Evidence Of Free Radical Damage Research Articles

Autism and EMF? Plausibility of a pathophysiological link – Part I

Although autism spectrum conditions (ASCs) are defined behaviorally, they also involve multileveled disturbances of underlying biology that find striking parallels in the physiological impacts of electromagnetic frequency and radiofrequency exposures (EMF/RFR). Part I of this paper will review the critical contributions pathophysiology may make to the etiology, pathogenesis and ongoing generation of core features of ASCs. We will review pathophysiological damage to core cellular processes that are associated both with ASCs and with biological effects of EMF/RFR exposures that contribute to chronically disrupted homeostasis. Many studies of people with ASCs have identified oxidative stress and evidence of free radical damage, cellular stress proteins, and deficiencies of antioxidants such as glutathione. Elevated intracellular calcium in ASCs may be due to genetics or may be downstream of inflammation or environmental exposures. Cell membrane lipids may be peroxidized, mitochondria may be dysfunctional, and various kinds of immune system disturbances are common. Brain oxidative stress and inflammation as well as measures consistent with blood–brain barrier and brain perfusion compromise have been documented. Part II of this paper will review how behaviors in ASCs may emerge from alterations of electrophysiological oscillatory synchronization, how EMF/RFR could contribute to these by de-tuning the organism, and policy implications of these vulnerabilities. Changes in brain and autonomic nervous system electrophysiological function and sensory processing predominate, seizures are common, and sleep disruption is close to universal. All of these phenomena also occur with EMF/RFR exposure that can add to system overload (‘allostatic load’) in ASCs by increasing risk, and worsening challenging biological problems and symptoms; conversely, reducing exposure might ameliorate symptoms of ASCs by reducing obstruction of physiological repair. Various vital but vulnerable mechanisms such as calcium channels may be disrupted by environmental agents, various genes associated with autism or the interaction of both. With dramatic increases in reported ASCs that are coincident in time with the deployment of wireless technologies, we need aggressive investigation of potential ASC – EMF/RFR links. The evidence is sufficient to warrant new public exposure standards benchmarked to low-intensity (non-thermal) exposure levels now known to be biologically disruptive, and strong, interim precautionary practices are advocated.

Autism and EMF? Plausibility of a pathophysiological link part II

Autism spectrum conditions (ASCs) are defined behaviorally, but they also involve multileveled disturbances of underlying biology that find striking parallels in the physiological impacts of electromagnetic frequency and radiofrequency radiation exposures (EMF/RFR). Part I (Vol 776) of this paper reviewed the critical contributions pathophysiology may make to the etiology, pathogenesis and ongoing generation of behaviors currently defined as being core features of ASCs. We reviewed pathophysiological damage to core cellular processes that are associated both with ASCs and with biological effects of EMF/RFR exposures that contribute to chronically disrupted homeostasis. Many studies of people with ASCs have identified oxidative stress and evidence of free radical damage, cellular stress proteins, and deficiencies of antioxidants such as glutathione. Elevated intracellular calcium in ASCs may be due to genetics or may be downstream of inflammation or environmental exposures. Cell membrane lipids may be peroxidized, mitochondria may be dysfunctional, and various kinds of immune system disturbances are common. Brain oxidative stress and inflammation as well as measures consistent with blood–brain barrier and brain perfusion compromise have been documented. Part II of this paper documents how behaviors in ASCs may emerge from alterations of electrophysiological oscillatory synchronization, how EMF/RFR could contribute to these by de-tuning the organism, and policy implications of these vulnerabilities. It details evidence for mitochondrial dysfunction, immune system dysregulation, neuroinflammation and brain blood flow alterations, altered electrophysiology, disruption of electromagnetic signaling, synchrony, and sensory processing, de-tuning of the brain and organism, with autistic behaviors as emergent properties emanating from this pathophysiology. Changes in brain and autonomic nervous system electrophysiological function and sensory processing predominate, seizures are common, and sleep disruption is close to universal. All of these phenomena also occur with EMF/RFR exposure that can add to system overload (‘allostatic load’) in ASCs by increasing risk, and can worsen challenging biological problems and symptoms; conversely, reducing exposure might ameliorate symptoms of ASCs by reducing obstruction of physiological repair. Various vital but vulnerable mechanisms such as calcium channels may be disrupted by environmental agents, various genes associated with autism or the interaction of both. With dramatic increases in reported ASCs that are coincident in time with the deployment of wireless technologies, we need aggressive investigation of potential ASC—EMF/RFR links. The evidence is sufficient to warrant new public exposure standards benchmarked to low-intensity (non-thermal) exposure levels now known to be biologically disruptive, and strong, interim precautionary practices are advocated.

