Protective Effect of Superoxide Dismutase Against Hair Graying in a Mouse Model¶

Oxygen free radicals play a role in the aging process, and the protective effect of various antioxidants has been intensively studied, in particular for cutaneous aging. Besides hereditary factors, free radical-mediated damage to melanocytes of the hair follicle has been considered as a mechanism for aging of the hair. It was the aim of this study to evaluate the role of photosensitization reactions for hair graying and to demonstrate potential protective effects of superoxide dismutase (SOD). Mice with black hair were depilated with the fingertips on a surface of 6 x 2.5 cm on both sides of the dorsum. The right side received five applications of a SOD-containing gel before exposure to psoralen (concentration 0.5 mg/mL) plus UV-A (365 nm, 4 J/cm2). The left side was pretreated in the same way with a gel free of SOD. When the hair started growing again, the SOD-protected side was covered with black hair, whereas the hair on the vehicle-treated side was gray or white in 27 of the 30 animals studied. The 0.01% SOD concentration was as protective as the 0.1% concentration. Heat-inactivated SOD, applied in another five animals, was not protective. Using fluorescent labeling of the SOD with fluorescein isothiocyanate, epifluorescence microscopy and digital imaging processing, we show that SOD applied to the skin surface penetrates through the follicular appendages, as well as through the unbroken stratum corneum. Our findings suggest that superoxide radicals, generated by interaction of UV-A light with the sensitizer, initiated the formation of secondary products with well-known DNA-damaging effects, such as lipid peroxidation products and tumor necrosis factor alpha. SOD prevented the damage to melanocyte DNA by dismutating superoxide. Photosensitization may be another mechanism for hair graying, which can be influenced by antioxidants. Given the large number of exogenous and endogenous sensitizers, this mechanism deserves further study for human hair graying.

Dietary and clastogenic factors in children who immigrated to Israel from regions contaminated by the Chernobyl accident

The authors evaluated the possible association between dietary history and plasma clastogenic factors in children who immigrated to Israel between 1989 and 1993 from regions contaminated by the Chernobyl accident. The authors compared questionnaire data about demographic variables, dietary histories before and after immigration occurred, and health status with clastogenic factor scores for 162 immigrants. Logistic regression analysis revealed a negative association between clastogenic factor scores and frequency of consumption of fresh vegetables and fruit among children < or = 7 yr of age during the postimmigration period. Intake of eggs and fish by boys who were < or = 7 yr of age prior to immigration was associated positively with clastogenic factor scores. Consumption of fresh vegetables and fruits afforded protection to the immune systems of children who were < or = 7 yr of age.

Clastogenic factors as biomarkers of oxidative stress in chronic hepatitis C

BACKGROUND/AIMS

Clastogenic factors (CFs) are composed of lipid peroxidation products, cytokines and other oxidants with chromosome-damaging properties. They are regularly observed after radiation exposure and in chronic inflammatory diseases, where they are supposed to be risk factors for carcinogenesis. It appeared of interest to investigate their presence in the plasma of patients with chronic hepatitis C.

METHODS

CFs are detected by chromosomal breakage studies. They were compared to malondialdehyde (MDA), total plasma thiols (t-SH), alanine aminotransferase (ALT), viral load and histological data.

RESULTS

CFs were increased in 19 of 20 patients, 16 had increased MDA levels and 15 had decreased t-SH levels. Mean values were significantly different from the 20 controls (p<0.001). After the first 3 months of interferon treatment, all three markers showed significant improvement, but were not completely normalized. There was a positive correlation between CFs and necroinflammatory activity (p<0.03), while MDA was correlated with fibrosis (p<0.03). Viral load was correlated with necrosis and inflammation (p<0.05).

CONCLUSION

The presence of CFs in chronic hepatitis C confirms the occurrence of oxidative stress in this disease and could be useful in clinical trials for testing antioxidants. The CF test is a sensitive assay for the detection of oxidative stress and correlates with necroinflammatory activity.

Oxidative stress in Adamantiades-Behçet's disease

BACKGROUND

Adamantiades-Behçet's disease is a chronic systemic disorder associating oral and genital ulcerative lesions with ocular and cutaneous manifestations. Previous publications report increased superoxide production by neutrophils and macrophages, increases in cytokines and malondialdehyde (MDA), as well as low levels of enzymatic antioxidant defenses.

AIM

We looked for another marker of oxidative stress in Adamantiades-Behçet's disease: the presence of clastogenic factors (CF) in patients' plasma. In addition, we determined plasma endproducts of lipid peroxidation (MDA).

PATIENTS AND METHODS

We studied 20 patients and 20 controls. The clastogenic activity was evaluated by means of cytogenetic methods. This test (CF test) detects circulating prooxidants, due to their clastogenic effects after exposure of lymphocyte cultures of healthy persons to plasma ultrafiltrates from patients. The clastogenic prooxidants are lipid peroxidation products and cytokines, in particular TNF-alpha. Lipid peroxidation was evaluated by the Yagi method.

RESULTS

The CF test was positive in 18 out of 20 patients, while it was negative in all 20 control persons. The mean increase in chromosomal breaks was 10.6 +/- 3.8 in cultures exposed to patients' plasma and 1.3 +/- 2.4 for cultures receiving control plasma (p <0.001). The clastogenic effect of patients' plasma ultrafiltrates was significantly inhibited by superoxide dismutase (EC 1.15.1.1), suggesting an important role of the superoxide radical in the clastogenic pathway. Thiobarbituric-acid-reactive substances (expressed as nanomoles MDA per milliliter) were also significantly increased in these patients: 10.6 +/- 3.2 for patients and 6.6 +/- 1.4 for controls (p <0.001).

CONCLUSION

The presence of CF in the plasma of patients, indicating the presence of circulating prooxidants with chromosome-damaging effects, confirms an oxidative stress in Adamantiades-Behçet's disease. The anticlastogenic effect of superoxide dismutase in vitro suggests the implication of the superoxide radical. MDA levels were also significantly increased in patients.

