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European Journal of Emergency Medicine... Apr 2005Pyridoxine (vitamin B6) is a co-factor in many enzymatic pathways involved in amino acid metabolism: the main biologically active form is pyridoxal 5-phosphate.... (Review)
Review
Pyridoxine (vitamin B6) is a co-factor in many enzymatic pathways involved in amino acid metabolism: the main biologically active form is pyridoxal 5-phosphate. Pyridoxine has been used as an antidote in acute intoxications, including isoniazid overdose, Gyromitra mushroom or false morrel (monomethylhydrazine) poisoning and hydrazine exposure. It is also recommended as a co-factor to improve the conversion of glyoxylic acid into glycine in ethylene glycol poisoning. Other indications are recommended by some sources (for example crimidine poisoning, zipeprol and theophylline-induced seizures, adjunct to d-penicillamine chelation), without significant supporting data. The value of pyridoxine or its congener metadoxine as an agent for hastening ethanol metabolism or improving vigilance in acute alcohol intoxication is controversial. This paper reviews the various indications of pyridoxine in clinical toxicology and the supporting literature. The potential adverse effects of excessive pyridoxine dosage will also be summarized.
Topics: Animals; Antidotes; Ethanol; Ethylene Glycol; Humans; Hydrazines; Isoniazid; Mushroom Poisoning; Poisoning; Pyridoxine; Pyrimidines
PubMed: 15756083
DOI: 10.1097/00063110-200504000-00007 -
The Journal of Emergency Medicine Feb 2005Mushrooms are ubiquitous in nature. They are an important source of nutrition, however, certain varieties contain chemicals that can be highly toxic to humans.... (Review)
Review
Mushrooms are ubiquitous in nature. They are an important source of nutrition, however, certain varieties contain chemicals that can be highly toxic to humans. Industrially cultivated mushrooms are historically very safe, whereas foraging for mushrooms or accidental ingestion of mushrooms in the environment can result in serious illness and death. The emergency department is the most common site of presentation for patients suffering from acute mushroom poisoning. Although recognition can be facilitated by identification of a characteristic toxidrome, the presenting manifestations can be variable and have considerable overlap with more common and generally benign clinical syndromes. The goal of this two-part article is to review the knowledge base on this subject and provide information that will assist the clinician in the early consideration, diagnosis and treatment of mushroom poisoning. Part I reviewed the epidemiology and demographics of mushroom poisoning, the physical characteristics of the most toxic varieties, the classification of the toxic species, and presented an overview of the cyclopeptide-containing mushroom class. Part II is focused on the presentation of the other classes of toxic mushrooms along with an up-to-date review of the most recently identified poisonous varieties.
Topics: 2,2'-Dipyridyl; Adult; Child; Disulfiram; Emergency Medicine; Enzyme Inhibitors; Gastroenteritis; Hallucinogens; Humans; Indoles; Irritants; Isoxazoles; Monomethylhydrazine; Muscarine; Mushroom Poisoning; Mycotoxins
PubMed: 15707814
DOI: 10.1016/j.jemermed.2004.08.019 -
Angewandte Chemie (International Ed. in... Sep 2004
PubMed: 15317015
DOI: 10.1002/anie.200454093 -
Aviation, Space, and Environmental... Dec 2003Exposure to hydrazine and hydrazines' alkylated derivatives is an important occupational health issue, which will increase in significance as space applications... (Review)
Review
Exposure to hydrazine and hydrazines' alkylated derivatives is an important occupational health issue, which will increase in significance as space applications increase. Despite their widespread usage as rocket fuels in manned and unmanned space and missile systems, serious exposures to hydrazines are rare. While a significant number of experimental studies were performed in the late 1950s through the mid-1960s, conflicting information exists concerning the most appropriate treatment for these exposures. A cross-sectional study evaluating the most common rocket fuels such as hydrazine; 1,1-dimethylhydrazine (UDMH); mono-methylhydrazine (MMH); and Aerozine-50 against the most commonly suggested therapies, such as pyridoxine, traditional antiseizure therapies, and arginine is needed to clarify the treatment implications for human exposure. Treatments that have been useful for hyperammonemic states, such as those for the six inherited urea cycle defects, have significant potential for the improvement of hydrazine exposure treatment.
