Spectroscopic evidence for the generation of singlet oxygen in the reduced nicotinamide adenine dinucleotide phosphate-dependent microsomal lipid peroxidation system

Biological autoluminescence as a perturbance-free method for monitoring oxidation in biosystems

Biological oxidation processes are in the core of life energetics, play an important role in cellular biophysics, physiological cell signaling or cellular pathophysiology. Understanding of biooxidation processes is also crucial for biotechnological applications. Therefore, a plethora of methods has been developed for monitoring oxidation so far, each with distinct advantages and disadvantages. We review here the available methods for monitoring oxidation and their basic characteristics and capabilities. Then we focus on a unique method - the only one that does not require input of additional external energy or chemicals - which employs detection of biological autoluminescence (BAL). We highlight the pros and cons of this method and provide an overview of how BAL can be used to report on various aspects of cellular oxidation processes starting from oxygen consumption to the generation of oxidation products such as carbonyls. This review highlights the application potential of this completely non-invasive and label-free biophotonic diagnostic method.

A meta-analysis and review examining a possible role for oxidative stress and singlet oxygen in diverse diseases

From kinetic data (k, T) we calculated the thermodynamic parameters for various processes (nucleation, elongation, fibrillization, etc.) of proteinaceous diseases that are related to the β-amyloid protein (Alzheimer's), to tau protein (Alzheimer's, Pick's), to α-synuclein (Parkinson's), prion, amylin (type II diabetes), and to α-crystallin (cataract). Our calculations led to ΔG^≠ values that vary in the range 92.8-127 kJ mol^-1 at 310 K. A value of ∼10-30 kJ mol^-1 is the activation energy for the diffusion of reactants, depending on the reaction and the medium. The energy needed for the excitation of O₂ from the ground to the first excited state (¹Δ_g, singlet oxygen) is equal to 92 kJ mol^-1 So, the ΔG^≠ is equal to the energy needed for the excitation of ground state oxygen to the singlet oxygen (¹Δ_g first excited) state. The similarity of the ΔG^≠ values is an indication that a common mechanism in the above disorders may be taking place. We attribute this common mechanism to the (same) role of the oxidative stress and specifically of singlet oxygen, (¹Δ_g), to the above-mentioned processes: excitation of ground state oxygen to the singlet oxygen, ¹Δ_g, state (92 kJ mol^-1), and reaction of the empty π* orbital with high electron density regions of biomolecules (∼10-30 kJ mol^-1 for their diffusion). The ΔG^≠ for cases of heat-induced cell killing (cancer) lie also in the above range at 310 K. The present paper is a review and meta-analysis of literature data referring to neurodegenerative and other disorders.

Singlet molecular oxygen generated by biological hydroperoxides

The chemistry behind the phenomenon of ultra-weak photon emission has been subject of considerable interest for decades. Great progress has been made on the understanding of the chemical generation of electronically excited states that are involved in these processes. Proposed mechanisms implicated the production of excited carbonyl species and singlet molecular oxygen in the mechanism of generation of chemiluminescence in biological system. In particular, attention has been focused on the potential generation of singlet molecular oxygen in the recombination reaction of peroxyl radicals by the Russell mechanism. In the last ten years, our group has demonstrated the generation of singlet molecular oxygen from reactions involving the decomposition of biologically relevant hydroperoxides, especially from lipid hydroperoxides in the presence of metal ions, peroxynitrite, HOCl and cytochrome c. In this review we will discuss details on the chemical aspects related to the mechanism of singlet molecular oxygen generation from different biological hydroperoxides.

Lipid hydroperoxides as a source of singlet molecular oxygen

Lipid hydroperoxides (LOOH) are formed in biological system by enzymatic and non-enzymatic pathways. These hydroperoxides exerts multiple damaging effects on cellular macromolecules and are also important regulators of cellular processes. Several classes of hydroperoxides including fatty acid, phospholipid, cholesterol and cholesteryl ester hydroperoxides have been detected and characterized both in vitro and in vivo. Although cells are normally endowed with enzymatic defenses capable to reduce LOOH to less reactive hydroxides, LOOH may accumulate in several pathological conditions and attention has been focused on elucidating their pathophysiological role. In the last years we have demonstrated the generation of singlet molecular oxygen (O2 (1)Δg or (1)O2) in several reactions involving LOOH. The generation of (1)O2 was directly evidenced by spectroscopic detection and characterization of its light emission at 1,270 nm. Moreover, using 18-oxygen labeled hydroperoxides (L(18)O(18)OH) we could detect the formation of (18)O-labeled (1)O2 by chemical trapping with anthracene derivatives followed by detection of the corresponding labeled endoperoxides by HPLC coupled to tandem mass spectrometry. The experimental evidences indicate that (1)O2 is generated at a yield close to 10 % by the Russell mechanism from LOOH, either free or in membranes, in the presence of biologically relevant oxidants, such as metal ions, peroxynitrite, HOCl and cytochrome c.

Human ultraweak photon emission and the yin yang concept of Chinese medicine

The relationship between connective tissue and meridian function is discussed in terms of energy transmission. The network of hydrogen-bonded water molecules interspersed within the collagen fibrillar matrix is especially significant for both the sensitivity of connective tissue to weak signals of mechanical pressure, heat, or electricity and the electrical intercommunication that may correlate with the meridian acupuncture system. Special electromagnetic properties of connective tissue have similar collective properties of ultraweak photon emission. A relationship between ultraweak photon emission and yin yang dynamics is based on three types of ultraweak photon emission studies, focusing on diurnal and annual dynamics, diseased states, and acupuncture points. A novel concept explains the functional (health) integrity of physiologic systems in relation to the left-right balance in ultraweak photon emission by pointing to, (1) balanced corticoneuromusculoskeletal activities and triboluminescent aspects of ultraweak photon emission by skeletal structures, and (2) local fine-tuning in oxygen supply and the formation of radical oxygen species. This approach offers testable hypotheses for further validation utilizing a combination of human photon recording techniques and specialized metabolomics for the estimation of organ-specific oxidative states.

