Micronucleus frequencies in workers exposed to lead, zinc, and cadmium

Micronuclei (MN) in blood lymphocytes were determined in 31 male workers occupationally exposed to lead (Pb), zinc (Zn), and cadmium (Cd) and 20 control workers matched for age and smoking habits. Exposed workers have higher MN mean values than control workers (p<0.01). In exposed workers, blood Pb concentrations were also significantly higher than in control workers (p<0.001), but the mean concentrations of Zn and Cd in the blood were not statistically significant compared to the controls (p>0.05). These results suggest that lead may be genotoxic and the human lymphocyte micronucleus test can be used to assess genotoxic effects that result from occupational exposures.     

Evaluation of increased proportion of cells with unusually high sister chromatid exchange counts as a cytogenetic biomarker for lead exposure

Sister chromatid exchange (SCE) frequency and high-frequency cells (HFCs) were analyzed in 50 storage battery plant workers with mean blood lead level (BLL) of 40.14±9.99 μg/dL. The mean BLL in the control group (n=30) was 9.77±1.67 μg/dL. This difference in mean BLLs between control and exposed group was statistically significant (p<0.05) and reflects clearly the lead exposure in the workers. Urinary aminolevulinic acid (U-ALA) was also determined in both control (3.37±0.89 mg ALA/g creatinine) and exposed groups (12.39±6.18 mg ALA/g creatinine) and U-ALA excretion was statistically higher (p<0.05) in lead-exposed workers. The relationship between biomarkers of lead exposure/effect and HFC percentage was higher than the relationship between biomarkers of lead exposure/effect and SCE frequency. Accordingly, HFC analysis seemed to be more sensitive than the SCE analysis as a cytogenetic biomarker for lead exposure. Additionally, the statistically significant correlation (r ²=0.880, p<0.01) between U-ALA excretion and HFC percentage in lead-exposed workers supported the probability of ALA mediated indirect mechanism for lead genotoxicity.     

Chromosomal Aberrations (CA), Sister Chromatid Exchanges (SCE), and High-Frequency Cells (HFC) Frequencies in Peripheral Blood Lymphocytes of Tunisian Gasoline Truck Loaders

Gasoline constitutes a mixture of chemicals that contain well-known genotoxicants. Thus, chronic occupational exposure to gasoline may be considered to possess genotoxic risk. In this study, the frequencies of total chromosomal aberrations (TCA), aberrant cells (Ab.c.), sister chromatid exchanges (SCE), high-frequency cells (HFC), and high-frequency cell individual (HFI) were investigated in peripheral blood lymphocytes from 17 gasoline-exposed workers (10 smokers and 7 non-smokers) and 22 unexposed reference subjects (12 smokers and 10 non-smokers). The exposed subjects were gasoline truck loaders at a gasoline company from Tunis City, north of Tunisia. The results indicate multiple CA, such as dicentrics (DIC), chromatid breaks (SB), and chromosome breaks (DB). A significant difference was observed in TCA and Ab.c. frequencies between exposed and unexposed groups (p < 0.01). A significant difference was found in frequencies of SCE (p < 0.01) and HFI (p < 0.05) between exposed and unexposed groups. SCE and TCA frequencies of smokers were found to be significantly higher than those of non-smokers in both groups. There was an interaction between gasoline exposure and smoking habit for TCA (p = 0.020), but not for SCE. Our findings indicate that gasoline truck loaders were under risk of significant cytogenetic damage that was enhanced by their smoking habit.     