Anticlastogenic effects of Ginkgo biloba extract (EGb 761) and some of its constituents in irradiated rats

In a previous study we reported that radiation-induced clastogenic factors (CF) are found in the plasma of Chernobyl accident recovery workers and that their chromosome damaging effects are inhibited by antioxidant treatment with a Ginkgo biloba extract (EGb761). In the present study, we induced CF in rats with a radiation dose of 4.5 Gy. The protective effects of the complete extract were compared to those obtained with the extract devoid of its terpene fraction (CP205), with isolated ginkgolides A+B and bilobalide at the concentrations present in EGb761. The pretreatment samples were taken at day 22 postirradiation, the posttreatment samples the day following arrest of the 3-week treatment. The adjusted clastogenic score (ACS) were reduced from 11.71+/-3.55 to 2.00+/-2.83 after treatment with 100 mg/kg and from 13.43+/-2.23 to 4.29+/-2.14 with 50 mg/kg of the complete extract (p<0.0001). Similar protective effects were observed with CP205, ginkgolides and bilobalide (p<0. 001), while the reduction of ACS in placebo-treated rats was not statistically significant (12.80+/-1.79 and 9.20+/-2.68). However, if the efficacy of the treatment was compared to placebo, only the complete extract was significantly protective. While all components exerted anticlastogenic effects at the concentrations present in the complete extract, the comparison of the different groups by analysis of variance did not reveal significant differences. This may be due to to the small number of animals available in each treatment group. The complete extract reduced the ACS by 83% at the dose of 100 mg/kg, while the lower dose of 50 mg/kg and the three components reached only 66%-68% reduction. The better protection provided by the complete extract is due to synergistic rather than to additive effects.

Cellular penetration of fluorescently labeled superoxide dismutases of various origins

BACKGROUND

Using fluorescently labeled superoxide dismutase (SOD) and flow cytometry, we have shown previously that the enzyme CuZn SOD (EC 1.15.1.1) from bovine erythrocytes binds rapidly to the cell surface with slow uptake into the cell during the following hours. The degree of labeling was most important for monocytes in comparison to other blood cells (erythrocytes, lymphocytes, and neutrophils) and fibroblasts. In agreement with the flow-cytometric findings, the inhibition of superoxide production was more important for SOD-pretreated monocytes than for neutrophils, as demonstrated with the cytochrome c reduction assay. It was thus of interest to confirm the observed differences between monocytes and neutrophils with confocal laser microscopy, study in greater detail the kinetics of binding, penetration, and intracellular localization of the enzyme, and compare the results obtained with bovine CuZn SOD with those from SODs of other origins and carrying different active sites.

MATERIALS AND METHODS

Recombinant human (rh), bovine, and equine CuZn SODs, as well as rh and E. coli Mn SODs, were studied before use with respect to specific activity and purity (HPLC, SDS-PAGE electrophoresis). Fluorescein isothiocyanate was covalently conjugated to the various SODs for study with high-resolution confocal scanning laser microscopy. Superoxide production by monocytes and neutrophils was measured with the cytochrome c assay.

RESULTS

As expected from our experiments with flow cytometry, only rare neutrophils were labeled with FITC-SOD, even with the longest incubation time of 3 hr and the highest dose of 1500 units/ml. In addition, they showed a localized fluorescence pattern that was quite different from the diffuse punctate fluorescence pattern of monocytes. Lymphocytes were not labeled at all. The rapid binding to the cellular surface of monocytes was confirmed, and even after 5 min of preincubation, FITC-SOD was found on a small percentage of monocytes. This was correlated with a reduction in superoxide release after phorbolmyristate acetate (PMA) stimulation by 40%. An interesting finding was the perinuclear accumulation of the penetrated SOD after the longest pretreatment of 3 hr, suggesting a barrier against further progression. Indeed, through confocal microscopy we were able to exclude any fluorescence at the nuclear level. While the fluorescence labeling patterns and the kinetics of penetration were quite similar for bovine, equine, and rh CuZn SOD, the Mn SODs showed poor labeling, correlated with a weak inhibitory effect on cytochrome c reduction, which was not statistically significant.

CONCLUSIONS

The rapid binding of native CuZn SODs on the surface of monocytes, leading to reduced superoxide release by these cells, explains the observation that beneficial effects of injected SOD lasted for months despite rapid clearance of the enzyme from the bloodstream, according to pharmacodynamic studies. The preferential binding to monocytes, in contrast to neutrophils, may play a role in chronic inflammatory diseases in which the monocytes are in an activated state. The differences in binding capacity between CuZn SODs and Mn SODs, correlated with different inhibitory effects of superoxide production by monocytes, may also have therapeutic significance.

Multiparameter analysis of clastogenic factors, pro-oxidant cytokines, and inflammatory markers in HIV-1-infected patients with asymptomatic disease, opportunistic infections, and malignancies

HIV-1-infected patients are in chronic oxidative stress and clastogenic factors (CFs) are present in their plasma. CFs from patients with HIV are formed via superoxide anion radical and stimulate further superoxide production. The pathophysiolgic significance and the exact composition of the circulating clastogenic material in patients with HIV is unknown. Cytokines, such as tumor necrosis factor-alpha (TNF-alpha), are increased in the plasma of patients with HIV and TNF-alpha shows clastogenic activity in vitro. The aim of this clinical study was to compare levels of CF in HIV-1-positive patients with asymptomatic disease, opportunistic infections, and malignancies with those in HIV-1-negative control groups and to correlate CF activity with CD4+ T cell numbers, the cytokines (TNF-alpha, interleukin-2 [IL-2], IL-6), and the inflammatory markers (C-reactive protein [CRP], neopterin, granulocyte elastase). CFs were significantly increased in all HIV-1-positive patients and in HIV-1-negative patients with malignant tumors. HIV-1-positive patients with Kaposi's sarcoma showed the highest CF activity in their plasma (p < 0.08). CFs appear very early in HIV infection, and they correlate negatively with CD4+ T cells, which are an indicator of disease activity. The presence of CF in the plasma of HIV-infected patients is not a general response to a viral infection because these factors are not increased in HIV-1-negative patients with viral infection (zoster). CFs are not specific for the HIV-1 infection; they also occur in HIV-1-negative patients with malignant tumors. There was a tendency towards a positive correlation (p < 0.14) between CF and TNF-alpha but there was no positive correlation of CF with IL-2, IL-6, CRP, elastase, and neopterin levels. This indicates that TNF-alpha may be among the components of CF in HIV-1-infected patients. In addition, other unidentified components may contribute to the clastogenic activity of the plasma or the composition of CF may vary from patient to patient. Further clinical studies with larger sample populations are necessary to analyze the composition of CF in HIV-1-positive patients.

Lessons learned from the study of immigrants to Israel from areas of Russia, Belarus, and Ukraine contaminated by the Chernobyl accident

During the past 6 years, immigration to Israel of 700,000 persons from the former Soviet Union (FSU) included about 140,000 from radiocontaminated regions of Belarus, Ukraine, and Russia near Chernobyl. In Beer Sheva, a major center for immigrant absorption in Israel, a primary objective was to evaluate their health status and to refer them for care. 137Cs levels in 1228 men, women, and children were measured with a portable whole-body counter. Whole-body counts showed clear correlation with the degree of 137Cs ground contamination in previous regions of residence. The population could thus be sub-divided according to degree of exposure, based on previous regions of residence. The thyroid status of 300 local immigrant children was evaluated because of the increased risk of childhood thyroid cancer in the regions from which they came. This group was subdivided into comparative groups of children who came from less and more contaminated areas according to the International Atomic Energy Agency soil 137Cs contamination maps. Enlarged thyroids were found in about 40% of both groups. One 12-year-old girl from Gomel had a malignant papillary carcinoma. Thyroid-stimulating hormone levels, though within normal limits, were significantly greater (p < 0.02) for girls from high exposure regions. Liquidators showed significant increases in serum clastogenic factor and in the number of circulating glycophorin A-mutated red cells. In studies of over 700 people from both radiocontaminated and unaffected regions of the FSU, evidence for posttraumatic stress disorder was found more frequently in persons coming from the more contaminated areas.

