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.

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.

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.

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 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 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 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.

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.

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.

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.

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.