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At least 253 records · Page 14Linked to original sources
PubMed1987

Lipoperoxides in plasma as measured by liquid-chromatographic separation of malondialdehyde-thiobarbituric acid adduct.

This assay of plasma lipoperoxides involves hydrolysis in dilute H3PO4 at 100 degrees C; complexation of malondialdehyde (MDA), a hydrolysis product, with thiobarbituric acid (TBA); methanol precipitation of plasma proteins; fractionation of the protein-free extract on a C18 column; and spectrophotometric quantification of the MDA-TBA adduct at 532 nm. The detection limit was 0.15 mumol of MDA per liter of plasma. Run-to-run precision (CV) averaged 8 to 13%. Analytical recovery of MDA after addition of tetraethoxypropane standards to 21 specimens of human or rat plasma averaged 98% (SD 7%). Lipoperoxide concentrations (as MDA) averaged 0.60 (SD 0.13) mumol/L in plasma specimens from 41 healthy persons and 1.4 (SD 0.3) mumol/L in plasma specimens from 12 control rats. Mean lipoperoxide concentrations were 1.5 to 2.3 times as great in plasma sampled from rats one to three days after subcutaneous administration of NiCl2 at dosages (250 to 750 mumol per kilogram body wt) previously shown to induce lipid peroxidation in lung, liver, and kidney.

Adult↗
PubMed1986

Copper inhibition of the thiobarbituric acid reaction in Bedlington terriers.

The effect of copper on thiobarbituric acid (TBA) reaction values, an index of lipid peroxidation, was examined in Bedlington Terriers, healthy dogs, and rats. High hepatic concentrations of copper appeared to lower TBA values in the inherited, chronic, progressive hepatic degeneration of Bedlington Terriers, a disease associated with copper toxicosis. The suspected TBA inhibition was confirmed when Cu2+ was added to homogenates of healthy dog or rat liver or a malondialdehyde standard. The amount of copper added approximated that in diseased Bedlington Terriers. Because of the interference by copper, the TBA test was judged to be an inappropriate test for the evaluation of lipid peroxidation in samples containing high copper concentrations such as those in diseased Bedlington Terriers.

Animals↗
PubMedDate not supplied

Free radical damage to polyene antifungal antibiotics: changes in biological activity and thiobarbituric acid reactivity.

Polyene antifungal antibiotics contain thiobarbituric acid-reactive substances suggestive of the presence of peroxidic compounds. These peroxides appear to play no part in the drug's antifungal activities. The polyenes were relatively stable to further oxidation in air, but lost biological activity and native ultraviolet absorption upon irradiation with ultraviolet light or incubation with iron salts. No evidence was found for the participation of hydroxyl radicals in the observed damage to the polyene molecules. However, organic oxygen radicals were implicated and protection against ferrous salt dependent damage could be afforded by the addition of the antioxidant propylgallate.

Air↗
PubMedDate not supplied

Malondialdehyde formation from lipid peroxides in the thiobarbituric acid test: the role of lipid radicals, iron salts, and metal chelators.

Most of the chromogen formed when peroxidized material is heated with thiobarbituric acid (TBA) can be ascribed to a colored complex formed between malondialdehyde (MDA) and TBA. Even when little MDA is present, large amounts of MDA-TBA adduct can be formed. This is because lipid peroxides break down to release MDA during the test conditions. Iron is not essential for the breakdown of the peroxides but is essential for the formation of TBA reactivity. This can be related to the ability of iron to decompose lipid peroxides with the release of peroxy radicals, which are precursors of MDA. These peroxy radicals, when released, can initiate further peroxidation during the heating stage of the TBA test. Fatty acids in the absence of lipid peroxides do not undergo significant peroxidation during the acid-heating stage of the TBA test.

Chelating Agents↗
PubMed1984

[Studies on pathogenesis of muscular dystrophy: levels of thiobarbituric acid-reactive products in avian muscular dystrophy].