Changes of total content of magnesium and zinc status in patients with chronic toxoplasmosis

The aim of this study was to investigate the effects of the Toxoplasma gondii infection on the total content of the essential elements Zn and Mg levels. Plasma zinc and magnesium concentrations were measured in 158 patients whose anti-T gondii IgG antibodies were positive. Scores were obtained for the patients and their age- and sex-matched 82 sero-negative healthy controls. The mean concentration of Mg in blood was significantly lower in sero-positive patients than in their controls both in females (p<0.01) and males (p<0.01). The average Zn concentration in seropositive female patients was 0.72±0.2 mg/L and 0.65±0.1 mg/L in controls (p>0.05). The mean values of the Zn in blood were 1.00±0.3 mg/L in seropositive male patients and 0.84±0.2 in controls (p>0.05). No correlation could be demonstrated between age and mean values of Zn and Mg in both sero-positive females/males and controls (p>0.05). No significant correlation could be found between blood Zn and Mg levels in seropositive female/male patients and controls (p>0.05). Mg levels were found to be clearly decreased in the patients with chronic toxoplasmosis, whereas no change was observed in Zn levels.     

Microelements in seminal plasma of infertile men infected with Ureaplasma urealyticum

The purpose of this study was to assess the association among male infertility, infection of Ureaplasma urealyticum (Uu), and microelements in seminal fluid. Semen analysis and cultivation of Uu were carried out on 160 samples of seminal fluid. The concentrations of microelements, such as arsenic (As), molybdenum (Mo), magnesium (Mg), lead (Pb), copper (Cu), cadmium (Cd), and zinc (Zn) in the samples were measured by an inductively coupled plasma quantometer (ICP). The ratios Cu/Zn and Cd/Zn in the poor spermatic quality group were obviously higher than those in seminal plasma of the group with normal spermatic quality (p<0.01 and p<0.05, respectively), whereas the concentrations of As, Mg, Mo, and Pb showed no difference in the two groups. The ratios Cu/Zn and Cd/Zn and the concentrations of As and Mg in seminal plasma infected with Uu were markedly higher than those not infected with Uu (p<0.05, p<0.01, p<0.05, and p<0.05, respectively), whereas the concentrations of Mo and Pb showed no statistical difference. The ratios Cu/Zn and Cd/Zn and the concentrations of As and Mg in seminal plasma of the semen with poor spermatic quality and Uu infection were obviously higher than those not infected with Uu (p<0.05), whereas the concentrations of Mo and Pb showed no statistical difference. Abnormally high ratios Cu/Zn and Cd/Zn as well as an overdose of As were found to be predisposed to Uu infection. Uu infection resulted in an increase of the ratios Cu/Zn and Cd/Zn and the concentrations of As and Mg in seminal fluid, which therefore caused spermatic quality decline.     

Determination of isocyanate biomarkers in construction site workers

4,4′-Methylenediphenyl diisocyanate (MDI) is the most important isocyanate in the manufacture of polyurethanes, dyes, pigments and adhesives. High concentrations of isocyanates are a potent respiratory irritant. Therefore, it is important to develop methods to monitor exposure to such compounds. We monitored biological samples from 40 non-exposed and 45 exposed construction site workers. 4,4′-Methylenedianiline (MDA) and N-acetyl-4,4′-MDA (AcMDA) were determined from untreated urine (U-MDA, U-AcMDA) and MDA was analysed from acid-treated urine (U-MDA-tot). Haemoglobin (Hb) adducts of MDA (Hb-MDA) were determined in all workers. The levels of biomarkers decreased in the following order: U-MDA-tot>U-AcMDA>U-MDA>Hb-MDA. The same order was found for the percentage of samples, which were found positive in exposed workers: 100%, 91%, 91%, 27%. The urine levels U-MDA-tot correlate with U-MDA, U-AcMDA and Hb-MDA with r=0.79, 0.86 and 0.39, respectively (Spearman rank order, p<0.01). U-AcMDA correlates with U-MDA and Hb-MDA with r=0.77 and 0.47, respectively (p<0.01). U-MDA correlates with Hb-MDA (r=0.38, p<0.05). The levels in the controls were significantly lower than in the exposed workers for all compounds (Mann–Whitney test, p<0.01). The median isocyanate-specific IgE-level was higher in the exposed workers, but the difference was statistically not significant. The change of the biomarker levels was compared in a group of workers (n=20), which were analysed prior to isocyanate exposure and after the exposure for ～4–7 months. All urine MDA metabolites and the Hb-adduct levels increased significantly (Wilcoxon sign test, p<0.01). Total IgE increased significantly after the exposure with isocyanate activity (p<0.01). With the present work it could be shown that outdoor workers are exposed to a similar extent as workers from a MDI factory.     

