Biomedical subjects
Publications and source records attributed to J D Rosen.
Fast atom bombardment mass spectrometry (FAB) was used to determine the glycation sites of lysozyme in a restricted water environment. A 30-day incubation at 25 degrees C, and 65% relative humidity (R.H.) resulted in glycation at lysine-1 while a much shorter (3-day) incubation at 50 degrees C and 65% R.H. resulted in diglycation at lysine-1 as well as glycation at lysine-13 and lysine-33.
14C-labeled benzo[a]pyrene (BaP) was used as a model-compound for polycyclic aromatic hydrocarbons (PAH) in order to assess the effect of photolytic pretreatment on the subsequent fate of BaP in sewage sludge and soil test systems. Photolysis was performed in methanolic solution with or without 0.1 M H2O2, under either UV light (300 nm) or natural sunlight. The presence of H2O2 greatly enhanced the rate of photolysis both with UV and with natural sunlight. Intact BaP resisted biodegradation in both test systems. Photolysis transformed BaP to polar materials that were subject to increased mineralization and binding in both biological test systems. As shown by the Ames assay, photolysis decreased the mutagenicity of BaP to test strains TA98 and TA104 only moderately. The photolysate had an increased acute toxicity and lost its need for activation by S-9 enzymes. However, during subsequent incubation in soil or sewage sludge, mutagenicity decreased rapidly by one to two orders of magnitude and acute toxicity disappeared due to the mineralization and binding of photoproducts to humic materials. Photolysis of BaP and similar PAH compounds represents a useful treatment option that could be applied to certain PAH-containing petroleum refinery sludge and to coal tar residues in order to facilitate their detoxification and environmentally safe disposal.
The effect of calcium antagonists and representative compounds from several classes of anti-promoters including anti-inflammatory sterols, protease inhibitors, retinoids and cyclic nucleotides on metabolic cooperation in cells treated with phorbol-12-myristate-13-acetate (PMA) was determined. Each compound was tested for its effect on metabolic cooperation and also for its ability to reverse or modify the inhibitory properties of PMA on intercellular communication at noncytotoxic exposure concentrations. Of all the compounds tested only cyclic AMP was able to antagonize the inhibitory effect of PMA. trans-Retinoic acid inhibited metabolic cooperation slightly at high exposure concentrations and acted synergistically with PMA to strongly inhibit intercellular communication in a dose-dependent manner.
The effect of cell density, PMA exposure time, concentration, pre-exposure and binding activity on the recovery of V 79 HGPRT- Chinese hamster cells in the metabolic cooperation assay was determined. A PMA exposure interval of only 1 min resulted in maximum recovery of HGPRT- cells. PMA began to inhibit metabolic cooperation at a dose as low as 0.1 ng/ml final media concentration. The recovery of HGPRT- cells varied according to cell density in the presence or absence of PMA, although the magnitude of this effect was much greater in untreated cells. Pre-exposure of cells to PMA increased the recovery of both post-PMA-treated and non-treated HGPRT- cells in a dose-dependent manner. [3H]PMA was rapidly bound to or taken up by V 79 cells. These results suggest that the inhibitory effect of PMA on metabolic cooperation in V 79 cells involves receptor binding.
A rapid method for the simultaneous determination of T-2 toxin, HT-2 toxin, diacetoxyscirpenol and zearalenone has been developed. Corn samples (10 g) are extracted with methanol, defatted with hexane and subsequently cleaned-up using both reversed-phase (C18) and normal-phase (silica gel) Sep-Pak cartridges. Confirmation of identity is made by gas chromatography-mass spectrometry-selected ion monitoring of three ions characteristic of the trimethylsilyl derivatives of the mycotoxins. Use of deuterated internal standards makes the method quantitatively reliable and increases sensitivity. Confirmation of identity as well as quantitation can be achieved at levels of ca. 20-50 ppb, depending on the mycotoxin. Detection limits (without confirmation of identity) are estimated at 1-20 ppb. Recoveries at the 46-111 ppb level ranged from 80 to 103% with coefficients of variation ranging from 1.6 to 14.2%.
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This study was performed to determine the usefulness of the intercellular metabolic cooperation assay for analysis of a complex mixture and to compare the results obtained with previously conducted in vivo tumor promoter assays. One hundred 2R1 cigarettes were smoked according to Federal Trade Commission guidelines and the resulting condensate was separated into a water/methanol-soluble fraction (which was further partitioned into acidic and basic components) and an organic solvent-soluble fraction (which was then chromatographed on silicic acid with petroleum ether, benzene/petroleum ether, benzene, ether, and methanol). The following fractions were positive in the metabolic cooperation assay (in decreasing order of activity): organic solvent-soluble, acidic, whole condensate, and water/methanol-soluble fractions as well as the ether, benzene, and benzene/petroleum ether eluates. The basic fraction and the petroleum ether and methanol eluates were negative. In general, the metabolic cooperation assay results were comparable to previously published results obtained on mouse skin.
