Significance of the excretion of urinary indicator proteins for a low level of occupational exposure to cadmium

Summary Urinary cadmium (Cd), N-acetyl-β-D-glucosaminidase (NAG), metallothionein (MT), β₂-microglobulin (BMG), and blood cadmium were determined in 79 workers who had been employed at a Cd pigment factory in Japan. The workers who had been dealing with Cd pigment manufacturing processes were estimated to be exposed to cadmium pigment dust at a maximum concentration of 3.0 [μg/m³/8 h for about 20 years. The urinary Cd level ranged from 0.2 to 9.7 μg/g creatinine with a geometric mean of 1.02 μg/g creatinine. Pearson's correlation coefficients between logarithm of urinary Cd and that of NAG, MT, and BMG in urine were 0.45, 0.62, and 0.05, respectively. The correlation coefficients between blood Cd and urinary NAG, MT, and BMG were 0.21, 0.40, and −0.074, respectively. When partial correlation coefficients were calculated to exclude the contribution of age factor, urinary Cd turned out to be significantly correlated with urinary MT (r = 0.55) and NAG (r = 0.52). The present results indicate that urinary Cd is more closely associated with urinary MT and NAG than with BMG, and suggest that MT and NAG could be good indicators of Cd absorption in a Cd-exposed population whose mean urinary Cd level is relatively low, or less than 10 μg/g creatinine.     

Mutagenicity studies and D-glucaric acid determination in urine of workers exposed to mineral oils

Summary Urine from workers of a cold-rolling steel plant exposed to mineral oils were tested for the mutagenic activity by the Salmonella/microsome assay, and for D-glucaric acid content as a measure of hepatic mixed-function oxidase activity. An occupationally unexposed group served as control. The biological monitoring phase followed an environmental phase carried out in the working environment that showed a substantially low mutagenic/carcinogenic risk for the exposed workers. Urine samples were collected before, during and after work. From the results it was observed that the urinary mutagenicity was detectable only with TA98 strain in the presence of enzymatic activation (+ S9 mix). Further addition of beta-glucuronidase did not give any enhanced mutagenic effects. There was a significant difference in urinary mutagenicity between the exposed and control workers. However, in both groups the highest mutagenicity data was found in smokers: both exposed smoking workers and smoking controls had significantly higher urine mutagenicity than the non-smoking exposed and control workers. The results suggested a synergistic effect of smoking with exposure to mineral oils: the mutagenicity of urine from exposed smokers was significantly higher than that of control smokers. There was no difference in urinary D-glucaric acid results between exposed and unexposed groups, however, smokers of both groups had a significant increase in D-glucaric acid excretion. The authors suggest that even for this workplace with its low mutagenic/carcinogenic risk, smoking could interact with the complex mixtures present in the environment, and thus modify urinary mutagenicity data.     

Production of <Emphasis Type="SmallCaps">l</Emphasis>-tryptophan-derived catabolites in hepatocytes from streptozotocin-induced diabetic rats

Background  Recently the l-tryptophan (Trp) metabolites such as l-kynurenine(Kyn), l-kinurenic acid, quinolinic acid (QA) and picolinic acid (PA) have been shown physiologically important in central nervous and immune system, and various enzyme activities concerning their production were reported to be affected by insulin-dependent diabetes mellitus. However, the states of these metabolites in diabetes have not been clarified enough yet. Aim of study  The present study was performed to make clear the states of the productions of l-Kyn, QA, PA and nicotinamide (Nam) in vitro in the hepatocytes prepared from streptozotocin (STZ)-induced diabetic rats using [5-³H]l-Trp. Methods  The diabetic model rats were made by STZ injection (60 mg/kg) and the hepatocytes isolated from the rats were incubated with [5-³H]l-Trp. The amounts of metabolites derived from l-Trp were determined by the isotope-dilution methods. Results  The α-amino-β-carboxymuconate-ε-semiarldehyde decarboxylase (ACMSD) mRNA level in the diabetic group was greatly higher than that in the control group. In the STZ-induced diabetes group, the amount of [5-³H]l-Trp converted to tritiated water, l-Kyn or QA were found to be more than 3 times of that in the control group, respectively. The produced amounts of PA and Nam were not significantly different between the diabetic and the control groups. Conclusions  It is suggested that STZ-diabetes mellitus causes augmentations of both l-Kyn and QA generations but not those of PA and Nam in liver, indicating the possibility that the immune and neuronal systems of insulin dependent diabetes mellitus would be influenced by the increased amounts of lKyn and QA but not by those of PA and Nam.     