Sister-chromatid exchanges in lymphocytes of workers at a phosphate fertilizer factory

The frequencies of sister-chromatid exchange (SCE) in peripheral blood lymphocytes of 40 workers at a phosphate fertilizer factory in North China were studied. HF and SiF₄ are main air pollutants in the factory, there is also some dust containing fluoride, phosphate fog, NH₃ and SO₂. It was shown that the chemicals caused an increase in SCE, and also induced cell mitotic delays. The mean SCEs/cell of the workers and the non-exposed controls were 7.47 ± 0.31 and 4.94 ± 0.14 (p < 0.01) respectively. SCEs/cell in 75% of 40 workers were higher than 6 while 40 controls all had values lower than 6. SCE frequencies of the workers increased with length of the chemical exposure period up to 10 years. Smoking enhanced the SCE frequencies induced by the chemicals.     

Concentrations of cadmium,lead, selenium,and zinc in human blood and seminal plasma

The concentrations of cadmium, lead, selenium, and zinc in blood and seminal plasma were determined in 76 Singapore males. Except for zinc, the concentrations were generally higher in blood than in seminal plasma (cadmium, 1.31 μg/L vs 0.61 μg/L; lead, 82.6 μg/L vs 12.4 μg/L, and selenium, 163.6 μg/L vs 71.5 μg/L). The mean concentration of zinc in seminal plasma was more than 30 times higher than in blood (202 mg/L vs 6.2 mg/L). Significant positive correlations were found between the concentrations in blood and seminal plasma for the two essential trace elements: selenium (r=0.45,p<0.001) and zinc (r=0.25,p<0.05). However, no relationships were found between the concentrations in blood and seminal plasma for two toxic metals (cadmium and lead). Significant inverse correlations were observed between Cd and Zn (r=−0.40,p<0.01), and Pb and Se (r=−0.32,p<0.05) in blood, whereas significant positive correlations were noted between Cd and Se (r=0.45,p<0.01), Cd and Zn (r=0.35,p<0.05), and Se and Zn (r=0.57,p<0.001) in seminal plasma. The physiological significance of these relationships are also discussed in this paper.     

Chromosome aberrations and response to γ-ray challenge in lymphocytes of workers exposed to 1,3-butadiene

An integrated population monitoring study was initiated to investigate whether occupational exposure to current low levels of butadiene is mutagenic to workers. Ten exposed workers (mean production area concentration of 3.5 ppm) and 10 matched plant controls(mean exposure to 0.03 ppm) were selected and blood samples were collected for our study. The standard cytogenetic assay was used to determine chromosome aberration frequencies. In addition, a challenge assay was used to determine response to γ-rays as an indication of DNA repair deficiencies. In the latter assay, cells were exposed to γ-rays at the G1 phase of the cell cycle in vitro and the frequencies of chromosome aberrations in the first post-irradiation metaphase cells were quantitated. Based on results of the cytogenetic assay, the exposed group had a higher frequency of cells with chromosome aberrations and higher chromatid breaks per 100 cells compared with the control. However, the difference was not significant (p > 0.1). With the challenge assay, the exposed group had a higher frequency of aberrant cells (p < 0.04), chromatid breaks (p < 0.05), deletions (p < 0.07), and dicentrics (p < 0.02) than the controls. In addition, the dicentric frequencies from workers were significantly correlated with the presence of a butadiene metabolite [1,2-dihydroxy-4-(N-acetyl-cysteinyl-S)butane] in urine with a correlation of coefficient of 0.6 (p < 0.01). Two outliers were identified and our interpretation of their responses will be discussed. This study indicates that the workers had exposure-induced mutagenic effects. Together with the observation of gene mutation in a subset of the present population, this study indicates that the current occupational exposure to butadiene may not be safe to workers.     

