Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00369 (ROS)
 19,271 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The oscillatory resistance to respiration ROS is not significantly influenced by the process of dialysis and thus does not allow a conclusion to a possible predialytic increase of the extravascular pulmonary water. The body-plethysmographically determined resistance of the respiratory tract Rt shows homogeneous behaviour. A functionally intact respiratory system is of vital importance for the patient with renal insufficiency.
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PMID:[Airway resistance in dialysis patients]. 395 25

An enzymatic procedure for the estimation of organic hydroperoxides has been adapted to biological tissues and applied to the measurement of hydroperoxides in the rat retina. Hydroperoxides are determined from the coupled activities of glutathione peroxidase and glutathione reductase as measured by the loss of NADPH absorbance. To minimize the effects of tissue catalyzed peroxide degradation, incubations were performed in the presence of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU); which inhibited the activity of retinal tissue glutathione reductase by 85%. For comparisons to the enzymatic technique, retinal tissue hydroperoxides were also estimated by the absorption of tissue extracts at 232 nm. Using the enzymatic procedure the hydroperoxide concentration in whole retina homogenates was significantly higher in 19-day-old rats than in either 35-day or adult animals. Hydroperoxides in the retina of young rats exposed to light for one hour were significantly lower than in non-exposed controls, while in adult rats, following light, hydroperoxides increased 13%. Fractionation of rat retinas into crude ROS and retina minus ROS components revealed that the ROS fractions contain at least twice the hydroperoxide concentration of the remaining retina. The concentration of hydroperoxides in the ROS fractions from dark-reared rats were significantly lower than in cyclic-light-reared animals. In both types of rats, one hour intense light exposure resulted in an increase in ROS hydroperoxides but the increases were not significant. ROS hydroperoxides were also found to be 85-90% water soluble. Estimates of the retinal hydroperoxide content obtained by absorption at 232 nm gave similar results to the enzymatic technique, but the levels were significantly lower. When retinas were maintained in vitro for one hour before analysis, hydroperoxides determined by either technique were significantly higher than in retinas assayed immediately, but A232 hydroperoxides were still significantly lower than hydroperoxides measured by the enzymatic procedure. It is concluded: (1) that the observed retinal hydroperoxide concentration depends upon animal age and the method of measurement; (2) that within the retina the photoreceptor cell contains at least a two-fold higher concentration of hydroperoxides than the remaining retina and that prior light history can affect those hydroperoxide levels (it appears that the photoreceptor cell is also a major site of hydroperoxide formation in the retina); (3) that during intense light exposure of short duration significant levels of hydroperoxides do not accumulate in the retinas of rats.
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PMID:The enzymatic estimation of organic hydroperoxides in the rat retina. 683 30

The most important electron acceptor in the biosphere is molecular oxygen which, by virtue of its bi-radical nature, readily accepts unpaired electrons to give rise to a series of partially reduced species collectively known as reduced (or 'reactive') oxygen species (ROS). These include superoxide (O.2-), hydrogen peroxide (H2O2), hydroxyl radical (HO.) and peroxyl (ROO.) and alkoxyl (RO.) radicals which may be involved in the initiation and propagation of free radical chain reactions and which are potentially highly damaging to cells. Mechanisms have evolved to restrict and control such processes, partly by compartmentation, and partly by antioxidant defences such as chain-breaking antioxidant compounds capable forming stable free radicals (e.g. ascorbate, alpha-tocopherol) and the evolution of enzyme systems (e.g. superoxide dismutase, catalase, peroxidases) that diminish the intracellular concentration of the ROS. Although some ROS perform useful functions, the production of ROS exceeding the ability of the organism to mount an antioxidant defence results in oxidative stress and the ensuing tissue damage may be involved in certain disease processes. Evidence that ROS are involved in primary pathological mechanisms is a feature mainly of extraneous physical or chemical perturbations of which radiation is perhaps the major contributor. One of the important radiation-induced free-radical species is the hydroxyl radical which indiscriminately attacks neighbouring molecules often at near diffusion-controlled rates. Hydroxyl radicals are generated by ionizing radiation either directly by oxidation of water, or indirectly by the formation of secondary partially ROS. These may be subsequently converted to hydroxyl radicals by further reduction ('activation') by metabolic processes in the cell. Secondary radiation injury is therefore influenced by the cellular antioxidant status and the amount and availability of activating mechanisms. The biological response to radiation may be modulated by alterations in factors affecting these secondary mechanisms of cellular injury.
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PMID:Free radicals in biology: oxidative stress and the effects of ionizing radiation. 790 6

