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At least 19 recordsLinked to original sources
PubMed2004

Novel source of semicarbazide: levels of semicarbazide in cooked crayfish samples determined by LC/MS/MS.

Nitrofuran antibiotics were previously used in animal healthcare but are now prohibited. Semicarbazide is a breakdown product of 5-nitrofurazone and protein-bound semicarbazide is used as a marker residue for the illegal use of 5-nitrofurazone. However, the presence of the prohibited semicarbazide has been reported in some food items of animal origin. A novel observation is reported that semicarbazide can be detected in Finnish crayfish samples, i.e. crustacea, never medicated with nitrofurazone. The origin of the semicarbazide is presently unknown. Positive identification was undertaken by liquid chromatography coupled with tandem mass spectrometry detection. The level of semicarbazide was determined as the protein-bound form as well as the total amount of semicarbazide in the sample. The average levels of total semicarbazide and the protein-bound form were 4.2 and 0.5 ng g(-1) fresh crayfish meat, respectively. All the tested samples (n = 18) contained traces of semicarbazide, the highest amount being 12 ng g(-1) fresh crayfish meat.

Animals↗
PubMed1989

The enhanced daily excretion of urinary methylamine in rats treated with semicarbazide or hydralazine may be related to the inhibition of semicarbazide-sensitive amine oxidase activities.

The effects of amine oxidase inhibitors upon the daily urinary excretion of monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA) and ammonia in the rat have been examined. Administration of hydralazine (5 mg kg-1) or semicarbazide (100 mg kg-1), drugs which irreversibly inhibit semicarbazide-sensitive amine oxidases (SSAO) but not monoamine oxidase (MAO), enhanced MMA excretion by around three- to six-fold above pretreatment levels, whereas no effect of pargyline (25 mg kg-1), a selective irreversible inhibitor of MAO was found. No apparent changes in DMA or TMA excretion in response to drug-treatment were observed. Ammonia excretion also was generally unchanged except for an apparent marked increase (approximately four-fold) over the 24 h following semicarbazide, a result which might be explained if ammonia is a degradation product of semicarbazide metabolism in the rat. With recent evidence that MMA is a substrate in-vitro for SSAO activities, results here may indicate that SSAO or related enzymes are involved in endogenous MMA turnover.

Animals↗
PubMed2003

Carcinogenic semicarbazide induces sequence-specific DNA damage through the generation of reactive oxygen species and the derived organic radicals.

Semicarbazide, a hydrazine derivative, is carcinogenic to mice but shows no or little mutagenicity in the Salmonella-microsome test. To clarify whether or not the genotoxic mechanism contributes to the non-mutagenic carcinogenicity of semicarbazide, we investigated DNA damage induced by semicarbazide using 32P-5'-end-labeled DNA fragments obtained from the c-Ha-ras-1 protooncogene and the p53 tumor suppressor gene. Semicarbazide caused DNA damage frequently at the thymine and cytosine residues in the presence of Cu(II). Catalase and bathocuproine partially inhibited DNA damage, suggesting that hydrogen peroxide plus Cu(I) participates in DNA damage. When a high concentration of semicarbazide was used in the presence of catalase, DNA damage was induced, especially at G in 5'-AG and slightly at 5'-G in GG and GGG sequences. An electron paramagnetic resonance (EPR) spectroscopic study has confirmed that the reaction of semicarbazide with Cu(II) produces carbamoyl radicals (z.rad;CONH(2)), possibly generated via the nitrogen-centered radicals of semicarbazide. Azodicarbonamide also produced carbamoyl radicals and induced DNA damage frequently at 5'-G in GG and GGG sequences, suggesting that carbamoyl radicals participate in this sequence-specific DNA damage by semicarbazide. On the basis of our previous reports, we consider that the sequence-specific DNA damage at G in 5'-AG in the present study is due to the nitrogen-centered radicals. This study has shown that semicarbazide induces DNA damage in the presence of Cu(II) through the formation of hydrogen peroxide and Cu(I). In addition, semicarbazide-derived free radicals participate in DNA damage. DNA damage induced by these reactive species may be relevant to the carcinogenicity of semicarbazide.

