Influence of sex, age, and smoking habits on the urinary excretion of D-glucaric acid

The contribution of the Clinica del Lavoro of Milan to the development of industrial hygiene and toxicology in the twentieth century

In 1910, the founder of the Clinica del Lavoro of Milan, Luigi Devoto established a chemistry laboratory in the new institute, sustaining its importance in the study of occupational diseases. In 1948, the new director of the Clinica, Enrico C. Vigliani established the first laboratory of industrial hygiene in Italy, in the years of the economic boom. In 1960s, this laboratory, directed by Nicola Zurlo, significantly contributed to the research in the field. In 1980s and 1990s, the laboratory of the Clinica started to explore the field of environmental toxicology, studying the effects of benzene and other traffic pollutants on the general population. The analysis of history of the Clinica del Lavoro of Milan may represent a valuable tool for studying the origin and the development of industrial hygiene, occupational and environmental toxicology in the twentieth century.

Requirement for specific gravity and creatinine adjustments for urinary steroids and luteinizing hormone concentrations in adolescents

OBJECTIVES

Urinary hormone concentrations are often adjusted to correct for hydration status. We aimed to determine whether first morning void urine hormones in growing adolescents require adjustments and, if so, whether urinary creatinine or specific gravity are better adjustments.

DESIGN AND METHODS

The study population was adolescents aged 10.1 to 14.3 years initially who provided fasting morning blood samples at 0 and 12 months (n = 343) and first morning urine every three months (n = 644). Unadjusted, creatinine and specific gravity-adjusted hormonal concentrations were compared by Deming regression and Bland-Altman analysis and grouped according to self-rated Tanner stage or chronological age. F-ratios for self-rated Tanner stages and age groups were used to compare unadjusted and adjusted hormonal changes in growing young adolescents. Correlations of paired serum and urinary hormonal concentration of unadjusted and creatinine and specific gravity-adjusted were also compared.

RESULTS

Fasting first morning void hormone concentrations correlated well and were unbiased between unadjusted or adjusted by either creatinine or specific gravity. Urine creatinine concentration increases with Tanner stages, age and male gender whereas urine specific gravity was not influenced by Tanner stage, age or gender. Adjustment by creatinine or specific gravity of urinary luteinizing hormone, estradiol, testosterone, dihydrotestosterone and dehydroepiandrosterone concentrations did not improve correlation with paired serum concentrations.

CONCLUSIONS

Urine steroid and luteinizing hormone concentrations in first morning void samples of adolescents are not significantly influenced by hydration status and may not require adjustments; however, if desired, both creatinine and specific gravity adjustments are equally suitable.

Dietary D-glucarate effects on the biomarkers of inflammation during early post-initiation stages of benzo[a]pyrene-induced lung tumorigenesis in A/J mice

Previous studies showed that dietary calcium D-glucarate (CG) inhibited benzo[a]pyrene (B[a]P)-induced A/J mouse lung tumorigenesis, suppressing cell proliferation and chronic inflammation and inducing apoptosis during late post-initiation stages. The present study aimed to investigate changes in the homeostasis of cytokines in blood serum, as well as alterations in biomarkers of inflammation and apoptosis in lung tissue caused by dietary CG during early post-initiation stages of B[a]P-induced lung tumorigenesis. Two doses of 3 mg of B[a]P were given intragastrically to A/J mice 2 weeks apart. CG administration in the AIN-93G diet (2 and 4%, w/w) commenced at 2 weeks following the second dose of B[a]P. The levels of interleukin (IL)-6, IL-10 and tumor necrosis factor α (TNFα) in blood serum were investigated by FCAP array analysis. Two weeks after the second dose of B[a]P, approximately 8- and 28-fold increases of TNFα and IL-6, respectively, occurred in the blood serum and an approximately 16% decrease of IL-10 levels compared to the untreated control group was noted. At 4 weeks after the second dose of B[a]P and after 2 weeks of CG administration in the diet, the 2 and 4% CG diets significantly reduced the levels of IL-6 and TNFα (by 70 and 33%, respectively). In a dose-related manner, the diets also increased the level of anti-inflammatory cytokine IL-10 compared to the B[a]P group. At 6 weeks after the second dose of B[a]P, the cytokine levels in the serum continued to show a decrease in the CG-treated groups. These events are accompanied by an increased level of cleaved caspase-9 product with a molecular weight of 37 kDa. In conclusion, dietary D-glucarate decreases the level of proinflammatory cytokines, increases the level of the anti-inflammatory cytokine IL-10 during early post-initiation stages of B[a]P-induced lung tumorigenesis in A/J mice and affects apoptotic induction.