Topics: Acute Disease; Aerospace Medicine; Central Nervous System; Cross-Sectional Studies; Humans; Hydrazines; Occupational Exposure; Poisoning; Spacecraft
PubMed: 14692474
DOI: No ID Found -
Biodegradation 2001The aerobic biodegradation of National Aeronautics and Space Administration (NASA) wastewater that contains mixtures of highly concentrated methylhydrazine/hydrazine,...
The aerobic biodegradation of National Aeronautics and Space Administration (NASA) wastewater that contains mixtures of highly concentrated methylhydrazine/hydrazine, citric acid and their reaction product was studied on a laboratory-scale fixed film trickle-bed reactor. The degrading organisms, Achromobacter sp., Rhodococcus B30 and Rhodococcus J10, were immobilized on coarse sand grains used as support-media in the columns. Under continuous flow operation, Rhodococcus sp. degraded the methylhydrazine content of the wastewater from a concentration of 10 to 2.5 mg/mL within 12 days and the hydrazine from approximately 0.8 to 0.1 mg/mL in 7 days. The Achromobacter sp. was equally efficient in degrading the organics present in the wastewater, reducing the concentration of the methylhydrazine from 10 to approximately 5 mg/mL within 12 days and that of the hydrazine from approximately 0.8 to 0.2 mg/mL in 7 days. The pseudo first-order rate constants of 0.137 day(-1) and 0.232 day(-1) were obtained for the removal of methylhydrazine and hydrazine, respectively, in wastewater in the reactor column. In the batch cultures, rate constants for the degradation were 0.046 and 0.079 day(-1) for methylhydrazine and hydrazine respectively. These results demonstrate that the continuous flow bioreactor afford greater degradation efficiencies than those obtained when the wastewater was incubated with the microbes in growth-limited batch experiments. They also show that wastewater containing hydrazine is more amenable to microbial degradation than one that is predominant in methylhydrazine, in spite of the longer lag period observed for hydrazine containing wastewater. The influence of substrate concentration and recycle rate on the degradation efficiency is reported. The major advantages of the trickle-bed reactor over the batch system include very high substrate volumetric rate of turnover, higher rates of degradation and tolerance of the 100% concentrated NASA wastewater. The results of the present laboratory scale study will be of great importance in the design and operation of an industrial immobilized biofilm reactor for the treatment of methylhydrazine and hydrazine contaminated NASA wastewater.
Topics: Alcaligenes; Biodegradation, Environmental; Bioreactors; Carbon; Chromatography, High Pressure Liquid; Citric Acid; Hydrazines; Kinetics; Monomethylhydrazine; Rhodococcus; United States; United States National Aeronautics and Space Administration; Waste Disposal, Fluid; Water Pollutants, Chemical
PubMed: 11693290
DOI: 10.1023/a:1011946114017 -
Journal of Pharmaceutical and... Feb 1999Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous detection of hydrazine, methylhydrazine, and isoniazid has been developed with a...
Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous detection of hydrazine, methylhydrazine, and isoniazid has been developed with a 4-pyridyl hydroquinone self-assembled microdisk platinum electrode. Such an electrode has very high catalytic ability for hydrazines and they could be detected even at 0.0 V. The responses for hydrazine, methylhydrazine, and isoniazid are linear over 3 orders of detected concentration and of magnitude of 0.2-400 microM, 0.2-400 microM, 0.5 microM-2 mM, with correlation coefficients of 0.9998, 0.9991, and 0.9982, respectively. And they could be detected to levels of 0.1, 0.1 and 0.2 microM, respectively. This modified electrode was found to be very stable and reproducible when continuously used as detector for capillary electrophoresis for period of at least 4 weeks with no apparent loss of response.