Animals↗
PubMed2000

Plasma semicarbazide-sensitive amine oxidase (SSAO) is an independent prognostic marker for mortality in chronic heart failure.

AIMS: Experimental evidence has suggested that semicarbazide-sensitive amine oxidase is involved in vascular endothelial damage and in the process of atherosclerosis, through the formation of reactive aldehydes, hydrogen peroxide and ammonia from endogenous substrates. Recent evidence indicates that semicarbazide-sensitive amine oxidase may be identical with the vascular adhesion protein-1. In patients with diabetes mellitus and chronic heart failure the plasma activity is raised relative to the severity of the disease. The prognostic value of plasma semicarbazide-sensitive amine oxidase is not known. METHODS AND RESULTS: Plasma semicarbazide-sensitive amine oxidase activity was measured at baseline in patients with moderate to severe chronic heart failure who participated in a large European study (PRIME-II). The 372 patients who took part in a pre-defined substudy in The Netherlands were investigated and a survival follow-up (maximum 5.4 years, mean 3.4 years) was carried out. Within the follow-up period 195 patients died. Plasma semicarbazide-sensitive amine oxidase was higher at baseline in those who died than in the survivors (653+/-258 vs 540+/-242 mU. l(-1), P<0.001). Dividing the patients into two groups according to plasma values above or below the median value of 550 mU. l(-1), semicarbazide-sensitive amine oxidase was found to be a prognostic parameter for survival, both in univariate (P<0.0001) and in multivariate (P=0.0106) analysis. Semicarbazide-sensitive amine oxidase values >550 mU. l(-1)had a 1. 50 (95% CI, 1.10-2.04) times increased risk of death. CONCLUSION: The finding that plasma semicarbazide-sensitive amine oxidase is an independent prognostic marker for mortality in chronic heart failure supports the concept that an elevated plasma semicarbazide-sensitive amine oxidase level has deleterious effects, possibly due to vascular endothelial damage.

Aged↗
PubMed1980

Subcellular location of semicarbazide-sensitive amine oxidase in rat aorta.

With tyramine as substrate, a considerable part of the amine oxidase activity of rat aorta was inhibited by 0.1 mM semicarbazide. The residual activity was little affected by 1 mM semicarbazide. Oxidation of 5-hydroxytryptamine was not inhibited by 0.1 mM semicarbazide. The subcellular location of the semicarbazide-sensitive and semicarbazide-resistant amine oxidases was investigated by analytical density gradient centrifugation. The semicarbazide-resistant enzyme was identified with the mitochondrial monoamine oxidase, located in the outer envelope of mitochondria. The semicarbazide-sensitive amine oxidase was ascribed to the plasma membrane because it was distributed like 5'-nucleotidase and (oligomycin-insensitive) Mg2+-ATPase in various fractionation experiments, and markedly shifted by digitonin towards higher equilibrium densities in sucrose gradient.

Animals↗
PubMed1980

Effects of semicarbazide on oxidative processes in human red blood cell membranes.

Semicarbazide can interfere with oxidative processes in the red blood cell membrane via different modes of action. Treatment of human red blood cell membranes with O3, results, among other effects, in cross-linking of membrane proteins and inhibition of glyceraldehyde-3-phosphate dehydrogenase activity. Semicarbazide inhibits these effects by acting as an O3 scavenger. The effect of semicarbazide as an O3 scavenger is complicated by the fact that ozonolysis of semicarbazide yields a product that causes inhibition of glyceraldehyde-3-phosphate dehydrogenase. Glyceraldehyde-3-phosphate dehydrogenase inhibition can also be provoked by incubation of membrane suspensions with O3-treated phospholipids. Semicarbazide prevented this effect by interaction with an inhibitory O3-phospholipid reaction product. Protoporphyrin-induced photodynamic cross-linking of membrane proteins is chemically distinct from O3-induced cross-linking. Photodynamic cross-linking is also inhibited by semicarbazide, in this case via reaction with a histidine photooxidation product.

