Effect of ascorbic acid prophylaxis on the frequency of chromosome aberrations, urine mutagenicity and nucleolus test in workers occupationally exposed to cytostatic drugs

The genetic risk of workers occupationally exposed to a series of newly developed cytostatic drugs and the presumed antimutagenic potential of ascorbic acid (AA) were studied in a group of 38 chemical laboratory personnel examined for chromosome aberrations in lymphocytes, urine mutagenicity and nucleolar RNA activity before and after a 6-month prophylactic administration of AA at daily doses of 1 g for 5 days a week. Chromosome aberration tests revealed elevated aberrant cell (AB.C) rates both prior to and after AA supplementation (3.9% and 3.65% of AB.C., respectively). These values were significantly higher than those found in 18 non-exposed matching controls (1.05% of AB.C.). Tests for mutagenic activity in the urine of drug-exposed workers revealed 64% positive urine samples prior to vitaminization and 60% positive urine specimens after it; positive urine samples in the group of controls accounted for 21% of samples. In the nucleolus test, numbers of inactivated micronuclei in the exposed were initially higher than those of controls (33.4% versus 24.3%), but dropped to 20.5% after AA supplementation. These findings show that AA prophylaxis alone cannot substantially reduce the hazards associated with exposure to anti-cancer drugs.     

Cytogenetic analysis of peripheral blood lymphocytes in glass workers occupationally exposed to mineral oils

Chromosome aberration tests were carried out in a group of 31 pressed glass makers operating an automatic line of press-and-blow machines known to release mineral oil mists containing relatively high concentrations of the mutagenic chemicals belonging to a class of polycyclic aromatic hydrocarbons (PAH). The workers were exposed to the mineral oil aerosol levels that did not exceed the Czechoslovak maximum allowable concentration limit of 5 mg . m-1 of air. The tests revealed that the frequency of aberrant cells (% AB.C.) and the value of breaks per cell (B/C) ratio found in mineral oil-exposed workers were increased significantly, accounting for 4.65 +/- 0.29% AB.C. (0.0532 B/C) vs. 1.13 +/- 0.19% AB.C. (0.0113 B/C) seen in matching controls. Also, a higher rate of dicentrics, reciprocal translocations and cells with pulverization was observed in this group of glass workers. These finding are considered as evidence suggesting that these workers might experience an increased risk of genetic injury due to exposure to mineral oil mists.     

The genotoxic risk of underground coal miners from Turkey

A cytogenetic monitoring study was carried out on a group of workers from a bituminous coal mine in Zonguldak province of Turkey, to investigate the genotoxic risk of occupational exposure to coal mine dust. Cytogenetic analysis, namely sister chromatid exchanges (SCEs), chromosomal aberrations (CAs) and micronucleus (MN) tests were performed on a strictly selected group of 39 workers and compared to 34 controls matched for gender, age, and habit. Smoking and age were considered as modulating factors. Both SCE and CA frequencies in coal miners appeared significantly higher than in controls. Similarly, there was a significant increase in the frequency of total micronuclei in exposed group as compared to control group. The effect of smoking on the level of SCE and MN was significant in the control group. A positive correlation between the age and the level of SCE was also found in controls. The frequencies of both SCE and CA were significantly enhanced with the years of exposure. The results of this study demonstrated that occupational exposure to coal mine dust leads to a significant induction of cytogenetic damage in peripheral lymphocytes of workers engaged in underground coal mining.     

The genotoxic risk of underground coal miners from Turkey

A cytogenetic monitoring study was carried out on a group of workers from a bituminous coal mine in Zonguldak province of Turkey, to investigate the genotoxic risk of occupational exposure to coal mine dust. Cytogenetic analysis, namely sister chromatid exchanges (SCEs), chromosomal aberrations (CAs) and micronucleus (MN) tests were performed on a strictly selected group of 39 workers and compared to 34 controls matched for gender, age, and habit. Smoking and age were considered as modulating factors. Both SCE and CA frequencies in coal miners appeared significantly higher than in controls. Similarly, there was a significant increase in the frequency of total micronuclei in exposed group as compared to control group. The effect of smoking on the level of SCE and MN was significant in the control group. A positive correlation between the age and the level of SCE was also found in controls. The frequencies of both SCE and CA were significantly enhanced with the years of exposure. The results of this study demonstrated that occupational exposure to coal mine dust leads to a significant induction of cytogenetic damage in peripheral lymphocytes of workers engaged in underground coal mining.     