Familial Mediterranean fever: clastogenic plasma factors correlated with increased O2(-)--production by neutrophils

Familial Mediterranean fever (FMF) is an autosomal recessive disease predominantly affecting Armenians and non-Ashkenazi Jews. The disease begins in childhood with paroxysmal attacks of pain and fever accompanied by peritonitis, pleuritis, and synovitis. During the acute phase, there is a massive influx of polymorphonuclear leukocytes into the serosal membranes, connected with degranulation of the neutrophils and with secretion of lysosomal enzymes and pyrogenic substances. An increase in the lipoxygenase product, leukotriene B4, a chemotactic agent, and a decrease in the activity of the inhibitor of chemotaxis, C5a, in serosal fluids have been considered responsible. Previous work from our laboratories had shown that the chromosomal instability observed in blood cultures of patients with FMF is secondary to circulating clastogenic factors (CFs), and that the antioxidant enzyme superoxide dismutase, as well as lipoxygenase inhibitors, reduce the chromosome damaging effects. CFs are observed in chronic inflammatory diseases and in various other pathological conditions accompanied by oxidative stress. Similar clastogenic materials were found in supernatants of neutrophils and monocytes after a respiratory burst and were shown to contain lipid peroxidation products and cytokines. In the present study we compared the clastogenic effects exerted by plasma ultrafiltrates from 20 adult patients with FMF to the unstimulated O2- production of their neutrophils. In comparison to 20 age- and sex-matched controls, which were studied simultaneously, the O2- production by patient's neutrophils was routinely higher than that of controls. The clastogenic effects of patient's plasma, expressed as the number of chromosomal aberrations induced in test cultures of healthy donors, were correlated with the importance of O2- production by their neutrophils (r = 0.5235). Even if the relative contribution of disturbance in arachidonic acid metabolism, neutrophil activation, and CF formation in the disease process remains unclear, the demonstration of oxidative stress in this genetic disorder suggests the use of antioxidants and free radical scavengers, in particular during acute attacks, when the classical colchicine treatment is without effect.

Oxyradical-mediated clastogenic plasma factors in psoriasis: increase in clastogenic activity after PUVA

Psoriasis is a common skin disorder characterized by hyperproliferation and incomplete differentiation of epidermal keratinocytes. Psoralen plus UVA (PUVA) is one of the treatments proposed for this disease. We had reported previously that exposure of regular blood cultures from healthy donors to PUVA leads to chromosomal breakage via the formation of transferable clastogenic materials, a phenomenon inhibitable by superoxide dismutase. In the present paper we show that these clastogenic factors (CF) are also formed in vivo. The CF were found in about 50% of the psoriasis patients studied (14 out of 31). In PUVA-treated psoriasis patients, the clastogenic activity of the plasma increased significantly between the first and the last (16th) exposure to PUVA. We hypothesize that CF formation in psoriasis is similar to that in other diseases accompanied by oxidative stress, in particular chronic inflammatory diseases with autoimmune reactions such as lupus erythematosus, progressive systemic sclerosis, rheumatoid arthritis and others. Increased superoxide production by phagocytes, formation of lipid peroxidation products and release of cytokines are considered to be responsible for the superoxide-stimulating and chromosome-damaging properties of patients' plasma. During PUVA therapy, superoxide generated via the interaction of psoralen with UVA may contribute to CF formation in addition to superoxide from inflammatory cells. An increased risk of cancer and leukemia is observed in diseases accompanied by CF formation. Therefore CF may contribute to the well-known risk of photocarcinogenesis by PUVA therapy. This additional risk may be preventable by antioxidants and superoxide scavengers.

Epidermal localization and protective effects of topically applied superoxide dismutase

Data from the literature, as well as our previous work, indicate a protective effect of superoxide dismutase (SOD) in topical application against UV-induced cutaneous damage. In the present article we show that pre-treatment of the skin with SOD protects against PUVA-induced inflammatory reactions not only in murine, but also in human skin. Using fluorescently labelled Cu,Zn SOD, epifluorescence microscopy and digital image processing, we demonstrate that the FITC fluorescence localizes in the stratum corneum and upper granulosa, as well as in the epidermal cell layer surrounding the lumina of the hair follicles. These findings were similar for murine and human skin. Since autofluorescence was eliminated by a special filter, it can be ascertained that the fluorescence observed in the tissues was due to FITC-labelled SOD.

Clastogenic factors in the plasma of children exposed at Chernobyl

Clastogenic factors (CFs), as they were described previously in accidentally or therapeutically irradiated persons, in A-bomb survivors and in liquidators of the Chernobyl nuclear power plant, were also detected in the plasma of Chernobyl-exposed children. A high percentage of plasma ultrafiltrates from 170 children, immigrated to Israel in 1990, exerted clastogenic effects in test cultures set up with blood from healthy donors. The differences were highly significant in comparison to children immigrated from 'clean' cities of the former Soviet Union or children born in Israel. The percentage of CF-positive children and the mean values of the adjusted clastogenic scores (ACS) were higher for those coming from Gomel and Mozyr, which are high exposure sites (IAEA measurements), compared to those coming from Kiev. There was no correlation between residual 137-Caesium body burden and presence of CFs. However, both measurements were not done at the same time (in 1990 and 1992-1994, respectively). Also no relationship could be revealed between enlargement of the thyroid gland and CF-positivity. CFs are not only observed after irradiation, but in a variety of chronic inflammatory diseases with autoimmune reactions. They were also described in the congenital breakage syndromes, which are hereditary diseases with the highest cancer incidence in humans. Whether the clastogenic effects continuously produced by circulating CFs represent a risk factor for malignant late effects deserves further study and follow-up. Since CF formation and CF action are mediated by superoxide radicals, prophylactic treatment with antioxidants may be suggested for Chernobyl-exposed children, whose plasma induces a strongly positive CF-test.

Clastogenic activity in the plasma of scleroderma patients: a biomarker of oxidative stress

BACKGROUND

Scleroderma patients exhibit increased chromosomal instability due to circulating clastogenic plasma factors (CF). Formation and action mechanisms of CF are mediated by superoxide. In addition, previous work detected inosine triphosphate (ITP) in the plasma of 2 patients, and the enzyme adenosine deaminase (ADA) was found to be increased.

