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At least 1,657 records · Page 92Linked to original sources
PubMed1999

Control of acetic acid concentration by pH-stat continuous substrate feeding in heterotrophic culture phase of two-stage cultivation of Alcaligenes eutrophus for production of P(3HB) from CO2, H2, and O2 under non-explosive conditions.

A-two stage culture method of hydrogen-oxidizing bacterium, Alcaligenes eutrophus, is used to produce poly-D-3-hydroxybutyrate, P(3HB) from CO2, O2, and H2 without using a very high oxygen transfer rate while maintaining the O2 concentration in gas phase below 6.9 (v/v)% to prevent detonation of the gas mixture. The two-stage method consists of a heterotrophic culture using fructose as carbon source for exponential cell growth and an autotrophic culture for P(3HB) accumulation. We investigated the use of acetic acid as a cheaper carbon source than fructose for the heterotrophic culture in the two-stage method. However, the acetate concentration in the culture system must be maintained at 1.0 g. dm-3 since its inhibitory effect on the cell growth is very strong. Then, high cell density cultivation of A. eutrophus was investigated by pH-stat continuous feeding of acetic acid to control acetate concentration. As a result, acetate concentration was automatically maintained around 1.0 g. dm-3 by using a feed with a composition in CH3COOH/CH3COONH4/KH2PO4 molar ratio of 5:1:0.084. Cell concentration increased to 48.6 g. dm-3 after 21 h of cultivation. The cell mass grown in the fed-batch culture on acetic acid was useful for P(3HB) production from CO2 in the subsequent autotrophic culture stage. Copyright 1999 John Wiley & Sons, Inc.

Journal Article↗
PubMed2002

Interplay between heredity and environment in the recent explosion of type 1 childhood diabetes mellitus.

The fast increase in the incidence of childhood type 1 diabetes mellitus (T1DM) that cannot be explained by changes in the genetic susceptibility, led us to look for environmental causes. To test the hypothesis that the initiation of the autoimmune process of childhood T1DM in genetically susceptible subjects begins in the perinatal period by a viral infection, we studied the seasonal variations in the month of birth of several cohorts of patients compared to the general population. Population groups with high or low T1DM incidence were analyzed separately by t-test and the Cosinor methods. In areas with populations with a high incidence (Israeli Jews, Sicily, Sardinia, Slovenia, Germany) we found that the children (in Sicily also young adults) who subsequently developed T1DM, have a higher incidence of births in the summer months than in other seasons of the year, a mirror image of the seasonality of the clinical onset of disease. This pattern differed significantly from the seasonality of the total live births in the same populations. In populations with a low T1DM incidence, (China, Japan and Cuba) no seasonality of month of birth was found. Similar findings have been reported, from five counties in the U.K. and the Netherlands. It is hypothesized that mothers who become pregnant during the period of yearly viral epidemics transmit to the fetus, either a virus or antiviral antibodies, which determine whether an autoimmune process against the pancreatic beta is initiated or whether the fetus is protected against that process.

Diabetes Mellitus, Type 1↗
PubMed1986

Metabolic studies of explosives. 5. Detection and analysis of 2,4,6-trinitrotoluene and its metabolites in urine of munition workers by micro liquid chromatography/mass spectrometry.

Metabolites of 2,4,6-trinitrotoluene (TNT) were found in the urine of a group of TNT munition workers. The urine extracts were analysed by micro liquid chromatography/mass spectrometry. The metabolites found included 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, 2,6-diamino-4-nitrotoluene and untransformed TNT. The detection limit of the metabolites in urine was 0.1 ng/ml for 20 ml urine samples.

Chromatography, High Pressure Liquid↗
PubMed1984

Metabolic studies of explosives. 1--EI and CI mass spectrometry of metabolites of 2,4,6-trinitrotoluene.

A series of metabolites of trinitrotoluene (TNT) have been synthesized and analysed by electron impact (EI) and chemical ionization (CI) mass spectrometry. Identification characteristics of these metabolites by their mass spectra have been determined. Differentiation of isomers is made possible by EI ions which are characteristic of the position of the methyl with regard to the nitro groups.

