Quantitative flow cytometry: inter-laboratory variation.

Quantitative flow cytometry (QFCM) offers a means of standardization within and between flow cytometers. QFCM parameters were set by determining the antibody-binding capacity (ABC) of CD4, CD8, and CD3 cells from 10 normal donors with the use of eight FACScan flow cytometers. QC3 beads and a certified blank bead were used to set up the instruments. Fluorescein isothiocyanate (FITC) conjugated to molecular equivalents of soluble fluorochrome (MESF) microbead standards was used before and after the donor samples were run to ensure that the machines were operating consistently. Lyophilized cells (Cytotrol) were used as a target, to control for antigen expression in the cell preparation. Quantitative Simply Cellular (QSC) beads were used to establish a standard calibration curve for each of the FITC and phycoerythrin antibody conjugates on each of the instruments. Single-parameter fluorescent histograms derived from list-mode files were used to calculate the slope (coefficient of response), intercept (zero channel), number of channels per decade, and ABC or MESF threshold (blank bead). The fluorescence intensity (geometric mean) of the positive and negative donor cell populations was compared with the standard curves, and the ABCs were calculated. The results show consistent instrument performance between laboratories. However, after standardization of CD3, CD4, and CD8 ABCs to microbeads, large variations were noted between donors and laboratories. The source of this variation does not appear to be in the instrumentation but may be due to the lack of an unified set-up protocol, introducing issues of antibody saturation, methods for whole blood lysis and fixation, and the behavior of the microbead standards.

Allergic reactivity of Parthenium hysterophorus (Santa Maria feverfew) pollen: an unrecognized allergen.

Parthenium hysterophorus (PH), a member of the Asteraceae, is a ubiquitous weed found in great profusion in the United States Gulf coast area. A plant survey carried out in Texas Gulf coast demonstrated that around Corpus Christi, PH is the most prevalent weed. We have studied known ragweed-sensitive patients living in Austin and Corpus Christi, by radioallergosorbent test (RAST) analysis for PH and Ambrosia psilostachya (AP; western ragweed). Nine of ten patients from Austin were RAST-positive to PH and AP; 8 of the 10 patients had positive scores to both pollen extracts. All of the 8 patients from Corpus Christi were positive to both PH and AP. The Austin group showed a significant correlation between AP and PH RAST scores while no correlation between RAST values was seen in the Corpus Christi group. RAST inhibition analysis in this highly selected population did reveal patients that had true sensitivity to PH pollen alone or who were sensitive to both PH and AP pollen. This suggests that in areas where it is highly prevalent PH pollen is an overlooked cause of allergic disease.

Effect of medium hypertonicity on reovirus translation rates. An application of kinetic modeling in vivo.

Translation rates were determined for host and virus mRNAs in reovirus-infected SC-1 cells in hypertonic medium. The effect of low doses of cycloheximide on these translation rates was also measured. The results show that hypertonicity selectively stimulates viral translation relative to host translation. Moreover, in hypertonic medium, host translation is slightly stimulated by low doses of cycloheximide, whereas viral translation is markedly inhibited. This effect of cycloheximide is precisely the opposite to what was previously observed in isotonic media [Walden, W. E., Godefroy-Colburn, T., & Thach, R. E. (1981) J. Biol. Chem. 256, 11739-11746]. It is shown that both these effects of hypertonicity are predicted by the message competition/discrimination model previously described and thus provide support for the applicability of certain aspects of the model to translation rates in vivo.

No adaptogen response of mice to ginseng and Eleutherococcus infusions.

There was no significant difference in mortality, weight gain, liquid consumed, or pathogenesis between mice ingesting four different ginseng infusions for up to 96 days, and control mice drinking distilled water. These results suggest no toxicity or tea selectivity of mice subjected to such regimens. Mice that drank concentrated Siberian ginseng wuchaseng extract with sugar showed significantly more aggressive behavior than those drinking other infusions or distilled water. However, there was no significant difference in stamina or longevity between mice drinking infusions of two preparations of Siberian ginseng, Oriental ginseng, or American ginseng, and control mice when subjected to swimming trials in cold water 38, 46 and 96 days after treatment began. Consequently, ingestion of adaptogenic glycosides did not significantly affect the survival of mice under major environmental stress.

Presence of Both Photosystems in Guard Cells of Vicia faba L: IMPLICATIONS FOR ENVIRONMENTAL SIGNAL PROCESSING.

A new procedure is reported for high-yield isolation of guard cell protoplasts from Vicia faba L. Delayed light emission and P(700) content plus absorption and fluorescence emission spectra of these protoplast extracts are reported. It is concluded that both photosystems are present. The presence of photosystem II and the absence of the reductive-step enzyme of the Calvin-Benson Cycle (Outlaw WH Jr, J Manchester, CH DiCamelli, DD Randall, B Rapp, GM Veith 1979 Proc Natl Acad Sci USA 76: 6371-6375) in a cell has no precedent in the literature. It is speculated that noncyclic photosynthetic electron flow is an environmental sensor which causes stomata to remain open in light.