Lead,copper, zinc,and magnesium levels in hair of children and young people with some disorders of the osteomuscular articular system

The lead, copper, zinc, and magnesium contents of scalp hair taken from 173 children aged 1–15 yr and young people (16–18 yr) with certain disorders of the osteomuscular articular system (osteomuscular pains of unknown origin, once described as “growing pains”) were measured, using the flame atomic absorption spectrometry method, and then compared with those of 108 normal, healthy children. The research showed increased average levels of lead (a statistically significant p<0.05 in both the overall group of children, and in those over 11 yr old), and zinc (increased in the total group, in a statistically significant way at p<0.10 only in adolescents over 15 yr old) and decreased levels of copper (although not significantly) in the hair of children suffering from “rheumatic” diseases, as compared with controls. The magnesium levels for the total group of ill children were admittedly enhanced, but in the youngest children, the levels were reduced. The values of the Mg/Pb and Mg/Zn ratios were lower (in the youngest children, 70% decrease of the Mg/Pb ratio) and Zn/Cu were higher in the group of children suffering from rheumatic diseases than in the healthy children. The difference of Mg/Pb ratio between the total controls and rheumatic subjects was statistically significant at p<0.05 and the Zn/Cu at p<0.10. The Mg/Zn ratio was not statistically significant.     

Some essential elements in maternal and cord blood in relation to birth weight and gestational age of the baby

Maternal and cord blood were collected from 54 Indian women at parturition and analyzed for Zn, Cu, and Fe by flame atomic absorption spectrophotometry to determine the relationship between levels of these elements in mother’s and infant’s blood and maternal age, birth weight, and gestational age of the baby. The blood Zn level of mothers in the age group 24–28 yr was significantly higher than those of mothers in the age group of 18–23 yr (p<0.05). Similarly, mothers in the 24 to 28-yr group also had higher blood Fe level than mothers in the group 29–38 yr (p<0.05). The levels of Zn, Cu, and Fe were higher in the maternal blood and lower, but not significantly, in the cord blood of low-birth-weight babies than in those of normal-birth-weight babies. However, differences in the levels of Zn, Cu, and Fe between maternal and cord blood of the two birth-weight groups was statistically significant. There were no significant differences in the levels of the three elements in maternal or cord blood by the gestational age of the baby. A weak but significant correlation was found between the birth weight of the baby and the Fe level in the cord blood (r=0.26; p<0.05). Also, weak significant correlations were observed between gestational age of the baby and Fe (r=0.23; p<0.05) and Cu (r=0.31; p<0.05) levels in the cord blood. Although, there are many confounders of low birth weight and preterm deliveries, a diminished placental transfer of these essential elements could be one of the several etiological factors for low birth weight of newborns.     

Significance of serum trace element status in patients with rheumatic heart disease

It is known that certain trace elements can affect various heart diseases. In this study, we aimed to evaluate the changes in concentrations of certain serum trace elements in patients with chronic rheumatic heart disease (RHD). Serum analysis of selenium (Se), zinc (Zn), and copper (Cu) trace elements was assayed by atomic absorption spectrophotometry. RHD patients had significantly lower serum concentrations of Se and Zn than control subjects (p<0.05 and p<0.001, respectively). However, the serum Cu concentration was significantly higher in RHD patients than in controls (1.93±0.59 μg/L vs 1.06±0.29 μg/L; p<0.001). Similarly, the Cu/Zn ratio in RHD patients was higher than in control subjects (4.70±0.92 vs 1.68±0.45; p<0.001). Additionally, no significant correlation was found among these trace element concentrations and the functional capacity classes (p>0.05). RHD patients had decreased serum Se and Zn element concentrations and increased serum Cu element concentration. We suggest that Se and Zn deficiency might be contributory factors in the development of rheumatic heart disease, and a high Cu concentration and a high Cu/Zn ratio might reflect an ongoing inflammatory process in this disease.     