Cytogenetic analysis of peripheral blood lymphocytes of workers occupationally exposed to styrene

The genetic risk run by workers occupationally exposed to styrene vapors was assessed in two different plants A and B, using the cytogenetic analysis of peripheral blood lymphocytes. In plant A engaged in the manufacture of polystyrene vessels the mean styrene exposure level was found to range between 70 and 150 mg . m-3, in plant B manufacturing sports boats, plastic slides for children and plastic guard-stones it reached the level of about 200 mg . m-3. The rate of aberrant cells (AB.C.) found in plant A workers (N = 36) at the time of first sampling was 1.38% and the value of break/cell (B/C) ratio was 0.015; at the second sampling the rate of AB.C. was 1.41% and the B/C ratio was 0.014. The group of matched controls (N = 19) was found to have 1.26% of AB.C. and 0.014 breaks per cell. Plant B workers (N = 22) exhibited at the first sampling 1.72% of AB.C. and their value of B/C ratio was 0.018, the group of matched controls (N = 22) had 1.36% of AB.C and the B/C ratio 0.015; the respective values at the time of second sampling were 2.81% for AB.C. rate and 0.029 for B/C ratio in the exposed and 1.89% for AB.C. rate and 0.021 for B/C ratio in the control group. It is concluded that styrene exposure levels below 100 mg . m-3 do not pose any serious genetic risk for the exposed population groups. The variations found in the degree of chromosome injury by smoking habits, drug intake pattern, or sex were not statistically significant.     

Chromosomal aberrations, SCE and urine mutagenicity in workers occupationally exposed to cytostatic drugs

The genetic risk run by workers occupationally exposed to chemicals, including the newly developed cytostatics, was assessed in large chemical laboratories. The exposed group comprising 38 people consisted of chemists, laboratory assistants and pilot plant workers. The average rate of aberrant cells in peripheral blood lymphocytes (AB.C). was 3.9% and the value of break/cell ratio was 0.046. The group of matched controls (N = 18) was found to have 1.5% of AB.C. and 0.020 breaks/cell. In the exposed group, there were, on average, 8.94 SCEs/cell, and in controls, 5.81. Urine mutagenicity tests on Salmonella typhimurium tester strain TA98 revealed a significant increase of activity in 23 (64%) out of 36 urine samples tested as compared to the control group (N = 19) with 4 (21%) positive urine samples. Strain TA100 showed only a weak response to urine mutagens.     

In vivo antimutagenic effect of ascorbic acid against mutagenicity of the common antiamebic drug diiodohydroxyquinoline

We have previously shown that the common antiamebic drug diiodohydroxyquinoline (DIHQ) exhibits mutagenic activity in the in vivo micronucleus test in Swiss albino mice. Results of experiments undertaken to study the influence of ascorbic acid (vitamin C) on the mutagenicity of DIHQ in this model system showed that ascorbic acid acts as an antimutagen against DIHQ. The effective antimutagenic doses of ascorbic acid themselves do not show any genotoxic effects in this in vivo system. It will be necessary, however, to elucidate the mechanism of action of ascorbic acid as well as its effects on the therapeutic properties of DIHQ before a practical use of ascorbic acid is contemplated for this purpose.     

A retrospective mortality study of workers exposed to radon in a Brazilian underground coal mine

Recently a high radon concentration was detected in the underground coal mine of Figueira, located in the south of Brazil. This coal mine has been operating since 1942 without taking cognizance of the high radon environment. In order to assess possible radon-related health effects on the workers, a retrospective (1979-2002) mortality study of 2,856 Brazilian coal miners was conducted, with 2,024 underground workers potentially exposed to radon daughters. Standard mortality ratio (SMR) analysis hints at lower mortality from all causes for both underground (SMR = 88, 95% CI = 78-98) and surface workers (SMR = 96, 95% CI = 80-114). A high statistically significant SMR for lung cancer mortality was observed only in the underground miners (SMR = 173, 95% CI = 102-292), with a statistically significant trend reflecting the duration of underground work. High statistically significant SMRs were observed for pneumonia as a cause of death between both surface (SMR = 304, 95% CI = 126-730) and underground miners (SMR = 253, 95% CI = 140-457). Because mortality from smoking-related cancers other than lung cancer was not found elevated in underground workers and because diesel equipments were not used in this mine, it can be concluded that the enhanced lung cancer mortality observed for underground miners is associated with exposure to radon and radon daughters, rather than other confounding risk factors.     