OBJECTIVE

To study correlations between CF, ITP and ADA levels, CF and disease activity, as well as other biomarkers of oxidative stress.

METHODS

Clastogenic activity was evaluated by means of cytogenetic methods in 48 patients and 55 healthy subjects. ITP was detected by mass spectrometry and electrospray ionisation. ADA was measured with a colorimetric assay and malondialdehyde using the Yagi method.

RESULTS

Clastogenic activity was significantly increased in patients' plasma compared to controls. In 10 patients CF, ITP and ADA were studied simultaneously. All three parameters were increased in the 7 patients of subgroups 2 (skin and esophagus involvement) and 3 (skin plus multiple organ involvement). ITP was not detected in 2 patients of subgroup 1 (skin involvement only) with low ADA and CF values.

CONCLUSION

ITP, the deamination product of ATP, is one of the clastogenic and superoxide generating components of CF. The formation of this deamination product of ATP is probably related to the increase in ADA. CF are biomarkers of oxidative stress and can be used for evaluation of antioxidant treatments in scleroderma.

Clastogenic factors in plasma of HIV-1 infected patients activate HIV-1 replication in vitro: inhibition by superoxide dismutase

The frequent neoplastic disorders present in HIV-infected patients and the implication of oxidative stress in AIDS-Kaposi's sarcoma pathogenesis prompted us to study whether the mechanisms implicated in genotoxic effects of clastogenic factors (CFs) (i.e., chromosome damaging materials released by cells under conditions of oxidant stress) can play a role in HIV-1 expression and whether exogenous superoxide dismutase can inhibit the clastogenic and HIV-inducing effects of CFs. CFs were found in the plasma of all HIV-1 infected patients (n = 21) of this study group, in asymptomatic (CDC II) as well as in symptomatic patients (CDC IV). In addition to their chromosome damaging effect, CFs are able to upregulate HIV-1 expression in U1 cells and in PBMCs activated with PHA and IL2 at all time points (p < .05). Their formation, therefore, is an early event in the disease. It occured despite antiviral medication in these patients. Superoxide dismutase inhibited the clastogenic and the viral inducing effects (p < .05). On the basis of our findings, association of SOD mimetics or superoxide scavengers with antiviral drugs may be a new therapeutic approach. This polytherapy, if started early enough after infection, may prolong the latency period and limit the emergence of drug-resistant viral strains.

Evaluation of the Radiation Exposures of Chernobyl "Liquidators": Exploratory Studies of a Sample of Immigrants to Israel

Workers who were involved in the clean-up and recovery operation after the Chernobyl disaster ("liquidators") numbered about 800,000. Estimates of their exposures are highly relevant to evaluation of possible effects on their health. While some exposure measurements were made, they were also used for job assignments and terminations. The earliest and probably greatest exposure preceded adequate monitoring. By means of exploratory studies, the authors evaluated an exposure-estimating system proposed by a WHO consultation team in St. Petersburg. An index is derived based on recorded or reported 1) calendar time of initiating work, 2) location near or distant from the reactor, 3) duration of exposure, 4) type of work, 5) post-exposure symptoms, 6) blood count decreases, and 7) use of protective equipment. Data were obtained by interviews of liquidators who presented at a Beer Sheva clinic during evaluation of Cs-137 body burden. Of 75 liquidators, four had no data, one had only one item, six had two, 11 had three, 210 had four, 20 had five, 11 had six, and one had seven items. Only 19 had dose estimates. There was no trend in mean scores/item with increase in the number of items, indicating lack of information bias. Measured values, when available, were consistent with the scores. Clastogenic scores were determined for 26 of these subjects; the correlation with exposure indexes was 0.02, but for those with "positive" clastogenic tests (more than six abnormal divisions per 100), the correlation with the scores was 0.44. No such relationship was found for the persons with elevated Cs-137 tests. Glycophorin A antigen tests discriminated between liquidators and others, but, in this small study, did not correlate with the indexes.

Superoxide-mediated clastogenesis and anticlastogenic effects of exogenous superoxide dismutase

Superoxide-mediated clastogenesis is characteristic for various chronic inflammatory diseases with autoimmune reactions and probably plays a role in radiation-induced clastogenesis and in the congenital breakage syndromes. It is consistently prevented by exogenous superoxide dismutase (SOD), but not by heat-inactivated SOD, indicating that the anticlastogenic effect is related to the catalytic function of the enzyme. Increased superoxide production by activated monocytes/macrophages is followed by release of more long-lived metabolites, so-called clastogenic factors, which contain lipid peroxidation products, unusual nucleotides of inosine, and cytokines such as tumor necrosis factor alpha. Since these components are not only clastogenic, but can stimulate further superoxide production by monocytes and neutrophils, the genotoxic effects are self-sustaining. It is shown here that anticlastogenic effects of exogenous SOD are preserved despite extensive washing of the cells and removal of all extracellular SOD. Using flow cytometry and confocal laser microscopy, rapid adherence of the fluorescently labeled enzyme to the cell surface could be observed with slow uptake into the cell during the following hours. The degree of labeling was concentration and time dependent. It was most important for monocytes, compared with lymphocytes, neutrophils, and fibroblasts. The cytochrome c assay showed significantly diminished O2- production by monocytes, pretreated with SOD and washed thereafter. The preferential and rapid binding of SOD to monocytes may be of importance not only for the superoxide-mediated genotoxic effects, described above, but also from a therapeutic standpoint. It can explain the observation that beneficial effects of injected SOD lasted for weeks and months despite rapid clearance of the enzyme from the blood stream according to pharmacodynamic studies.

New approaches to biochemical radioprotection: antioxidants and DNA repair enhancement

Chemical repair may be provided by radioprotective compounds present during exposure to ionizing radiation. Considering DNA as the most sensitive target it is feasible to biochemically improve protection by enhancing DNA repair mechanisms. Protection of DNA by reducing the amount of damage (by radical scavenging and chemical repair) followed by enhanced repair of DNA will provide much improved protection and recovery. Furthermore, in cases of prolonged exposure, such as is possible in prolonged space missions, or of unexpected variations in the intensity of radiation, as is possible when encountering solar flares, it is important to provide long-acting protection, and this may be provided by antioxidants and well functioning DNA repair systems. It has also become important to provide protection from the potentially damaging action of long-lived clastogenic factors which have been found in plasma of exposed persons from Hiroshima & Nagasaki, radiation accidents, radiotherapy patients and recently in "liquidators"--persons involved in salvage operations at the Chernobyl reactor. The clastogenic factor, which causes chromatid breaks in non-exposed plasma, might account for late effects and is posing a potential carcinogenic hazard. The enzyme superoxide dismutase (SOD) has been shown to eliminate the breakage factor from cultured plasma of exposed persons. Several compounds have been shown to enhance DNA repair: WR-2721, nicotinamide, glutathione monoester (Riklis et al., unpublished) and others. The right combination of such compounds may prove effective in providing protection from a wide range of radiation exposures over a long period of time.