Analysis of a 'yellow rain' sample by selected ion monitoring revealed the presence of three trichothecenes: T-2 toxin, diacetoxyscirpenol and 4-deoxynivalenol in concentrations of at least 48, 42 and 58 ppm, respectively. The concentration of zearalenone, another Fusarium mycotoxin, was estimated to be at least 265 ppm. Evidence for a formulation which contained polyethylene glycol was also obtained.
2-Chloroacrolein, the ultimate mutagen, formed on metabolism of the carcinogenc herbicides, diallate and sulfallate, and its 2-bromo-, 2,3-dichloro- and 2,3,3-trichloro- analogs are much more potent mutagens in the Ames Salmonella typhimurium strain TA1U0 assay than any other aldehydes examined previously or in this study. Polymer formation on reaction of deoxyadenosine with the difunctional 2-chloroacrolein probably involves crosslinking via Schiff base formation at the carbonyl group and Michael addition at the doubts bond.
The potent bacterial mutagen 2-chloroacrolein is formed from the carcinogenic herbicide S-2,3-dichloroallyl diisopropylthiocarbamate (diallate) on incubation with hepatic microsomal monooxygenases or on reaction with m-chloroperbenzoic acid. A proposed activation mechanism for this promutagen involves sulfoxidation followed by [2,3] sigmatropic rearrangement and 1,2-elimination reactions. A portion of the highly reactive intermediate, diallate sulfoxide (proximate mutagens), is attacked by glutathione in a reaction which competes with its transformation to the ultimate mutagen, 2-chloroacrolein.
A method for the analysis of T-2 toxin in milk is presented. Ethyl acetate extracts of milk samples which had been spiked with T-2 toxin were purified by thin layer chromatography and derivatized with N,O-bis(trimethylsilyl)acetamide to produce the T-2 toxin trimethylsilyl ether (T-2 toxin-TMS). N,O-bis(trimethylsilyl-d9)acetamide was used to make T-2 toxin d9-trimethylsilyl ether (T-2 toxin-d9 TMS) which was added to the derivatized milk extract as an internal standard. Samples were analyzed by combined gas-liquid chromatography/mass spectrometry using either electron impact ionization or chemical ionization mass spectrometry. In electron impact ionization analyses, simultaneous monitoring of the T-2 toxin-TMS fragment ion at m/z 436 and the T-2 toxin-d9TMS fragment ion at m/z 445 gave a T-2 toxin-TMS detectability estimated at 6 microgram/kg. In chemical ionization analyses, the T-2 toxin-TMS fragment ion at m/z 377 and the T-2 toxin-d9TMS fragment ion at m/z 386 were simultaneously monitored to give a T-2 toxin-TMS detectability estimated at 3 microgram/kg. Average recovery was 85% at 200 microgram/kg and 65% at 20 microgram/kg.
The microbiological assay for penicillin residues was improved by using centrifugation to remove physical barriers to diffusion, a small buffer/meat extraction ratio, and a more sensitive 2-layer assay system. Recoveries from muscle, kidney, and liver tissues ranged between 70.1 and 86.7% with measurable levels of 0.03--0.05 unit/g. By comparison, the Food and Drug-suggested methodology yielded recoveries of 45.9--54.0% and levels of detectability of 0.08--0.10 unit/g. Cooking of hamburger, steaks, and port chops indicated that procaine penicillin withstood cooking conditions, and significant levels of the original activity remained.
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A rapid and sensitive high pressure liquid chromatographic method for the analysis of dexamethasone (9 alpha - fluoro - 11 beta, 17 alpha, 21 - trihydroxy - 16 alpha - methylpregna - 1,4-diene-3,20-dione) in milk has been developed. The corticosteroid can be quantitated at 20 ppb, with the limit of detectability estimated at 5 ppb. Recoveries ranged from 72 to 94%. After dexamethasone was injected into 5 Holstein-Friesian cows, no residues were dound in milk, even after the first milking.
Vinyl chloride is analyzed by mass fragmentography by simultaneously recording its m/e 62 and 64 ions. The minimum quantity necessary for detection is 8.7 X 10(-12) g/10 ml injection. At this level the coefficient of variation is 8.51%.
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