Comparative antimutagenicity of 5 compounds against 5 mutagenic complex mixtures in Salmonella typhimurium strain TA98

Using the Ames Salmonella/microsome assay, we compared the antimutagenic activities of chlorophyllin, retinol, beta-carotene, vitamin C, and vitamin E against solvent extracts of coal dust, diesel emission particles, airborne particles, fried beef, and tobacco snuff. The results show that chlorophyllin inhibited 69% of the mutagenic activity of tobacco snuff and over 90% of that of the other 4 complex mixtures. Retinol inhibited 29-48% of the mutagenic activity of all 5 complex mixtures. beta-Carotene, vitamin C, and vitamin E inhibited, if any, less than 39% of the activity of the complex mixtures studied. Vitamin C enhanced the mutagenicity of airborne particles. These results indicate that for these dietary and environmental complex mixtures chlorophyllin is a more effective antimutagen than retinol, beta-carotene, vitamin C, and vitamin E.     

Antioxidant status and levels of different vitamins determined by high performance liquid chromatography in diabetic subjects with multiple complications

Plasma vitamin A, C and E levels and erythrocyte antioxidant enzyme activities were investigated in type I and type II diabetic subjects with and without complications, i.e., hypertension, coronary artery disease and renal failure. Reverse phase HPLC was used to quantify vitamin A and E levels. We observed that the vitamin C levels were not significantly different between control and diabetic subjects. However, vitamin A and E levels were significantly lower in type I and type II diabetic subjects compared to controls. Superoxide dismutase (SOD) activity was significantly lower in type II, but not in type I, diabetic patients compared to controls. Interestingly, glutathione reductase and peroxidase activities were diminished in type I, but not in type II, diabetic subjects as compared to controls. Catalase activity was lower in both types of diabetic patients in comparison with their respective controls. Altogether these results suggest that diabetes mellitus may be associated with altered antioxidant status regardless to various complications.     

Antimutagenic effects of the mushroom Agaricus blazei Murrill extracts on V79 cells

Agaricus blazei Murrill, a native mushroom in Brazil, has been widely consumed in different parts of the world due to its medicinal power. Its anticarcinogenic activity has been shown in experimental animals, and antimutagenic activity has been demonstrated only in Salmonella. In this work, the mutagenic and antimutagenic activities of mushroom teas of strains AB96/07, AB96/09 and AB97/11 were evaluated in Chinese hamster V79 cells, using the comet assay and the micronucleus test. The cells were treated with three different concentrations (0.05, 0.1 and 0.15) of teas prepared from a 2.5% aqueous solution, under three different temperatures: (1) room (20-25 degrees C); (2) ice-cold (2-8 degrees C); and (3) warm (60 degrees C). The teas were applied in co-, pre- and post-treatments in combination with the mutagen methyl methanesulfonate (MMS; 1.6x10(-4) and 4x10(-4)M). The duration of the treatment was 1h in the comet assay and 2h in the micronucleus test. The results showed that the mushroom was not mutagenic itself. Nevertheless, the mushroom is an efficient antimutagen against the induction of micronuclei by MMS in all concentrations and preparations tested. The observed reductions in the frequencies of micronuclei ranged from 61.5 (room temperature 0.1% tea in post-treatment) to 110.3% (co-treatment with warm and ice-cold 0.15% tea). In the comet assay, the antimutagenic activity was detected only when the cells were pre-treated with the following teas: warm 0.1 and 0.15%, room temperature 0.05% and ice-cold 0.1%. The results indicate that the mushroom A. blazei extracts are antimutagenic when tested in V79 cells.     

The presence of promatrix metalloproteinase-3 and its relation with different categories of coal workers' pneumoconiosis

Extracellular matrix formation (ECM) and remodeling are critical events related to the pathogenesis of pulmonary fibrosis. Matrix metalloproteinases play an essential role in degrading and remodeling the ECM. In this study, we tried to show the presence and correlation of promatrix metalloproteinase-3 (proMMP-3) (the inactive form of metalloproteinase-3) levels in coal workers' pneumoconiosis (CWP) with different categories. The study population consisted of 44 coal miners with CWP (pos CWP). Coal miners without CWP (neg CWP, n = 24) and non-underground personnel (controls, n = 17) were taken as controls. All coal miners were stable and had no systemic infection or disease. Standard posterio-anterior chest radiographs and pulmonary function tests were performed to exclude any diseases other than CWP. Serum proMMP-3 was analysed using the sandwich enzyme-linked immunosorbent assay according to the manufacturer's instructions (The Binding Site, Birmingham, UK). Mean proMMP-3 values of the all three groups were compared and a significant statistical difference obtained (p < 0.001). In addition, a statistically significant difference was found between categories of the disease and proMMP-3 values (p < 0.05). The effects of age, exposure duration and cigarette smoking on proMMP-3 values in coal miners with CWP were investigated. There were no correlations between age, smoking and proMMP-3 values. However, a positive correlation was found between exposure duration and proMMP-3 values (r = 0.447, p = 0.008). In conclusion, proMMP-3 (prostromelysin 1) may play an essential role in degrading and remodeling the ECM in workers with pneumoconiosis. ProMMP-3 may also reflect the stage of pneumoconiosis disease.     

