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[A study of lipid peroxidation in neonates--(1) Daily change of serum lipid peroxides in full term neonates].

Lipid peroxide has been highlighted as a possible marker of cell destruction by oxygen derived free radical reactions. We, therefore, examined serum lipid peroxides, malondialdehydes (MDA) in 106 healthy full term neonates (aged 0.5 to 317 hrs, averaged 79.3 +/- 69.9 hrs). Their lipid peroxides in capillary blood were determined by the luminescence method (Yagi method). Based on our data, we conclude as follows: 1) MDA concentrations were influenced by the serum bilirubin concentrations. We, therefore, adjusted our data according to the serum bilirubin concentrations. 2) We found significantly higher values of MDA (4.76 +/- 1.35 nmol.ml-1) than those in adult (3.12 +/- 0.35 nmol.ml-1). In fact, these values increased gradually on the second day, and the high values were maintained until the fifth day. 3) The values of MDA and total bilirubin concentrations in the vaginally delivered neonates were significantly higher than those delivered by Cesarean section (P less than 0.05). 4) There were no correlations between the values of MDA and values of other serum lipid and bilirubin.

Humans↗

Participation of superoxide, hydrogen peroxide and hydroxyl radicals in NADPH-cytochrome P-450 reductase-catalyzed peroxidation of methyl linolenate.

1. NADPH-cytochrome P-450 reductase-catalyzed peroxidation of methyl linolenate is inhibited by superoxide dismutase, catalase, ethanol, and mannitol, and is potentiated by H2O2. 2. H2O2 is shown to be generated in the incubation mixture in the presence of NADPH and NADPH-cytochrome P-450 reductase. If the system contains Fe-EDTA complex, H2O2 is not formed. In the presence of the enzyme and Fe-EDTA complex, added H2O2 is consumed. 3. In the presence of Fe-EDTA complex, NADPH-cytochrome P-450 reductase is shown to generate O-2 at a slow rate. These results suggest that H2O2 produced from O-2 is decomposed to form OH . by the action of Fe-EDTA complex in the lipid peroxidation system, and that OH . is a trigger of lipid peroxidation.

Catalase↗

Lipid peroxidation and its inhibition by tinoridine, II. Ascorbic acid-induced lipid peroxidation of rat liver mitochondria.

Incubation of rat liver mitochondrial suspension with ascorbic acid and Fe2+ resulted in the formation of malondialdehyde and a decrease in the turbidity of the suspension. The maximum amount of malondialdehyde formed during the peroxidation reaction was estimated to be 1 mol per approximately 6 mol of mitochondrial phospholipids. Tinoridine and alpha-tocopherol at the concentration of 5 micron and 1 mM, respectively, completely inhibited the peroxidative disintegration of mitochondria. From the relationship between the concentration of tinoridine and the amount of malondialdehyde formed, it was demonstrated that 1 mol of tinoridine prevents the formation of about 6 mol of malondialdehyde. These findings suggest that there is a limit in the chain reaction of the lipid peroxidation of mitochondria and that the limit is the membrane sphere which is capable of releasing 6 molecules of malondialdehyde and contains about 36 molecules of the constitutive phospholipids.

Animals↗

[Cerebral vasospasm and lipid peroxidation--lipid peroxides in the cerebrospinal fluid after subarachnoid hemorrhage].

The relationship between lipid peroxides in cerebrospinal fluid (CSF) and the occurrence of cerebral vasospasm following subarachnoid hemorrhage (SAH) was evaluated by analyzing CSF with high-performance liquid chromatography (HPLC) and gas chromatography mass spectrometry (GC-MS). Hydroperoxy eicosatetraenoic acids (HPETEs) and hydroxy eicosatetraenoic acids (HETEs) were synthesized by the treatment of arachidonic acid with hydrogen peroxide and cupric chloride. The retention time of these HPETEs and HETEs were determined on HPLC. The position of oxydation occurred was determined after methylation, reduction and trimethyl silylation using GC-MS. Thus the elucidation of positional isomers of HPETEs and HETEs was made possible by the retention time on HPLC. The supernant of CSF after SAH was adjusted to pH 3.0 and then absorbed to octadecyl silyl silica column. The eluted fraction with 15% ethanol-water from octadecyl silyl silica column was analyzed by HPLC detecting at 238 nm. No peak was observed on HPLC at the region of HPETEs and HETEs in the CSF obtained from healthy person. In SAH patients, several peaks were recognized in accordance with the occurrence of cerebral vasospasm. One of the peaks was identified as 5-HETE by HPLC and GC-MS. In 10 SAH patients, semi-quantitative analysis of 5-HETE in the CSF was performed by measuring the height of the peak identified as 5-HETE on HPLC. The close correlation was recognized between the occurrence of cerebral vasospasm and the appearance of 5-HETE in the CSF. The results of the present study suggest that lipid peroxidation is involved in the pathogenesis of chronic vasospasm after SAH.