Biophoton detection and low-intensity light therapy: a potential clinical partnership

Low-intensity light therapy (LILT) is showing promise in the treatment of a wide variety of medical conditions. Concurrently, our knowledge of LILT mechanisms continues to expand. We are now aware of LILT's potential to induce cellular effects through, for example, accelerated ATP production and the mitigation of oxidative stress. In clinical use, however, it is often difficult to predict patient response to LILT. It appears that cellular reduction/oxidation (redox) state may play a central role in determining sensitivity to LILT and may help explain variability in patient responsiveness. In LILT, conditions associated with elevated reactive oxygen species (ROS) production, e.g. diabetic hyperglycemia, demonstrate increased sensitivity to LILT. Consequently, assessment of tissue redox conditions in vivo may prove helpful in identifying responsive tissues. A noninvasive redox measure may be useful in advancing investigation in LILT and may one day be helpful in better identifying responsive patients. The detection of biophotons, the production of which is associated with cellular redox state and the generation of ROS, represents just such an opportunity. In this review, we will present the case for pursuing further investigation into the potential clinical partnership between biophoton detection and LILT.

Differential effects of relaxation techniques on ultraweak photon emission

BACKGROUND

Evidence has accumulated favoring the possible role of oxidative stress in the pathogenesis of many chronic diseases. Meditation is utilized as an adjunct to conventional medical treatment for several clinical conditions. A few studies suggest a role of long-term meditation in the control of the free-radical metabolism. Many techniques for recording reactive oxygen species (ROS) have been made available. However, most are invasive and none are applicable to all conditions. Attention has recently been drawn to spontaneous ultraweak photon emission (UPE). However, the application of this method in meditation studies is very limited.

OBJECTIVE

The present study recorded spontaneous UPE at multiple anatomic locations of subjects with long-term experience in transcendental meditation (TM) and compared this with a group that practiced other meditation techniques (OMT) and with subjects having no meditation experience.

METHODS

The study examined the anatomic pattern of UPE of 20 subjects practicing TM, compared to 20 subjects practicing OMT, and 20 control subjects with no experience in meditation. Subjects were men who were reported to be healthy and nonsmokers. Meditation was not practiced on the day prior to recording. UPE was recorded in a dark room, using a highly sensitive, cooled photomultiplier system designed for manipulation in three directions. The protocol for the multisite registration of UPE included recording 12 anatomic locations, including the anterior torso, head, neck, and hands.

RESULTS

Data demonstrated emission intensities in the TM and OMT groups that were 27% and 17% lower, respectively, compared to the control group. The decrease was recorded at all anatomic locations. The percent emission contribution of each location to total emission was very similar for the three groups.

CONCLUSIONS

Data supported the hypothesis that persistent meditation resulted in decreased UPE. However, the determination of oxidation levels as the source of group differences needs to be verified further to confirm our hypothesis.

Melatonin and N-acetyl serotonin inhibit selectively enzymatic and non-enzymatic lipid peroxidation of rat liver microsomes

Melatonin (N-acetyl-5-methoxytryptamine) and its immediate precursor N-acetyl serotonin in the metabolism of tryptophan are free radical scavengers that have been found to protect against non-enzymatic lipid peroxidation in many experimental models. By contrast, little is known about the antioxidant ability of these indoleamines against NADPH enzymatic lipid peroxidation. The light emission produced by rat-liver microsomes, expressed as total cpm during 180 min of incubation at 37 degrees C, was two-fold greater in the presence of ascorbate (0.4mM) when compared with NADPH (0.2 mM). Maximal peaks of light emission produced by microsomes lipid peroxidized with ascorbic-Fe(2+) or NADPH and expressed as cpm were 354,208 (at 60 min) and 135,800 (at 15 min), respectively. During non-enzymatic lipid peroxidation a decrease of total chemiluminescence (inhibition of lipid peroxidation) was observed when increasing concentrations of melatonin were added to liver microsomes. The protective effect was concentration-dependent. The inhibition observed in light emission was coincident with the protection of the most PUFAs. Preincubation of microsomes with N-acetyl serotonin reduced these changes very dramatically. Thus, in the presence of both antioxidants (0.36, 0.75, 1.5 mM), light emission percent inhibition during non-enzymatic (ascorbate-Fe(2+)) lipid peroxidation of rat liver microsomes was for melatonin: 6.12, 16.20, 34.88 and for N-acetyl serotonin: 85.10, 88.48, 84.4 respectively. The incubation of rat liver microsomes in the presence of NADPH (0.36, 0.75, 1.5 mM) produce a sudden increase of chemiluminescence that gradually increased and reached a maximal value at about 15 min; however, N-acetyl serotonin reduced these changes very efficiently.

Anatomic characterization of human ultra-weak photon emission in practitioners of transcendental meditation(TM) and control subjects

BACKGROUND

Research on human ultra-weak photon emission (UPE, biophoton emission) has raised the question whether a typical human emission anatomic percentage distribution pattern exists in addition to individual subject overall anatomic summation intensity differences. The lowest UPE intensities were observed in two subjects who regularly meditate. Spectral analysis of human UPE has suggested that ultra-weak emission is probably, at least in part, a reflection of free radical reactions in a living system. It has been documented that various physiologic and biochemical shifts follow the long-term practice of meditation and it is inferred that meditation may impact free radical activity.

OBJECTIVE

To systematically quantify, in subjects with long-term transcendental meditation (TM) experience and subjects without this experience, the UPE emission of the anterior torso, head and neck plus the hands in an attempt to document the differences by the two groups.

SUBJECTS

Subjects were 20 men reported to be healthy and nonsmokers. Each of the subjects in the meditation group had practiced TM twice daily for at least the past 10 years.

METHODS

UPE in 20 subjects was recorded in a dark room using a highly sensitive, cooled photomultiplier system designed for manipulation in three directions. The protocol for multisite registration of spontaneous emission includes recording of 12 anatomic locations of anterior torso, head, and hands.

RESULTS

Data demonstrate emission intensities that are lower in TM practitioners as compared to control subjects. The percent contribution of emission from most anatomic locations was not significantly different for TM practitioners and control subjects. Exceptions are the contributions of throat and palm.

