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PubMed1980

[Lipid peroxides and atherosclerosis. Free radical peroxidation of polyene lipids in the blood in ischemic heart disease].

Examination of blood in 114 males (35--60 years of age) with stage III of lipid hydroperoxides, acylhydroperoxides, intermol ecular cross-links in the aminophosphatides and secondary products of lipoperoxidation was increased considerably as compared to that in practically healthy males (30) of the same age. The activity of blood glutathione lipoperoxidase in the examined group of patients was sharply reduced.

Adult↗
PubMed1995

Bacteria in human mouths involved in the production and utilization of hydrogen peroxide.

Earlier studies have demonstrated that pure cultures of oral streptococci produce hydrogen peroxide but none has found any free peroxide in dental plaque or salivary sediment despite streptococci being major components of their mixed bacterial populations. The absence of peroxide in plaque and sediment could be due to the dominance of its destruction over its formation by bacterial constituents. To identify which of the oral bacteria might be involved in such a possibility, pure cultures of 27 different oral bacteria were surveyed (as well as dental plaque and sediment) for their peroxide-forming and peroxide-removing capabilities. Peroxide production was measured for each of the pure cultures by incubation with glucose at low and high substrate concentrations (2.8 and 28.0 mM) for 4 h and with the pH kept at 7.0 by a pH-stat. Removal of hydrogen peroxide was assessed in similar experiments where peroxide at 0, 29.4, 147.2 or 294.4 mM [0, 0.1, 0.5 and 1% (w/v)] replaced the glucose. Hydrogen peroxide formation was seen with only three of the bacteria tested, Streptococcus sanguis I and II (sanguis and oralis), and Strep. mitior (mitis biotype I); levels of hydrogen peroxide between 2.2 and 9.8 mM were produced when these micro-organisms were grown aerobically and 1.1 and 3.9 mM when grown anaerobically. Earlier reports indicate that such levels were usually sufficient to inhibit the growth of many plaque bacteria. The amounts formed were similar at the two glucose levels tested, suggesting that maximum peroxide production is reached at low glucose concentration. None of the three peroxide-producing organisms was able to utilize hydrogen peroxide but five of the other 24 tested, Neisseria sicca, Haemophilus segnis, H. parainfluenzae, Actinomyces viscosus and Staphylococcus epidermidis, could readily do so, as could the mixed bacteria in salivary sediment and dental plaque, both of which contain relatively high numbers of these peroxide-utilizing micro-organisms. The ability of the bacteria in plaque and sediment to degrade hydrogen peroxide was considerable and extremely rapid; peroxide removal and usually complete within the first 15 min of the incubation even when its initial level was as high as 294.4 mM. This almost overwhelming ability to remove peroxide was confirmed when peroxide-producing and -using cultures were mixed and when each of eight salivary sediments was incubated with glucose and with peroxide at concentrations up to 294.4 mM. In the glucose incubations, no hydrogen peroxide was observed, indicating dominance of microbial peroxide removers over hydrogen peroxide producers.(ABSTRACT TRUNCATED AT 400 WORDS)

Actinomyces viscosus↗
PubMed1969

Lipid peroxide formation in microsomes. General considerations.

1. Liver microsomes form lipid peroxide when incubated with ascorbate or NADPH, but not with NADH. Increasing the concentration of ascorbate beyond the optimum (0.5mm) decreases the rate of lipid peroxide formation, but this effect does not occur with NADPH. Other reducing agents such as p-phenylenediamine or ferricyanide were not able to replace ascorbate and induce lipid peroxide formation. 2. The rate of ascorbate-induced peroxidation is optimum at pH6.0 whereas the rate of the NADPH system is optimum at pH7.0. Both systems require phosphate for maximum activity. 3. Lipid peroxide formation occurs at the maximum specific rate in very dilute microsome suspensions (0.15mg. of protein/ml.). 4. Treatment of microsomes with deoxycholate and other detergents causes membrane disintegration and inhibits lipid peroxide formation. 5. Lipid peroxide formation is accompanied by a rapid uptake of oxygen and there is a large excess of oxygen utilized for each molecule of malonaldehyde measured in the peroxide method. 6. Boiled microsomes form lipid peroxide in the presence of ascorbate, but not if NADPH is added. 7. Lipid peroxide formation induced by NADPH is strongly inhibited by p-chloromercuribenzoate, weakly inhibited by N-ethylmaleimide and unaffected by iodoacetamide. Ascorbate-induced peroxidation in untreated microsomes is unaffected by p-chloromercuribenzoate, but inhibited if boiled microsomes are used. These experiments may be interpreted on the basis that a ferredoxin-type protein forms part of the system in which NADPH induces lipid peroxide formation. 8. Most heavy-metal ions, with the exception of inorganic iron (Fe(2+) or Fe(3+)), which activates, inhibit both ascorbate-induced and NADPH-induced peroxidation. Mg(2+) increases the rate of peroxidation whereas Ca(2+) inhibits it. 9. Lipid peroxide formation is inhibited strongly by GSH and weakly by cysteine. Ascorbate-induced peroxidation is much more sensitive than NADPH-induced peroxidation. 10. Peroxidation is strongly inhibited by addition of low concentrations (0.01-0.1mm) of cytochrome c or of haemoglobin. 11. It is considered that lipid peroxide formation occurs as a result of the operation of the microsomal electron-transport chain switching from hydroxylation to oxidize unsaturated lipids of the endoplasmic reticulum.