Aniline Compounds↗
PubMed1989

Metabolic studies of explosives 6. Electron impact and chemical ionization mass spectrometry of metabolites of 2,4-dinitrotoluene.

A series of metabolites of 2,4-dinitrotoluene have been synthesized and analysed by electron impact and chemical ionization mass spectrometry. Identification characteristics of these metabolites by their mass spectra have been determined. Differentiation of isomers is made possible by electron impact ions which are characteristic to the position of the methyl group with regard to the nitro group and to the position of the carboxylic acid group with regard to the nitro group. Metabolites containing an acetyl amino group are characterized by an [M - COCH2]+. electron impact ion.

Biotransformation↗
PubMed2003

Marcella: the transition from explosive sensoriality to the ability to think.

The author discusses an analytic case in which it was necessary to first address the patient's need for containment of her protoemotions--her sensoriality--before the analysis could proceed along more standard lines, with interpretation of the transference, work on displacement and aspects of her childhood history, and so forth. Prior to treatment, the patient had resorted to a sort of affective autism in order not to experience dangerously overwhelming emotions, and her emotional lethargy in sessions at first engendered similar feelings in the analyst, making progress impossible until a container was established for her projective identifications.

Adult↗
PubMed2003

Liquid chromatography/mass spectrometric analysis of explosives: RDX adduct ions.

In liquid chromatography/mass spectrometry (LC/MS) of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), attachment of an anion to the analyte molecule is the major way of producing characteristic ions under electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) conditions. The formation of RDX cluster ions in LC/MS and the origin of the clustering agents have been studied. In order to determine whether the clustering anions originate from self-decomposition of RDX in the source or from impurities in the mobile phase, isotopically labeled RDX ((13)C(3)-RDX and (15)N(6)-RDX) and isotopically labeled glycolic acid, acetic acid, ammonium formate and formaldehyde have been used in order to establish the composition and formation route of RDX adduct ions produced in ESI and APCI sources. The results showed that, in ESI, self-decomposition of RDX plays no role in adduct ion formation; rather, RDX clusters with formate, acetate, hydroxyacetate, and chloride anions present in the mobile phase as impurities at ppm levels. In APCI, part of the RDX molecules decompose yielding NO(2) (-) species which in turn cluster with a second RDX molecule producing abundant [M+NO(2)](-) cluster ions.

Journal Article↗
PubMed1996

Elimination of nitrite from the explosive 2,4,6-trinitrophenylmethylnitramine (tetryl) catalyzed by ferredoxin NADP oxidoreductase from spinach.

Nitroreductase enzymes generally catalyze the reduction of nitroaromatic compounds to the corresponding amines. In contrast, ferredoxin NADP oxidoreductase (FNR), glutathione reductase, xanthine oxidase, and cytochrome c reductase catalyze the NADPH dependent elimination of the nitramine nitro group from 2,4,6-trinitrophenylmethylnitramine to form N-methylpicramide (NMP). Nitrite elimination was inhibited under aerobic conditions. Our results suggest that under aerobic conditions, tetryl is enzymatically reduced to the nitroanion radical which is then involved in the reduction of molecular oxygen. Under anaerobic conditions, the radical is reduced to NMP and nitrite is eliminated.

Anaerobiosis↗
PubMed2002

Screening for soil toxicity and mutagenicity using luminescent bacteria--a case study of the explosive 2,4,6-trinitrotoluene (TNT).

