Dose-survival curves for murine hematopoietic stem cells and transplanted syngeneic lymphoma cells were constructed for a variety of alkylating agents administered in vivo. A comparison of the slopes of the dose-survival curves, defined as the efficacy ratio, provided a quantitative measure of the differential sensitivity of these two cell populations to a given alkylating agent. Nitrogen musta...

OBJECTIVES To develop a novel and automated assay determining plasma thiol/disulphide homeostasis, which consists of thiol-disulphide exchanges. DESIGN AND METHODS Native thiol and total thiol concentrations were synchronously measured as a paired test. In the first vessel, the amount of native thiol groups was measured by a modified Ellman reagent. At the parallel run, first, dynamic disulph...

The complex OsO4.(S,S)-1,2-diphenyl-N,N'-bis(2,4,6-trimethylbenzyl)ethane-1,2-diamine is an effective reagent for the desymmetrisation of meso-1,2-bis(3,6-dihydro-2H-pyran-2-yl)ethanes by asymmetric dihydroxylation; this process, whose sense of diastereoselectivity depends on substitution and stereochemistry, has been exploited in the synthesis of a C-linked analogue of allolactose.

Although the antitumor effects of chloroethylnitrosoureas have been shown to be due primarily to DNA-DNA cross-linking by the alkylating moieties of these agents, the basis of the often accompanying bone marrow toxicity has been more controversial. We report on the relative bone marrow toxicity of four model nitrosoureas with different alkylating and carbamoylating activities: 1,3-bis(2-chloroe...

The activity of the nuclear factor I/CCAAT transcription factor (NFI/CTF) is negatively regulated by oxidative stress. The addition of relatively high (millimolar) H(2)O(2) concentrations inactivates cellular NFI DNA-binding activity whereas lower concentrations can repress NFI/CTF transactivating function. We have investigated the mechanism of this regulation using Gal4 fusion proteins and tra...

Experiments are described which have led to the selective alkylation of a histidine residue in streptococcal proteinase without concomitant reaction with the single essential sulfhydry1 group. The reduced, active form of the enzyme was first treated with sodium tetrathionate to protect the sulfhydry1 group and to introduce a negative charge near the active center. The resulting inactive derivat...

A series of seed priming experiments were conducted to test the effects of different pretreatment methods to seed germination, seedling growth, and seed yield traits in maize (Zea mays L.). Results indicated that the seeds primed by gibberellins (GA), NaCl, and polyethylene glycol (PEG) reagents showed a higher imbibitions rate compared to those primed with water. The final germination percenta...

The purpose of this study was to compare quantification of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 by precipitation with polyethylene glycol (PEG) with that by density-gradient ultracentrifugation. Fresh serum samples from 32 fasting, obese children were analyzed with precipitation reagent "Quantolip" (Immuno AG), and then fractionated with a Beckman TL 100 ultracentr...

The traceless Staudinger ligation can be mediated by phosphinothiols under physiological conditions. Proximal positive charges are necessary to achieve that transformation, presumably because those charges discourage protonation of the key iminophosphorane intermediate. Here, a series of cationic phosphinothiols is used to probe Coulombic effects on the traceless Staudinger ligation in aqueous ...