Advantages of the Use of Deciduous Teeth,Hair, and Blood Analysis for Lead and Cadmium Bio-Monitoring in Children. A Study of 6-Year-Old Children from Krakow (Poland)

The population of about 300 6-year-old preschool children was studied for lead (Pb) and cadmium (Cd) in deciduous teeth, scalp hair, and capillary blood. Zinc (Zn) content in hair was also measured due to its possible interferences with the elements studied. The Pb and Cd contents were measured by graphite furnace atomic absorption spectrometry with Zeeman background correction, and Zn, by flame method. Metal levels found were comparable to those in European countries. Positive correlations between Pb and Cd in the same and different tissues were widespread (r = 0.23–0.68). A positive correlation was found between Pb in teeth and blood (r = 0.65, p < 0.001). Pb blood threshold 100 μg L⁻¹ referred to 2.6 μg g⁻¹ Pb in teeth. Predictability of this Pb teeth limit was 14% vs. 5% for Pb blood. Strong negative correlation was found between hair Pb and Zn (r = −0.68, p < 0.001). Enhanced Cd and Zn levels in hair were associated with the household drinking water hardness. The associations with some other environmental and behavioral factors were also presented and discussed. The results proved the advantage of analysis of primary teeth for Pb exposure screening of preschool children.     

Essential trace and toxic element distribution in the scalp hair of Pakistani myocardial infarction patients and controls

The pathogenesis of heart disease has been associated with changes in the balance of certain trace elements. The aim of this study was to evaluate the Zn, Fe, Cu, Cr, Ni, Pb, and Cd contents in scalp hair samples of myocardial infarction (MCI) patients hospitalized in the cardiac ward of National Hospital in Hyderabad city (Pakistan). Scalp hair samples were collected from 193 patients (104 male, 89 female) of 3 age groups (46–60, 61–75, and 76–90 yr), for a comparative study, 200 normal, healthy subjects (103 male, 97 female) of the same age groups residing in the same city were selected. All metals in scalp hair samples were assessed by a flame/graphite furnace atomic absorption spectrophotometer, prior to microwave-assisted and conventional wet acid digestion methods. Results were calculated in micrograms per gram. The mean values of Fe and Zn of scalp hair samples of MCI patients were significantly reduced compared to the control subjects of both genders. The mean Fe concentrations in male patients were 19.42, 12.36, and 6.98 vs 30.69, 24.42, and 16.75 for the control patients in the three age groups (46–60, 61–75, and 76–90 yrs, respectively). The mean Zn concentration in male patients were 169.2, 149.4, and 107.7 μg/g vs 206.1, 188.0, and 154.4 μg/g for the control group (p<0.002, 0.004, and 0.001) in all three age groups, respectively. These differences were also observed in the female study groups. The mean values of Pb, Cd, and Ni were significantly high in patients compared to healthy subjects (mean Pb in male patients: 11.85, 12.89, and 14.52 those of female patients were 11.88, 12.73, and 14.21 vs the male controls patients (6.08, 7.56, and 8.56) and female controls (5.99, 7.41, and 8.25) for all three age groups, respectively. The concentration of Ni and Cd in the scalp hair samples of the heart patients of both sexes were significantly higher compared to the control; in the case of Ni the range of significant difference for males was found to be p<0.001–0.009 and for females to be p<0.0.002–0.007 and significantly high concentration of Cd were observed in hair samples of patients than in controls in the range for males (p<0.001–0.009) and in females (p<0.001–0.011). The Zn/Cu and Zn/Cd ratios in the scalp hair (p<0.01) of the diseased groups were significantly lower than that of the healthy groups. Deficiency of essential trace metals and high level of toxic metals might play a role in the development of heart disease in the subjects of this study. Toxic metals might also cause diminished absorption of essential elements.     

