Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The promutagenic base 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA is known to be formed from oxygen radical attack on 2'-deoxyguanosine (dG) as a result of oxidative stress. Formation of 8-OH-dG from dG during workup is strongly dependent on temperature and transition metals and is mediated by oxygen radicals. The 8-OH-dG formation at temperatures between 0 and 140 degrees C for 1.5 h in an "ultrapure" solution followed a third-order equation. Fe2+ in the nM range mediated the formation of 8-OH-dG from dG without addition of H2O2. Fe3+, Cu+, and Cu2+ were shown to have weaker oxidative effects in comparison to Fe2+. The pH (5.0-9.0) had a very limited effect on 8-OH-dG formation. Acid phosphatase, which contains iron at its active site, caused the formation of 8-OH-dG, whereas alkaline phosphatase did not. Phenol was not found to be oxidative. Fe2+-catalyzed formation of 8-OH-dG was completely blocked by the nitroxide 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), whereas DMSO, mannitol, and DMPO had a significantly weaker protecting effect. Catalase cleaved the dG molecule and was not suitable for use. A simple, fast, and inexpensive method for 8-OH-dG workup and analysis was developed, and the background level seen in liver from 13-week-old male Sprague-Dawley rat was 0.23 +/- 0.020 8-OH-dG/10(5) dG, which is up to 200 times lower than reported values from some other methods and up to 26 times lower when compared to other reports using HPLC-EC methods. In summary, the TEMPO method reduces oxidation of dG to 8-OH-dG during workup by (1) using chemicals low in transition metals, (2) using a cold workup procedure, (3) limiting the incubation time, and (4) using the nitroxide TEMPO in all steps.
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PMID:Reduction of oxidation during the preparation of DNA and analysis of 8-hydroxy-2'-deoxyguanosine. 970 49

A flow-injection cold vapor atomic absorption spectrometry (FI-CV-AAS) method was developed to determine inorganic mercury and total mercury in mussel samples obtained from the Galicia coasts. The mussel samples were digested in a microwave oven using an HNO3/H2O2 mixture and then total mercury was determined using sodium borohydride as reducing agent. In a separate subsample, following ultrasonic extraction in hydrochloric acid medium, inorganic mercury was determined by selective reduction using stannous chloride in acid medium as reducing agent. The accuracy of the digestion method was checked by analyzing BCR Reference Material No. 278 Mussel Tissue (Mytilus edulis). There were no significant differences between the certified and found concentration values. As a certified reference material of mussel tissue containing both methylmercury and inorganic mercury was not available, recovery studies on mussel tissue samples spiked with inorganic mercury and methylmercury were done to check the reliability of the method. The results revealed that the mercury contained in mussel samples was methylmercury.
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PMID:Selective reduction method for separate determination of inorganic and total mercury in mussel tissue by flow-injection cold vapor technique. 1009 Aug 13

An extracellular serine proteinase purified from cultures of a psychrotrophic Vibrio species (strain PA-44) belongs to the proteinase K family of the superfamily of subtilisin-like proteinases. The enzyme is secreted as a 47-kDa protein, but under mild heat treatment (30 min at 40 degrees C) undergoes autoproteolytic cleavage on the carboxyl-side of the molecule to give a proteinase with a molecular mass of about 36 kDa that apparently shares most of the enzymatic characteristics and the stability of the 47-kDa protein. In this study, selected enzymatic properties of the Vibrio proteinase were compared with those of the related proteinases, proteinase K and aqualysin I, as representative mesophilic and thermophilic enzymes, respectively. The catalytic efficiency (kcat/Km) for the amidase activity of the cold-adapted enzyme against succinyl-AAPF-p-nitroanilide was significantly higher than that of its mesophilic and thermophilic counterparts, especially when compared with aqualysin I. The stability of the Vibrio proteinase, both towards heat and denaturants, was found to be significantly lower than of either proteinase K or aqualysin I. One or more disulfide bonds in the psychrotrophic proteinase are important for the integrity of the active enzyme structure, as disulfide cleavage, either by reduction with dithiothreitol or by sulfitolysis, led to a loss in its activity. Under the same conditions, aqualysin I was also partially inactivated by dithiothreitol, but the activity of proteinase K was unaffected. The disulfides of either proteinase K or aqualysin I were not reactive towards sulfitolysis, except under denaturing conditions, while all disulfides of the Vibrio proteinase reacted in absence of a denaturant. The reactivity of the disulfides of the proteins as a function of denaturant concentration followed the order: Vibrio proteinase > proteinase K > aqualysin I. The same order of reactivity was also observed for the inactivation of the enzymes by H2O2-oxidation, as a function of temperature. The order of reactivity observed in these reactions most likely reflects the accessibility of the reactive cystine or methionine side chains present in the three related proteinases, and hence a difference in the compactness of their protein structures.
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PMID:Properties of a subtilisin-like proteinase from a psychrotrophic Vibrio species comparison with proteinase K and aqualysin I. 1010 4