Lipid peroxidation and other free radical reactions are known to disrupt and damage cellular structures and function, and it has been postulated as possible mechanisms of cellular damage of muscular dystrophy because increased levels of thiobarbituric acid (TBA)-reactive products and increased activities of superoxide dismutase and glutathione peroxidase were reported in avian muscular dystrophy. We reported that activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase were significantly increased in avian muscular dystrophy from the early developmental stage. Since these enzymes protect cellular structures from free radicals and peroxides, increased activities of these enzymes would indicate increased formation of radicals. Then it seems to be important to assay TBA-reactive products which indicate tissue malondialdehyde content, a by-product of lipid peroxidation. We used dystrophic chickens of New Hampshire series line 413 and their controls line 412 for assay of TBA-reactive products. Four or five birds from respective lines were killed by decapitation two weeks, four weeks and four months after hatching. The superficial pectoral muscle was immediately weighed and levels of TBA-reactive products in the muscle homogenate was assayed by fluorophotometry according to the modified method of Ohkawa and Tanizawa. Levels of TBA-reactive products were significantly higher in dystrophic chickens at all stages of development studied than those of the control group. At two weeks of age morphological changes are minimum if present and increased levels of TBA-reactive products cannot be considered as a secondary change of morphological alterations. Therefore, the results indicate involvement of lipid peroxidation damage in pathogenesis of this avian muscular dystrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

A simple method for estimation of lipoxygenase and cyclo-oxygenase pathways in human platelets--the use of thiobarbituric acid reaction.

To develop a simple method for estimation of platelet lipoxygenase (PLO) and cyclo-oxygenase (PCO) pathways, the arachidonic acid (AA) metabolism of human platelet was investigated under various experimental conditions by the use of the thiobarbituric acid (TBA) reaction and a radioisotope technique. A TBA-reactive substance different from malondialdehyde (MDA) via PCO pathway was detected and shown to be derived from the PLO pathway. Since the optimal pH and time course of its formation were different from those of MDA formation via PCO pathway, PLO and PCO pathways were estimated by quantitating the TBA-reactive substances produced by the incubation of AA either with aspirin-treated platelets or with untreated ones, respectively, each under optimal conditions. Normal values expressed in terms of nmol MDA/10(8) platelets were 1.17 +/- 0.34 (M +/- SD, n = 31) and 0.79 +/- 0.15 (n = 31) for PLO and PCO pathways respectively.

Adult↗
PubMed1981

Some new 5-substituted benzylidene-1-phenyl-3-(2'-pyridinobutan-4'-yl) thiobarbituric acids as psychopharmacological agents.

Ten substituted thiobarbiturates have been prepared in order to evaluate their anticonvulsant activity in vivo and MAO inhibitory activity in vitro. All the compounds have been found good MAO and convulsion inhibitors. 5-(4-N,N-dimethylaminobenzylidene)-1-phenyl-3-(2'-pyridinobutan-4'-yl)thiobarbi turic acid has been found to be best in both these activities.

Animals↗
PubMed1993

[Measurement of myeloperoxidase and thiobarbituric acid-reactive material in plasma and bronchoalveolar lavage in E. coli-induced acute lung injury].

Myeloperoxidase (MPO), which is exclusively contained in neutrophils, is released on their activation. Therefore, MPO may possibly be used as a parameter of neutrophil activation. Thiobarbituric acid-reactive material (TBARM) reflects lipid peroxidation and is a parameter of oxygen radical-mediated cell membrane damage. Using our guinea pig model of septic lung injury we measured MPO and TBARM in the setting of acute lung injury. The two experimental groups were saline controls (n = 8) and an E. coli septic group to which 2 x 10(9) live E. coli were administered intravenously (n = 8). Lung damage was assessed by measuring wet to dry lung weight ratio (W/D) and lung tissue to plasma accumulation of 125I-albumin (AL: albumin leakage). We measured MPO and TBARM in plasma and BAL fluid. Increased W/D and AL were observed in the E. coli group suggesting the development of acute lung injury. In the E. coli group, plasma MPO increased and MPO in BAL fluid was significantly increased as compared with the saline control group. There was no difference in plasma TBARM between the two groups, while TBARM in BAL fluid of the E. coli group was greater than in that of controls. Although BAL fluid TBARM correlated with both W/D and AL, there was no relation between BAL fluid MPO and either of these parameters. We conclude that TBARM in BAL fluid may be useful for assessing E. coli-induced acute lung injury in guinea pigs.