Arachidonic Acids↗

Iron promoters of the Fenton reaction and lipid peroxidation can be released from haemoglobin by peroxides.

Hydrogen peroxide and organic hydroperoxides react with haemoglobin to release iron which can be complexed to apotransferrin, bleomycin and desferrioxamine. This released iron promotes deoxyribose degradation by a Fenton reaction, DNA degradation in the presence of bleomycin and stimulates lipid peroxidation. It is likely that iron released from haemoglobin is the true generator of hydroxyl radicals in the Fenton reaction.

Apoproteins↗

Safety evaluation of a novel whitening gel, containing 6% hydrogen peroxide and a commercially available whitening gel containing 18% carbamide peroxide in an exaggerated use clinical study.

OBJECTIVES: The aim of this study was to compare the effect on oral soft tissue of a self-applied tooth whitening gel containing 6% hydrogen peroxide (Xtra White) with a marketed paint-on whitening gel containing 18% carbamide peroxide (Colgate Simply White) after 2-weeks of using products four times daily. METHODS: A 2-week, examiner-blind, stratified, parallel design clinical trial was conducted. Twenty subjects were divided into two groups, balanced according to age and gender. Subjects followed a 2-week, twice-daily regimen of brushing with standard fluoride toothpaste and applied gel product to facial aspects of six upper and six lower incisors/canines, twice in succession with 30 min between applications. Soft tissue examinations were performed on Day 1, before the first application of the test products, and on Day 2, 5, 8 and 15. RESULTS: During the 2-week treatment period, twelve adverse reactions were recorded as potentially attributable to the study products, evenly split between the two test groups. All reports were mild in symptoms and resolved without the need of medical intervention. None of the subjects experiencing an adverse event requested to be withdrawn from the study. CONCLUSIONS: Under the exaggerated use conditions of this test, there was no evidence to suggest that either of the whitening gels produced irritation that was building or developing during the course of the study. It is concluded that both products are safe for their intended use.

Adolescent↗

A clinical evaluation of carbamide peroxide and hydrogen peroxide whitening agents during daytime use.

BACKGROUND: Vital tooth bleaching for esthetic reasons has gained in popularity during the last few years. However, few studies have investigated the efficacy of daytime bleaching products. The purpose of this double-blind in vivo study was to evaluate the efficacy of 20 percent carbamide peroxide, or CP, and 7.5 percent hydrogen peroxide, or HP, during daytime use. The degree of color change, any color relapse, and tooth or gingival sensitivity were evaluated. METHODS: Twenty-four patients participated in this study. The bleaching gels were randomly applied to the right and left maxillary anterior teeth. Patients were shown how to place the two bleaching agents in a custom tray for one hour, twice a day for two weeks. Patients returned in one, two, three, six and 12 weeks for color evaluation with the colorimeter and shade guides as well as to have color slide photographs taken. The authors evaluated sensitivity by asking the patients to record daily for 21 days any tooth or gingival sensitivity they experienced. RESULTS: Use of the 20 percent CP resulted in significantly more lightness than the 7.5 percent HP during the first 14 days of the study, but at the end of the study, there was no significant difference between products with regard to tooth lightness. In addition, the authors found no statistically significant difference between products with regard to gingival or tooth sensitivity. CONCLUSIONS: Both CP and HP are effective at-home bleaching agents when daytime bleaching is preferred. CLINICAL IMPLICATIONS: Dentists who choose to use daytime bleaching can select either CP or HP.