The behavior of Escherichia coli O157:H7 on alfalfa seeds subjected to conditions similar to those used commercially to grow and market sprouts as it is affected by applications of NaOCl, Ca(OCl)2, acidified NaClO2, acidified ClO2, Na3PO4, Vegi-Clean, Tsunami, Vortexx, or H2O2 at various stages of the sprouting process was determined. Application of 2,000 ppm of NaOCl, 200 and 2,000 ppm of Ca(OCl)2, 500 ppm of acidified ClO2, 10,000 ppm of Vegi-Clean, 80 ppm of Tsunami, or 40 and 80 ppm of Vortexx to germinated seeds significantly reduced the population of E. coli O157:H7. With the exception of acidified NaOCl2 at 1,200 ppm, spray applications of these chemicals did not significantly reduce populations or control the growth of E. coli O157:H7 on alfalfa sprouts during the sprouting process. Populations of E. coli on alfalfa sprouts peaked at 6 to 7 log10 CFU/g 48 h after initiation of the sprouting process and remained stable despite further spraying with chemicals. The population of E. coli O157:H7 on sprouts as they entered cold storage at 9 +/- 2 degrees C remained essentially unchanged for up to 6 days. None of the chemical treatments evaluated was able to eliminate or satisfactorily reduce E. coli O157:H7 on alfalfa seeds and sprouts. Observations on the ability of E. coli O157:H7 to grow during production of alfalfa sprouts not subjected to chemical treatments are similar to those from a previous study in our laboratory on the behavior of Salmonella Stanley. Our results do not reveal a chemical treatment method to eliminate the pathogen from alfalfa sprouts. We have demonstrated that currently recommended procedures for sanitizing alfalfa seeds fail to eliminate E. coli O157:H7 and that the pathogen can grow to populations exceeding 7 1og10 CFU/g of sprouts produced using techniques not dissimilar to those used in the sprout industry.
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PMID:Behavior of enterohemorrhagic Escherichia coli O157:H7 on alfalfa sprouts during the sprouting process as influenced by treatments with various chemicals. 1045 35

Formation of oxygen free radicals during heart transplantation seems to be related to the alterations occurring during ischemia and reperfusion and could explain the short preservation time of donor hearts. The aim of our study was (a) to analyze the protective effects of pyruvate during cold cardioplegia and ischemia/reperfusion sequence, and (b) to investigate in vitro the radical scavenging properties of this compound. After 30 min of perfusion, isolated working rat hearts were arrested by cardioplegic solution, stored 4 h in B21 solutions at 4 degrees C, and reperfused with Krebs-Henseleit buffer for 45 min. Pyruvate (2 mM) was added to Krebs-Henseleit, cardioplegic, and storage solutions, and functional parameters were recorded throughout the experiments. In a second part, control hearts and hearts treated with pyruvate were cannulated via the aorta and perfused for 30 min by the Langendorff method, arrested by cardioplegic solution, stored 4 h in B21 solutions at 4 degrees C, and reperfused for 45 min by the Langendorff method. Malonedialdehyde and alpha-tocopherol levels were determined on heart homogenate. In situ detection of apoptotic cells also was performed on tissue samples (left ventricle) at the end of the ischemia/reperfusion sequence. To demonstrate in vitro the antioxidant effects of pyruvate, we monitored (a) its hydroxyl radical scavenging properties by using electron paramagnetic resonance (EPR) spectroscopy, and (b) the decrease of fluorescence of allophycocyanin, in the presence of a Fenton system (H2O2/Cu2+). Ischemia for 4 h, followed by myocardial reperfusion, resulted in substantially reduced mechanical function. Hearts subjected to this ischemia and pretreated with pyruvate showed a significant improvement in the function recovery. After the ischemia/reperfusion protocol, no significant decrease of malonedialdehyde levels was shown on hearts treated with pyruvate. However, alpha-tocopherol levels were higher in the pyruvate group compared with the control group. At the end of the reperfusion period, levels of apoptotic cells were significantly lower in hearts treated with pyruvate compared with control hearts. EPR studies showed that pyruvate was an efficient hydroxyl scavenger, with a median inhibitory concentration (IC50) of 8 mM. The allophycocyanin assay also showed a dose-dependent effect of pyruvate against hydroxyl radicals. In conclusion, these findings showed that pyruvate could prevent reperfusion injuries in the isolated heart, probably by its antioxidative properties. The application of pyruvate may contribute to the preservation of hearts for organ transplantation.
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PMID:Antioxidative properties of pyruvate and protection of the ischemic rat heart during cardioplegia. 1054 80