Total antioxidant capacity and lipid peroxidation in liver transplantation.

Liver transplantation is an accepted therapy for chronic liver disease patients. These patients generally have low levels of fat soluble vitamins, which have important antioxidant roles. Therefore, this study was undertaken to investigate whether such patients had evidence of antioxidant depletion and increased lipid peroxidation before transplant and whether the subsequent ischemia and reperfusion encountered during liver transplantation have any effect on antioxidant levels and lipid peroxidation. We assessed plasma total antioxidant capacity and serum lipid peroxide in 12 patients undergoing liver transplantation and equal numbers of healthy subjects. We found that before reperfusion, antioxidant levels were significantly decreased along with significantly elevated lipid peroxidation levels as compared with healthy controls (P<0.001). On reperfusion of the liver graft, further declined values of total antioxidant accompanied with highly elevated lipid peroxidation were seen than those of pre-reperfusion samples (P<0.001). This data shows that patients undergoing liver transplant have lowered antioxidant defenses and evidence of free radical damage, which compound the additional insult of reperfusion injury. Therefore antioxidant therapy in these patients before transplantation may ameliorate the effects of reperfusion.

Prion disease and Alzheimer's disease: pathogenic overlap

Prion diseases are widely recognized for their transmissibility, and it is this feature that has been studied most extensively. In recent years, public health concerns over the transmission of animal forms of prion disease, such as bovine spongiform encephalopathy and chronic wasting disease, to humans has only augmented the notion that prion diseases are primarily infectious. Yet within the spectrum of human prion diseases, often overlooked is the fact that the overwhelming majority of cases are age-dependent sporadic, or inherited processes. Closer examination of the pathophysiological processes involved in prion disease further indicates a neurodegenerative, rather than infectious disease. Indeed, the age requirement, the numerous kindreds carrying point mutations in an amyloidogenic protein, the copper binding properties of the amyloidogenic protein, the evidence of free radical damage, the presence of polymorphisms that influence disease susceptibility, the formation of amyloid plaques, and in some cases the presence of neurofibrillary pathology, are features common to both prion disease and Alzheimer's disease. Therefore, while transmissibility will continue to be a major subject of prion disease research, we suspect that further characterization of its pathophysiological mechanisms will only substantiate the notion that prion disease is fundamentally a neurodegenerative process.

Free radical production by antibiotic-killed bacteria in the guinea pig middle ear.

Oxygen free radicals are implicated in the pathogenesis of otitis media Recent investigations with animal models have demonstrated that free radical-mediated damage of the middle ear mucosa, measured as lipid hydroperoxide, occurs when the middle ear cavity is inoculated with Streptococcus pneumoniae. The present study was conducted to examine the effect of antibiotics on free radical-mediated damage in pneumococcal acute otitis media. Animal model of acute otitis media. Seventy-eight guinea pigs underwent bilateral middle ear inoculation with 100 microl of 1) sterile saline as a control, 2) 50 microg/mL amoxicillin, 3) 10(7) colony forming units (CFU)/mL Streptococcus pneumoniae killed with 50 microg/mL amoxicillin, or 4) 10(7) CFU/mL S. pneumoniae. Animals were killed on postoperative day 1 or 5, and the middle ear mucosa was examined for lipid peroxidation as evidence of free radical damage. Mucosal lipid hydroperoxide was significantly elevated compared with control subjects on day 1 in both the antibiotic-killed S. pneumoniae group and the S. pneumoniae-infected group. On day 5, the S. pneumoniae-infected mucosa had significantly higher lipid hydroperoxide levels compared with the antibiotic-killed group and the control subjects. Histological studies confirmed mucosal edema and the presence of inflammatory cells in the infected groups. Antibiotic-killed bacteria seem to produce free radical-mediated damage to the middle ear mucosa in the early phase of acute otitis media. The clinical implication of this study is that free radical damage to the middle ear mucosa may occur in otitis media despite appropriate antibiotic therapy.

Evidence of oxygen free radical damage in human otitis media

Recent work with a guinea pig model of otitis media has demonstrated evidence of oxygen free radical damage to the middle ear mucosa. However, the relevance of an animal model to human disease is uncertain. Accordingly, the following pilot study was conducted to examine human middle ear fluid for lipid hydroperoxides as evidence of free radical damage. Thirty-five specimens of middle ear fluid from children with chronic otitis media were collected and described as mucoid (n = 19), purulent (n = 10), or serous (n = 6); specimens were weighed and analyzed for lipid hydroperoxide content. The results demonstrated the presence of lipid hydroperoxide in all 3 types of middle ear fluid. Additionally, there was a statistically significant elevation of total lipid hydroperoxide content in mucoid effusions compared with serous effusions, as well as a significant elevation of lipid hydroperoxide divided by weight of purulent effusions compared with serous effusions. This is the first study to document free radical damage in human otitis media. (Otolaryngol Head Neck Surg 1999;120:638-42.)