Adult↗

Tooth bleaching by different concentrations of carbamide peroxide and hydrogen peroxide whitening strips: an in vitro study.

OBJECTIVE: To investigate the tooth whitening effects of various concentrations of carbamide peroxide (CP) gels and 6% hydrogen peroxide (HP) whitening strips used on an intrinsic, in vitro stain model in a simulated home-applied bleaching protocol. METHOD: Extracted third molars were sectioned and stained to Vita shade C4 using a standardized tea solution. Stained specimens were then bleached with 10, 15, 20, 22, and 30% CP gels applied in custom-made trays for 8-hour sessions for 14 days. A 6% HP whitening strip product was also tested in a regimen of twice-daily 30-minute treatments for 14 days. Shades were assessed at baseline and at 2, 5, 7, 10, and 14 days of treatment using a shade guide (SG) and a shade vision system (SVS), recorded as shade guide unit (SGU) changes from baseline, and CIE L*a*b* recordings using a chromometer. RESULTS: By day 14, all CP treatments resulted in at least 12 SGU improvements by SG and SVS methods: the HP treatment mean was just less than 12 SGU. With the chromometer, the CP improvements ranged from approximately 19 to 28 units and 16 units for the HP whitening strips. Observationally, by SG and SVS, CP treatments achieved the maximum improvement (12-13 SGU) at different time points: day 5 for 30% CP, day 10 for 22% CP, and day 14 for the other three treatments. SG and SVS data were virtually binary, switching from 0 to scores of 9 or above as bleaching progressed. The differences between the six treatments in the mean day to achieve a positive SG or SVS score (9 or more units) approached significance. For each of the SG, SVS, and L*a*b* scores, the dose-response correlation with CP concentration was significant at one or more assessment times. SG and SVS showed extremely strong agreement in detecting change and substantial agreement with L*a*b*. CONCLUSION: This in vitro study supports the limited data available from the very few available randomized controlled clinical trials indicating that CP and HP home-use bleaching systems can achieve considerable tooth whitening outcomes, albeit at different rates, which appear to be concentration dependent. CLINICAL SIGNIFICANCE: There is a clear significant relationship for both concentration and duration of exposure for CP bleaching agents. The final shade change is independent of the concentration of bleaching agent, with time as the dominant variable. Higher concentrations of CP that have not been investigated previously may be a treatment option for esthetic improvement of shade where time is at a premium, but caution must be exercised in view of the possible increased incidence of sensitivity.

Carbamide Peroxide↗

Protection of HLE B-3 cells against hydrogen peroxide- and naphthalene-induced lipid peroxidation and apoptosis by transfection with hGSTA1 and hGSTA2.

PURPOSE: To investigate the physiological role of two major alpha-class glutathione S-transferases (GSTs), hGSTA1-1 and hGSTA2-2 in protection against oxidative stress and lipid peroxidation (LPO) in human lens epithelial (HLE B-3) cells. METHODS: Total GSTs were purified from HLE B-3 cells by glutathione (GSH)-affinity chromatography and characterized by Western blot analysis, isoelectric focusing, and kinetic studies. The relative contributions of the alpha-class GSTs and the Se-dependent glutathione peroxidase (GPx)-1 in GSH-dependent reduction of phospholipid hydroperoxide (PL-OOH) were quantitated through immunoprecipitation studies using separately the specific polyclonal antibodies against human alpha-class GSTs and GPx-1. HLE B-3 cell membranes were prepared, peroxidized, and used to examine whether hGSTA1-1 and hGSTA2-2 catalyzes the reduction of membrane PL-OOH in situ using the microiodometric and spectrophotometric assays. The protective effects of the alpha-class GSTs against H2O2- and naphthalene-induced LPO and apoptosis were examined by transfecting HLE B-3 cells with cDNAs of hGSTA1 and hGSTA2. RESULTS. HLE B-3 cells expressed only the alpha and pi class GSTs. The Michaelis-Menten constant (k(m)) and turnover number (k(cat)) of purified total GSTs toward phosphatidylcholine hydroperoxide (PC-OOH) were found to be 30 +/- 4 microM and 1.95 +/- 0.26 seconds, respectively. The alpha-class GSTs accounted for approximately 65% of the total GPx activity of HLE B-3 cells toward PC-OOH. Our results demonstrate for the first time that hGSTA1-1 and hGSTA2-2 effectively catalyzed GSH-dependent reduction of membrane PL-OOH in situ in HLE B-3 cells. Transfection with hGSTA1 or hGSTA2 protected these cells from H2O2- and naphthalene-induced LPO and attenuated H2O2- and naphthalene-induced apoptosis through inhibiting caspase 3 activation. CONCLUSIONS: These results demonstrate that the alpha-class GSTs hGSTA1-1 and hGSTA2-2 play a major role as antioxidant enzymes and are the main determinants of the levels of LPO caused by oxidative stress in human lens epithelial cells.