Animals↗
PubMed2002

Clindamycin/benzoyl peroxide gel: a review of its use in the management of acne.

UNLABELLED: Clindamycin/benzoyl peroxide gel has demonstrated clinical efficacy in the treatment of acne vulgaris through both antibacterial and anti-inflammatory means. Benzoyl peroxide may exert its antibacterial activity by the interaction of oxidized intermediates with elements of bacterial cells. Clindamycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunits causing inhibition of peptide-bond formation. Benzoyl peroxide decreases inflammatory damage by inhibiting the release of reactive oxygen species from polymorphonuclear leukocytes (PMNs) through the killing of PMNs. Clindamycin suppresses the complement-derived chemotaxis of polymorphonuclear leukocytes in vitro, thereby reducing the potential for inflammation. Several well designed clinical trials have demonstrated that twice-daily application of clindamycin 1%/benzoyl peroxide 5% gel for 10 to 16 weeks was more effective in reducing the number of inflammatory lesions than benzoyl peroxide 5%, clindamycin 1% or vehicle in patients with mild to moderately severe acne. Two studies also showed clindamycin/benzoyl peroxide to be more effective than benzoyl peroxide, clindamycin or vehicle in reducing total lesions, and one study showed clindamycin/benzoyl peroxide to be significantly more efficacious than clindamycin or vehicle in reducing the number of noninflammatory lesions. Moreover, in two trials, physician-rated mean global improvement scores, as well as patient-rated scores in one of those trials, were significantly greater in the clindamycin/benzoyl peroxide group than in the benzoyl peroxide, clindamycin or vehicle groups. In another study, clindamycin/benzoyl peroxide was as efficacious as benzoyl peroxide/erythromycin in the reduction of inflammatory and noninflammatory lesions and in raising mean global improvement scores, but was significantly more effective than benzoyl peroxide in the reduction of inflammatory lesions and in increasing both physician- and patient-assessed global improvement scores. Clindamycin/benzoyl peroxide gel applied twice daily was well tolerated in clinical trials in patients with acne, and has a tolerability profile similar to that of benzoyl peroxide alone. The most common adverse events were dry skin, peeling, erythema and rash; however, adverse event-caused treatment discontinuation rates for patients using clindamycin/benzoyl peroxide were low, ranging from 0 to 0.8%. CONCLUSIONS: Clindamycin/benzoyl peroxide gel has demonstrated efficacy and good overall tolerability in several well designed clinical studies in the topical treatment of patients with mild to moderately severe acne vulgaris. Clindamycin/benzoyl peroxide was more effective than benzoyl peroxide, clindamycin or vehicle, and similar in efficacy to benzoyl peroxide/erythromycin in the reduction of inflammatory lesions and in raising physician- and patient-assessed mean global improvement scores. It may be useful in treating patients with acne caused by resistant strains of Propionibacterium acnes. Clindamycin/benzoyl peroxide gel is an effective topical agent in the treatment of patients with mild to moderately severe acne. It is a suitable alternative for patients who are currently using topical antibacterials either alone or in conjunction with other topical anti-acne agents or systemic antibacterials.

Acne Vulgaris↗
PubMed1993

Deficient glutathione peroxidase activity in preeclampsia is associated with increased placental production of thromboxane and lipid peroxides.