Xanthine oxidase activity and free radical generation in patients with sepsis syndrome.

To determine xanthine oxidase activity, free radical concentrations, and lipid peroxidation in patients with sepsis syndrome compared with noninfected critically ill patients. A prospective observational study. A nine-bed intensive care unit in a university teaching hospital trust. Fourteen consecutive patients who met the established criteria for sepsis syndrome with multiple organ dysfunction syndrome, and ten noninfected critically ill patients were studied. None. Xanthine oxidase activity was increased in septic patients compared with both healthy volunteers (p < .01) and noninfected patients (p < .05), and was highest in the six patients who survived (p < .05). Lipid peroxides were increased in both septic patients (p < .001) and nonseptic controls (p < .001). Xanthine oxidase activity did not relate to the Acute Physiology and Chronic Health Evaluation (APACHE) II score or to the presence of organ dysfunction. The mean ascorbyl radical concentration (arbitrary units) determined by electron paramagnetic resonance following spin trapping was increased in patients compared with healthy subjects (p < .05). Patients with sepsis have xanthine oxidase activation, high free-radical concentrations, and evidence of free radical damage. The finding that xanthine oxidase activity was lower in those patients who died, coupled with increased lactate concentrations implies more severe ischemia with incomplete reperfusion resulting in less xanthine oxidase "wash out" into the circulation. Increased ascorbyl radical concentrations may be due to an increased radical generation and oxidant scavenging, but appears to be unrelated to xanthine oxidase activity within the circulation.

Ascorbate and malondialdehyde in stroke patients

It is believed that free radical formation and subsequent oxidative damage in the form of lipid peroxidation may be a factor in the cerebral damage secondary to the ischaemia of a cerebrovascular accident (CVA). Total serum ascorbate and malondialdehyde (MDA) were measured in 45 patients with CVA on the day of admission to hospital (Time 0) and 48 hours later (Time 48 hours) and also in 45 age and sex matched controls. There was no statistical difference in total serum ascorbate between the control group (34.2 mumol/l +/- 3.1, mean +/- SEM) and the CVA patients at Time 0 (37.3 +/- 2.9) but there was a statistically significant decrease at Time 48 hours (22.7 +/- 2.0) (p < 0.001) in the CVA patients. With MDA there was no statistical difference between the patients at Time 0 (0.79 mumol/l +/- 0.06) and the control group (0.83 +/- 0.06) but there was a significant increase at Time 48 hours (1.65 +/- 0.08) (p < 0.001). These findings are in keeping with possible evidence of free radical damage in CVA.

Reperfusion injury, antioxidants and hemodynamics during orthotopic liver transplantation

Endothelial injury occurs as a result of oxygen free radical production after ischemia and reperfusion of transplanted livers, causing hemodynamic disturbance. Patients with chronic liver disease generally have low levels of fat-soluble vitamins, which have important antioxidant roles. We therefore assessed circulating levels of the antioxidants vitamin A, vitamin E, β-carotene and lycopene, indices of lipid peroxidation and hemodynamic changes during elective orthotopic liver transplantation in 12 patients. We found that initial antioxidant levels were severely depleted compared with healthy subjects, and in some patients carotene and lycopene levels were undetectable. Increased lipid peroxidation was also evident, as shown by thiobarbituric acid–reactive substances. On reperfusion of the liver graft, vitamin A and E levels fell (p < 0.01) and were associated with decreases in systemic vascular resistance (p < 0.02). These data show that patients undergoing liver transplant have lowered antioxidant defenses and evidence of free radical damage, which compound the additional insult of reperfusion injury. Antioxidant therapy in these patients before transplantation may ameliorate the effects of reperfusion. (Hepatology 1994;19:354–359).