Oxidative Decomposition of Vitamin C in Drinking Water

We have previously shown that vitamin C (ascorbic acid) can initiate hydroxyl radical formation in copper contaminated household drinking water. In the present study, we have examined the stability of vitamin C in copper and bicarbonate containing household drinking water. In drinking water samples, contaminated with copper from the pipes and buffered with bicarbonate, 35% of the added vitamin C was oxidized to dehydroascorbic acid within 15?min. After 3?h incubation at room temperature, 93% of the added (2?mM) ascorbic acid had been oxidized. The dehydroascorbic acid formed was further decomposed to oxalic acid and threonic acid by the hydrogen peroxide generated from the copper (I) autooxidation in the presence of oxygen. A very modest oxidation of vitamin C occurred in Milli-Q water and in household water samples not contaminated by copper ions. Moreover, addition of vitamin C to commercially sold domestic bottled water samples did not result in vitamin C oxidation. Our results demonstrate that ascorbic acid is rapidly oxidized to dehydroascorbic acid and further decomposed to oxalic- and threonic acid in copper contaminated household tap water that is buffered with bicarbonate. The impact of consuming ascorbic acid together with copper and bicarbonate containing drinking water on human health is discussed.     

Effect of vitamins C and E on toxicity and mutagenicity of hexavalent chromium in rat and guinea pig

The effect of simultaneous pretreatment with vitamins C and E on the toxicity and mutagenicity of K₂Cr₂O₇ in rats and guinea pigs was evaluated. Dietary pretreatment of Cr(VI)-intoxicated rats with ascorbic acid or α-tocopherol normalized vitamin C levels in lungs but not in kidneys. The synergistic preventive effect of both vitamins was confirmed in the production of lipoperoxides in Cr(VI)-intoxicated rats. Simultaneous administration of vitamins C and E in guinea pigs prevented the decrease of vitamin C levels provoked by the oxidative effects of Cr(VI). The results of the micronucleus test in bone marrow showed that it was vitamin C that caused the antimutagenic effect against bichromate, in both rats and guinea pigs. The effect of vitamin E was demonstrated only in an increase of the ratio of NCE to PCE, i.e., in a decrease of the cytotoxic but not the mutagenic effects of hexavalent chromium.     

Oxidative decomposition of vitamin C in drinking water

We have previously shown that vitamin C (ascorbic acid) can initiate hydroxyl radical formation in copper contaminated household drinking water. In the present study, we have examined the stability of vitamin C in copper and bicarbonate containing household drinking water. In drinking water samples, contaminated with copper from the pipes and buffered with bicarbonate, 35% of the added vitamin C was oxidized to dehydroascorbic acid within 15 min. After 3 h incubation at room temperature, 93% of the added (2 mM) ascorbic acid had been oxidized. The dehydroascorbic acid formed was further decomposed to oxalic acid and threonic acid by the hydrogen peroxide generated from the copper (I) autooxidation in the presence of oxygen. A very modest oxidation of vitamin C occurred in Milli-Q water and in household water samples not contaminated by copper ions. Moreover, addition of vitamin C to commercially sold domestic bottled water samples did not result in vitamin C oxidation. Our results demonstrate that ascorbic acid is rapidly oxidized to dehydroascorbic acid and further decomposed to oxalic- and threonic acid in copper contaminated household tap water that is buffered with bicarbonate. The impact of consuming ascorbic acid together with copper and bicarbonate containing drinking water on human health is discussed.     

Influence of Trace Elements on Stabilization of Aqueous Solutions of Ascorbic Acid

Together with vitamin C, zinc, selenium, manganese, and magnesium play a vital role in the preservation of organs scheduled for transplantation. In the present study, it is shown that addition of 1?mg/l of these elements influences the stability of 0.3?mM ascorbic acid solutions. The solution??s stability was estimated using an accelerated stability test. The concentration of vitamin C was measured using a validated spectrophotometric method, which uses the reduction of 2,6-dichlorophenoloindophenol by ascorbic acid. Elevated temperatures, the factor accelerating substances?? decomposition reaction rate, were used in the tests. The research was conducted at two temperatures at intervals of 10?°C: 80?±?0.1 and 90?±?0.1?°C. It was stated that the studied substances?? decomposition occurred in accordance with the equation for first-order reactions. The function of the logarithmic concentration (log%C) over time was revealed to be rectilinear. This dependence was used to determine the kinetics of decomposition reaction rate parameters. The stabilization of vitamin C solutions was measured as the time in which 10?% of the substance decomposed at 20 and 0?°C. Addition of Se(IV) or Mg(II) ions significantly increase the stability of ascorbic acid solution (??34 and ??16?%, respectively), but Zn(II) causes a significant decrease in stability by ??23?%. Addition of Mn(II) has no significant influence on vitamin C stability.     