Animals↗
PubMedDate not supplied

Variations in temperature and oxygen content do not alter levels of thiobarbiturate reactive material in human breast tumour cells (ZR-75-1) incubated with gamma-linolenic acid.

The mechanism by which tumour cells may be killed in vitro by exogenous polyunsaturated fatty acids may involve lipid peroxidation. Gamma-linolenic acid caused a dose and time-dependent reduction in ZR-75-1 cell growth. However, altering either the incubator temperature (35, 37 and 39 degrees C) or the oxygen content (16, 21 and 26%) had little effect on either the growth of cells in the presence of gamma-linolenic acid or on thiobarbiturate reactive material levels over a 7 day period. Thus, small changes in cell culture conditions do not affect 18:3n-6 cytotoxicity or markers of lipid peroxidation.

Breast Neoplasms↗
PubMed1993

[Changes in gastric mucosal glycosidases and thiobarbituric acid reactants induced by burn stress in obstructive jaundice rats].

To elucidate the pathogenesis of acute gastric mucosal lesion (AGML), burn stress was loaded in rats with and without obstructive jaundice. The activation of gastric mucosal glycosidases (beta-N-acetyl-D-glucosaminidase (NAG), beta-glucuronidase (BG)), which were released into the cytoplasm as a results of instability of the lysosomal membrane, was studied biochemically, enzymatically and histochemically after burn stress with and without obstructive jaundice. The latent enzyme activity calculated by NAG or BG, which represented the stability of lysosomal membrane, was lowest at 2-3 hour after burn stress in both groups. In other words, the degree of activation of the glycosidases was highest at 2-3 hour after burn stress. The latent enzyme activity calculated by NAG decreased significantly (p < 0.05) at 1 hour after burn stress in obstructive jaundice group compared with the non-obstructive jaundice group. The staining of NAG before burn stress was observed in mucus neck cell and surface epithelial cell in granular shape and it was observed diffusely after burn stress, especially in obstructive jaundice group. The changes in staining of BG was similar to NAG. Before activation of glycosidases, the thiobarbituric acid reactants, which are considered products of lipid peroxidation, increased promptly at 30 min after burn stress in both groups. Ulcer index increased gradually after burn stress and the significance was found between in the obstructive jaundice group and in non-obstructive jaundice group at 3 hour after burn stress. It's concluded that obstructive jaundice accelerated the fragility of lysosomal membrane after burn stress and these change were considered to be the reasons of frequent occurrence of AGML.

Acetylglucosaminidase↗
PubMed1993

Effect of oxidative stress on (3H)N-methylscopolamine binding and production of thiobarbituric acid reactive substances in rat cerebral cortex membranes.

We investigated the effect of lipid peroxidation, in vitro induced by H2O2 or FeSO4 and ascorbic acid, on binding properties of muscarinic receptors in rat cerebral cortex membranes. Simultaneously the concentrations of thiobarbituric acid reactive substances (TBARS) were measured to assess the extent of lipid peroxidation. In conditions of increased TBARS levels the density of (3H)N-methylscopolamine [(3H)NMS] binding sites in rat cerebral cortex membranes was not affected. Decreased numbers of (3H)NMS binding sites observed in the presence of high concentrations of H2O2 (100 and 1000 mmol.l-1) accompanied by a decrease of TBARS levels might be related to a nonspecific effect of H2O2 on cellular proteins.

Animals↗
PubMed1977

Hyperglycemia in the hamster anesthetized with Inactin [5-ethyl-5-(-methyl propyl)-2-thiobarbiturate].

Adult, male hamsters anesthetized with lnactin [5-ethyl-5-(1-methyl propyl)-2-thiobarbiturate] were found to be hyperglycemic. Blood glucose concentrations in anesthetized hamsters (300.1+/-15.6 mg/dl) were more than twice those of control animals (144.8+/-7.7 mg/dl). Neither the length of time under anesthesia nor the performance of surgery influenced the blood glucose concentration.