Effect of long-term swimming exercise on zinc,magnesium, and copper distribution in aged rats

Trace element content of different tissues might be altered by both age and exercise training. We aimed to determine the effects of a 1-yr swimming protocol (60 min/d, 5 day/wk) on tissue levels and the distribution of zinc (Zn), magnesium (Mg), and copper (Cu) in aging rats. Three groups were formed: sedentary and trained old groups and a young control group. Tissue Zn, Mg, and Cu concentrations were measured in the kidney, heart, liver, lungs, and gastrocnemius and soleus muscles. Kidney zinc concentration significantly decreased in the sedentary old group compared to the young control group (p<0.01) and was significantly higher in the trained old group compared to the sedentary old group (p<0.01), whereas Zn levels in the soleus muscle significantly increased in the sedentary old group in comparison to young controls (p<0.05). Tissue Mg concentrations remained unchanged. The sedentary old group exhibited a significant decrease in kidney Cu concentration compared to the young control group (p<0.01). Although kidney Cu levels also decreased in trained old rats in comparison to young controls (p<0.05), they were significantly higher than in sedentary old rats (p<0.01). The decrease in kidney Zn and Cu content as a result of aging was partly prevented by long-term swimming exercise.     

Zinc prevention of electromagnetically induced damage to rat testicle and kidney tissues

The aim of this study was to investigate the extent of lipid peroxidation when zinc is administered to rats periodically exposed to a 50-Hz electromagnetic field for 5 min at a time over a period of 6 mo. Twenty-four Sprague-Dawley adult male rats were subdivided in groups of eight animals each. Group 1 served as untreated controls, group 2 was exposed to an electromagnetic field but received no additional treatment, and group 3 was exposed to electromagnetic radiation and treated with 3-mg/kg daily intraperitoneal injections of zinc sulfate. The erythrocyte glutathione activity (GSH) and the plasma, testicle, and kidney tissue levels of zinc (Zn) and of malondialdehyde (MDA) were measured in all of the animals. The plasma and testicle MDA levels in group 2 were higher than those in groups 1 and 3, with group 3 values significantly higher than those in group 1 (p<0.001). The kidney MDA levels in group 2 were higher than in groups 1 and 3 (p<0.001). The erythrocyte GSH level was lower in group 2 than in groups 1 and 3, with group 1 significantly lower than group 3 (p<0.001). In testicle and kidney tissues, the GSH levels in group 1 were lower than for groups 2 and 3, with group 2 significantly lower than group 3 (p<0.001) The plasma zinc levels were highest in group 3, followed by group 1 and group 2, which showed the lowest value (p<0.001). These results indicate that testicle and kidney tissue damage caused by periodic exposure to an electromagnetic field are ameliorated or prevented by zinc supplementation.     

Angiotensin-converting enzyme and metals in untreated essential hypertension

Hpertension is an important health problem throughout the world and a risk factor for many diseases. Angiotensin-converting enzyme (ACE), a component of the renin-angiotensin system, has an important role in the regulation of blood pressure. Zinc (Zn), a trace element with important biological functions, is located in the catalytic site of ACE. Calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) also appear to be involved in hypertension pathogenesis. In this study, plasma ACE activities and Ca_t, Ca_i, Mg, Na, K, and plasma/erythrocyte Zn levels of 20 untreated patients with essential hypertension and 28 helthy individuals were evaluated. Plasma ACE activities (p<0.05) and erythrocyte Zn concentrations (p<0.001) were significantly higher in patients with essential hypertension than values of the control group. No significant difference was found between plasma Zn concentrations of the groups (p>0.05). Plasma Ca_t (p<0.001) and Mg levels (p<0.05) in essential hypertension were significantly lower than those of controls. Plasma Na, K, and Ca_i levels remained normal in essential hypertension. There are complex associations between metals and arterial pressure. Ca and Mg deficiencies seem to be associated with increased prevalence of hypertension. Increases in erythrocyte Zn may have a future potential use for diagnosis of hypertension.     