Animals↗

Chemiluminescence study on the peroxidation of linoleic acid initiated by the reaction of ferrous iron with hydrogen peroxide.

Linoleic acid was used as a model system to study lipid peroxidation initiated by the reaction of ferrous iron with hydrogen peroxide. Low-level chemiluminescence of the peroxidation was measured with a high-sensitivity single-photon counter. It was found that the luminescence primarily comes from the dimol reaction of singlet oxygen and that the peak intensity of emission is a quadratic function of the concentration of either Fe2+ or H2O2, provided that the other Fenton reagent is in great excess. Under the same conditions, analysis on reaction kinetics shows a linear relationship between the maximal level of the initiator formed by the Fenton reaction and the initial concentration of Fe2+ or H2O2. This implies that the peak intensity of the chemiluminescence may be a good index of the maximal level of the initiator.

Journal Article↗

Effect of free radical scavengers and metal ion chelators on hydrogen peroxide and phenylhydrazine induced red blood cell lipid peroxidation.

Desferrioxamine a well-known iron chelator was found to decrease hydrogen peroxide and phenylhydrazine induced lipid peroxidation of red blood cell membranes assessed by hydrocarbon gas release and loss of polyunsaturated fatty acids. Hydroxyl radical scavengers like mannitol and thiourea and proteins like albumin were unable to reduce peroxidative reactions to our system. Addition of uric acid (in an unphysiological concentration of 5 mM) to the incubation medium resulted in a slight reduction in H2O2/phenylhydrazine mediated break-down of arachidonic (20:4) and docosahexaenoic acid (22:6) in the erythrocyte membrane and consequently in a decreased alkane release and haemolysis.

Alkanes↗

Inverse deuterium kinetic isotope effect for peroxidation in human low-density lipoprotein (LDL): a simple test for tocopherol-mediated peroxidation of LDL lipids.

alpha-Tocopherol (alpha-TOH) can act as a pro- or antioxidant for isolated ubiquinol-10-free human low density lipoprotein (LDL). We demonstrate that alpha-TOH is a more potent pro-oxidant than other forms of vitamin E for LDL peroxidation initiated by mild fluxes of aqueous peroxyl radicals and low concentrations of Cu2+. A simple deuterium exchange test shows that alpha-TOH switches from pro- to anti-oxidant at Cu2+:LDL ratios > 2.5. The results suggest that this test may be useful to distinguish 'inhibited' peroxidation of emulsion lipids propagated via the lipid peroxyl radical from that mediated via the antioxidant radical.

Adult↗

Skin-tumour promoting activity of methyl ethyl ketone peroxide--a potent lipid-peroxidizing agent.

The tumour-promoting activity of methyl ethyl ketone peroxide (MEKP) was tested on the skin of hairless mice using a two-stage initiation-promotion protocol. When ultraviolet radiation in the UVB region (280-320 nm) was used as tumour initiator, MEKP showed weak promoting activity. The promotional activity of MEKP was potentiated by diethyl maleate, which is known to deplete intracellular glutathione, suggesting that lipid peroxidation may be important in the tumour promotion.

Acetone↗

Effects of paraquat administration on longevity, oxygen consumption, lipid peroxidation, superoxide dismutase, catalase, glutathione reductase, inorganic peroxides and glutathione in the adult housefly.