Effect of occupational exposure to aldrin on urinary d-glucaric acid,plasma dieldrin,and lymphocyte sister chromatid exchange

The effects of exposure to the chlorinated cyclodiene termiticide aldrin was evaluated in pest control workers potentially exposed to this material. Sister chromatid exchange (SCE) frequencies were not elevated in workers handling aldrin. This is consistent with the fact that chlorinated cyclodienes are not genotoxic. Plasma dieldrin concentrations (up to 250 ng/ml) confirmed exposure in workers actively performing termiticide treatments and in maintenance and store workers, when compared with unexposed control workers (median concentration, 4.8 ng/ml). Urinary d-glucaric acid (DGA), an index of hepatic enzyme activity, was elevated in pesticide-exposed groups but urinary DGA was poorly correlated with plasma dieldrin level. This indicates that concurrent exposures of these groups to other pesticides may have influenced mixed-function oxidase metabolic activity.     

Urinary cadmium and N-acetyl-β-D-glucosaminidase excretion of inhabitants living in a cadmium-polluted area

Summary Urinary cadmium (Cd), N-acetyl--D-glucosaminidase (NAG), and creatinine levels were determined for 400 inhabitants living in Cd-polluted districts of Annaka City in Gunma Prefecture, Japan. The Cd pollution was mainly due to falling dust from a zinc smelter factory according to seasonal winds. The Cd-polluted areas were divided into five administrative districts around the factory. The geometric mean of the urinary Cd level of the inhabitants in the five districts, Nodono, Iwai, Ooya, Nakajyuku, and Itahana, were 2.95, 2.66, 2.45, 1.97, and 1.67 g/g creatinine, respectively. The geometric means for Nodono and Iwai are statistically larger than that for Itahana (P < 0.01). These results were well explained by the wind direction and proximity to the factory. In addition, a two-way analysis of variance on the urinary Cd level was made using place of residence and smoking habits. The effect was mainly due to the place of residence, and no interactions were found. There were statistically significant differences in NAG excretion among the five groups, but no difference could be found between two groups using a multiple comparison. Pearson's correlation coefficient between the logarithm of urinary Cd content and that of NAG was 0.203, but statistically significant (r = 0.462 without creatinine correction; P < 0.01). The present results indicate the association of urinary Cd and NAG levels in a Cd-exposed population whose geometric mean of urinary Cd content is about 2 g/g creatinine. We recommend a continuous survey of the minimum health effects of the Cd pollution using urinary levels of Cd and protein including NAG.     

Urinary excretion of mutagens,thioethers and d-glucaric acid in workers exposed to bitumen fumes

Summary The authors carried out biological monitoring of the mutagenic/carcinogenic hazards associated with exposure to bitumen fumes during paving operations, analysing some biological parameters in the urine of a group of exposed workers. The urine samples were studied for mutagenicity by the Ames test and for thioethers concentration. d-Glucaric acid urine excretion was also determined to investigate the enzymatic induction potential of bitumens. Even though, in a previous environmental monitoring phase, a low content of mutagenic/carcinogenic compounds was found in bitumen and air samples, urinary mutagenicity data of exposed workers were statistically higher than those of a group of unexposed subjects. The urinary mutagenicity increased further if exposure to bitumens was associated with cigarette smoking. Thioethers were higher only in subjects exposed simultaneously to bitumens and cigarettes. d-Glucaric acid excretion did not increase significantly. The authors think that this type of coupled environmental and biological monitoring is a valid tool for a better evaluation of the mutagenic/carcinogenic exposure to bitumens or similar complex mixtures.     