CONCLUSION

In subjects with long-term TM experience, the UPE emission is different from control subjects. Data support the hypothesis that free radical reactions can be influenced by TM.

Inactivation mechanism of tyrosinase in mouse melanoma

Tyrosinase [EC 1.14.18.1] isolated from mouse melanoma was inactivated during the dopa-tyrosinase reaction. When ascorbate was added to the reaction system, in which dopa-quinone is immediately converted back to dopa by ascorbate thus preventing the formation of melanin, tyrosinase inactivation similarly occurred. If superoxide anions (O2-) or singlet oxygens (1O2), are generated during the reaction they can attack the enzyme protein to be inactivated. Therefore an estimate was made with scavengers for oxygen radicals and with a liquid scintillation counter but neither was detectable. Thus the inactivation involved is not due to reaction products nor oxygen

Mitochondrial GPx1 decreases induced but not basal oxidative damage to mtDNA in T47D cells

The production of oxyradicals by mitochondria (mt) is a source of oxidative damage to mtDNA such as 8-oxo-dG lesions that may lead to mutations and mitochondrial dysfunction. The potential protection of mtDNA by glutathione peroxidase-1 (GPx1) was investigated in GPx1-proficient (GPx-2) and GPx1-deficient (Hygro-3) human breast T47D cell transfectants. GPx activity and GPx1-like antigen concentration in mitochondria were respectively at least 100-fold and 20- to 25-fold higher in GPx2 than Hygro-3 cells. In spite of this large difference in peroxide-scavenging capacity, the basal 8-oxo-dG frequency in mtDNA, assessed by carefully controlled postlabeling assay, was strikingly similar in both cell lines. In contrast, in response to menadione-mediated oxidative stress, induction of 8-oxo-dG and DNA strand breaks was much lower in the GPx1-proficient mitochondria (e.g., +14% 8-oxo-dG versus +54% in Hygro-3 after 1-h exposure to 25 microM menadione, P < 0.05). Our data indicate that the mitochondrial glutathione/GPx1 system protected mtDNA against damage induced by oxidative stress, but did not prevent basal oxidative damage to mtDNA, which, surprisingly, appeared independent of GPx1 status in the T47D model.

Characteristics of chemiluminescence observed in the horseradish peroxidase-hydrogen peroxide-tyrosine system

Electrolysis or horseradish peroxidase (HRP)-catalyzed oxidation of tyrosine and bityrosine in aqueous solution at pH 7.4 resulted in light emission in the visible region. Electrolysis of tyrosine emitted light which peaked at 490 nm and was almost completely quenched by superoxide dismutase (SOD), while emission by bityrosine peaked at 530 nm. In the HRP-H(2)O(2)-tyrosine system the oxidation-reduction of tyrosine emitted light with two prominent peaks, 490 and 530 nm, and was not quenched by SOD. The phenoxyl neutral radical of the tyrosine in HRP-H(2)O(2)-tyrosine system was detected by electron spin resonance (ESR) spectrometry using tert-nitrosobutane as a spin trap; the spin adduct was found to adhere to the HRP molecule during the enzymatic reaction. Further, bityrosine was detected in the HRP-H(2)O(2)-tyrosine reaction system. Changes in absorption spectra of HRP and chemiluminescence intensities during HRP-catalyzed oxidation of tyrosine suggest that for photon emission compound III is a candidate superoxide donor to the phenoxyl cation radical of tyrosine on the enzyme molecule. The luminescence observed in this study might be originated from at least two exciplexes involved with the tyrosine cation radical (Tyr(*+)) and the bityrosine cation radical (BT(*+))

Antioxidant status following acute ischemic limb injury: a rabbit model

Although ischemic injury to skeletal muscle is a matter of great clinical importance, relatively little is known about the mechanisms which determine systemic responses. One purpose of this study is to elucidate the systemic antioxidant status following an episode of acute ischemic limb injury and subsequent reperfusion. Twelve New Zealand white rabbits were used in this study. After the animals were anesthetized, an ischemic insult was created in the right hind limb for twelve hours, followed by four hours of reperfusion. Several series of blood samples were obtained. At the end of the experiment, the animals were killed and necropsies undertaken in order to evaluate the antioxidant status of various visceral organs. The results link ischemia and reperfusion injury to a significant decline in antioxidative activity in various tissues. The weakening in antioxidant status after ischemic limb injury was most pronounced in the heart tissue, followed in descending order by the spleen, skeletal muscle, lung, liver, and kidney tissue. The levels of specific antioxidants and reactive oxygen species in various organs changed significantly, and the changes were tissue specific. Endogenous radical scavenging systems were not entirely overwhelmed in most of the tissues studied. But higher levels of malondialdehyde (MDA) found in cardiac tissue suggest that the production of oxygen free radicals is accelerated by an ischemic injury. Based on the study, we believe that the cardiac tissue is particularly susceptible to the effects of ischemia and reperfusion injury. Damage to cardiac tissue is probably the major cause of mortality following acute ischemic injury in a limb.

Roles of oxygen radicals and elastase in citric acid-induced airway constriction of guinea-pigs

Antioxidants attenuate noncholinergic airway constriction. To further investigate the relationship between tachykinin-mediated airway constriction and oxygen radicals, we explored citric acid-induced bronchial constriction in 48 young Hartley strain guinea-pigs, divided into six groups: control; citric acid; hexa(sulphobutyl)fullerenes + citric acid; hexa(sulphobutyl)fullerenes + phosphoramidon + citric acid; dimethylthiourea (DMTU) + citric acid; and DMTU + phosphoramidon + citric acid. Hexa(sulphobutyl)fullerenes and DMTU are scavengers of oxygen radicals while phosphoramidon is an inhibitor of the major degradation enzyme for tachykinins. Animals were anaesthetized, paralyzed, and artificially ventilated. Each animal was given 50 breaths of 4 ml saline or citric acid aerosol. We measured dynamic respiratory compliance (Crs), forced expiratory volume in 0.1 (FEV0.1), and maximal expiratory flow at 30% total lung capacity (Vmax30) to evaluate the degree of airway constriction. Citric acid, but not saline, aerosol inhalation caused marked decreases in Crs, FEV0.1 and Vmax30, indicating marked airway constriction. This constriction was significantly attenuated by either hexa(sulphobutyl)fullerenes or by DMTU. In addition, phosphoramidon significantly reversed the attenuating action of hexa(sulphobutyl)fullerenes, but not that of DMTU. Citric acid aerosol inhalation caused increases in both lucigenin- and t-butyl hydroperoxide-initiated chemiluminescence counts, indicating citric acid-induced increase in oxygen radicals and decrease in antioxidants in bronchoalveolar lavage fluid. These alterations were significantly suppressed by either hexa(sulphobutyl)fullerenes or DMTU. An elastase inhibitor eglin-c also significantly attenuated citric acid-induced airway constriction, indicating the contributing role of elastase in this type of constriction. We conclude that both oxygen radicals and elastase play an important role in tachykinin-mediated, citric acid-induced airway constriction.