Peripherin/rds and rom-1 are homologous integral membrane protein subunits found as an oligomeric complex at the rim regions of rod and cone photoreceptor outer segment disks. These proteins are essential for the morphogenesis of normal outer segments and have been linked to a variety of human retinal degenerative diseases. Previous studies have suggested that disulfide-linked homodimers of peripherin/rds and rom-1 can associate noncovalently to form higher order structures. We have characterized the hydrodynamic properties of Triton X-100 solubilized peripherin/rds-rom-1 complexes from bovine ROS membranes by gel exclusion chromatography on Sepharose C1-6B and velocity sedimentation through H2O- and D2O-based sucrose gradients. A single hydrodynamic species is observed which has a Stokes radius of 6.2 nm, a sedimentation coefficient (S20,w) of 5.8 S, and a partial specific volume of 0.83 mL/g. From these data the molecular mass of the detergent-peripherin/rds-rom-1 complex is calculated to be 240 kDa. The protein component of this complex is estimated to be 135 kDa, providing direct evidence that the solubilized peripherin/rds-rom-1 complex is a tetramer. The abundance of this complex as measured by competitive ELISA and immunoaffinity purification is approximately 4% of total bovine ROS membrane protein and indicates that peripherin/rds-rom-1 tetramers are present at a relatively high average surface density (ca. 4100/ microns m2) at the rim surfaces of rod outer segment disks.
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PMID:Subunit composition of the peripherin/rds-rom-1 disk rim complex from rod photoreceptors: hydrodynamic evidence for a tetrameric quaternary structure. 863 57

The disinfectant activity of ozone is well recognized and ozone is used worldwide for sterilization of water. The use of ozone as a complementary medical approach is less known, because it has mostly been used in an empirical fashion without a rational basis and appropriate controls. In spite of this drawback, the use of judicious and standardized ozone dosages can elicit the formation of ROS acting as natural physiological activators of several biological functions. There is now a reasonable understanding of a few mechanisms of action and, using classical pharmacological concepts, it appears possible to formulate a rationale for optimizing clinical applications. A further exciting development is that ozone, being an oxidizer, can upregulate the intracellular anti-oxidant enzymes eventually inhibiting the constant, life-long oxidative stress responsible for degenerative diseases and aging. Among various routes for the administration of ozone, the autohemotransfusion procedure, consisting in exposing blood to ozone, i.e. to a calculated and brief oxidative stress, appears safe, simple, inexpensive and amenable to be adjusted to different pathological states It is hoped that this review will help to dispel prejudices, to clarify that ozone toxicity can be tamed, to show that ozone can act as a bioregulator and to encourage controlled clinical investigations to evaluate definitely the validity of ozonetherapy.
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PMID:Ozone as a bioregulator. Pharmacology and toxicology of ozonetherapy today. 925 Aug 84

Postnatally a rapid change occurs from a relatively hypoxic to a relatively hyperoxic environment, especially during artificial ventilation with all risks of ROS-formation. Among the non enzymatic antioxidative strategies the vitamins E, C, A and B2 are of major importance. Vitamin E is considered the most important radical scavenging vitamin of the lipid soluble compartment. Hereby vitamin E itself is converted into a radical which is handed over to vitamin C and glutathione into the water soluble compartment. The vitamin E content of the fetus increases with the fetal fat mass mainly during the last trimester of pregnancy. Placenta is only slightly permeable to lipid soluble vitamins. Vitamin E deficiency may rapidly develop typically at about 6-8 weeks of age. Vitamin E is able to prolong significantly the onset of retinopathic changes during oxygen therapy and may prevent intraventricular hemorrhage. Vitamin C is together with glutathione a major representative of the non enzymatic antioxidative system in the water soluble compartment. The best determinant of the vitamin C status is its concentration in leukocytes. Vitamin C reduces iron to the divalent state which supports the hydroxyl radical formation (Haber-Weiss reaction). This should be considered mainly in cases of intraventricular hemorrhage. Vitamin B2 acts mainly as cofactor of glutathione reductase which keeps glutathione in the reduced state. It can therefore be considered an indirect antioxidative vitamin. Vitamin B2 is destroyed by light. Phototherapy has been recognized as a cause of riboflavin deficiency. Vitamin A comprises all retinols with properties like trans-retinol. Retinol storage in the fetal liver increases during late pregnancy. In both, premature and mature newborns, the serum concentrations amount to only about 50% of those of their mothers. Vitamin A has a paramount importance for fetal lung development, because the individual surfactant proteins are selectively regulated by retinoic acid.
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PMID:Antioxidative vitamins in prematurely and maturely born infants. 935 Apr 73

The effects of dental materials on osteoblastic responses in bone were measured using biosynthesis of matrix proteins, osteopontin (OPN), and osteocalcin (OCN) as indices. Materials used in perforation repair were standardly mixed and extracted in sterile water for 10 days. Extracts were added to the medium of osteoblastic ROS 17/2.8 cells and cultured for 48 h. Water incubated in parallel served as the vehicle/dilution control. 1,25-Dihydroxyvitamin D3, which increases biosynthesis of OPN and OCN, served as the positive control. After culture, total cellular RNA was isolated from individual monolayers, and Northern blotting was performed to quantitate mRNA levels encoding OCN and OPN. mRNA levels in treated samples were compared with controls, and significant differences were detected for several materials. Changes in matrix biosynthesis were modest (< 2-fold), compared with 1,25-dihydroxyvitamin D3 (6-fold). Materials used in perforation repair may produce small, but measurable effects on osteoblastic responses.
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PMID:Effect of agents used in perforation repair on osteoblastic cells. 959 55