Erythrocyte Membrane↗
PubMedDate not supplied

Polypeptide semicarbazide glass slide microarrays: characterization and comparison with amine slides in serodetection studies.

We have described in the accompanying article the preparation of peptide-protein semicarbazide microarrays and their use for the simultaneous serodetection of antibodies directed against different pathogens. Here, we present a comparative study between semicarbazide and amine glass slides in an immunofluorescent serodetection assay using HIV (Gp120, Gp41), HCV (mix-HCV, core, NS3, and NS4), and HBV (HBs) recombinant antigens. Amine and semicarbazide surfaces displayed the same sensitivity for antibodies detection just after printing. However, the reactivity of protein antigens changed rapidly upon aging on amine slides but not on semicarbazide slides. Peptide or protein semicarbazide microarrays were found to be remarkably stable for months. Additional data concerning the characterization of the semicarbazide surface (homogeneity of the slides, chemical stability, contact angle measurements, atomic force microscopy studies, reproducibility of serodetection results) are also presented and discussed.

Adsorption↗
PubMed2004

Semicarbazide formation in azodicarbonamide-treated flour: a model study.

Semicarbazide was previously found in foods that were in contact with rubber gaskets foamed at high temperatures with a blowing agent azodicarbonamide. Because azodicarbonamide is an approved flour additive in certain countries, we set out to ascertain if semicarbazide is formed during the baking process from flours containing that additive. The levels of semicarbazide in baking flour treated with azodicarbonamide and bread baked from such flours were determined by isotope dilution (13C15N2-semicarbazide) liquid chromatography electrospray tandem mass spectrometry (LC-MS/MS). The samples were homogenized with HCl, extracted with n-pentane, derivatized with 2-nitrobenzaldehyde, and the derivative was extracted with ethyl acetate. After solvent exchange to 10% acetonitrile in water containing 0.1% acetic acid, the samples were analyzed using a 2.1 mm x 150 mm C18 column eluted with 2 mM ammonium formate in water/methanol (40:60). Semicarbazide was formed during the dry heating of commercial azodicarbonamide-containing flours at temperatures of 150-200 degrees C reaching levels of 0.2 mg/kg. Similar levels of semicarbazide were found in the crusts of breads made from azodicarbonamide-treated flour.

Azo Compounds↗
PubMed1999

Elevated activity of semicarbazide-sensitive amine oxidase in blood from patients with skeletal metastases of prostate cancer.

The semicarbazide-sensitive amine oxidases constitute a group of copper-containing enzymes whose physiological function is unclear. The enzymes are present in various tissues, including blood plasma. At present, the source of the plasma enzyme in humans is not known. Results of a recent study suggested that semicarbazide-sensitive amine oxidase is expressed in the skeleton, e.g. in the spine. Using an indirect autoradiographic method in mice, we provide evidence that semicarbazide-sensitive amine oxidase is present in high abundance in bone tissue. Specific activities of semicarbazide-sensitive amine oxidase were estimated in blood samples from subjects with femoral bone fractures. Moreover, enzyme activities were also measured in patients suffering from prostate cancer with skeletal metastases. The level of specific semicarbazide-sensitive amine oxidase activity in serum was significantly elevated in patients with skeletal metastases compared with both healthy controls and patients having prostate cancer without signs of skeletal metastases. Based on the results of the present study, we propose that semicarbazide-sensitive amine oxidase in blood plasma may originate, at least in part, from the skeleton.

Aged↗
PubMed1993

Semicarbazide protection from in vivo oxidant injury of vascular tissue by allylamine.