Anesthesia↗
PubMedDate not supplied

Vitamin E, thiobarbituric acid reactive substance concentrations and superoxide dismutase activity in the blood of children with juvenile rheumatoid arthritis.

OBJECTIVE: To study the role of active oxygen species in tissue injury in rheumatoid arthritis. METHODS: We examined the levels of thiobarbituric acid reactive substances (TBARS) and antioxidants of the first line antioxidative defence of the organism, i.e. vitamin E (VE) and superoxide dismutase (SOD) in the blood of 74 young patients with juvenile rheumatoid arthritis (JRA) and in 138 healthy children, all aged 3-15. RESULTS: A statistically significant increase of TBARS was found in the blood plasma of the children with JRA compared with the control group. In the whole group of patients and in the patients over 6 years of age, the VE concentration was in the red blood cells (RBC) was significantly lower in children who had suffered from JRA for more than one year and in those with the systemic form of the disease. The type of treatment also affected the values for the plasma VE and SOD in the RBC. CONCLUSION: Our results seem to confirm the supposition of increased oxidative stress in children with JRA and low antioxidant levels in terms of SOD activity and vitamin E concentrations.

Adolescent↗
PubMed1981

Parathyroid hormone effects on calcium metabolism in the rat are impaired by 5-ethyl-5'-(1-methylpropyl)-2-thiobarbiturate (inaktin).

The mechanism by which inaktin, a thiobarbiturate, promotes a moderate drop in serum calcium has been investigated. The effect was cancelled in hypocalcemic parathyroidectomized rats. On the other hand inaktin antagonized the serum calcium raising effects of parathyroid extract in these animals. In rats wit intact parathyroid glands inaktin caused a two-fold increase in urinary calcium excretion and a marked decrease in body and bone calcium turnover (measured with 45 Ca). These results support the view that inaktin impairs the parathyroid hormone effects on calcium metabolism.

Anesthetics↗
PubMed2000

New conjugated polyenes with 1,3-dialkyl-2-thiobarbituric acid moiety as materials for nonlinear optics: theoretical calculations, synthesis and spectral properties

In this work we report the results of our study on electronic and spectral properties of conjugated polyenes with electron-accepting 1,3-dialkyl-2-thiobarbituric acid moiety. In model calculations, we examine the effect of the conjugated polyene length on infrared (IR) and Raman spectra of the polyenes by means of ab initio HF/3-21G*. Nonlinear properties were also studied by AM1 method in frames of the sum-over-states (SOS) and finite-field formalism. It was concluded that in well-resolved IR and Raman spectra the frequencies and band intensities can provide valuable information relating to C=C bond lengths in polyene chain and relative polarizabilities. Near-linear correlation between polarizability and integral IR band intensity, corresponding to all C=C stretching modes, and the rather nonlinear relationship of polarizability with integral Raman activity, was found. In our calculation we predict that polarizability and the first hyperpolarizability increases with elongation of polyene chain while the second hyperpolarizability increases smoothly in a quadratic way. In contrast to the linear relationship between polarizability and polyene chain length the dipole moment versus chain length is predicted to be nonlinear. A good agreement was found between experimental and calculated Raman spectra of one newly synthesized compound studied.

Journal Article↗
PubMed2001

Effects of magnetic fields on the accumulation of thiobarbituric acid reactive substances induced by iron salt and H(2)O(2) in mouse brain homogenates or phosphotidylcholine.

In this study, we examined the effects of magnetic fields (MFs) on the generation of thiobarbituric acid reactive substances (TBARS) in the mouse brain homogenates or phosphotidylcholine (PC) solution, incubated with FeCl(3) and/or H(2)O(2). Active oxygen species were generated and lipid peroxidation was induced in mouse brain homogenates by incubation with iron ions, resulting in the accumulation of TBARS. Lipid peroxidation was induced in PC by incubation with iron ions and H(2)O(2). Exposure to sinusoidal MFs (60 Hz, 0.2-1.2 mT), symmetric sawtooth-waveform MFs (50 Hz, 25-600 mT/s), rectangular MFs (1/0.4-1/16 Hz, 3.3 mT) and static MFs (1, 5-300 mT) had no effect on the accumulation of TBARS in brain homogenates induced by FeCl(3). In contrast, when the homogenates were incubated with FeCl(3) in static MFs (2-4 mT), the accumulation of TBARS was decreased. However, this inhibitory effect disappeared when EDTA was added to the homogenate and incubated with H(2)O(2). The accumulation of TBARS in PC solution incubated with FeCl(3) and H(2)O(2) was also inhibited by the static MF. These results indicate that only static MFs had an inhibitory effect on iron-induced lipid peroxidation and the effectiveness of this magnetic field on iron ion-induced active oxygen species generation is restricted to a so called 'window' of field intensity of 2-4 mT.

