We recently reported that a cloned murine cell line with "natural killer (NK)-like" cytolytic function and prominent cytoplasmic granules also expressed large numbers of plasma membrane receptors (Fc ...epsilon R) which bound mouse immunoglobulin E (IgE) with high affinity (S.J. Galli et al., 1982, Nature (London) 298, 288). We have now performed IgE-binding studies with 31 additional cloned murine cell lines exhibiting "NK-like" lytic activity (defined as the ability to kill YAC-1 lymphoma cells) and three antigen-specific cytotoxic-T-cell clones. One of the NK-like clones expressed a small number of Fc epsilon R (3.0 X 10(4)/cell) on one of the two occasions it was tested. None of the other clones, which were derived by several different approaches and which had a variety of surface glycoprotein phenotypes, expressed any detectable specific binding of mouse IgE. By contrast, mast cell clones consistently expressed large numbers of Fc epsilon R. The expression of large numbers of high-affinity Fc epsilon R would appear to represent a very uncommon characteristic of NK-like murine cell lines isolated under conditions similar to those described in this report.
Abstract
Mature circulating guinea pig basophils, purified to comprise 25% or more of leukocytes, have been successfully maintained in short-term tissue culture for up to 72 hr. These cells were ...found to retain the ability to synthesize histamine, as assayed by a new isotopic-thin layer chromatographic assay which can reliably detect as little as 0.5 pg of 3H-histamine.
Cell-associated, newly synthesized histamine was detectable as early as 1 hr of culture, was substantially increased at 6 hr, and reached maximal levels at 24 hr, when it accounted for approximately 6.5% of total cell histamine. Newly synthesized histamine was still detectable at 48 and 72 hr of culture. Histamine synthesis was decreased by lowering the concentration of histidine in the culture medium, and was markedly reduced by all of the specific histidine decarboxylase (HDC)3 inhibitors tested, but not by α-methyl-DOPA, pyrilamine maleate, or metiamide. Increasing the concentration of pyridoxal phosphate, the HDC coenzyme, above that normally present in culture medium resulted in only an equivocal increase in the amount of newly synthesized histamine, whereas aminoguanidine, an inhibitor of histaminase, had no detectable effect. Uptake of exogenous histamine by cultured basophils was trivial compared to histamine synthesis.
Both newly synthesized and previously manufactured, nonisotopic, histamine seemed to be stored in the same pool, as the same proportion of both was released by concanavalin A (Con A). Cellular histamine was largely conserved, with little or no spontaneous release into the medium of detectable isotopic or nonisotopic histamine.
These techniques provide a model for studying granulocyte metabolic processes in vitro, and should assist in the direct investigation of a variety of their physiologic functions.
To compare patching and atropine as treatments for moderate amblyopia in children younger than 7 years.
In a randomized clinical trial, 419 children younger than 7 years with amblyopia and visual ...acuity in the range of 20/40 to 20/100 were assigned to receive either patching or atropine at 47 clinical sites.
Visual acuity in the amblyopic eye and sound eye after 6 months.
Visual acuity in the amblyopic eye improved in both groups (improvement from baseline to 6 months was 3.16 lines in the patching group and 2.84 lines in the atropine group). Improvement was initially faster in the patching group, but after 6 months, the difference in visual acuity between treatment groups was small and clinically inconsequential (mean difference at 6 months, 0.034 logMAR units; 95% confidence interval, 0.005-0.064 logMAR units). The 6-month acuity was 20/30 or better in the amblyopic eye and/or improved from baseline by 3 or more lines in 79% of the patching group and 74% of the atropine group. Both treatments were well tolerated, although atropine had a slightly higher degree of acceptability on a parental questionnaire. More patients in the atropine group than in the patching group had reduced acuity in the sound eye at 6 months, but this did not persist with further follow-up.
Atropine and patching produce improvement of similar magnitude, and both are appropriate modalities for the initial treatment of moderate amblyopia in children aged 3 to less than 7 years.
Histamine-releasing activity (HRA) is an approximately 10,000-15,000 dalton, protease-sensitive factor that induces the rapid liberation of histamine from human basophils. Production of HRA by human ...peripheral blood mononuclear cells in vitro is augmented by concanavalin A or antigen, suggesting a mechanism whereby lymphocytes may regulate basophil mediator release in vivo. In order to determine whether HRA provokes conventional exocytosis of basophil granules or, alternatively, results in mediator release by some other mechanism such as vesicular transport or cytotoxicity, we investigated the ultrastructural features of human blood basophils purified over Percoll and exposed to HRA in vitro. HRA preparations induced a noncytotoxic pattern of basophil degranulation very similar to that previously observed in basophils triggered to release histamine in response to specific antigen, C5a, or mannitol. Thus, cytoplasmic granules were extruded singly through multiple separate points of fusion between perigranular membranes and the plasma membrane. Degranulating basophils exhibited plasma membrane activation but lacked a polarized configuration. By contrast, those basophils exposed to HRA that did not exhibit evidence of degranulation displayed a single elongated cellular process. The development of this polarized cellular configuration, similar in some respects to that of uropod-bearing motile guinea pig basophils, may have reflected chemokinetic or chemotactic effects of preparations containing HRA activity.
Direct-sampling observations of interstellar neutral (ISN) He by Interstellar Boundary Explorer (IBEX) provide valuable insight into the physical state of and processes operating in the interstellar ...medium ahead of the heliosphere. The ISN He atom signals are observed at the four lowest ESA steps of the IBEX-Lo sensor. The observed signal is a mixture of the primary and secondary components of ISN He and H. Previously, only data from one of the ESA steps have been used. Here, we extended the analysis to data collected in the three lowest ESA steps with the strongest ISN He signal, for the observation seasons 2009-2015. The instrument sensitivity is modeled as a linear function of the atom impact speed onto the sensor's conversion surface separately for each ESA step of the instrument. We found that the sensitivity increases from lower to higher ESA steps, but within each of the ESA steps it is a decreasing function of the atom impact speed. This result may be influenced by the hydrogen contribution, which was not included in the adopted model, but seems to exist in the signal. We conclude that the currently accepted temperature of ISN He and velocity of the Sun through the interstellar medium do not need a revision, and we sketch a plan of further data analysis aiming at investigating ISN H and a better understanding of the population of ISN He originating in the outer heliosheath.
The CTFA Evaluation of Alternatives Program is a multi-year effort, organised by the CTFA Animal Welfare Task Force, designed to evaluate the performance of currently promising in vitro (alternative) ...methods to the Draize eye irritancy test. The sole criterion for inclusion of a particular test is that it shows some initial promise as an alternative to the Draize eye test, and that it is under evaluation or development by a participating CTFA member company. Tests are evaluated for their ability to rank and discriminate the ocular irritation potential of prototype cosmetic and personal care formulations compared to the Draize eye test. Test materials and in vitro methods currently under evaluation in Phase Il of the CTFA Program are described. Additional tests may be included in subsequent phases of the Program, should it be determined that they show particular promise as replacements for specific types of formulation. Conversely (at the discretion of sponsors), tests may be removed from the Program should initial promise be unfulfilled.
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