Detection of active oxygen species in biological systems

1. Cypridina luciferin analogues, 2-methyl-6-(p-methoxyphenyl)-3,7- dihydroimidazo[1,2-a]pyrazin-3-one (MCLD) and 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one(CLA ), react with O2- or 1O2 to emit light in visible region. Such chemiluminescences were used for the detection of O2- or 1O2 in activated leukocyte systems and myeloperoxidase (granulocyte-extract) + Br- + H2O2 systems in vitro. 2. The mechanisms of MCLA (CLA)-dependent luminescence is described in detail. Superoxide generated from sinusoidal cells in acute ethanol intoxication of rats was detected by MCLA-dependent luminescence from the surface of perfused rat liver (organ luminescence). 3. Furthermore, with alive animals, O2- generated in the lung of rats with necrotized pancreatitis and that in the stomach of rats after ischemia/reperfusion were detected by their organ luminescences.

An ultra-weak chemiluminescence study on oxidative stress in rabbits following acute thermal injury

It is not easy to detect oxygen free radicals directly because of their very short half-life. In the present study, a sensitive ultra-weak chemiluminescence detector was used to detect the generation of oxygen free radicals following thermal injury. Twelve New Zealand white rabbits were used in this study. After anesthesia, the bilateral hind-limbs were exposed to 100 degrees C water for 30 s. Six control animals were exposed to 22 degrees C water to act as a control. The chemiluminescence of whole blood and visceral organs were measured with both luminol-amplified t-butyl hydroperoxide-initiated and lucigenin-initiated methods. The results showed that chemiluminescence of blood was affected significantly by acute thermal injury. The chemiluminescence of blood increased significantly at 1 h following acute thermal injury, reached a peak at 2 h, then decreased but still remained above the control level at 4 h following thermal injury. The results for TBHP-initiated chemiluminescence from visceral organs following acute thermal injury were much higher than that of the control rabbits. The effects of lucigenin-initiated tissue chemiluminescence following acute thermal injury were not statistically significant. It is suggested that the decreased vascular antioxidant activity following local thermal injury is partially contributed by the superoxide pathway; while, the remote pathophysiologic events are mediated by the defective scavenging defenses.

Quantification of singlet oxygen from hematoporphyrin derivative by electron spin resonance

The mechanism of the generation and the quantitative analysis of singlet oxygen (1O2) formed by the exposure of a hematoporphyrin derivative (HpD) to light was re-evaluated by electron spin resonance (ESR) combined with 2,2,6,6,-tetramethyl-4-piperidine (TMPD). The change from TMPD to 2,2,6,6,-tetramethyl-4-piperidine-N-oxide (TAN) has been reported to depend on singlet oxygen. However, we confirmed that this reagent also react with superoxide anion (O2-) and hydroxyl radicals (OH). Therefore, the reactions between TMPD and 1O2, O2- and OH were re-examined using a kinetic approach. We found that the generation of TAN was proportional to the concentration of TMPD and HpD, as well as to the duration and strength of the illumination. The generation of TAN was not inhibited by dimethyl-sulfoxide (DMSO) or superoxide dismutase (SOD). The reaction rate between TMPD and 1O2 was determined to be 5.0 x 10(-7) M min-1. The generation of 1O2 from HpD was 2.7 x 10(-7) M min-1 under our conditions. The competitive reaction observed between 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and TMPD for O2- or OH shows that TMPD reacts with both forms of active oxygen, but gave no ESR signal. The second-order reaction rate constant of TMPD between O2- and OH was calculated as 73 M-1 s-1 and 1.5 x 10(9) M-1 s-1, respectively. The photochemical generation of 1O2 from methylene blue, another sensitizer, was also demonstrated by this method. These results show that ESR signal of TAN can be used for the highly selective monitoring of 1O2.

Chemiluminescence from human polymorphonuclear leukocytes activated with opsonized zymosan

To prove the mechanism of photon emission during activation of leukocytes, a model system of human polymorphonuclear leukocytes (PMNs)-opsonized zymosan (OZ)-tyrosine (or none) or myeloperoxidase (MPO)-H2O2-tyrosine was employed, and three parameters-chemiluminescence yield and intensity, a metabolite such as bityrosine (BT), and chemiluminescence spectra-were studied. With the PMN system, the luminescence was enhanced by addition of tyrosine, its analogues, or albumin, but was inhibited by hydroxyurea, superoxide dismutase (SOD), or NaN3 (an inhibitor of MPO), indicating participation of tyrosine phenoxyl radicals, O2.- and MPO in the luminescence. With the PMN-OZ-tyrosine system, chemiluminescence yield was parallel to the BT formation. These results were essentially the same as those obtained with the MPO-H2O2-tyrosine system, except that luminescence from the latter system was not inhibited by SOD. When human albumin was exposed to the MPO-H2O2 system, BT was detected after hydrolysis of the protein in the mixture. Judging from the chemiluminescence spectra of activated PMNs and the MPO-catalyzed tyrosine oxidation, at least two excited species in triplet states-one for tyrosine and another for BT-would be generated in these systems. The luminescence may originate from the reaction of tyrosine phenoxyl radicals (cation radicals) with O2.- and/or peroxidase compound III (Fe...IIIO2.-).