Noninvasive assessment of microsomal enzyme activity in occupational medicine:

Summary The activity of the hepatic microsomal enzyme system, which may be of great importance for metabolic activation and deactivation of hepatotoxic agents and carcinogens, is changed by exposure to commonly used industrial chemicals. The antipyrine test is the most widely used method for assessing microsomal enzyme activity in man. The clearance of antipyrine can be accurately calculated from one sample of saliva obtained about 24 h after an oral dose of the drug. By measuring antipyrine metabolism during exposure to industrial chemicals and at the end of 3–4 weeks free from exposure, the impact of industrial chemicals on antipyrine metabolism can be estimated, provided the chemicals are eliminated within 3–4 weeks. This test can be performed by skilled and unskilled workers using written instructions. This has broadened the application of the test. Other noninvasive indices of microsomal enzyme activity include the aminopyrine and caffeine breath tests and the urinary excretion of 6--hydroxycortisol and d-glucaric acid. These tests probably reflect the activity of different but overlapping parts of the microsomal enzyme system and may be of value in research in occupational medicine. Previous studies indicate that chlorinated hydrocarbon insecticides, phenoxyacids, chlorophenols, polychlorinated biphenyles, some organic solvents and high concentrations of inhalation anaesthetics may stimulate microsomal enzyme activity, while styrene, toluene and inhalation anaesthetics in concentrations at about the allowed safety limit values have no effect. Lead, chemicals used by spray painters, and carbon disulphide probably inhibit the activity. While the short-term consequences of these changes include altered metabolism of hormones, vitamins, drugs, and other microsomally metabolized compounds, the possible impact on health on a long-term scale is unknown. It is now possible to study this with the use of the available noninvasive simple indices of microsomal enzyme activity. The potentially useful applications include biological monitoring of environmental carcinogenesis and hepatotoxicity.     

Biological variations in cadmium, α1-microglobulin, β2-microglobulin and N-acetyl-β-d-glucosaminidase in adult women in a non-polluted area

Objectives This study was initiated to investigate the extents of biological variations in cadmium and three common tubular dysfunction marker levels in blood and urine through repeated sampling. Methods A 12-month survey and a 10-week survey were conducted in an area with no known cadmium pollution. In the 12-month survey, five adult women offered urine samples once every month and blood samples once in every season, respectively. In the 10-week survey, 17 adult women gave urine samples once every week. Blood and urine samples were analyzed for cadmium (Cd-B and Cd-U) by graphite-furnace atomic absorption spectrometry, and urine samples were analyzed also for α₁-microglobulin (α₁-MG-U), β₂-microglobulin (β₂-MG-U) and N-acetyl-β-d-glucosaminidase (NAG-U) by conventional methods, all under strict quality control. The results were subjected to statistical analysis to examine the extents of biological variations through-out the study periods. Results Variations in geometric means (GMs) for Cd-B, Cd-U, α₁-MG-U, β₂-MG-U, and NAG-U were all small; the ratio of the largest GM over the lowest GM was 1.1 for Cd-B, 2 for Cd-U and 2 to 3 for α₁-MG-U, β₂-MG-U, and NAG-U in the 12-month survey, and 1.7 at largest for all parameters in the 10-week survey. The within-subject variations during the 12-month or 10-week periods were however large, i.e., more than 4–5-fold difference between the smallest and the largest values obtained for the same subject. Effects of the correction for urine density to reduce the variations were limited. In contrast, within-subject variation in Cd-B was small with a ratio of 1.3. Conclusions Variations in GM values for Cd-U, α₁-MG-U, β₂-MG-U, and NAG-U at different time of sampling are small so that single measurement would be acceptable as far as the evaluation on a group basis is the study objective. Within-subject variations are wide however, the ratio of the largest value over the smallest value being 4–5 or more, irrespective of correction for urine density. Therefore, care should be practiced when evaluation on an individual basis is intended. Very low within-subject variation in Cd-B may suggest the advantage of Cd-B over Cd-U for individual evaluation among general populations if blood sampling is accepted.     

UrinaryN-acetyl-β-d-glucosaminidase and β-aminoisobutyric acid in workers occupationally exposed to metals such as chromium,nickel, and iron

Summary To examine the relationships between the urinary excretion ofN-acetyl--d-glucosaminidase (NAG) and -aminoisobutyric acid (AIBA) as a metabolite of thymine, and exposure to chromium, nickel, and iron, we determined these parameters in 58 workers engaged in the cutting and grinding of stainless steel or iron-steel plates. A significant increase in urinary NAG activity or urinary AIBA excretion was found in some of these workers. However, we could not find a significant positive correlation between the urinary excretion of NAG or AIBA and the urinary concentration of chromium, nickel, or iron as an indicator of internal dose.     