99mTc glucarate high-resolution imaging of drug sensitive and drug resistant human breast cancer xenografts in SCID mice

BACKGROUND AND AIM

Previous studies have showed that 99mTc labelled glucarate (GLA) might be an agent for non-invasive detection of breast tumours. In xenografted BT20 breast tumours, GLA was found to have higher uptake than 99mTc sestamibi (MIBI). It is unclear whether GLA can localize in all cell line breast cancer xenografts, as well as breast tumours with multidrug resistance (MDR). The present study aimed to investigate the properties of GLA in detecting drug sensitive and drug resistant MCF7 breast cancer xenografts in mice by using dynamic single photon emission computed tomography (SPECT) imaging.

METHODS

MCF7/S cells are drug sensitive breast carcinoma cells. MCF7/D40 cells are 40-fold more resistant to doxorubicin compared to MCF7/S. Subcutaneous tumours were grown in SCID mice for 10-14 days after injection of 1 x 10(6) cells into the right thigh. Anaesthetized mice with MCF7/S (MIBI, n=9; GLA, n=8) and MCF7/D40 (MIBI, n=6; GLA, n=5) tumours were imaged using a high-resolution SPECT system called FASTSPECT. Dynamic images were acquired for 2 h after intravenous injection of GLA or MIBI. Expression of MDR P-glycoprotein (Pgp) in the tumours was demonstrated in the MCF7/D40 tumours by western blotting, not in the MCF7/S tumours.

RESULTS

The xenografted tumours were visualized unequivocally within 10-30 min in GLA images and remained detectable for at least 2 h after injection. Drug resistant tumours, from which MIBI was rapidly expelled, retained GLA as readily as did drug sensitive tumours. The biodistribution data of GLA demonstrated significantly higher accumulation (%ID/g) compared to MIBI.

CONCLUSION

MCF7 tumour xenografts can be detected by 99mTc glucarate imaging. More importantly, 99mTc glucarate can potentially localize drug resistant breast tumours.

Detoxifying cancer causing agents to prevent cancer

Different vitamins and other micronutrients in vegetables, fruits, and other natural plant products may prevent cancer development (carcinogenesis) by interfering with detrimental actions of mutagens, carcinogens, and tumor promoters. The goal of current studies in cancer prevention is to determine the mechanisms of synergistic action of the natural source compounds known to inhibit one or more stages of carcinogenesis, that is, initiation and promotion/progression. Many natural cancer preventive agents are effective inhibitors of tumor initiation, promotion, and/or progression. The mechanism of action is related to their abilities to prevent critical carcinogen metabolism and to increase detoxification of carcinogens and tumor promoters. The authors review here the potential role of the detoxification system and, in particular, the roles of D-glucaric acid and the enzyme beta-glucuronidase in early detection and prevention of cancer. There is now growing evidence for the possible control of different stages of the cancer induction by inhibiting beta-glucuronidase with D-glucaric acid derivatives, especially with its salts (D-glucarates). D-Glucaric acid has been found in many vegetables and fruits. Therefore, the consumption of fruits and vegetables naturally rich in D-glucaric acid or self-medication with D-glucaric acid derivatives such as calcium D-glucarate offers a promising cancer prevention approach.

Evaluation of urinary D-glucaric acid excretion in workers exposed to butyl glycol

The biological follow-up of subjects exposed to butyl glycol (BG) is generally accomplished using a standard blood count that is not sensitive enough to reveal early intoxication by this molecule. For this reason we have used an indirect test for evaluating the induction of hepatic enzymes, the measurement in urine of D-glucaric acid (DGA), which reflects the activity of the glucuronic acid enzyme pathway. This study was performed on 17 foundry workers exposed to BG emissions coming from paints used in cataphoresis. The airborne concentration of BG was less than 0.3 times the average limit exposure value. This study shows that BG emissions at low concentrations are able to increase the activity of the enzymes of the glucuronic acid pathway. DGA urinary excretion increased by 165% in winter (p < .01) and by 85% (p < .05) in summer when the doors are open and the BG concentration lower. DGA urinary excretion is significantly higher in smoking than in nonsmoking exposed workers. None of these workers had a perturbed blood count. This study shows that the urinary level of DGA provides a good test for the follow-up of exposure to BG in the electrophoresis painting plant, and that the exposed smoking workers seem to be more sensitive to BG exposure than do the nonsmokers. In conclusion, the measurement of urinary DGA might be considered as a useful test for the surveillance of subjects exposed to vapors containing BG.