Free radicals production and estimation of oxidative stress related to gamma irradiation

The effectiveness of chemiluminescence (ChL) in vitro to measure free radicals generated as a result of metabolic disorganization caused by radiation sickness is evaluated. The results are correlated with those obtained by measuring superoxide dismutase (SOD) activity and lipid peroxide as levels of thiobarbituric acid reacting substances (TBARS). To this aim, livers from irradiated Wistar rats were removed immediately (day 0) after irradiation and also 7 and 14 d later. ChL results, expressed in arbitrary units (AU)/min/mg protein, were analyzed for irradiated samples and controls, for different doses at different times. Increased levels of ChL emission were observed not only on day 0, but also on days 7 and 14. On the other hand, SOD activity showed a decrease on the 7th d, and significantly higher lipid peroxide levels were observed in the assays performed on the 14th d, at all exposure doses. The correlation between temporal changes in the SOD activity, ChL emission, and higher TBARS levels a week later were evident from the data. These results indicate that the ChL technique proved to be useful in combination with other techniques currently used for evaluating radiation oxidative injury.

Lipid peroxidation and chemiluminescence during naproxen metabolism in rat liver microsomes

1. Rat liver microsomal suspension containing NADPH and MgCl2 was incubated at 37 degrees C with naproxen, a non-steroidal anti-inflammatory drug. Thiobarbituric acid reactive substances (TBA-RS), high molecular weight protein aggregates and fluorescent substances were formed in the microsomal suspension. 2. Chemiluminescence was produced from the microsomal suspension. This chemiluminescence production was well correlated to the TBA-RS formation, indicating that the chemiluminescence production was closely associated with the lipid peroxidation. 3. The addition of SKF-525A to the microsomal suspension inhibited the production of TBA-RS, chemiluminescence and 6-demethylnaproxen (6-DMN), the oxidative product of naproxen. Further, the antioxidant, alpha-tocopherol and singlet oxygen quenchers like histidine, dimethylfuran and 1,4-diazabicyclo[2,2,2]octane strikingly inhibited the productions of chemiluminescence and TBA-RS. 4. Neither naproxen nor 6-DMN caused lipid peroxidation in the absence of NADPH. Thus, lipid peroxidation and chemiluminescence during the oxidation of naproxen in liver microsomes was suggested to be provoked by reactive oxygen species and an origin of chemiluminescence was shown to be singlet oxygen.

Mutational specificity of oxidative DNA damage

In this paper we describe our studies on the mutagenic consequences of oxidative DNA damage introduced by radiation-induced OH radicals (.OH) and by exposure to singlet oxygen (1O2), released by thermo-dissociation of the endoperoxide 3,3'-(1,4-naphthalidene) dipropionate (NDPO2). We have made use of M13mp10 bacteriophage and pUC18 plasmid DNA, containing a 144 base pair (bp) insert in the lacZ alpha gene. This 144 bp insert was used as a mutational target sequence. When dilute aqueous solutions of double-stranded (ds) M13mp10 (plus 144 bp insert) were gamma-irradiated in the presence of oxygen (O2; 100% .OH) or nitrous oxide (N2O; 90% .OH, 10% .H), very specific mutation spectra were found. Mainly bp substitutions were observed, of which C/G to G/C transversions are the predominant type. Moreover, the mutations are for the most part concentrated into two mutational hot spots: a minor and major one. Differences between the oxic (O2) and anoxic (N2O) mutation spectra could also be observed. Under N2O-1 bp deletions were detected, which are absent in the presence of O2, and in the anoxic spectrum more C/G to A/T transversions are present. To investigate whether these differences were due to the small amount of H radicals, which are formed under N2O, ds M13mp10 (plus 144 bp insert) was exposed to gamma-rays in phosphate buffer under nitrogen (55% .H, 45% .OH). Under these conditions a remarkable shift was observed from C/G-->G/C to C/G-->A/T transversions, while the mutations were far more scattered along the 144 bp sequence and no -1 bp deletions were detected. These results strongly suggest that H radicals do not cause -1 bp deletions, but may be responsible for the observed C/G to A/T transversions. The kind of bp substitution not only appeared to be dependent on the type of the water radicals, but also appeared to be strongly influenced by the replicon in which the target sequence is incorporated. When an oxygenated solution of pUC18 plasmid DNA (plus 144 bp insert) is irradiated, mainly C/G to A/T transversions were found at the same major hot spot instead of C/G to G/C transversions when the 144 bp sequence is part of M13mp10 DNA. Finally, in agreement with the observation that 1O2 reacts preferentially with guanine in DNA, a guanine is involved in most of the mutations scored after exposure of single-stranded (ss) M13mp10 DNA to NDPO2-generated 1O2.(ABSTRACT TRUNCATED AT 400 WORDS)

Lipid peroxidation in rat liver microsomes during naproxen metabolism

Naproxen, a non-steroidal anti-inflammatory drug, is known to be highly effective and relatively safe, but some side-effects in the liver have been reported. In the present study, the effect of naproxen metabolism on rat liver microsomes was studied by determining lipid peroxidation in terms of thiobarbituric acid reactive substances (TBA-RS), high molecular weight protein aggregates and fluorescent substances formed in the microsomal suspension containing naproxen, NADPH and MgCl2. Lipid peroxidation was found to occur at 10 mM naproxen. Production of chemiluminescence from the microsomal suspension was observed during naproxen metabolism. The time course of 6-demethyl-naproxen formation by O-demethylation of naproxen appeared to be comparable to that of the chemiluminescence production in their initial periods of production. These results suggest that the lipid peroxidation was provoked through the reactive oxygen species generated during the oxidative metabolism of naproxen.