Allylamine is a specific cardiovascular toxin that causes vascular and myocardial lesions. Previous studies showed that allylamine-induced chronic lesions are markedly reduced by semicarbazide, an inhibitor of semicarbazide-sensitive amine oxidase (SSAO), and that allylamine is metabolized to the aldehyde, acrolein, by SSAO. We hypothesized that inhibitors of SSAO might reduce the acute cardiovascular toxicity of allylamine. To test our hypothesis, we fed 150 mg/kg allylamine to semicarbazide-pretreated (3 h; 98 mg/kg) rats. Animals were sacrificed 1 h after allylamine treatment. Aorta, epicardium, and endocardium were assayed for SSAO, glutathione peroxidase, catalase, thiol status and lipid peroxidation. SSAO activity was decreased significantly in aorta, epicardium and endocardium. Activity was 30-times higher in aorta than in epicardium and endocardium. A striking decrease in malonaldehyde level (lipid peroxidation) was found in aorta of pretreated rats as compared to allylamine-only treated rats. The reduction of free-SH content in aortic mitochondria was also attenuated in pretreated rats. Changes were not so marked in epicardium and endocardium. These results suggest that in vivo pretreatment with semicarbazide at least partially protects aortic mitochondria from allylamine toxicity. The mechanism can be explained on the basis of the fact that semicarbazide inhibits acrolein formation in allylamine-treated rats.

Allylamine↗
PubMed1976

Reaction of cytidine with semicarbazide in the presence of bisulfite. A rapid modification specific for single-stranded polynucleotide.

Semicarbazide reacted rapidly with 5,6-dihydrocytidine-6-sulfonate, which was formed from cytidine by addition of bisulfite across the 5,6-double bond. The transaminated product, 5,6-dihydro-4-semicarbazido-2-ketotopyrimidine-6-sulfonate ribofuranoside, was identified by comparison with that formed by treatment of 4-semicarbazido-2-ketopyrimidine ribofuranoside with bisulfite. The progress of the transamination was monitored spectrophotometrically by use of a strong absorbance of the product in alkali. The reaction between cytidine and the semicarbazide-bisulfite mixture was optimal at pH 4.5. Complete transformation of cytidine into the product required only 5 min with the use of 3M semicarbazide-1M sodium bisulfite, pH 5.0, at the reaction temperature 37 degrees C. The product was stable in unbuffered solution but in phosphate buffers it underwent elimination of bisulfite to give 4-semicarbazido-2-ketopyrimidine ribofuranoside. The rate of the elimination at pH 7.0 and 37 degrees C increased proportionally with the increase of the phosphate concentration. Complete elimination was obtained by treatment with 1 M sodium phosphate for 2 h. When heat-denatured calf-thymus DNA was treated with 3 M semicarbazide-1 M bisulfite at 37 degrees C and pH 5.0 the transamination of reactive cytosine residues was completed by 10 min of incubation. At 20 degrees C, it required 85 min of incubation. Cytosine residues in native DNA did not react at all even by prolonged incubations. The modified DNA samples were further treated with a phosphate buffer at pH 7, producing 4-semicarbazido-2-ketopyrimidine residues in the DNA. Analysis of the base compositions of these samples by perchloric acid hydrolysis showed that the modification was selective to cytosine, which had been expected from studies with monomers. It also showed that the reactive cytosine residues in the denatured DNA, constitute about 80% of the total cytosine, which was consistent with the view that heat-denatured DNA still contains a considerable amount of secondary structure. The semicarbazide-bisulfite modification is expected to be a sensitive method to locate cytosine residues in single-stranded regions of polynucleotides.

Binding Sites↗
PubMed1967

The action of semicarbazide on the aggregation of the tropocollagen macromolecule.

1. A difference in conformation was found between the collagen in solutions treated with semicarbazide hydrochloride and those treated with sodium chloride. This difference could be correlated with the difference in extent of aggregation between the fibrils precipitated from these solutions. 2. The action of semicarbazide hydrochloride depended on the pH and temperature of treatment in a complex manner. At constant temperature semicarbazide enhanced aggregation at pH values less than 4.3, but decreased aggregation was observed at pH values greater than 5.0. At pH 4.3 the effect of semicarbazide on aggregation varied with temperature, the tendency to increased aggregation being more pronounced at 34 degrees and 36-37 degrees . Similar increased aggregation tendencies superimposed on an overall decreased aggregation were observed at these temperatures at pH8.9. 3. A specific binding of semicarbazide to the collagen molecule was indicated.