Ethanol-ascorbate interrelationship in acute and chronic alcoholism in the guinea pig

The effects of low (200 ppm) and of high (2000 ppm) ascorbic acid, in a nutritionally adequate diet, on blood ethanol levels have been studied in permanently carotid-cannulated, ethanol-infused, unanesthetized guinea pigs. In the acute study, the postinfusion rate of ethanol decline in the blood of animals treated with ascorbic acid was significantly higher when compared with animals treated with fructose, and the rate in the two treated groups was significantly higher than in untreated controls. In the chronic study, animals were infused with sublethal doses of ethanol (30% of the total caloric intake) for 8 weeks. Blood ethanol levels monitored throughout this period showed, at 3 hr postinfusion, a lower concentration in the group on a high ascorbic acid diet. Both experimental groups receiving ethanol lost significantly more body weight in the second week of dieting; but, while the group on high ascorbic acid regained weight steadily thereafter, the group on low ascorbic acid was still 50 g below the controls at the end of the experiment. Liver, kidney, and adrenal ascorbic acid concentrations were lower in the ethanol-treated groups compared to controls. Examination of the liver revealed more fatty metamorphosis or steatosis in the low ascorbic acid group, but there was no evidence of liver fibrosis or cirrhosis. These results demonstrate the feasibility of utilizing the guinea pig for the study of the biochemical and morphological sequelae of alcoholism. They further support the contention that a diet which is nutritionally adequate may no longer be so in the presence of high ethanol intake, and that supplemental vitamin C ingestion may afford protection against ethanol toxicity.     

Antimutagenicity of some citrus fruits in Salmonella typhimurium

The antimutagenic effect of 10 citrus fruit juices was observed against the mutagenicity of N-nitro-o-phenylenediamine (NPD) in TA97a and sodium azide in TA100 tester strains of Salmonella typhimurium using the Ames test. It was noticed that the juices of all these fruits reduced significantly the NPD and sodium azide induced revertant colonies. The inhibitory activity was enhanced if the mutagen and juice were co-incubated for about 30 min at 37 degrees C prior to performing the mutagenicity assay. Dilution with distilled water led to the reduction in the inhibitory activity. The antimutagenic activity of synthetic ascorbic acid or citric acid or combined ascorbic acid and citric acid was also seen. But the results with fruit juices tempted us to believe that in addition to ascorbic acid and citric acid, the presence of other factor(s) possessing antimutagenic properties cannot be ruled out.     

Effect of oxygen on ascorbic acid uptake and concentration in embryonic chick brain

The effects of oxygen on ascorbic acid concentration and transport were studied in chick embryo (Gallus gallus domesticus). During normoxic incubations, plasma ascorbic acid concentration peaked on fetal day 12 and then fell, before increasing again on day 20 when pulmonary respiration began. In contrast, cerebral ascorbic acid concentration rose after day 6, was maintained at a relatively high level during days 8–18, and then fell significantly by day 20. Exposure of day 16 embryos for 48 h to 42% ambient O₂ concentration decreased ascorbic acid concentration by four-fifths in plasma and by one-half in brain, compared to values in normoxic (21% O₂) or hypoxic (15% O₂) controls. Hyperoxic preincubation of embryos also inhibited ascorbic acid transport, as evidenced by decreased initial rates of saturable and Na⁺-dependent [¹⁴C]ascorbic acid uptake into isolated brain cells. It may be concluded that changes in ascorbic acid concentration occur in response to oxidative stress, consistent with a role for the vitamin in the detoxification of oxygen radicals in fetal tissues. However, changing O₂ levels have less effect on ascorbic acid concentration in brain than in plasma, indicating regulation of the vitamin by brain cells. Furthermore, the effect of hyperoxia on cerebral vitamin C may result, in part, from inhibition of cellular ascorbic acid transport.     

Experimental hypovitaminosis D in guinea pigs administered different amounts of vitamin C

The experimental model of D-hypovitaminosis is first obtained on guinea pigs. It is established that the least degree of its manifestation is determined under conditions of the optimal supply of the organism with vitamin C. The necessity of using ascorbic acid in a complex of rachitis prophylaxis measures is substantiated.