Topics: Electrochemistry; Electrophoresis, Capillary; Hydrazines; Hydrogen-Ion Concentration; Hydroquinones; Indicators and Reagents; Isoniazid; Microelectrodes; Monomethylhydrazine; Platinum
PubMed: 10698584
DOI: 10.1016/s0731-7085(98)00130-7 -
Proceedings of the National Academy of... Oct 1999Soluble glucose dehydrogenase (s-GDH) from the bacterium Acinetobacter calcoaceticus is a classical quinoprotein. It requires the cofactor pyrroloquinoline quinone (PQQ)...
Soluble glucose dehydrogenase (s-GDH) from the bacterium Acinetobacter calcoaceticus is a classical quinoprotein. It requires the cofactor pyrroloquinoline quinone (PQQ) to catalyze the oxidation of glucose to gluconolactone. The precise catalytic role of PQQ in s-GDH and several other PQQ-dependent enzymes has remained controversial because of the absence of comprehensive structural data. We have determined the crystal structure of a ternary complex of s-GDH with PQQ and methylhydrazine, a competitive inhibitor of the enzyme. This complex, refined at 1.5-A resolution to an R factor of 16.7%, affords a detailed view of a cofactor-binding site of s-GDH. Moreover, it presents the first direct observation of covalent PQQ adduct in the active-site of a PQQ-dependent enzyme, thereby confirming previous evidence that the C5 carbonyl group of the cofactor is the most reactive moiety of PQQ.
Topics: Binding Sites; Crystallography, X-Ray; Glucose Dehydrogenases; Models, Chemical; Models, Molecular; Molecular Sequence Data; Monomethylhydrazine; Protein Binding; Protein Conformation; Quinolones; Quinones
PubMed: 10518528
DOI: 10.1073/pnas.96.21.11787 -
Free Radical Research May 1999Our previous studies have shown that iron is released in a free (desferrioxamine-chelatable) form when erythrocytes undergo oxidative stress (incubation with oxidizing...
Our previous studies have shown that iron is released in a free (desferrioxamine-chelatable) form when erythrocytes undergo oxidative stress (incubation with oxidizing agents or aerobic incubation in buffer for 24-60 h (a model of rapid in vitro ageing)). The release is accompanied by oxidative alterations of membrane proteins as well as by the appearance of senescent antigen, a signal for termination of old erythrocytes. In hemolytic anemias by hereditary hemoglobin alterations an accelerated removal of erythrocytes occurs. An increased susceptibility to oxidative damage has been reported in beta-thalassemic erythrocytes. Therefore we have investigated whether an increased iron level and an increased susceptibility to iron release could be observed in the erythrocytes from patients with beta-thalassemia. Erythrocytes from subjects with thalassemia intermedia showed an extremely higher content (0 time value) of free iron and methemoglobin as compared to controls. An increase, although non-statistically-significant, was seen in erythrocytes from subjects with thalassemia major. Upon aerobic incubation for 24 h the release of iron in beta-thalassemic erythrocytes was by far greater than in controls, with the exception of thalassemia minor. When the individual values for free iron content (0 time) seen in thalassemia major and intermedia were plotted against the corresponding values for HbF, a positive correlation (P < 0.001) was observed. Also, a positive correlation (P < 0.01) was seen between the values for free iron release (24 h incubation) and the values for HbF. These results suggest that the presence of HbF is a condition favourable to iron release. Since in beta-thalassemia the persistance of HbF is related to the lack or deficiency of beta chains and therefore to the excess of alpha chains, the observed correlation between free iron and HbF, is consistent with the hypothesis by others that excess of alpha chains represents a prooxidant factor.
Topics: Adult; Erythrocytes; Fetal Hemoglobin; Glutathione; Humans; Iron; Monomethylhydrazine; Phenylhydrazines; Reference Values; beta-Thalassemia
PubMed: 10342333
DOI: 10.1080/10715769900300441 -
Carcinogenesis Jan 1998Several hydrazine derivatives (HD) tested so far have pharmacological activities, but many also have toxic side effects, including carcinogenesis. Their toxicity has...