Fibrillin was originally identified as a chromoplast protein involved in the assembly of carotenoid-containing fibrils and was also found to accumulate in chloroplasts of wounded or water-stressed leaves. We now show that the promoter from the pepper fibrillin (nuclear) gene can be induced in leaves of stable tomato transformants by various stresses, namely wounding, drought, cold and salt stress, in light but not in darkness, as well as by high light intensities. Various herbicides causing reactive oxygen (superoxide, singlet oxygen) production in chloroplasts also induce the promoter. Higher expression levels are observed in transgenic tobacco plants which are apparently more sensitive to photo-oxidative stress than tomato. Similarly, wounding which causes strong induction of the promoter in tobacco, produces only weak induction in tomato. Hydrogen peroxide produced in plastids or added exogenously causes the induction of this nuclear gene. Our data suggest that the ascorbate/glutathione pathway (which eliminates hydrogen peroxide) can influence indirectly the induction of the fibrillin promoter. We propose a generalized model which links stresses of external origin to nuclear gene induction, via the plastid compartment which is subjected to photo-oxidative stress.
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PMID:Stress induction of a nuclear gene encoding for a plastid protein is mediated by photo-oxidative events. 1058 Feb 86

Expression of CIRP (cold-inducible RNA-binding protein) is inducible at 32 degrees C in cultured fibroblasts. Because ischemia is known to induce expression of heat shock proteins, its effect on the CIRP expression was examined using the rat transient forebrain ischemia model. The isolated rat CIRP cDNA encoded amino acids 100% identical in its sequence to mouse CIRP. Northern blot analysis revealed that the CIRP transcripts were ubiquitously expressed in various tissues. In situ hybridization histochemistry of normal rat brain revealed the expression of CIRP in neurons in the hippocampus and the cerebral cortex among others. In the hippocampus of postischemic rats, CIRP mRNA level decreased from 3-6 h after the onset of reperfusion, while it did not change in the cerebral cortex. When PC12 pheochromocytoma cells were cultured at 32 degrees C, the CIRP mRNA level was increased. The presence of H2O2 in the culture media inhibited dose dependently this induction as well as constitutive expression, suggesting that the effect of brain ischemia on CIRP expression is related to generation of reactive oxygen species. Further studies are necessary to clarify the roles played by cold shock proteins in the hypothermic therapy of brain damages.
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PMID:Effects of ischemia and H2O2 on the cold stress protein CIRP expression in rat neuronal cells. 1064 16