Reperfusion injury, antioxidants and hemodynamics during orthotopic liver transplantation

Endothelial injury occurs as a result of oxygen free radical production after ischemia and reperfusion of transplanted livers, causing hemodynamic disturbance. Patients with chronic liver disease generally have low levels of fat-soluble vitamins, which have important antioxidant roles. We therefore assessed circulating levels of the antioxidants vitamin A, vitamin E, beta-carotene and lycopene, indices of lipid peroxidation and hemodynamic changes during elective orthotopic liver transplantation in 12 patients. We found that initial antioxidant levels were severely depleted compared with healthy subjects, and in some patients carotene and lycopene levels were undetectable. Increased lipid peroxidation was also evident, as shown by thiobarbituric acid-reactive substances. On reperfusion of the liver graft, vitamin A and E levels fell (p < 0.01) and were associated with decreases in systemic vascular resistance (p < 0.02). These data show that patients undergoing liver transplant have lowered antioxidant defenses and evidence of free radical damage, which compound the additional insult of reperfusion injury. Antioxidant therapy in these patients before transplantation may ameliorate the effects of reperfusion.

Evidence of free radical damage in the central nervous system of guinea-pigs at the prolonged acute and early relapse stages of chronic relapsing experimental allergic encephalomyelitis

Central nervous system tissue from guinea-pigs in various stages of chronic relapsing experimental allergic encephalomyelitis (CR-EAE) has been analysed for evidence of free radical damage using the thiobarbituric acid test as an indicator of oxidative changes. Levels of thiobarbituric acid-reactive materials in brain and spinal cord regions from prolonged acute and early relapse phases of CR-EAE were significantly higher than in central nervous system tissue from Freund's adjuvant control and normal uninoculated animals. In the late relapse phase of CR-EAE, levels of thiobarbituric acid-reactive materials in CNS samples were at control values. Fluorescence analysis of central nervous system tissue confirmed evidence of increased free radical damage in prolonged acute and early relapse stages of CR-EAE. The increased oxidative damage observed in the central nervous system in CR-EAE is discussed in relation to the role of macrophages and their oxidative burst.

Assessment of free radical-induced damage in brain proteins after ischemia and reperfusion.

Brain damage initiated during global ischemia has been shown to be exacerbated by iron-dependent lipid peroxidation during early reperfusion. We hypothesized that other cellular components might be involved in similar free radical reactions. In this study we examined three brain protein fractions and ribosomal RNA for evidence of free radical damage during post-ischemic reperfusion. Global brain ischemia was induced by 20-min cardiac arrest. Dogs were divided into four groups: (1) non-ischemic controls; (2) 20-min cardiac arrest without reperfusion; (3) 20-min cardiac arrest and 2 h reperfusion; (4) 20-min cardiac arrest and 8 h reperfusion. Soluble proteins and proteins from ribosomes and synaptosomes were assayed by a dinitrophenylhydrazine method for carbonyl groups, which are characteristic products of protein peroxidation. The ribosomal RNA was also examined by electrophoresis. When proteins from each fraction were peroxidized in vitro by Fenton reagents, carbonyl content increased as [Fe2+] was increased from 0 to 100 microM. However, following reperfusion there was no significant accumulation of carbonyl content in either the soluble (ANOVA P = 0.92) or ribosome (P = 0.10) protein fractions. There was a significant decrease in the carbonyl content of the synaptosome protein fraction after 8 h of reperfusion (P = 0.03). Similarly, although ribosomal RNA fragmentation was observed in ethidium stained agarose gels following in vitro reaction with Fenton reagents, there was no evidence of ribosomal RNA fragmentation or cross-linking following reperfusion. These results suggest that reperfusion free radical reactions do not involve these cellular proteins or ribosomal RNA.

Reduced susceptibility to lipid peroxidation in cold ischemie rabbit kidneys after addition of desferrioxamine, mannitol, or uric acid to the flush solution

Rabbit kidneys were stored for 24 hr at 0 °C after single passage arterial flush with 30 ml of cold isotonic 0.9% sodium chloride (saline) solution alone or saline to which was added 12, 30, or 60 m M desferrioxamine, 1 or 3 m M uric acid, or 100 m M mannitol. They were then subjected to in vitro biochemical assay for evidence of free radical damage immediately after storage. Results were compared to those obtained with fresh, unstored kidneys. Levels of Schiff base fluorescence, diene conjugates, and thiobarbituric acid-reactive material were each significantly elevated in kidneys stored for 24 hr after flush with saline alone. These levels were in turn each significantly reduced by the addition of 60 m M desferrioxamine, 3 m M uric acid, and 100 m M mannitol to the flush solution. Likewise, glutathione redox activity fell in those flushed with saline alone, presumably in line with increased lipid peroxidation, but was restored to control levels by inclusion of the three scavenging agents.

Evidence of free-radical damage in rabbit kidneys during warm and cold ischemia

Evidence of free-radical damage in rabbit kidneys during warm and cold ischemia