OBJECTIVE: Thromboxane and lipid peroxide levels are abnormally increased in preeclamptic placentas. The cause of this increase is not known. Peroxides stimulate prostaglandin H2 synthase to increase thromboxane and oxygen radicals, which increase lipid peroxides. Glutathione peroxidase inactivates peroxides, thereby decreasing peroxide stimulation of prostaglandin H synthase. If glutathione peroxidase activity were deficient, then peroxides could increase, leading to increased stimulation of prostaglandin H synthase, resulting in increased production of thromboxane and lipid peroxides. The following study tested this hypothesis. STUDY DESIGN: Placental tissues from 11 normal and 11 preeclamptic women were immediately frozen in liquid nitrogen after delivery. One gram of tissue from each placenta was homogenized for analysis. Placental tissues were also obtained from six normal pregnancies for incubation with a glutathione peroxidase inhibitor, N-ethylmaleimide. Samples were analyzed for glutathione peroxidase activity, lipid peroxides by hydrogen peroxide equivalents, thromboxane by thromboxane B2, and prostacyclin by 6-keto-prostaglandin F1 alpha. RESULTS: Glutathione peroxidase activity was significantly lower in preeclamptic than in normal placentas (9.41 +/- 0.05 vs 13.41 +/- 0.63 units/gm, p < 0.001, mean +/- SE). Lipid peroxides and thromboxane were significantly higher in preeclamptic than in normal placentas (hydrogen peroxide equivalents 4.23 +/- 0.32 vs 2.84 +/- 0.27 mumol/gm, p < 0.01; thromboxane B2 215 +/- 31 vs 138 +/- 15 ng/gm, p < 0.05), whereas prostacyclin was significantly lower (6-keto-prostaglandin F1 alpha 23.3 +/- 2.2 vs 41.6 +/- 6.0 ng/gm, p < 0.01). Inhibition of glutathione peroxidase activity in normal placentas resulted in a dose-response increase in placental production of both lipid peroxides and thromboxane without affecting prostacyclin, so the ratio of thromboxane to prostacyclin increased progressively with inhibition of glutathione peroxidase. CONCLUSIONS: Glutathione peroxidase activity is significantly lower, and lipid peroxides and thromboxane are significantly higher, in preeclamptic placentas compared with normal placentas. Inhibition of glutathione peroxidase activity in normal placentas results in significantly increased production of lipid peroxides and thromboxane and an increase in the thromboxane to prostacyclin ratio. We speculate that in normal placentas, glutathione peroxidase limits prostaglandin H synthase activity by reducing the amount of peroxide present, thus reducing peroxide stimulation of prostaglandin H synthase. In preeclampsia deficient glutathione peroxidase activity results in in increased peroxide levels leading to increased stimulation of prostaglandin H synthase, which results in increased production of lipid peroxides and thromboxane.

Case-Control Studies↗
PubMed1998

Comparison of the skin tumor-promoting potential of different organic peroxides in SENCAR mice.

The skin tumor-promoting activities of three organic peroxides were evaluated and compared to the activity of benzoyl peroxide, a well-characterized tumor promoter. Two of the compounds (di-t-butyl peroxide and dicumyl peroxide) were dialkyl peroxides and the other (di-m-chlorobenzoyl peroxide) was a diacyl peroxide. These compounds were selected based on a previous study in which we evaluated their capacity to induce epidermal hyperplasia, ornithine decarboxylase activity, and dark basal keratinocytes, which have been reliable short-term markers of tumor promotion. Dicumyl peroxide was a weak tumor promoter despite its high activity in inducing hyperplasia. Like benzoyl peroxide, di-m-chlorobenzoyl peroxide generally had intermediate activity as an inducer of short-term markers of tumor promotion and was a moderately effective tumor promoter. However, compared to benzoyl peroxide, di-m-chlorobenzoyl peroxide was more toxic to the skin, which may have limited its tumor-promoting activity. The final compound, di-t-butyl peroxide, which was essentially inactive in short-term assays, was also totally inactive in promoting papillomas or carcinomas in initiated skin. Tumor-promoting efficacy generally showed an inverse association with thermal stability for the compounds tested, suggesting that the rate of formation of free radicals is a key factor contributing to tumor promotion by organic peroxides. However, a number of other factors can potentially affect the activity of different organic peroxides as tumor promoters. Each compound evaluated had a different spectrum of activities, and these compounds should be useful for studying mechanisms of organic peroxide-induced tumor promotion.