All components of an intracerebral kallikrein-kinin system have been described. Thus, bradykinin (BK) acting from the parenchymal side as well as from the blood side may influence cerebral microcirculation. BK is a potent dilator of extra- and intraparenchymal cerebral arteries when acting from the perivascular side. The vasomotor effect of BK is mediated by B2 receptors which appear to be located at the abluminal membrane of the endothelial cell. Signal transmission from the endothelial to the smooth muscle cell is mediated by NO, prostanoids, free radicals or H2O2 depending on the animal species and on the location of the artery. Selective opening of the blood-brain barrier for small tracers (Na+-fluorescein: MW, 376) has been found in cats during cortical superfusion or intraarterial application of BK. This leakage is mediated by B2 receptors located at the luminal and abluminal membrane of the endothelial cells and probably mediated by an opening of tight junctions. Formation of brain edema has been found after ventriculo-cisternal perfusion or interstitial infusion of BK. This can be explained by increase of vascular permeability and cerebral blood flow due to arterial dilatation thus enhancing driving forces for the extravasation. An increase of the BK concentration in the interstitial space of the brain up to concentrations which induce extravasation, dilatation and edema formation has been found under several pathological conditions. Thus, BK may be involved in edema and necrosis formation after cold lesion, concussive brain injury, traumatic spinal cord and ischemic brain injury.
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PMID:Effects of bradykinin in the cerebral circulation. 1074 74

When incubated at 4 degrees C, cultured rat hepatocytes or liver endothelial cells exhibit pronounced injury and, during earlier rewarming, marked apoptosis. Both processes are mediated by reactive oxygen species, and marked protective effects of iron chelators as well as the protection provided by various other antioxidants suggest that hydroxyl radicals, formed by classical Fenton chemistry, are involved. However, when we measured the Fenton chemistry educt hydrogen peroxide and its precursor, the superoxide anion radical, formation of both had markedly decreased and steady-state levels of hydrogen peroxide did not alter during cold incubation of either liver endothelial cells or hepatocytes. Similarly, there was no evidence of an increase in O2-/H2O2 release contributing to cold-induced apoptosis occurring on rewarming. In contrast to the release/level of O2- and H2O2, cellular homeostasis of the transition metal iron is likely to play a key role during cold incubation of cultured hepatocytes: the hepatocellular pool of chelatable iron, measured on a single-cell level using laser scanning microscopy and the fluorescent indicator phen green, increased from 3.1 +/- 2.3 microM (before cold incubation) to 7.7 +/- 2.4 microM within 90 min after initiation of cold incubation. This increase in the cellular chelatable iron pool was reversible on rewarming after short periods of cold incubation. The cold-induced increase in the hepatocellular chelatable iron pool was confirmed using the calcein method. These data suggest that free radical-mediated hypothermia injury/cold-induced apoptosis is primarily evoked by alterations in the cellular iron homeostasis/a rapid increase in the cellular chelatable iron pool and not by increased formation of O2-/H2O2.
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PMID:Hypothermia injury/cold-induced apoptosis--evidence of an increase in chelatable iron causing oxidative injury in spite of low O2-/H2O2 formation. 1102 79

A new oxidation method based on room-temperature ultrasonic irradiation (sonolysis) is proposed for conversion of organomercurials into inorganic mercury and subsequent determination by flow injection-cold vapor atomic absorption spectrometry. This advanced oxidation process eliminates the need for chemical oxidants, high temperature, and pressure for degradation of organomercurials so that total mercury can be determined with sodium tetrahydroborate(III) or tin(II) chloride as reducing agents. Complete oxidations can be accomplished within 3 min, using a 40% sonication amplitude (100 W nominal power) provided by a probe ultrasonic device (20 kHz frequency) and a 1 mol L(-1) HCl liquid medium. The presence of HCl was seen to be necessary for fast oxidation of organomercurials, in contrast to other chemical oxidants such as H2O2 or HNO3 which yielded incomplete oxidation. Further advantages of the proposed method over existing methods which are currently employed for oxidation prior to total Hg determination are the removal of hazardous wastes and the decreased risk of Hg losses by volatilization. Oxidation kinetics indicated a pseudofirst-order reaction with apparent rate constants (k) of 3.2 x 10(-2) and 1.6 x 10(-2) s(-1) for methylmercury and phenylmercury, respectively. Oxidation experiments in the presence of foreign substances acting as OH radical scavengers showed a tolerance at least up to a concentration of 1000 mg L(-1). Likewise, model wastewaters with chemical oxygen demand of up to 1000 mg L(-1) could be processed without diminishing the oxidation efficiency. The method was applied to determination of inorganic and total mercury in simulated wastewaters and spiked environmental waters in combination with selective reduction.
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PMID:Room temperature sonolysis-based advanced oxidation process for degradation of organomercurials: application to determination of inorganic and total mercury in waters by flow injection-cold vapor atomic absorption spectrometry 1105 18


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