Degradation of methyl and ethyl mercury into inorganic mercury by hydroxyl radical produced from rat liver microsomes

Liver microsomes were prepared from Wistar rat by the Ca2+ aggregation method. Under various conditions, ethyl mercury chloride (EtHgCl) or methyl mercury chloride (MeHgCl) was incubated with the microsomal preparations. After the incubation, the amounts of inorganic Hg and hydroxyl radical (.OH) in the preparations were determined. Although the preparations alone produced a small amount of inorganic Hg and .OH, the addition of NADPH to the preparations increased both inorganic Hg and .OH production, which were further accelerated by the addition of KCN. The addition of Fe(III)EDTA, a .OH formation promoter, to the microsome-NADPH-KCN system increased inorganic Hg production, whereas the addition of diethylenetriamine pentaacetic acid, a .OH formation inhibitor, decreased inorganic Hg production. When .OH scavengers such as mannitol and dimethyl sulfoxide were added to this system, the inorganic Hg production decreased. These results suggested that the .OH produced from liver microsomes was responsible for the degradation of MeHg and EtHg. Since both .OH and inorganic Hg production decreased with a concomitant decrease in NADPH-cytochrome P-450 reductase activities, it is suggested that this enzyme may be involved in the microsomal degradation of MeHg and EtHg.

Mechanism for the generation of superoxide anion and singlet oxygen during heme compound-catalyzed linoleic acid hydroperoxide decomposition

Heme compound, hematin or cytochrome c, catalyzes the decomposition of 13-hydroperoxy linoleic acid yielding both O2- and 1O2 under aerobic conditions. No 1O2 is produced when hydrogen peroxide and cumene hydroperoxide are used as substrates. In these experiments, both O2- and 1O2 could be precisely detected by a chemiluminescence method using a cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin++ +-3-one, as a chemiluminescence probe, in the absence and presence of Cu-Zn superoxide dismutase in catalytic amounts. The reduction and oxidation cycle of ferric heme compound and the bimolecular reaction of peroxyl radicals are plausible reaction mechanisms for O2- and 1O2 production, respectively, in the systems studied.

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.

Light-induced photon emission by rat hepatocytes and hepatoma cells

We have investigated spontaneous and light-induced photon emission of suspensions of rat hepatocytes and of HTC hepatoma cells. Rat hepatocytes exhibit spontaneous biophoton emission, but from hepatoma cells this was not detectable. In contrast, after irradiation with white light, the reemission intensity was found to be lower for hepatocytes than for the tumor cell line. Induced photon emission was neither influenced by anaerobiosis nor by the intactness of the cells. Cell-fractionation studies demonstrate that the induced photon emission was caused by the nuclear fraction and by isolated chromatin. Phenol-extracted DNA, however, has lost this capacity. Our data suggest that differences in the chromatin structure may explain the cell-specific induced photon emission.

The pentose phosphate pathway in skeletal muscle under patho-physiological conditions. A combined histochemical and biochemical study

Over the last 30 years, research into the neuromuscular apparatus, has expanded greatly. Multidisciplinary investigations have rapidly advanced our understanding both of diseases and of the basic neuromuscular mechanisms. The mode of pathological reaction of the neuromuscular apparatus is now quite well understood. The most notable aspect of the reaction of the injured neuromuscular apparatus is the remarkably stereotyped character of the resulting pathological changes as demonstrated by a wide variety of harmful causes, producing surprisingly similar effects. The findings of our combined histochemical and biochemical investigations presented in this monograph, are in complete harmony with the stereotyped character of the pathological changes. For example, it is particularly striking that many affected muscle fibres of patients with muscular dystrophies, congenital myopathies, inflammatory myopathies, metabolic myopathies, endocrine myopathies, or with diseases of the lower motor neuron, display an enhanced activity of both oxidative enzymes of the pentose phosphate pathway. Likewise, we found that experimental animals with disordered skeletal muscles, provoked by different types of agents or treatments, reveal the same marked rise in activity of GPDH and PGDH in the muscle fibres, with a positive correlation between the activity of both enzymes. Other findings of our investigations point to a positive correlation between the activity of GPDH and PGDH on the one hand and that of the non-oxidative enzymes of the pentose phosphate pathway, the enzymes TA, TK, RPI and RPE on the other hand. The rise in activity of PGDH and, in particular, of GPDH is regulated by two different mechanisms. The first represents a rapid control mechanism based on the stimulation of both oxidative enzymes of the pentose phosphate pathway by NADP+ and on their inhibition by NADPH. The other mechanism represents a long-term effect directed at the synthesis of the enzymes. It is this type of mechanism which is responsible for the rise in activity of GPDH and PGDH we observed. The findings obtained with the applied enzyme histochemical techniques clearly demonstrated that the rise in activity of both enzymes is not homogeneously distributed in the disordered skeletal muscles of man and experimental animals. For that reason, in order to obtain reliable quantitative information about enzyme activities in the muscle fibres themselves, the application of biochemical assays on a micro-scale was indispensable. The biochemical assay of enzyme activities was performed on histologically and histochemically selected dissected muscle specimens.(ABSTRACT TRUNCATED AT 400 WORDS)

Singlet oxygen induced mutagenesis of benzo[a]pyrene derivatives

Singlet oxygen activates the mutagenicity of several benzo[a]pyrene (BP) derivatives in the absence of mammalian metabolic action. This has been demonstrated using a separated-surface-sensitizer system for generating chemically pure singlet oxygen, eliminating most of the complications that arise with singlet oxygen generation by conventional photosensitization. Salmonella typhimurium bacteria were exposed to singlet oxygen in the presence of certain BP derivatives and the mutation frequency determined with an azaguanine forward mutation assay. The mutation frequency was increased by exposure to singlet oxygen compared to light-only controls for those BP derivatives that were saturated at either the 7,8 or 9,10 positions but not both. The increase in mutation frequency depends on both the concentration of BP derivative and on the dose of singlet oxygen. Mutation frequency was also significantly increased when bacteria were treated with a solution of trans-7,8-dihydrodiol-BP that had been separately exposed to singlet oxygen, unequivocally demonstrating that the mutagenicity is due to the formation of a product of BP derivative oxidation by singlet oxygen and that this product has a lifetime at least on the order of minutes in acetonitrile. The requirement for singlet oxygen rather than some other form of reactive oxygen was confirmed by determination of the gas phase lifetime of the intermediate responsible for activating mutagenicity. This was performed by measuring the dependence of the mutation frequency on the distance separating the sensitizer from the target. This gives a value of 88 +/- 35 ms, which is in excellent agreement with the mean value of 89 ms calculated from previous independent determinations of the gas phase lifetime of singlet oxygen reported in the literature.