Hyaluronic acid in progressive systemic sclerosis

BACKGROUND

The glycosaminoglycans metabolism is disturbed in progressive systemic sclerosis (PSS). Serum hyaluronic acid (HA) is elevated in this disease.

OBJECTIVE

This study was conducted to determine the HA plasma concentrations of patients with PSS according to the different stages of the disease.

METHODS

We studied 48 patients divided into three subgroups: subgroup 1 (n = 10), with skin compromise without evidence of other organ involvement; subgroup 2 (n = 21), with skin and esophagus involvement; subgroup 3 (n = 17), with skin, lung and other internal organ involvement. A radiometric assay was performed for quantification of HA.

RESULTS

Our results confirm the increase in plasma HA in patients with PSS. They also suggest that lung involvement is the main feature responsible for high plasma concentrations of HA. The plasma HA levels were elevated in patients compared to normals (p <0.001). Significant differences were observed between subgroups 1 and 3 (p <0.01) and between subgroups 2 and 3 (p <0.01). A positive correlation between disease severity scores and plasma HA values was observed (p <0.01).

CONCLUSION

An important elevation of HA plasma levels could be a serologic marker of disease severity, progression and degree of visceral involvement.

Clastogenic factors in plasma of HIV-1 infected patients

The objective of this study was to investigate the clastogenic activity of plasma ultrafiltrates from HIV-1 infected patients. Clastogenic factors are chromosome-damaging agents with low molecular weight (< 10,000 daltons) which cause chromosome aberrations, sister chromatid exchanges, DNA strand breakage, and gene mutation. They have first been described in the plasma of irradiated persons, but they are also found in hereditary breakage syndromes and chronic inflammatory diseases with autoimmune reactions. Their formation and their clastogenic effects are modulated by superoxide anion radicals. We analyzed a total of 22 HIV-1 positive patients in comparison to 20 reference plasma samples from healthy HIV negative blood donors of similar age. The plasma ultrafiltrates (filter cutoff 10,000 daltons) from patients induced a statistically significant increase in chromosomal breakage in the cytogenetic test system (20.5 +/- 6.8 aberrations per 100 cells), while no increase was observed in test cultures exposed to plasma ultrafiltrates from healthy blood donors (6.3 +/- 2.9 aberrations per 100 cells). The breakage values were slightly, but not significantly, lower in the 10 patients with more than 200 T-helper cells/ml (18 +/- 4 aberrations per 100 cells), than in the 12 patients with less than 200 T-helper cells/ml (22.3 +/- 7.9 aberrations per 100 cells). HIV patients with high clastogenic activity (induction of more than 20 aberrations per 100 cells, range 20 to 39) showed higher plasma levels for malondialdehyde than those with lower clastogenic activity (less than 20 aberrations per 100 cells, range 12 to 18). However, the difference was statistically not significant. Another lipid peroxidation product, 4-hydroxynonenal, was increased equally in both groups. There were no significant differences in water- and lipid-soluble plasma antioxidants between the low- and high-breakage group. In agreement with previous findings, the clastogenic effects of plasma ultrafiltrates in the test cultures were reduced by the antioxidant enzyme superoxide dismutase. The presence of clastogenic factors in the plasma of HIV patients is further evidence for a prooxidant state in these persons. Since clastogenic factor formation appears to occur at an early stage of the disease, it may be significant for virus release or activation, because of the superoxide anion stimulating effects of clastogenic factors. From a practical standpoint, clastogenic factors may be useful for evaluation of promising drugs.

Clastogenic factors in the plasma of Chernobyl accident recovery workers: anticlastogenic effect of Ginkgo biloba extract

Clastogenic factors are found in the plasma of persons irradiated accidentally or therapeutically. They persisted in the plasma of A-bomb survivors over 30 years. Clastogenic factors were found in 33 of 47 Chernobyl accident recovery workers (often referred to as liquidators) in a previous study (I. Emerit et al., J. Cancer Res. Clin. Oncol. 120, 558-561, 1994). In the present study, we show that there is a positive correlation between clastogenic activity and dose and that these biomarkers of oxidative stress can be influenced successfully by appropriate antioxidant treatment. With the authorization of the Armenian Ministry of Health, 30 workers were treated with antioxidants from Ginkgo biloba leaves. The extract EGb 761 containing flavonoids and terpenoids was given at a daily dose of 3 x 40 mg (Tanakan, IPSEN, France) during 2 months. The clastogenic activity of the plasma was reduced to control levels on the first day after the end of the treatment. A 1-year follow-up showed that the benefit of the treatment persisted for at least 7 months. One-third of the workers again had clastogenic factors after 1 year, demonstrating that the process which produced clastogenic factors continued. However, the observation that antioxidants do not have to be given continuously is encouraging for intervention trials on a large-scale basis. These appear justified, since clastogenic factors are thought to be risk factors for the development of late effects of irradiation.

Plasma from patients exposed to ischemia reperfusion contains clastogenic factors and stimulates the chemiluminescence response of normal leukocytes

Clastogenic factors (CFs) are released by cells exposed to superoxide radicals and are found in various situations of oxidative stress. Certain of their components stimulate further superoxide production by competent cells, as shown with cytochrome c assay in previous work. In the present study, we report CF formation after ischemia reperfusion in patients undergoing coronary bypass surgery. Plasma ultrafiltrates, collected 20 min after reperfusion, had clastogenic properties in contrast to those collected before ischemia. We also show that the luminol-enhanced chemiluminescence response of neutrophils from healthy persons is increased when these cells are exposed to CF-containing postreperfusion samples from patients. Light emission was reduced to control values in the presence of superoxide dismutase. The burst of oxyradicals upon reperfusion is probably the initiating event of CF formation, which in turn leads to further oxyradical generation. This amplification process may explain why detectable levels of CF need a delay of at least 10 min. The activated state of neutrophils in ischemia reperfusion is at once a consequence and a source of CFs. Individual variation in the persistence of this clastogenic and leukocyte-activating material was observed. Therefore, antioxidants for prevention of ischemia reperfusion injury should be continued during the postoperative course.

Adenosine deaminase in progressive systemic sclerosis

The aim of the present study was to confirm the increase of adenosine deaminase (ADA) activity in progressive systemic sclerosis (PSS), described by Sasaki & Nakajima, and to compare plasma ADA activity of patients in different stages of the disease. Enzyme activity was measured with a colorimetric assay. The 48 patients were subdivided into 3 groups: subgroup 1 (n = 10), disease still limited to the skin; subgroup 2 (n = 21), involvement of the skin and oesophagus; and subgroup 3 (n= 17), involvement of the skin and multiple internal organs. ADA levels were highest in subgroup 3. However, the difference with respect to subgroup 2 did not reach statistical significance. Subgroup 1 was different from controls and subgroups 2 and 3 (p<0.001). Our results confirm that ADA activity is increased in PSS, and that this finding is observed even in the early stages of the disease process. We speculate that the increase in ADA, a well-known marker of T-cell activation, might be an indicator of disease activity in PSS, in the beginning as well as during phases of exacerbation in later stages of the disease.