Animals↗
PubMed1987

Initiation of lipid peroxidation in biological systems.

The direct oxidation of PUFA by triplet oxygen is spin forbidden. The data reviewed indicate that lipid peroxidation is initiated by nonenzymatic and enzymatic reactions. One of the first steps in the initiation of lipid peroxidation in animal tissues is by the generation of a superoxide radical (see Figure 16), or its protonated molecule, the perhydroxyl radical. The latter could directly initiate PUFA peroxidation. Hydrogen peroxide which is produced by superoxide dismutation or by direct enzymatic production (amine oxidase, glucose oxidase, etc.) has a very crucial role in the initiation of lipid peroxidation. Hydrogen peroxide reduction by reduced transition metal generates hydroxyl radicals which oxidize every biological molecule. Hydrogen peroxide also activates myoglobin, hemoglobin, and other heme proteins to a compound containing iron at a higher oxidation state, Fe(IV) or Fe(V), which initiates lipid peroxidation even on membranes. Complexed iron could also be activated by O2- or by H2O2 to ferryl iron compound, which is supposed to initiate PUFA peroxidation. The presence of hydrogen peroxide, especially hydroperoxides, activates enzymes such as cyclooxygenase and lipoxygenase. These enzymes produce hydroperoxides and other physiological active compounds known as eicosanoids. Lipid peroxidation could also be initiated by other free radicals. The control of superoxide and perhydroxyl radical is done by SOD (a) (see Figure 16). Hydrogen peroxide is controlled in tissues by glutathione-peroxidase, which also affects the level of hydroperoxides (b). Hydrogen peroxide is decomposed also by catalase (b). Caeruloplasmin in extracellular fluids prevents the formation of free reduced iron ions which could decompose hydrogen peroxide to hydroxyl radical (c). Hydroxyl radical attacks on target lipid molecules could be prevented by hydroxyl radical scavengers, such as mannitol, glucose, and formate (d). Reduced compounds and antioxidants (ascorbic acid, alpha-tocopherol, polyphenols, etc.) (e) prevent initiation of lipid peroxidation by activated heme proteins, ferryl ion, and cyclo- and lipoxygenase. In addition, cyclooxygenase is inhibited by aspirin and nonsteroid drugs, such as indomethacin (f). The classical soybean lipoxygenase inhibitors are antioxidants, such as nordihydroguaiaretic acid (NDGA) and others, and the substrate analog 5,8,11,14 eicosatetraynoic acid (ETYA), which also inhibit cyclooxygenase (g). In food, lipoxygenase is inhibited by blanching. Initiation of lipid peroxidation was derived also by free radicals, such as NO2. or CCl3OO. This process could be controlled by antioxidants (e).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Application of a newly developed hydrogen peroxide vapor phase sensor to HPV sterilizer.

A new type of concentration sensor for hydrogen peroxide vapor has been developed by making use of a semiconductor. Output from the vapor sensor has been shown to have a good linear relationship with the logarithm of the concentration of hydrogen peroxide vapor. Concentration of hydrogen peroxide vapor introduced into the sterilization chamber could be kept constant by monitoring the concentration of the hydrogen peroxide vapor continuously and controlling the vapor supply. Temperature and humidity have also been kept constant. D-values for B. stearothermophilus ATCC 12980 at various concentrations of hydrogen peroxide vapor have been determined by using the combination system of the hydrogen peroxide vapor sensor, the hydrogen peroxide vapor supplier, thermosensor and humidity sensor. D-values at the temperature of 30 degrees C and the absolute humidity of 0.7 mg H2O/L thus obtained, were 0.2 minutes at hydrogen peroxide concentration of 600 ppm and 1.2 minutes at 200 ppm at the temperature of 30 degrees C and 0.7 mg/L absolute humidity. D-values for B. stearothermophilus ATCC 12980 at various temperatures, humidity and levels of hydrogen peroxide concentration have also been determined. These fundamental data indicate that the sterilization by hydrogen peroxide vapor can be validated as precisely as steam sterilization by measuring and controlling the concentration of hydrogen peroxide vapor using a combination of the hydrogen peroxide concentration sensor and the vapor generator. Influence of temperature and humidity have also been studied. The hydrogen peroxide sensor has been calibrated and standardized by using the standard hydrogen peroxide vapor whose concentration has been determined by calculating partial pressure of hydrogen peroxide over the water-hydrogen peroxide solution.

Calibration↗