Determination of Myo-inositol and d-chiro-inositol in black rice bran by capillary electrophoresis with electrochemical detection

A high-performance capillary electrophoresis (CE) method with electrochemical detection (ED) is developed for simultaneous determination of myo-inositol and d-chiro-inositol in black rice bran in this work. A 140 μm diameter copper-disk electrode operated in a wall-jet configuration, which exhibited good response at +0.65 V (relative to the saturated calomel electrode (SCE)) for the two analytes in 50 mm sodium hydroxide solution, was used as working electrode. The optimum conditions for determination was optimized with regard to the potential applied to the working electrode, concentration of the running buffer, separation voltage and injection time. The analytes were separated within 20 min. Excellent linearity was obtained in the concentration range from 1.0×10⁻⁶ to 1.0×10⁻⁴ g/ml for both analytes. The detection limit (S/N=3) was 5.3×10⁻⁷ and 7.3×10⁻⁷ g/ml for myo-inositol and d-chiro-inositol, respectively. The work provides a useful method for the analysis of myo-inositol and d-chiro-inositol in black rice bran.     

广东省2007-2016年人源沙门菌流行现状及病原学特征

目的 了解广东省人源沙门菌1,4,[5],12：i：-的流行现状、耐药性与分子特征。方法 对2007－2016年广东省沙门菌腹泻病例监测检出的人源沙门菌1,4,[5],12：i：-进行药物敏感试验、PCR检测和PFGE分型。结果 2007－2016年广东省共检出人源沙门菌1,4,[5],12：i：-2 960株,检出率逐年增多,至2015年成为广东省人源沙门菌中最主要的血清型。病例中男女性别比为1.58∶1,发病年龄以婴幼儿为主。沙门菌1,4,[5],12：i：-除对亚胺培南100%敏感外,对其他17种抗生素均有不同程度的耐药。2011－2016年对头孢他啶、头孢噻肟和环丙沙星的耐药率呈上升趋势。多重耐药现象严重,具有ASSuT多重耐药的有70.62%（435/616）,具有ACSuGSTTm多重耐药的有27.11%（167/616）。第Ⅱ相鞭毛蛋白不表达主要（75.53%）是缺失fljA、fljB和hin基因,但保留了iroB、STM2740、STM2757基因,共有8种不同的缺失方式。2 347株菌有934种PFGE谱型别,表现出较大的指纹图谱多态性,最主要的优势PFGE谱型为JPXX01.GD0226型（97株菌,4.13%）。168株沙门菌1,4,[5],12：i：-的PFGE图谱与鼠伤寒沙门菌PFGE图谱一致。结论 沙门菌1,4,[5],12：i：-已成为广东省人源沙门菌中最主要的血清型,且多重耐药现象严重,第Ⅱ相鞭毛蛋白不表达主要由缺失fljA、fljB和hin基因引起,其PFGE型别多样,呈遗传多态性。     

Silk protein hydrolysate increases glucose uptake through up-regulation of GLUT 4 and reduces the expression of leptin in 3T3-L1 fibroblast

The purpose of our research was to test the hypothesis that silk protein hydrolysate increases glucose uptake in cultured murine embryonic fibroblasts. Insulin sensitizing activity was observed in a cell-based glucose uptake assay using 3T3-L1 embryonic fibroblasts. The treatment of 1 mg/mL of silk peptide E5K6 plus 0.2 nM insulin was associated with a significant increase in glucose uptake (124.0% ± 2.5%) compared to treatment with 0.2 nM insulin alone. When the 3T3-L1 cells were induced to differentiate into fibroblasts, fat droplets formed inside the cells. Silk peptide E5K6 reduced the formation of fat droplets at the 1-mg/mL dosage (86.1% ± 2.5%) when compared to the control (100.0% ± 5.8%). A 1 mg/mL dose of silk peptide E5K6 significantly increased GLUT 4 expression (131.5% ± 4.0%). The treatment of 1 mg/mL of silk peptide E5K6 did not present any changes for adipogenic expressed genes, but leptin expression was significantly increased by silk peptide E5K6 supplementation (175.9% ± 11.1%). From these results, silk peptide E5K6 increased glucose uptake via up-regulation of GLUT 4 and decreased fat accumulation via the up-regulation of leptin.