Urinary D-glucaric acid, a marker substance for microsomal enzyme induction. Methodological aspects, responses to alcohol and findings in workers exposed to toluene

D-glucaric acid, an end product of glucuronic acid metabolism, has been used as a marker substance for microsomal enzyme induction. In this study a convenient microtitre-plate based method for the quantification of urinary D-glucaric acid has been developed and validated. Mean urinary D-glucaric acid excretion in 20 health humans as measured by this method was 3.2 mumol glucaric acid mmol-1 creatinine, 95% confidence interval 3.0-3.4. Moderate alcohol consumption in 18 healthy volunteers did not significantly augment the urinary D-glucaric acid excretion. Occupational exposition to toluene in a printing plant was investigated. In spite of considerable intra- and inter-individual variability, a significant difference between exposed (3.5, 3.1-3.9) and non-exposed (2.6, 2.2-3.0) workers was observed, p < 0.025. We conclude that the measurement of D-glucaric acid can be utilized for biological screening of enzyme induction on a group basis.

Potential use of D-glucaric acid derivatives in cancer prevention

There is now growing evidence from animal models for the possible control of different stages of the carcinogenic process by the beta-glucuronidase inhibitor D-glucaro-1,4-lactone and its precursors such as D-glucaric acid salts, D-glucarates. D-Glucaric acid is a natural, non-toxic compound produced in small amounts by mammals, including humans. It was recently found in some vegetables and fruits. D-Glucaro-1,4-lactone and D-glucarate exhibit potent antiproliferative properties in vivo. Some human subpopulations could have reduced risk of cancer development by ingesting food rich in D-glucaric acid or self-medication with D-glucarates alone or in combination with other chemopreventive agents.

Specific enzymatic assay for D-glucarate in human serum

A sensitive and specific spectrophotometric assay was developed to determine levels of D-glucarate in human serum. This assay makes use of the Escherichia coli glucarate catabolic enzymes D-glucarate dehydrase, alpha-keto-beta-deoxy-D-glucarate aldolase, and tartronate semialdehyde (TSA) reductase, to convert D-glucarate to equimolar quantities of pyruvate and TSA. In a one-tube reaction that included NADH, lactate dehydrogenase, and the three E. coli enzymes, 1 mumol of D-glucarate was quantitatively converted to 1 mumol each of D-glycerate and L-lactate with concomitant utilization of 2 mumol of NADH. Using this method, D-glucarate in serum was measured, along with quantitative recovery of authentic D-glucarate from duplicate serum samples to which it had been added. Glucarate is a major serum organic acid, approximating blood pyruvate levels previously determined by others.

Exposure to toluene increases the urinary excretion of D-glucaric acid

Workers at a printing plant exposed to low concentrations of toluene (43-401 mg/m3, median 155 mg/m3) had increased urinary D-glucaric acid (3.55-5.12 mmol/mol creatinine) excretion at the end of the shift compared with controls (2.45-3.35 mmol/mol creatinine). No increase was found after the summer holiday (1.92-2.89 mmol/mol creatinine) but excretion had increased two weeks later (4.05-5.55 mmol/mol creatinine). These changes in the excretion of D-glucaric acid were not correlated to levels of exposure, to changes of urinary hippuric acid and o-cresol half lives (three to eight hours), nor to o-cresol/hippuric acid concentration ratios when measured at the end of daily exposure. Since a significant intra and interindividual variability of urinary D-glucaric acid was found in all groups, urinary D-glucaric acid excretion is suitable to monitor group but not individual exposure.

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

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.

Thioethers, mutagens, and D-glucaric acid in urine of operating room personnel exposed to anesthetics

Mutagenic hazards related to occupational exposure to nitrous oxide and enflurane was studied in the personnel of five operating rooms using a coupled environmental and biological monitoring approach. The environmental monitoring revealed air concentrations of the two anesthetics exceedings the TLVs by 10-15-fold. These values were correlated individually with the concentrations of the two anesthetics in the expired air of the exposed subjects. The biological monitoring was carried out by determining two parameters associated with mutagen exposure (urinary mutagenicity and thioethers) and a parameter associated with the enzymatic induction (D-glucaric acid) in the urine of exposed and unexposed subjects (N = 64 and N = 37, respectively). The results showed no difference in the two groups for urine mutagenicity and D-glucaric acid, but urine thioethers were significantly increased among highly exposed subjects.