Low-level chemiluminescence during lipid peroxidations and enzymatic reactions

Low-level chemiluminescence during lipid peroxidation and enzymatic reaction have been analysed by a filter type spectrometer. Tyrosine and tryptophan residues in proteins were found to be emitters in the visible region during their enzymatic oxidation. The natural chemiluminescence from fertilization of sea urchin eggs was found to have originated from tyrosine--cation radical mediated reaction in ovo-peroxidase--membrane protein--H2O2 system.

Changes in membrane constituents and chemiluminescence in vitamin E-deficient red blood cells induced by the xanthine oxidase reaction

The oxidation of vitamin E-deficient rat red blood cells (RBCs) induced by the hypoxanthine-xanthine oxidase (HX-XOD) system has been performed in an aqueous suspension. The generation of chemiluminescence and the accumulation of thiobarbituric acid-reactive substances (TBARS) were observed initially and were followed by hemolysis. Interestingly, the total counts of chemiluminescence were closely related to the amount of TBARS. The predominant change of membrane proteins induced by the reaction was the depletion of spectrin bands in gel electrophoresis. When RBC ghosts were oxidized with HX-XOD, the sulfhydryl (SH) groups of membrane proteins decreased at an early stage of the incubation, which was coincident with the above protein alteration. Membrane alpha-tocopherol suppressed not only the formation of TBARS but also chemiluminescence and hemolysis; nevertheless, it did not inhibit the protein damage and the loss of SH groups. Moreover, it was concluded that the chemiluminescence observed during the oxidation of RBC membranes was associated mainly with the peroxidation of lipids and only to a minor extent with the oxidation of proteins.

Steady-state fluorescence anisotropy and multifrequency phase fluorometry on oxidized phosphatidylcholine vesicles

Multilamellar liposomes, from mixtures of unoxidized (control) and singlet oxygen oxidized phosphatidylcholine, were studied by steady-state fluorescence anisotropy and multifrequency phase fluorometry using 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescent probe. Lifetime fluorescence decay of the DPH-labeled liposomes was analyzed either by a model of discrete exponential components and a model that assumes a continuous distribution of lifetime values. Increasing the oxidized phosphatidylcholine content in the liposomes, an increase of the membrane interior polarity and a decrease of membrane fluidity occurs which can be related to the hydroperoxide-lipids and double bonds conjugation, respectively.

Singlet oxygen production by biological systems

Singlet oxygen (1 delta g) is a highly reactive, short-lived intermediate which readily oxidizes a variety of biological molecules. The biochemical production of singlet oxygen has been proposed to contribute to the destructive effects seen in a number of biological processes. Several model biochemical systems have been shown to produce singlet oxygen. These systems include the peroxidase-catalyzed oxidations of halide ions, the peroxidase-catalyzed oxidations of indole-3-acetic acid, the lipoxygenase-catalyzed oxidation of unsaturated long chain fatty acids and the bleomycin-catalyzed decomposition of hydroperoxides. Results from these model systems should not be uncritically extrapolated to living systems. Recently, however, an intact cell, the human eosinophil, was shown to generate detectable amounts of singlet oxygen. This result suggests that singlet oxygen may be shown to be a significant biochemical intermediate in a few biological processes.

Regulatory aspects of low intensity photon emission

Photon emission from unicellular and multicellular organisms has been a subject of study for many decennia. In contrast to the well-known phenomenon of bioluminescence originating in luciferin-luciferase reactions, low intensity emission in the visible region of the electromagnetic spectrum has been found in almost every species studied so far. At present, the nomenclature of this phenomenon has not crystallized and it is referred to by a variety of names, such as mitogenetic radiation 29, dark luminescence 7, low-level chemiluminescence 20,36, and biophotons 57. Particular attention has been focussed on the relationship between photon emission and the regulation of various aspects of cellular metabolism, although in many cases quantitative data are still lacking. Throughout the history of this field of research the question of a functional biological role of the low intensity emission has been repeatedly raised; this is reflected, for instance, in the heterogeneity of the terms used to describe it. The discussion concerns the possible participation of photons of low intensity in intra- and intercellular communication. This paper reviews literature on the metabolic regulation of low intensity emission, as well as the regulation of photon emission initiated by external light. Furthermore, recent data are discussed with respect to a possible biocommunicative function of low intensity photon emission.

Super-high sensitivity systems for detection and spectral analysis of ultraweak photon emission from biological cells and tissues

In this paper we summarize and discuss the modern technology and systems, studied and established by our research group, for performing the detection and special analysis incorporated with the super-high sensitivity photon counting method for the study of ultraweak photon emission; for example, extra-weak bioluminescence and chemiluminescence from living cells and tissues, closely related to biochemical and biophysical processes and activities. An excellent sensitivity of the basic photon counting system, making it possible to achieve count rates in the very low range of one photoelectron per second to one per minute, allowed us to carry out in vivo as well as in vitro measurements, and analyses of ultraweak bioluminescence and chemiluminescence. Recent results concerning ultraweak photon emission from blood samples and organ homogenates of rats are presented and reviewed as one of the interesting and valuable applications of our modern technology for studying ultraweak cell and tissue radiation.

Chemiluminescence studies on the generation of oxygen radicals from the interaction of NADPH-cytochrome P-450 reductase with iron