Transferable clastogenic activity in plasma from patients with Fanconi anemia

The present study was conducted on 13 patients with Fanconi anemia. 25 parents and 12 siblings. The chromosomal instability characteristic of this congenital breakage syndrome was associated with the presence of transferable clastogenic material in the plasma, as also reported previously for ataxia telangiectasia and Bloom's syndrome. While all plasma ultrafiltrates from homozygotes had chromosome damaging properties, the clastogenic material had to be concentrated in most heterozygotes to reach detectable levels. The clastogenic effect was exerted via the intermediacy of superoxide radicals, since it was regularly inhibited by superoxide dismutase (SOD). This adds further evidence for a prooxidant state in this hereditary disease. The autosustained clastogenic activity possibly plays a role in the progressive impairment of blood cell-producing bone marrow and may predispose patients to develop cancer and leukemia. Prophylactic use of antioxidants may be recommended, using clastogenic plasma activity as a guide.

Radiation-induced clastogenic factors: anticlastogenic effect of Ginkgo biloba extract

Clastogenic factors (CFs) were first described in the blood of persons irradiated accidentally or for therapeutic reasons. Work of our laboratory has shown that they occur also under other circumstances, which are characterized by oxidative stress, and that CF-induced chromosome damage is regularly prevented by superoxide dismutase (SOD). Recently we found CFs in a high percentage of salvage personnel of the Chernobyl reactor accident. These liquidators represent a high-risk population and might benefit from cancer chemoprevention by antioxidants. SOD would have to be injected and is not appropriate for long-term prophylactic treatment. In the present study, we therefore evaluated the anticlastogenic effect of the Ginkgo biloba extract EGb 761, which is known for its superoxide scavenging properties. EGb 761 was tested on CF-treated blood cultures of healthy donors. After establishing the optimal protective EGb concentration, using CFs produced by irradiation of whole blood from healthy volunteers, the extract was tested on cultures exposed to CFs from plasma of persons irradiated as liquidators. The anticlastogenic effect could be confirmed for a final concentration of 100 micrograms/ml. In 12 consecutive experiments, CFs induced an average of 18.00 +/- 4.41 aberrations/100 cells. This was reduced to 7.33 +/- 3.08 in the parallel cultures receiving 100 micrograms/ml EGb 761 (p < .001). SOD was anticlastogenic in the same system at concentrations of 30 cytochrome C units/ml (approximately 10 micrograms/ml). Preliminary results obtained in a small series of liquidators showed regression or complete disappearance of CFs in the plasma after 2 months of treatment with EGb 761 (3 x 40 mg/d).

Transferable clastogenic activity in plasma from persons exposed as salvage personnel of the Chernobyl reactor

Clastogenic factors were first described in the plasma of people who had been accidentally or therapeutically irradiated. They were found also in A-bomb survivors, where they persisted for many years after the irradiation. The present study searched for these factors in the plasma of 32 civil workers from Armenia, who had been engaged as "liquidators" around the Chernobyl atomic power station in 1986. It also included 15 liquidators who had emigrated from the ex-Soviet Union to Israel. Reference plasma samples were obtained from 41 blood donors from the Armenian Blood Center in Yerevan. The samples were tested for their clastogenic activity in blood cultures from healthy donors. The majority of results from the liquidators exceeded those from the unexposed reference samples. The samples from the first Armenian group, with the higher average irradiation dose (0.6 +/- 0.6 Gy), were more clastogenic than those from the second group exposed to 0.2 +/- 0.2 Gy. The number of aberrations in the test cultures was 17.9 +/- 2.9% and 10.5 +/- 3.8% respectively, compared to 5.7 +/- 3.2% in the cultures exposed to the reference ultrafiltrates from Armenian blood donors. The samples from the Israeli liquidators also induced significantly increased aberration rates (14.0 +/- 3.9% aberrant cells). The clastogenic activity was regularly inhibited by superoxide dismutase, indicating that the chromosome-damaging effects of radiation-induced clastogenic factors are exerted via the intermediation of superoxide radicals, as is known for clastogenic factors of different origin.

Chromosome damage in PUVA-treated human lymphocytes is related to active oxygen species and clastogenic factors

Besides the direct interaction of psoralens with DNA and other macromolecules, the role of reactive oxygen species in the PUVA-induced cellular injury has been stressed. The present study shows that treatment of human blood cultures with 5-methoxypsoralen or 8-methoxypsoralen, followed by UVA exposure, results in chromosome damage. The supernatant of these cultures contains secondarily formed chromosome damaging material, called clastogenic factor (CFs). Not only CF formation, but also CF action is inhibited by superoxide dismutase (SOD), suggesting that superoxide is formed on the pathway to chromosome aberration. CF is detectable in the cell culture supernatants after a minimal delay of 18 h, and reaches a plateau at 24 h of cultivation. SOD is no longer protective if added after 24 h, i.e., the enzyme can prevent, but not repair the oxyradical-induced damage.

Reactive oxygen species, chromosome mutation, and cancer: possible role of clastogenic factors in carcinogenesis

Superoxide radicals may induce genotoxic effects by indirect action mechanisms, implicating the formation of more long-lived, secondary clastogenic material called chromosome breakage factors or clastogenic factors (CF). CF are produced via the intermediacy of superoxide, and stimulate further superoxide production by competent cells. This results in a selfsustaining and longlasting process of clastogenesis, which may exceed the DNA repair system and ultimately lead to cancer. An increased cancer risk is indeed observed in conditions accompanied by CF formation. These include irradiated persons, asbestos workers, patients with chronic inflammatory diseases, HIV-infected persons, and the congenital breakage syndromes ataxia telangiectasia, Bloom's syndrome, and Fanconi's anemia. Because reactive oxygen species (ROS) are implicated in CF formation and CF action, antioxidants may be protective as anticlastogens and consequently as anticarcinogens. In persons at high risk because of their occupation, life style or place of residence, the presence of CF may represent an indication for chemoprevention of cancer by antioxidants. CF can be useful as biochemical markers and intermediate endpoints for the evaluation of promising drugs. They are therefore not only of interest as a mechanism by which ROS may exert genotoxic effects, but also have practical implications.