Longitudinal study of serum zinc and copper levels in hemodialysis patients and their relation to biochemical markers

A 6-mo longitudinal study of 48 hemodialysis patients (HPs) with chronic renal failure was performed. Three blood samplings were done. Samples of whole blood from each patient were collected during hemodialysis sessions after passing through the artificial kidney. Zinc and copper levels were measured by atomic absorption spectrometry. Additionally, 36 biochemical indexes were evaluated during the study. Fifty-two healthy matched controls were also considered. Mean serum zinc and copper concentrations in HPs were significantly decreased (Zn) and increased (Cu), when compared with healthy controls (p<0.01). Zinc concentrations found in the first and second blood samplings from patients were significantly lower than those measured for the third sampling (p<0.01). The etiology of chronic renal failure influenced the statistically serum Zn levels of patients (p<0.05). Serum copper levels of HPs were significantly diminished by the existence of secondary associated diseases (p<0.01). Uric acid and parathyroid hormone, and total-cholesterol and glutamic-pyruvic-transaminase levels were significantly (p<0.05) and linearly related with serum zinc and copper concentrations, respectively. From all of indexes, creatinine, direct bilirubin, magnesium, calcium, parathyroid hormone, transferrin, and albumin were statistically modified along the longitudinal study (p<0.05). Transferrin serum levels were significantly diminished in the third blood sampling, indicating the tendency toward anemia in the patients. This result is reinforced by low levels of biochemical and hematological indexes related with iron body staus.     

Urinary excretion of lead and δ-aminolevulinic acid in workers occupationally exposed to tetraethyl lead

Forty-nine refinery workers and 50 motor mechanics were selected and examined for total lead (PbT), inorganic lead (PbI), and δ-aminolevulinic acid (ALA) in urine. The worker groups were exposed to tetraethyl lead (TEL) mainly by inhalation, but motor mechanics received additional exposure by skin because of hand cleansing with gasoline. The levels of urinary ALA (ALA-U) and urinary PbT (PbT-U) in refinery workers and motor mechanics were found to be significantly higher than the control group (p<0.05). The correlation between the ALA-U and PbT-U was found significant in both worker groups (p<0.001); however, relatively higher positive correlation was found between ALA-U and urinary inorganic lead (PbI-U) in TEL-exposed workers.     

Effect of zinc and melatonin supplementation on cellular immunity in rats with toxoplasmosis

The effects of zinc (Zn) and/or melatonin supplementation on cellular immunity were investigated in rats infested with Toxoplasma gondii. Fifty Sprague-Dawley male rats were used for this study. All animals were fed a normal diet, ad libitum, containing 97 mg Zn/kg. They were divided into five experimental groups, as follows. Group I (n=10) received intraperitoneal injections of zinc sulfate at a dose of 3 mg/kg/d for 3 wk. Group II (n=10) received intraperitoneal injections of melatonin at a dose of 3 mg/kg/d for 3 wk. Group III (n=10) received intraperitoneal injections of zinc sulfate (3 mg/kg/d) and melatonin (3 mg/kg/d) for 3 wk. Group IV (n=10) was infested controls. Group V (n=10) was healthy controls. There were no differences in the percentage of CD3+ lymphocytes among all groups. For groups I–III, the CD4+ and CD8+ ratios were higher than those of the groups IV and V controls (p<0.01). Similarly, the total lymphocyte ratios in groups I–III were higher than those of infested and healthy controls (p<0.01). The total lymphocyte ratios in group III were significantly higher than those of groups I and II (p<0.01). The plasma Zn levels in the supplemented groups were significantly higher than those of control groups IV and V (p<0.01). These results suggest that melatonin and/or Zn supplementation may activate cellular immunity by stimulating CD4+ and CD8+ production in infected rats with T. gondii.