An evaluation of the low-pH enzymatic assay of urinary D-glucaric acid, and its use as a marker of enzyme induction in exocrine pancreatic disease

We have evaluated a low-pH enzymatic method for measuring urinary D-glucaric acid, and its usefulness as a marker of 'enzyme induction' in patients with exocrine pancreatic disease. The coefficient of variation lay between 7.5 and 10.9% for within-batch precision, and between 7.9 and 19.8% for between-batch precision. The useful range of the method was 20-200 mumol/l, with a lower detection limit of 11 mumol/l. The molar concentration ratio of D-glucaric acid to creatinine in urine correlated with the 8-h output of D-glucaric acid (p less than 0.005): both indices were significantly higher in a group of 29 patients with exocrine pancreatic disease than in controls (median ratios 4.6 and 2.9 X 10(-3), p less than 0.005; median outputs 14.0 and 8.8 mumol/8 h, respectively, p less than 0.005). Comparison with the results of theophylline tests in the same group of patients showed that whereas 72% of patients had theophylline clearances higher than the highest value in controls, 45% of the group had increased D-glucaric acid/creatinine ratios, whilst only 21% had increased outputs of D-glucaric acid. Paradoxically, in patients with established liver disease in whom drug metabolism was impaired urinary D-glucaric acid values were amongst the highest encountered in the study. Thus, the obvious advantages of the method--non-invasive, simple, reproducible, inexpensive, easily applied to out-patients--are offset by an unacceptably low predictive value as an indicator of microsomal 'enzyme induction'.

Dietary glucarate-mediated reduction of sensitivity of murine strains to chemical carcinogenesis

Serum beta-glucuronidase activity is shown to differ quantitatively in the following strains of mice, listed in order of increasing activity: C3H, C57BL/6 less than BALB/c, DBA/2, ICR less than SENCAR, A/He. The level of the enzyme in the murine strains is shown to correlate with the urinary excretion of 17-ketosteroids, which in turn reflects the endogenous level of androgens. Dietary calcium D-glucarate, an in vivo beta-glucuronidase inhibitor, reduced the steady state level of both beta-glucuronidase and 17-ketosteroid excretion in the highly susceptible A/He and SENCAR strains to that of strains known to be resistant to chemical carcinogenesis. Sensitivity of the A/He strain is significantly reduced by dietary calcium glucarate, which is shown to inhibit DNA binding and the induction of pulmonary adenomas by benzo[a]pyrene.

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

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.

Reliability of urinary creatinine as a parameter used to adjust values of urinary biological indicators

The values of biological indicators used in biological monitoring are usually determined on spot samples of urine. In order to reduce the variations due to dilution, it is common practice to correct the values according to reference parameters, such as urinary creatinine concentration and specific gravity. The aim of the present study was to verify whether creatinine possesses the necessary characteristics for adjustment. The levels of creatinine were not influenced by diuresis, but, contrary to what was expected, the values of the metabolite showed marked intra- and interindividual variations. These data raise serious doubts as to the validity of creatinine as a parameter that can be used for adjustment purposes, and suggest that it would be advisable to ascertain for each biological indicator whether in fact adjustment is of any use. Lastly, since there was only a slight correlation between creatinine levels and specific gravity values, it is concluded that these two parameters cannot be used indifferently for adjustment.

Low-pH method for the enzymatic assay of D-glucaric acid in urine

The enzymatic methods for measuring D-glucaric acid in urine are based on the conversion of D-glucaric acid into its 1,4-lactone and measurement of inhibition of 1,4-lactone against beta-glucuronidase at pH 5.0. All the enzymatic methods described suffer from the disadvantage of a procedure that is complicated and inherently inaccurate, because the nature of glucaric acid/1,4-lactone equilibrium has not been properly considered in the development of such methods. After elucidating the factors influencing glucaric acid/1,4 lactone equilibrium in more detail, a low-pH enzymatic method has been developed in which the 1,4-lactone is formed in the urine sample by acid boiling at pH 3.8 and assayed at the same pH using beta-glucuronidase from Limpets. This procedure allows the acid/lactone equilibrium to remain stable during both the lactonization step and the enzymatic assay. The coefficient of variation for the proposed method (within-run and between-day precision) was from 4.2 to 8.7. The analytical recovery varied from 92-108%.