Animals↗
PubMed1974

13C high-resolution nuclear magnetic resonance studies of enzyme-substrate reactions at equilibrium. Substrate studies of chymotrypsin-N-acetyltyrosine semicarbazide complexes.

N-Acetyl-L-tyrosine semicarbazide is hydrolyzed by chymotrypsin (EC 3.4.21.1) to N-acetyl-L-tyrosine and semicarbazide. If a high concentration of semicarbazide is present, the equilibrium for the reaction can be shifted from hydrolysis to synthesis. Using N-acetyl-L-[(13)C]tyrosine enriched at the carboxyl carbon and high concentrations of semicarbazide hydrochloride, we have studied the enzyme-substrate complex of N-acetyl-L-[(13)C]tyrosine semicarbazide and chymotrypsin A(delta) by (13)C nuclear magnetic resonance. We observe no shift within the experimental accuracy of +/-0.05 ppm as the fraction of substrate bound is changed from 0.17 to 0.70. Since E + S right arrow over left arrow ES is in fast exchange on the nuclear magnetic resonance time scale, it is possible to show that when the substrate is bound to the enzyme in the Michaelis complex, the (13)C resonance is shifted less than 0.1 ppm, indicating that negligible substrate strain occurs in this complex at the site of enzymatic attack. These experiments demonstrate the application of nuclear magnetic resonance to the study of particular states along the reaction pathway for enzyme-substrate reactions at equilibrium.

Carbon Isotopes↗
PubMed2004

Implications of the use of semicarbazide as a metabolic target of nitrofurazone contamination in coated products.

Data from the Brazilian Agricultural Ministry show that before the implementation of the Brazilian programme of nitrofuran control in February 2003, the cases of contamination of Brazilian chicken by nitrofurans were almost exclusively due to furaltadone. After May 2003, such cases decreased until no more reports of Brazilian chicken contamination with this nitrofuran were reported. Curiously, after April 2003, an increase was observed in the numbers of contaminated samples by semicarbazide, the target metabolite of nitrofurazone. Most Brazilian chicken found to be contaminated with semicarbazide has been covered with flour, salt and spices. For this reason, the authors' laboratory initialized a programme for tracing possible sources of food contamination by semicarbazide. After several semicarbazide positives in flour of controlled origin (results varying between 2.2 and 5.2 microg kg(-1)), the different additives used in the cereal industry as flour improvement agents were studied. The results indicate that the compound azodicarbonamide was responsible for the source of the contaminant semicarbazide.

Animals↗
PubMed2006

Semicarbazide in Canadian bakery products.

Levels of semicarbazide were determined by liquid chromatography-tandem mass spectrometry using isotope dilution ((13)C(15)N(2)-semicarbazide) methodology, and they were measured, after hydrolysis in 0.125 M hydrochloric acid and derivatization with 2-nitrobenzaldehyde, as a sum of free and bound semicarbazide. Levels of semicarbazide in 11 bakery products, which were sampled at three time intervals from the same source, varied from not detected (<1ng g(-1)) to 560 ng g(-1). In some instances, concentrations of semicarbazide varied between batches of the same product, at times more than tenfold, suggesting that the addition of azodicarbonamide to the same product is not standardized in many baking establishments.

Azo Compounds↗
PubMed2002

Involvement of semicarbazide-sensitive amine oxidase-mediated deamination in atherogenesis in KKAy diabetic mice fed with high cholesterol diet.