The presented study explored the suitability of aquatic bioassays based on the marine luminescent bacterium Vibrio fischeri as screening indicators for soil toxicity and mutagenicity. The study consists of two parts: (i) determination of the bacterial toxicity and mutagenicity of the single substance 2,4,6-trinitrotoluene (TNT) and its primary reduced metabolites using three different luminescent bacteria assays and (ii) determination of the water-extractable toxicity and mutagenicity of soil samples taken at a former production plant for TNT showing complex contamination (TNT, metabolites of TNT, PAHs, and heavy metals). Resulting data indicate TNT to be predominantly responsible for the observed biological effects of soil leachates. A strategy for soil toxicity screening based on luminescent bacteria is proposed which may especially be applicable for the case of bioremediation of TNT-contaminated soils. Potentials and restrictions of this approach to soil toxicity assessment are discussed.

Aniline Compounds↗
PubMed1997

Effects of androgens on male sexual behavior and secondary sex characters in the explosively breeding spadefoot toad, Scaphiopus couchii.

In male Scaphiopus couchii, plasma elevations in androgens are associated with the seasonal expression of sexual behavior. To test the hypothesis that androgens are necessary for the expression of one aspect of sexual behavior, amplexus, and for the development of secondary sex characteristics in male S. couchii, the effects of testosterone (T) and dihydrotestosterone (DHT) on clasping behavior and thumb pad growth were investigated. Forty toads were divided into five treatment groups as follows: (1) intact, with no hormonal or surgical treatment; (2) sham-castrated, with silastic implants of cholesterol; (3) sham-castrated, with implants of T and DHT; (4) castrated, with implants of cholesterol; and (5) castrated, with implants of T and DHT. Displays of sexual behavior (amplexus) for each individual were counted during a 3-hr observation period at 2, 4, and 7 weeks after the surgical procedure. For each observation trial, there was no significant difference in the amount of clasping among treatment groups: virtually all individuals from each group displayed vigorous clasping. No calling was noted at any time. Thumb pad darkness of each individual was assessed at the 4- and 7-week time intervals. At both time periods, the thumb pads of androgen-treated males were significantly darker than those of cholesterol-treated males, while intact males remained intermediate. Measurement of plasma steroid levels from the treatment groups indicated that androgens were basal in the castrate group and higher in the implant treatment. These results suggest that in S. couchii, although androgens are associated temporally with the onset of reproductive behavior, they are not necessary for its expression. The elevation in androgens during the reproductive period may be instead important in the development and maintanence of secondary sex characteristics and possibly other reproductive functions.

Androgens↗
PubMed2002

Percutaneous absorption of explosives and related compounds: an empirical model of bioavailability of organic nitro compounds from soil.

The percutaneous absorption potentials of (14)C-labeled 2,4,6-trinitrotoluene (TNT), trinitrobenzene, 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, 2,6-diamino-4-nitrotoluene, N-methyl-N,2,4,6-tetranitrobenzamine, hexahydro-1,3,5-trinitro-1,3,5-triazine, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, and 2,2-thiobis(ethanol) were determined from two soil types, Yolo having 1.9% carbon and Tinker having 9.5% carbon. TNT skin absorption from another low-carbon soil (Umatilla) was also determined. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 5 microl of acetone or 10 mg/cm(2) of soil to excised pigskin mounted in skin penetration-evaporation chambers. Absorption from acetone served as a control. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine the percentage of absorption from the soils. For each compound, percentage absorptions of radiolabel were highest from acetone solution and lowest from Tinker soil, with the results from Yolo soil being intermediate. Skin absorptions of TNT from Yolo and Umatilla soils were similar. For TNT in all vehicles, the penetration rate of radiolabel into the receptor fluid was highest during the 1- to 2-h interval after dosing. HPLC analysis of TNT radiolabel in receptor fluid at maximum flux indicated extensive conversion to monoamino derivatives and other metabolites. For 2,4-DNT and 2,6-DNT applications in Yolo soil, percentage absorptions approached those obtained from acetone applications. After 2,4-DNT and 2,6-DNT applications (acetone and soils), HPLC analysis of radiolabel in receptor fluid during the period of maximum flux revealed no significant metabolites. Skin absorption of the nitro compounds from soils was found to correlate with the compound's water solubility and vapor pressure. These findings formed the basis of an empirical model to predict skin bioavailability.

Animals↗