The ability of NADPH-cytochrome P-450 reductase to interact with iron and generate oxygen radicals was evaluated by assaying for low level chemiluminescence. The basic reaction system which contained the reductase, an NADPH-generating system, ferric-EDTA as an electron acceptor, and t-butyl hydroperoxide as the oxidant acceptor, resulted in the production of chemiluminescence. Omission of any of these components resulted in a complete loss of chemiluminescence. The light emission was completely sensitive to inhibition by glutathione and butylated hydroxytoluene, partially sensitive (about 60% decrease) to catalase and hydroxyl radical scavengers, and relatively insensitive (about 20% decrease) to superoxide dismutase. The ability of other ferric chelates to replace ferric-EDTA in catalyzing the reductase-dependent chemiluminescence was evaluated. Ferric-citrate, -ADP, -ATP, and ferric-ammonium sulfate were ineffective in promoting chemiluminescence, whereas ferric-diethylenetriaminepentaacetic acid was even more effective than ferric-EDTA. Thus, the ferric chelates, which catalyze reductase-dependent chemiluminescence, are those which are efficient electron acceptors from the reductase and were previously shown to be those capable of catalyzing hydroxyl radical production by microsomes and the reductase. It is suggested that chemiluminescence results from (a) the direct interaction of the reduced iron chelate with the hydroperoxide (Fenton-type of reaction) to generate alkoxyl and peroxyl radicals, and (b) the generation of hydroxyl radicals, which subsequently react with the hydroperoxide to generate secondary radicals. The latter, but not the former, would be sensitive to inhibition by catalase and competitive hydroxyl radical scavengers, whereas both would be sensitive to antioxidants such as butylated hydroxytoluene. Chemiluminescence appears to be a versatile tool for studying the reductase-dependent generation of oxygen radicals and for the interaction of reductase with iron.

Chemiluminescence probe with Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one, for estimating the ability of human granulocytes to generate O2-

The Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA), in Hanks' balanced salt solution, emitted a weak luminescence which was not affected by superoxide dismutase or catalase and was not augmented by resting human granulocytes. In contrast, activated granulocytes caused a dramatic increase in the luminescence of CLA. The light emission by CLA in the presence of activated granulocytes was inhibited by superoxide dismutase, but not by catalase or benzoate. Azide at 0.5 mM did not inhibit light emission significantly. These results indicate that O2-, rather than H2O2, HO., singlet oxygen, or HOCl, was the agent responsible for eliciting the chemiluminescence of CLA. Moreover, the intensity of light emission by CLA correlated with the rate of production of O2- either by activated neutrophils or by the xanthine oxidase reaction.

Visible chemiluminescence from rat brain homogenates undergoing autoxidation. I. Effect of additives and products accumulation

Rat brain homogenate autoxidation was assessed from thiobarbituric acid reactant accumulation (TBAR), light emission, and oxygen uptake. The effect of several additives upon TBAR accumulation and light intensity suggests that these parameters can be employed as a reliable measure of the lipoperoxidation extent. From the different time profiles of TBAR accumulation and light emission, it is concluded that instantaneous light emission is not a measure of the lipoperoxidation rate but it is related to the accumulation of products. The time dependence of the light emitted after addition to an incubated sample of an excess of free radical scavengers indicates that at least two intermediates of widely different lifetimes are contributing to the observed light emission.

Generation of electronically excited species during enzymatic oxidation of chlorpromazine and related compound

Chemiluminescence in visible region was detected, during peroxidase-catalyzed oxidation of chlorpromazine at pH7.5 (but not at pH4.25) or of propericiazine, both at pH7.5 and at pH4.25. Red colored intermediates, cation radicals, were produced and decayed in all enzymatic systems used. Chemiluminescence was also detected at pH7.5, but not at pH4.25, when synthesized cation radical of chlorpromazine in water was mixed with concentrated buffer. Protonation of alkyl nitrogen in the cation radical of chlorpromazine was highly related to the appearance of luminescence. Possible mechanisms of the generation of the excited phenothiazine analogs were discussed.

Chemiluminescence in L-tyrosine-H2O2-horseradish peroxidase system: possible formation of tyrosine cation radical

Tyrosine-H2O2-horseradish peroxidase system at pH 7.4 emitted light in visible region. Phenolic compounds other than tyrosine were also emissive, whereas methoxy phenylalanine and phenyl compounds were not, in H2O2-peroxidase systems. Chemiluminescence spectrum of tyrosine of tyrosine-H2O2-horseradish peroxidase system showed two prominent peaks at 478 nm and 500 nm (Luminescence 1) and additional two or three peaks near 550 and 610 nm (Luminescence 2). Luminescence 1 is quite similar to the phosphorescence originated from an excited tyrosine in triplet state, while Luminescence 2 is quite similar to the phosphorescence originated from an indole in triplet state. Possible formation of tyrosine cation radical (a precursor of the excited tyrosine) and indole cation radical in the enzyme protein (a precursor of the excited tryptophan residue) were discussed.

Singlet oxygen in copper-catalyzed lipid peroxidation in erythrocyte membranes

Lipid hydroperoxide was generated in human erythrocyte membranes by irradiation with near ultraviolet (UV) light in the presence of a photosensitizer, hematoporphyrin, but no production of 2-thiobarbituric acid-reactive materials (malonaldehyde and its precursors) was detected. Incubation of the irradiated membranes with CuSO4 led to increased levels of hydroperoxide and formation of malonaldehyde. Hydroperoxides were essential for initiating the Cu(II)-catalyzed peroxidation as no significant activity was observed with nonirradiated membranes and Cu(II) unless an organic peroxide, either t-butyl hydroperoxide or cumene hydroperoxide, was added. Catalytic activity was also found with Fe(II), but not with other metal ions tested. The peroxidation catalyzed with Cu(II) was partially inhibited by several singlet oxygen quenchers but was not affected by superoxide dismutase, catalase or OH radical scavengers. The possible involvement of singlet oxygen in the Cu(II)-catalyzed peroxidation reaction was further supported by a 3-fold enhancement of malonaldehyde production in D2O.

Correlation between hydroperoxide-induced chemiluminescence of the heart and its function

The isolated perfused rat heart emits a spontaneous ultraweak chemiluminescence. When the perfusion is stopped, light emission decreases, indicating the dependency of this phenomenon on aerobic metabolism. Emitted chemiluminescence was markedly enhanced following perfusion with 0.05 mM H2O2 or cumene hydroperoxide or tert-butyl hydroperoxide; substitution of O2 for N2 in the gassing mixture of the perfusion media significantly lowered photon emission. Lipid peroxidation, which is known to be associated with chemiluminescence, was evaluated by HPLC analysis of peroxidized and unperoxidized heart phosphatidylcholines. During hydroperoxide perfusion, coronary flow and heart rate progressively decreased, while lactic dehydrogenase was released after complete cardiac arrest. The resultant morphology of this damage corresponds to the so-called 'stone heart', a pattern already described in both human and experimental pathology.