Chromosomal aberrations and neutrophil activation induced by reperfusion in the ischaemic human heart

Imperfect myocardial protection during prolonged ischaemia results in adverse changes during reperfusion. Clinical studies carried out during cardiac surgery show that: (1) Oxygen free radicals produced during reperfusion can lead to chromosomal damage in leukocytes. However, this effect seems to be prevented by the addition of allopurinol in the cardioplegic solution. (2) Polymorphonuclear leukocytes are directly implicated in situ in the genesis of free radicals responsible for reperfusion injury. (3) Pre-treatment with trimetazidine, an anti-ischaemic drug with antioxidant properties, and addition of the drug to the cardioplegic solution reduced oxygen free radical damage, as shown by a reduced release of malondialdehyde increase and of myosin; moreover, pre-treatment with trimetazidine enabled patients to undergo surgery with improved left ventricular function.

Oxyradical-mediated chromosome damage in patients with familial Mediterranean fever

Increased chromosome breakage is observed in patients with familial mediterranean fever (FMF). Their plasma contains clastogenic material inducing chromosome damage in cells from healthy persons. It is proposed that increased oxyradical generation by activated polymorphonuclear cells in blood and serosal fluids of these patients leads to the formation of a clastogenic factor (CF), as it is observed in other chronic inflammatory diseases. Also similar to these diseases, the clastogenic effects are prevented by superoxide dismutase and partially by inhibitors of arachidonic acid metabolism.

Cardioprotective effect of trimetazidine during coronary artery graft surgery

Reperfusion injury remains the most uncontrolled phenomenon during cardiac surgery. Potential myocardial protection by trimetazidine was tested in a double blind placebo controlled study on 19 patients undergoing aorto-coronary bypass surgery. The trimetazidine group was composed of 10 patients and the placebo group of 9 patients. Pretreatment was started three weeks before surgery with 1 tablet (trimetazidine 20 mg) t.i.d. and the same drug was added to the cardioplegic solutions (trimetazidine: 10(-6) M). The cross clamping time was 41.1 +/- 3.8 minutes in the trimetazidine group and 39.8 +/- 2.3 minutes in the placebo group. Metabolic measurements showed that the increase of malondialdehyde measured in the coronary sinus 20 minutes after reperfusion was significantly (p = 0.014) less in the trimetazidine group (from 1.60 +/- 0.11 to 1.79 +/- 0.2 mumol/L-1) than in the placebo group (from 1.17 +/- 0.11 to 2.84 +/- 0.58 mumol/L-1). Myosin was present 4 hours after surgery in all patients in the placebo group and in 5 of the 10 of the trimetazidine group (p = 0.036). Haemodynamic measurements showed that patients pretreated with trimetazidine had a better ventricular function, as assessed by the stroke work index (SWI) significantly (p = 0.01) higher in the trimetazidine group (0.0391 +/- 0.0029 g/min/m2/beta) than in the placebo group (0.0282 +/- 0.0026 g/min/m2/beat), the evolution of SWI during surgery was not significantly different between the two groups. Thus trimetazidine seems to reduce ischaemia-reperfusion damage during cardiac surgery; moreover pretreatment with trimetazidine allows the patient to face the operation with better ventricular function.

Free radicals and aging of the skin

Cutaneous aging is the result of genetically determined or intrinsic aging superimposed by degenerative changes due to actinic irradiation, also called photoaging. The manifestations of cutaneous aging, as it relates to the perception of age, is caused by ultraviolet light, in particular in those parts of the body exposed daily to solar radiation. Free radical generation in the skin by UV light and from other sources, such as cellular infiltrations or the xanthine oxidase reaction, may be detected by direct and indirect methods. The decrease in antioxidant enzymes and small molecular weight antioxidants such as glutathione, vitamin E and ubiquinone upon exposure to UV light is an indication that the pro-antioxidant balance can be overwhelmed by acute or chronic photo-oxidative stress. Antioxidant supplementation is therefore a means for prevention or at least retardation of premature cutaneous aging.

Active oxygen species, articular inflammation and cartilage damage

Rheumatoid arthritis and osteoarthritis are age-related diseases, in which degenerative changes (arthrosis) and superimposed inflammatory reactions (arthritis) lead to progressive destruction of the joints. Active oxygen species derived from various sources play a role in this process, which may be influenced by appropriate treatment with antioxidants and free radical scavengers.

Formation of a clastogenic factor by asbestos-treated rat pleural mesothelial cells

The data of the present study indicate that chrysotile induces the formation of a clastogenic factor (CF) when mesothelial cells are exposed to these fibers in vitro. Ultrafiltrates of culture media induce chromosome damage in human lymphocytes used as a test system for the detection of clastogenic activity in conditioned media. According to the cut off of the filters (10,000 dalton), CF is a small molecule. Its exact nature is unknown. The intermediacy of active oxygen species in CF formation is suggested by the anticlastogenic effect of antioxidant enzymes such as superoxide dismutase and catalase. The data are similar to those obtained with other membrane-active agents, in particular the tumor promoter tetra-decanoylphorbol acetate (TPA). The model of membrane-mediated chromosome damage with CF formation is proposed for asbestos-induced cell injury.

Hydroxynonenal, a component of clastogenic factors?

Exposure of human lymphocyte cultures to superoxide generated by the xanthine-xanthine oxidase (X-XO) system, resulted in formation of a clastogenic factor (CF), as expected from previous work. We speculated that arachidonic acid (AA), the major polyunsaturated fatty acid of biological membranes, was oxidized via the cyclooxygenase-lipoxygenase pathways or nonenzymatically by oxygen free radicals in the culture medium to products with clastogenic properties. In the present study, we analyzed CF for AA-derived products and tested corresponding commercial standards for their clastogenic properties. The results show that prostaglandins, thromboxane, and H(P)ETEs were not increased in supernatants from X-XO treated cultures compared to untreated cultures. Synthetic H(P)ETEs added to the medium of lymphocyte cultures were only slightly or not clastogenic. In contrast hereto, the degradation product 4-hydroxynonenal was found in 50% of CF samples, while it was absent in all 43 control samples. The kinetics of detectability in the culture medium was similar to that of CF. Also, the clastogenic effect of synthetic 4-hydroxynonenal at concentrations as low as 0.1 microM suggested that this aldehyde, known for its genotoxic effects, was a clastogenic component of CF. The indirect action mechanisms of 4-hydroxynonenal via inactivation of functional SH groups in DNA polymerases, may explain why chromatid-type damage is predominant in lymphocytes exposed to CF in the Go-G1 phase of the cell cycle. This particularly was already stressed 20 years ago in the first observations of radiation-induced CF. However, 4-hydroxynonenal is not the only clastogenic component of CF.(ABSTRACT TRUNCATED AT 250 WORDS)

Clastogenic inosine nucleotide as components of the chromosome breakage factor in scleroderma patients

In the present study, we attempted to identify the chemical nature of the clastogenic factor (CF) from patients with progressive systemic sclerosis (scleroderma). Computerized mass spectrometry of clastogenic fractions obtained by HPLC of plasma ultrafiltrates detected molecular peaks compatible with inosine triphosphate and inosine diphosphate (ITP and IDP). The concomitant detection of IDP, together with ITP, and the absence of these peaks in nonclastogenic fractions and corresponding control fractions are arguments in favor of a biological relevance of these observations. The most important confirmation came from the clastogenic effect of commercial ITP and IDP added to the culture medium of the test cultures. The induction of chromatid type damage by these substances in lymphocytes exposed in the G0 phase of their cell cycle and the prevention of this damage by superoxide dismutase are analogous to the observations with CF.

