of endogenous arachidonic acid within amnion cells causing an increase in prostaglandin E₂ production as well as a smaller increase in non-cyclooxygenase metabolism. When amnion cells and leukocytes are cultured together, in addition to prostaglandin E₂ production by amnion cells, arachidonic acid released by the amnion cells appears to be metabolised by leucocytes to prostaglandin F_2α, prostacyclin and thromboxane A₂. Prostaglandins E₂ and F_2α are the principal cyclo-oxygenase products of this interaction.We postulate that chorioamnionitis stimulates preterm labour not only by causing an increase in prostaglandin E2 synthesis by amnion cells but by metabolism of amnion derived arachidonic acid to the powerfully oxytocic prostaglandin F_2α by leukocytes.