AIMS/HYPOTHESIS: Semicarbazide-sensitive amine oxidase has been recognised to be a potential risk factor in vascular disorders associated with diabetic complications and to be related to mortality in patients suffering from heart disease. This enzyme, associated with the vascular system, catalyses the deamination of methylamine and aminoacetone, and also acts as an adhesion molecule related to leucocyte trafficking and inflammation. The deaminated products include the toxic aldehydes, formaldehyde and methylglyoxal, respectively, hydrogen peroxide and ammonia. MATERIALS AND METHODS: In this study, the KKAy mouse, a strain possessing features closely resembling those of Type II (non-insulin-dependent) diabetes mellitus has been used to substantiate the hypothesis. Vascular lesions were induced via chronic feeding of a high cholesterol diet. RESULTS: Both MDL-72974A, a selective mechanism-based semicarbazide-sensitive amine oxidase inhibitor and aminoguanidine effectively inhibited aorta semicarbazide-sensitive amine oxidase activity, and caused a substantial increase in urinary methylamine, and a decrease in formaldehyde and methylgloxal levels. Inhibition of semicarbazide-sensitive amine oxidase also reduced oxidative stress, as shown by a reduction of malondialdehyde excretion. Both MDL-72974A and aminoguanidine reduced albuminuria, proteinuria and the number of atherosclerotic lesions in animals fed with a cholesterol diet over a period of treatment for 16 weeks. CONCLUSION/INTERPRETATION: Increased semicarbazide-sensitive amine oxidase-mediated deamination could be involved in the cascade of atherogenesis related to diabetic complications.

Albuminuria↗
PubMed1995

Plasma semicarbazide-sensitive amine oxidase activity is elevated in diabetes mellitus and correlates with glycosylated haemoglobin.

1. Semicarbazide-sensitive amine oxidase is a common name for a group of heterogeneous amine oxidases which are present in various mammalian tissues, especially in vascular smooth muscle cells, cartilage and adipose tissue, but also in plasma. 2. Plasma semicarbazide-sensitive amine oxidase activity was elevated in a group of 104 patients with insulin-dependent diabetes mellitus compared with normal control subjects (555 +/- 172 versus 352 +/- 102 m-units/l, P < 0.0005). 3. Plasma semicarbazide-sensitive amine oxidase activity was higher in subgroups with either retinopathy or nephropathy or both [583 +/- 116 (n = 34), 581 +/- 229 (n = 10) and 646 +/- 249 m-units/l (n = 19), respectively] than in the subgroup without overt complications [486 +/- 129 m-units/l (n = 41), P < 0.005]. 4. Plasma semicarbazide-sensitive amine oxidase activity was positively correlated with plasma glycosylated haemoglobin (r = 0.40; P < 0.0001) and with log urinary albumin excretion (r = 0.26; P < 0.025). 5. The possibility that semicarbazide-sensitive amine oxidase, by its conversion of endogenous amines like methylamine and aminoacetone into cytotoxic aldehydes, plays a role in the development of microvascular complications in diabetes mellitus, needs further investigation.

Adult↗
PubMed1993

High activity of semicarbazide-sensitive amine oxidase (SSAO): an important source of errors in the determination of the concentration of dopamine in pig plasma.

We noted rapid breakdown at 4 degrees and 20 degrees C of dopamine (DA) (but not of (nor)epinephrine and epinine) in pig plasma, but not in human plasma. The enzyme responsible appears to be a semicarbazide-sensitive amine oxidase (SSAO) because the breakdown can be inhibited by semicarbazide, but not by pargyline, clorgyline, EDTA, or (extra) glutathione. Among catecholamines tested, only DA and 3,4-dihydroxybenzylamine (DHBA, the internal standard of most catecholamine assays using high-performance liquid chromatography (HPLC) with electrochemical detection) were good substrates for the pig plasma SSAO. At 37 degrees C, especially after prolonged storage, all catecholamines break down. This breakdown results from autoxidation since it can be prevented by addition of extra glutathione (but not by semicarbazide) for all catecholamines except DA and DHBA. Breakdown at 37 degrees C of these two compounds cannot be prevented by addition of extra glutathione or semicarbazide, but only by addition of both. For reliable measurements of DA concentrations in pig plasma, blood should be collected in tubes containing not only glutathione, but also semicarbazide. The possibility of similarly high plasma SSAO activity in other species should be investigated further.

Amine Oxidase (Copper-Containing)↗