Superoxide and hydrogen peroxide production by macrophages of New Zealand black mice

Resident peritoneal macrophages from New Zealand Black (NZB) mice release O2- and H2O2 after adherence to a plastic surface without any chemical or particulate stimulant. This phenomenon is age dependent and more pronounced in animals with sever autoimmune disease. Significant differences were observed between the high and low breakage NZB sublines (HB and LB), which were previously developed by selective matings on the basis of chromosome breakage rates. The LB subline differs significantly from the HB subline with respect to autoimmune hemolytic anemia and tumor incidence. When the macrophages were stimulated with the tumor promoter TPA, the number of "responders" was higher in the HB than in the LB subline and correlated with the degree of splenomegaly, that is, with the severity of the disease. A negative response to agonist stimulation and very low spontaneous production of active oxygen species was observed in NZW and Swiss mice, which is the normal finding for resident macrophages according to data from the literature. The increased superoxide and hydrogen peroxide production by macrophages of NZB mice is discussed with respect to autoimmune disease and cancer.

Mutagenic effects of TPA-induced clastogenic factor in Chinese hamster cells

Previous work in our laboratory has shown that the clastogenic and SCE-inducing effects of 12-O-tetradecanoylphorbol 12-acetate (TPA) are mediated by secondary products formed by the cell in response to the tumor promoter. A low-molecular-weight clastogenic factor (CF) was isolated from the medium of TPA-treated human leukocytes and caused chromosome aberrations and sister-chromatid exchanges (SCE) in fresh cultures not exposed to TPA itself. In the present study, we show that Chinese hamster fibroblasts (V79 cells) also produce CF when exposed to TPA. CF from V79 cells induced SCE not only in hamster cells, but also in human lymphocytes. Vice versa, CF from human leukocyte cultures induced SCE in hamster cells. It also increased the frequency of 6-thioguanine-resistant mutants in this cell system. All cyto- and geno-toxic effects of TPA-induced CF were prevented if the cells were treated with superoxide dismutase before exposure. The lipophilic CF seems to be derived from arachidonic acid of cell membranes released as a consequence of oxidative damage and subsequently degraded to genotoxic aldehydes in an autoxidative process. CF is formed only under culture conditions with low antioxidant content in culture media and sera. This may explain the discordant results obtained by different laboratories with regard to the genotoxic effects of TPA.

Monocyte-derived clastogenic factor in rheumatoid arthritis

Blood or lymphocyte cultures from patients with rheumatoid arthritis show increased chromosome breakage. This is due to the presence of a clastogenic factor (CF) inducing also chromosome damage in blood cultures of healthy persons. CF may be isolated not only from patients' plasma or synovial fluid, but also from the supernatant of blood or lymphocyte cultures. No CF was detectable, if the lymphocyte cultures were free of other contaminating blood cells. Addition of neutrophils did not considerably influence the production of CF, and platelets were without any effect. However, addition of increasing numbers of monocytes resulted in increasing clastogenic activity. Also monocytes in adherence, in absence of lymphocytes and without any chemical stimulant, produced CF. This indicates that monocytes are responsible for CF production. The protective effect of superoxide dismutase, as well against CF formation as against CF action on cells of normal subjects, suggests a role of the superoxide radical O2-. Inhibitors of arachidonic acid metabolism were only slightly anticlastogenic.

Clastogenic factor in ischemia-reperfusion injury during open-heart surgery: protective effect of allopurinol

The hypothesis tested was that free radicals generated following ischemia and reperfusion in cardiac operations can produce clastogenic factor that results in chromosomal aberration. Fourteen randomized patients undergoing coronary artery bypass grafting were divided into two groups. In Group 1 (7 patients), myocardial protection was achieved using a cardioplegic solution without allopurinol. In Group 2 (7 patients), 100 mg of allopurinol (xanthine oxidase inhibitor) was added to the solution. In both groups, blood samples were taken from the coronary sinus before the aorta was clamped and 20 minutes after myocardial reperfusion was achieved. The blood samples were used to study the patients' chromosomes. The results were given as the percentage of chromosomal aberrations observed in 100 mitoses. There were no significant differences between the preischemic values in both groups and the postischemic values in Group 2. On the other hand, there was a significant difference between the postischemic values in Groups 1 and 2 (p less than 0.01). In conclusion, reperfusion following myocardial ischemia in cardiac operations can produce clastogenic aberrations. This clastogenic activity can be reduced by adding allopurinol to the cardioplegic solution.

Phorbol ester-induced formation of clastogenic factor from human monocytes

Phorbol-12-myristate-13-acetate (PMA) acts as a tumor promoter on mouse skin. It induces inflammation and leukocyte-mediated clastogenicity which appears to be related to rapid changes in lipid metabolism. To identify lipids possessing clastogenic and/or tumor-promoting properties, we have characterized the metabolism and release of arachidonic acid (AA) and related lipids during the formation of lipophilic clastogenic factors by PMA-treated human monocytes. In 1 h, [3H]AA-labeled monocytes spontaneously released significant amounts of their total radioactivity (4%) which increased nearly 4-fold (15%) with PMA (30 ng/ml) treatment. Eighty-five per cent of extracellular 3H-label from both control and PMA-treated monocytes was composed of free AA (plus AA-metabolites), while the remaining radioactivity was incorporated in phospholipids and mono- and diacylglycerols. Treated and non-treated cells released essentially the same kind of metabolites but PMA induced a 3- to 4-fold increase in total amounts. The major products consisted of prostaglandins F2 alpha and E2, thromboxane B2, 12-hydroxy-5,8,10-heptadecatrienoic acid and 5-, 11- and 15-hydroxyeicosatetraenoic acids. PMA also induced increases in the levels of three unidentified products. Neither leukotrienes nor 4-hydroxynonenal, a major alkenal degradation product of AA, were found in medium from PMA-treated monocytes. PMA, in contrast to the first-stage tumor promoter calcium ionophore A23187, failed to stimulate the release of platelet activating factor. The increased formation of phorbol ester-induced AA metabolites was proportional to the increase in free extracellular AA. The source of AA from treated and untreated monocytes consisted of cellular phospholipids with phosphatidylcholine and phosphatidylethanolamine accounting for 85%.