The effects of oxidative stress in the adult male housefly were examined by the administration of 1 mM paraquat. Houseflies exhibit NADH and NADPH-diaphorase activity. Paraquat caused a significant decrease in life span, metabolic rate and the concentration of thiobarbituric acid-reactants. Concentrations of reduced glutathione and inorganic peroxides were increased by paraquat. Paraquat stimulated the activity of catalase but did not affect activities of superoxide dismutase and glutathione reductase. The levels of oxidized glutathione and the rate of fluorescent age pigment accumulation were unaffected by paraquat. Results indicate that paraquat toxicity does not result from lipid peroxidation.

Animals↗

Olefin epoxidation with bis(trimethylsilyl) peroxide catalyzed by inorganic oxorhenium derivatives. Controlled release of hydrogen peroxide.

The replacement of organometallic rhenium species (e.g., CH(3)ReO(3)) by less expensive and more readily available inorganic rhenium oxides (e.g., Re(2)O(7), ReO(3)(OH), and ReO(3)) can be accomplished using bis(trimethylsilyl) peroxide (BTSP) as oxidant in place of aqueous H(2)O(2). Using a catalytic amount of a proton source, controlled release of hydrogen peroxide helps preserve sensitive peroxorhenium species and enables catalytic turnover to take place. Systematic investigation of the oxorhenium catalyst precursors, substrate scope, and effects of various additives on olefin epoxidation with BTSP are reported in this contribution.

Alkenes↗

Lipid peroxidation contributes to hydrogen peroxide induced cytotoxicity in renal epithelial cells.

We have examined the role of lipid peroxidation in the cytotoxicity of H2O2 in OK cells containing markedly differing amounts of cell membrane polyunsaturated fatty acids (PUFA). In OK cells grown in a serum free medium, PUFA were undetectable. The membranes of these cells contained predominantly oleic, stearic and palmitic acids. When cultured in medium containing 10% calf serum, OK cells contained measurable amounts of PUFA [linoleic (5 +/- 1%) and arachidonic acids (8 +/- 1%)]. When the serum containing medium was supplemented with 60 mM linoleic acid, the membrane content of both linoleic (21 +/- 1%) as well as arachidonic acid (15 +/- 1%) as substantially increased. The severity of injury induced by H2O2 in OK cells was substantially altered by the PUFA content of the cell membrane. Exposure of OK cells to 1.25 mM H2O2 for one hour resulted in more cell death (determined by a trypan blue assay) in cells grown in serum supplemented with linoleic acid with "normal" PUFA content (90 +/- 2%) than in cells with "reduced" levels of PUFA grown in unsupplemented calf serum (81 +/- 3%). Cells gown in defined, serum free medium with undetectable levels of PUFA suffered the least H2O2-induced lethal cell injury (47 +/- 8%). Comparable differences in the cytotoxicity of H2O2 among cells with differing PUFA content were found using a clonogenic assay of cell viability. Malondialdehyde (MDA) accumulation induced by 1.25 mM H2O2 was greater in cells with "normal" PUFA content (702 +/- 103 pM/microgram cell DNA/hr) than in cells with "reduced" PUFA (328 +/- 112 pM/100 microgram DNA/hr) and was undetectable in cells grown in defined, serum free medium. In summary, the content of PUFA of cells in culture is profoundly influenced by culture conditions. Our data provide novel and direct evidence that peroxidation of cell membranes contributes directly to the severity of cell injury and death induced by H2O2.

Animals↗

Skin tolerability and efficacy of combination therapy with hydrogen peroxide stabilized cream and adapalene gel in comparison with benzoyl peroxide cream and adapalene gel in common acne. A randomized, investigator-masked, controlled trial.