The purpose of this study was: (a) to examine the effect of plasma-gas composition on plasma polymer oxygen/carbon (O/C) ratio, functional group composition and stability in water, and then (b) to examine cell attachment to surfaces containing different concentrations of O/C and functional groups. Oxygen-functionalised surfaces were deposited by means of the plasma copolymerisation of acrylic acid/1,7-octadiene. The use of a diluent hydrocarbon allowed the deposition of surfaces with a range of O/C concentrations. Plasma copolymer surfaces were characterised by X-ray photoelectron spectroscopy (XPS). Changes in functional group composition with % acrylic acid monomer and the non-dispersive and dispersive parts of the surface energy of these plasma copolymers were measured. The solubility of the plasma copolymers was assessed by means of XPS. The degree of attachment of ROS 17/2.8 osteoblast-like cells to plasma copolymer surfaces deemed to be 'stable' in aqueous medium was measured. Tissue culture polystyrene (TCPS) was included as a control. Attachment was found to be greatest to the plasma copolymer surface with an O/C of 0.11. This surface had a carboxylic acid concentration of ca. 3%. Attachment did not correlate with increased surface wettability (i.e. the non-dispersive component of the surface energy).
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PMID:Plasma copolymer surfaces of acrylic acid/1,7 octadiene: surface characterisation and the attachment of ROS 17/2.8 osteoblast-like cells. 985 82

The ability of vanillin (4-hydroxy-3-methoxybenzaldehyde), a naturally occurring food flavouring agent, in inhibiting photosensitization-induced single-strand breaks (ssbs) in plasmid pBR322 DNA has been examined in an in vitro system, independent of DNA repair/replication processes. Photosensitization of DNA with methylene blue, visible light and oxygen, induced ssbs resulting in the production of open circular form (OC form) in a concentration-dependent manner. The yield of OC form induced by photosensitization was increased several-fold by deuteration of the buffer and was found to be inhibited by sodium azide, a scavenger of singlet oxygen (1O(2)). Vanillin, per se, did not induce but inhibited photosensitization-induced ssbs in plasmid DNA, at millimolar concentrations. The inhibitory effect of vanillin was both concentration- and time-dependent. On a molar basis, vanillin was, however, less effective than trolox, a water-soluble analogue of alpha-tocopherol. Photosensitization by methylene blue system generates singlet oxygen, as one of the major components of ROS. Therefore, interaction of singlet oxygen with vanillin was investigated. The rate constant of vanillin with 1O(2) was estimated to be 5.93x10(7)M(-1)s(-1) and that of sodium azide as 2. 7x10(8)M(-1)s(-1). The present investigations show that vanillin can protect against photosensitization-induced ssbs in the plasmid pBR322 DNA, and this effect may partly be due to its ability to scavenge 1O(2).
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PMID:Effect of vanillin on methylene blue plus light-induced single-strand breaks in plasmid pBR322 DNA. 1098 81

Aflatoxin B(1) (AFB(1)), a potent hepatocarcinogen, enhances ROS formation and causes oxidative DNA damage, which may play a role in its carcinogenicity. We have demonstrated recently that ebselen, an organic selenium compound, protects against the cytotoxicity of AFB(1) through its antioxidant capability. The present study was designed to investigate the effect of ebselen on AFB(1)-induced hepatocarcinogenesis in an animal model. Fischer 344 rats were first treated with either deionized water or ebselen (5 mg/kg, 5 days/week) via gavage for 4 weeks, then given AFB(1) (0.4 mg/kg, gavage, once a week) or AFB(1) plus ebselen (5 mg/kg, 5 days/week) for another 24 weeks. The results showed that the hepatocarcinogenicity of AFB(1) in rats was significantly reduced by ebselen treatment as indicated by a decrease in: (i) serum gamma-glutamyl transpeptidase activity; (ii) expression of mRNAs of liver alpha-fetoprotein and the placental form of glutathione S-transferase (GST-P); and (iii) the area and mean density of staining of liver GST-P foci. Ebselen treatment significantly reduced the formation of hepatic AFB(1)-DNA adducts and 8-hydroxydeoxyguanosine caused by AFB(1) exposure. These findings suggest that ebselen can inhibit the carcinogenicity of AFB(1). In addition to the reduction of AFB(1)-DNA adduct formation, the protective effect of ebselen against AFB(1)-induced oxidative DNA damage may also, at least in part, contribute to its anticarcinogenic property.
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PMID:Inhibition of ebselen on aflatoxin B(1)-induced hepatocarcinogenesis in Fischer 344 rats. 1113 13


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