Journal Article↗
PubMed2002

Supramolecular gold(I) thiobarbiturate chemistry: combining aurophilicity and hydrogen bonding to make polymers, sheets, and networks.

The cooperative forces of aurophilic and hydrogen bonding have been used in the self-assembly of phosphine or diphosphine complexes of gold(I) with the thiolate ligands derived from 2-thiobarbituric acid, SC(4)H(4)N(2)O(2), by single or double deprotonation. The reaction of the corresponding gold(I) trifluoroacetate complex with SC(4)H(4)N(2)O(2) gave the complexes [Au(SC(4)H(3)N(2)O(2))(PPh(3))], 1, [(AuSC(4)H(3)N(2)O(2))(2)(micro-LL)], with LL = Ph(2)PCH(2)PPh(2), 2a, Ph(2)P(CH(2))(3)PPh(2), 2b, or Ph(2)PCH=CHPPh(2), 2c, or the cyclic complex [Au(2)(micro-SC(4)H(2)N(2)O(2))(micro-Ph(2)PCH(2)CH(2)PPh(2))], 3. In the case with LL = Ph(2)P(CH(2))(6)PPh(2), the reaction led to loss of the diphosphine ligand to give [Au(6)(SC(4)H(3)N(2)O(2))(6)], 4, a hexagold(I) cluster complex in which each gold(I) center has trigonal AuS(2)N coordination. Structure determinations show that 1 has no aurophilic bonding, 2b, 3, and 4 have intramolecular aurophilic bonding, and 2c has intermolecular aurophilic bonding that contributes to the supramolecular structure. All the complexes undergo supramolecular association through strong NH...O and/or OH...N hydrogen bonding, and complex 3 also takes part in CH...O hydrogen bonding. The supramolecular association leads to formation of interesting polymer, sheet, or network structures, and 4 has a highly porous and stable lattice structure.

Journal Article↗
PubMed1994

Ion-exchange microchromatography and thiobarbituric acid colorimetry for the measurement of canine glycated hemoglobins.

Nonenzymatic glycation of hemoglobin is a slow, continuous, and irreversible process which takes place during the whole lifespan of the erythrocyte. When hemolytic diseases are ruled out, the levels of glycated hemoglobins reflect the time-averaged serum glucose concentration for the preceding weeks. Canine hemoglobin also binds physiologically to intraerythrocytic glucose to form a glycated fraction which provides information on the animal's long-term glycemic status. This study describes an overall evaluation of ion-exchange microchromatography and thiobarbituric acid (TBA) colorimetry for the measurement of canine glycated hemoglobins. The intra- and inter-assay coefficients of variation (CVs) found were less than 5% in normal and diabetic canine samples, and both assays proved linear over the analytical range tested, which was wide enough to include the expected clinical values. Under our laboratory's conditions, the reference range for HbA(1) was 5.82 +/- 0.62% and for HbA(1)c was 2.35 -/+ 0.47%. Sample stability was lower using the ion-exchange procedure, with increases in HbA(1) observed after 4 days in whole blood and hemolysates stored at room temperature, after 12 days in whole blood stored at 4 degrees C, and after 7 days in hemolysates stored at 4 degrees C and -20 degrees C. In the case of TBA colorimetry, whole blood was stable for at least 21 days at room temperature and at 4 degrees C, and hemolysates were stable for 18 days at room temperature, at least 21 days at 4 degrees C, and up to 3 months at -20 degrees C.

Journal Article↗