BACKGROUND: Combination therapy with antiseptics such as benzoyl peroxide (BP) and topical retinoids is widely used as first-line treatment for acne vulgaris (AV). However, these combinations could have a suboptimal skin tolerability. Recently, a new formulation of hydrogen peroxide (HP) 1% in stabilized cream (Crystacide; Mipharm, Milan, Italy) became available. A previous clinical study has shown that HP cream monotherapy presents a better skin tolerability in comparison with BP in patients with mild AV. OBJECTIVES: To evaluate the tolerability and the efficacy of combination therapy with HP cream and adapalene 0.1% gel in comparison with the combination of BP 4% cream and adapalene 0.1% gel in the treatment of mild to moderate AV. METHODS: In a randomized, investigator-blinded trial, 52 patients (mean +/- SD age 25 +/- 6 years; 19 men and 33 women) with AV were randomly assigned to HP cream and adapalene gel (group HP + A) or to BP cream and adapalene gel (group BP + A), for eight consecutive weeks. Efficacy was assessed by total (TL), inflammatory (IL) and noninflammatory (NL) lesion counts performed at baseline and weeks 4 and 8. Tolerability was assessed by evaluating skin erythema, burning and dryness at weeks 4 and 8. RESULTS: All patients completed the study. At baseline, the mean +/- SD numbers of TL, IL and NL were 44 +/- 9, 25 +/- 7 and 19 +/- 6 in group HP + A and 40 +/- 9, 21 +/- 7 and 19 +/- 9 in group BP + A, respectively. At the end of the treatment period, TL, IL and NL were reduced by 93%, 92% and 95%, respectively, in group HP + A and by 88%, 86% and 90%, respectively, in group BP + A. A significantly (P = 0.0025) greater reduction in NL was observed in group HP + A in comparison with group BP + A. Tolerability was significantly better in group HP + A in comparison with group BP + A (P = 0.02). Skin dryness and burning sensation were more frequent in group BP + A. CONCLUSIONS: The combination of adapalene and HP cream is an effective topical treatment regimen in mild to moderate AV. This combination has shown a better tolerability profile in comparison with the combination of BP and adapalene.

Acne Vulgaris↗

Efficacy and safety of stabilised hydrogen peroxide cream (Crystacide) in mild-to-moderate acne vulgaris: a randomised, controlled trial versus benzoyl peroxide gel.

BACKGROUND: Benzoyl peroxide (BP) is a first-line topical treatment in acne vulgaris (AV). However, its use can cause mild skin irritation and dryness. A new formulation of hydrogen peroxide stabilised (HPS) in monoglycerides cream (Crystacide 1%), indicated in the topical treatment of superficial skin infections, is now available as an alternative treatment. STUDY AIM: To evaluate efficacy and local tolerability of HPS in mild-to-moderate AV in comparison with BP gel. METHODS AND PATIENTS: In a randomised, prospective, investigator-masked parallel-group, 8-week trial, 60 patients (24 men, 36 women, mean age 25 +/- 6 years) with mild-to-moderate AV, affecting mainly the face, were enrolled in the study, after their informed consent. HPS or BP (PanOxyl gel 4%) was applied topically twice daily for 8 weeks. STUDY OUTCOMES: The study endpoints were: (1) Reduction in mean inflammatory (IL), noninflammatory (NIL) and total (TL) acneic lesions in comparison with baseline; (2) Local tolerability assessed evaluating erythema, dryness and burning sensation, using a 0-3 qualitative score (score 0 = poor tolerability; score 3 = very good tolerability). RESULTS: TL, NIL, and IL were assessed by an investigator unaware of treatment allocation at baseline, and week 8. The tolerability score (TS) was assessed at week 4 and 8. At baseline, the two groups were well matched for the main clinical and demographic characteristics. All patients concluded the trial. At week 0, in the HPS group TL, NIL and IL (mean +/- SD) were: 35 +/- 8, 20 +/- 6 and 16 +/- 7. At week 8, HPS reduced TL to 16 +/- 7; NIL to 9 +/- 3 and IL to 7 +/- 3 (p < 0.001). At baseline, TL, NIL and IL, in the BP group, were 32 +/- 9, 24 +/- 8 and 18 +/- 7, respectively. At week 8, BP reduced TL, NIL and IL to 14 +/- 9; 7 +/- 5 and 7 +/- 3 (p < 0.001). In comparison with baseline values, the percentage reductions of IL were 58% and 61% for HPS and BP,respectively (p = n.s.). At the end of the study the TS was 2.9 +/- 0.2 in HPS group and 2.4 +/- 0.8 in BP group (p < 0.025). Two patients in HPS group (6%) and seven patients (23%) in BP group suffered from mild-to-moderate local erythema. CONCLUSIONS: HPS has shown to be as effective as BP in reducing both inflammatory and noninflammatory AV lesions in patients with mild-to-moderate disease. In comparison with BP 4% gel, HPS cream shows a better local tolerability profile.

Acne Vulgaris↗