Several hydrazine derivatives (HD) tested so far have pharmacological activities, but many also have toxic side effects, including carcinogenesis. Their toxicity has been ascribed to carbocations (via formation of azoxy intermediates), alkyl radicals or reactive oxygen species. Cytotoxicity and transformation by carbocations is widely accepted, but the role of alkyl radicals is still questioned. We have investigated the cytotoxicity of HD to mouse fibroblasts in three activation systems in which enhanced alkyl radical formation is demonstrated by electron spin resonance/spin-trapping. Cytotoxicity was assayed by inhibition of [3H-methyl]thymidine uptake into DNA of Balb/c 3T3 and/or Myc 9E fibroblasts (normal Balb/c 3T3 cells over-expressing the c-myc proto-oncogene). Based on the results obtained in the cytotoxicity assays we also investigated the transforming potential of procarbazine (PCZ) and methylhydrazine (MeH) activated by horseradish peroxidase (HRP) using the Myc 9E cell line, which aims at the activation of a second cooperating oncogene. Our results show that: (i) cytotoxicity of HD to mouse fibroblasts is increased by HRP activation of MeH, phenelzine and PCZ, which displayed enhanced alkyl radical formation, but not of 1,2-dimethylhydrazine (DMH), which did not produce increased alkyl radical formation under these conditions; (ii) cytotoxicity of neutrophil-activated MeH (producing a 10-fold higher concentration of methyl radicals), is more pronounced than DMH; (iii) MeH and DMH activated by prolonged auto-oxidation in 24-h incubations have comparable cytotoxicity and alkyl radical formation; and (iv) PCZ and MeH activation by HRP to alkyl radicals increased the transformation induced in Myc 9E cells. Taken together, our results strongly support a role for hydrazine-derived alkyl radicals in HD-induced cytotoxicity and cell transformation.
Topics: 3T3 Cells; Animals; Cell Survival; Cell Transformation, Neoplastic; DNA Damage; DNA Replication; Electron Spin Resonance Spectroscopy; Exons; Female; Free Radicals; Genes, myc; Horseradish Peroxidase; Hydrazines; In Vitro Techniques; Mice; Monomethylhydrazine; Neutrophil Activation; Neutrophils; Procarbazine; Proto-Oncogene Proteins c-myc; Rats; Rats, Wistar; Recombinant Proteins; Thymidine; Transfection
PubMed: 9472706
DOI: 10.1093/carcin/19.1.147 -
Analytical Chemistry Apr 1997A novel integrated acoustooptic tunable filter (IAOTF) has been developed. This tunable filter is based on the Bragg interactions between waveguide and surface acoustic...
Determination of monomethylhydrazine with a high-throughput, all-fiber near-infrared spectrometer based on an integrated acoustooptic tunable filter and an erbium-doped fiber amplifier.
A novel integrated acoustooptic tunable filter (IAOTF) has been developed. This tunable filter is based on the Bragg interactions between waveguide and surface acoustic waves. Compared to (bulk) AOTF, its advantage include all-fiber construction, smaller size, narrower spectral resolution (1.7 nm), higher diffraction efficiency (37%), and lower rf power requirement (150 mW). A relatively narrow spectral tuning range (about 80 nm) is the only drawback for this integrated tunable filter. However, this disadvantage was overcome by judiciously using the filter for measurements in which its tuning range is coincident with the light source and also with absorption bands of analytes. In fact, an all-fiber, compact, high-throughput near-infrared spectrophotometer has been successfully constructed by synergistic use of this integrated AOTF and the erbium-doped fiber amplifier (EDFA), which has been shown to provide high intensity and wide spectral band-width in the near-infrared region from 1500 to 1600 nm. This spectral region is particularly useful for the determination of samples which have O-H and/or N-H groups. The all-fiber nature, compactness, high throughput, and high sensitivity of this spectrophotometer make it particularly suitable for on-line and real-time detection of trace gases in hostile environments, including leak detection of monomethylhydrazine (at a limit of detection of 191 ppm), which is often used as the hypergolic propellant for the space shuttle thruster systems.
Topics: Acoustics; Erbium; Filtration; Monomethylhydrazine; Spectrophotometry, Atomic; Spectrophotometry, Infrared
PubMed: 9105182
DOI: 10.1021/ac960919u