Urinary PSA-ZINC biomarker outperforms standard of care in early detection of prostate cancer.

BACKGROUND: Urine is a promising biological fluid for prostate cancer (PCa) diagnostics due to its non-invasive collection and wide range of biomarkers. The aim of this study was to assess the role of urinary PSA (uPSA) and urinary Zinc (uZinc) as biomarkers for the diagnosis of PCa in combination with routine parameters of standard of care (SOC - blood PSA, abnormal DRE, age) and MRI in patients candidates for prostate biopsy. METHODS: Urine samples after prostatic massages were collected from men with suspected PCa scheduled for prostate biopsy. Quantification of uPSA was performed by ECLIA platform and confirmed by ELISA assay, while uZinc measurement was evaluated by ICP-MS and confirmed by colorimetric in vitro assay. Six multivariate logistic regression analysis were performed to assess diagnostic performance of uPSA and uZinc (urine), SOC and MRI alone, and combination of MRI+SOC, MRI+urine and SOC+MRI+urine. The discriminative power of the logistic models was assessed by calculating the area under the receiver operating characteristic (ROC) curves (AUC). RESULTS: Two hundred thirty-eight patients were included in the analysis; 145 of them were diagnosed with PCa. Urine test showed a better discrimination of HS from CP, in respect of uPSA and uZinc alone, both for PCa of any grade and Gleason Score ≥7 (4+3) (AUC 0.804 and 0.823 respectively). ROC curve combining SOC+MRI+urine showed an AUC=0.882, that is statistically different from SOC or MRI alone, or MRI+SOC (P=0.0001, P=0.0001, and P=0.008 respectively). PCa risk algorithm designed considering SOC+MRI+urine results in potential reduction of 57% of unnecessary biopsies compared to the current standard parameters. CONCLUSIONS: The loss of uPSA and Zinc production and secretion during neoplastic transformation of the prostate could potentially represent a hallmark of PCa. Its combination with age, PSA and DRE, as well as with mpMRI could represent an interesting approach to improve the diagnostic accuracy of PCa.

Binder-free and efficient voltammetric sensor based on Zn-Ca2CuO3 nanoparticles for simultaneous determination of amlodipine, acetaminophen, and ascorbic acid in hypertension patients.

Amlodipine (AM) is a long active calcium channel blocker used to relax blood vessels by preventing calcium ion transport into the vascular walls and its supporting molecules acetaminophen (AP) and ascorbic acid (AA) are recommended for hypertension control and prevention. Considering their therapeutic importance and potential side effects due to over dosage, we have fabricated a sensor for individual and simultaneous determination of AA, AP, and AM in pharmaceuticals and human urine using novel Zn-doped Ca2CuO3 nanoparticles modified glassy carbon electrode (GCE). Optimally doped Ca2CuO3 (2.5 wt% Zn at Cu site) enhanced the detection of target molecules over much wider concentration ranges of 50 to 3130 µM for AA, 0.25 to 417 µM for AP, and 0.8 to 354 µM for AM with the corresponding lowest detection limits of 14 µM, 0.05 µM, and 0.07 µM, respectively. Furthermore, the Zn-Ca2CuO3/GCE exhibited excellent selectivity and high sensitivity even in the presence of several potential interfering agents. The usefulness of the developed electrode was tested using an amlodipine besylate tablet and urine samples of seven hypertension patients under medication. The results confirmed the presence of a significant amount of AP and AM in six patients' urine samples indicating that the personalized medication is essential and the quantum of medication need to be fixed by knowing the excess medicines excreted through urine. Thus, the Zn-Ca2CuO3/GCE with a high recovery percentage and good sensitivity shall be useful in the pharmaceutical and biomedical sectors.

Simple distance-based thread analytical device integrated with ion imprinted polymer for Zn2+ quantification in human urine samples.

This article presents the development of a distance-based thread analytical device (dTAD) integrated with an ion-imprinted polymer (IIP) for quantitative monitoring of zinc ions (Zn2+) in human urine samples. The IIP was easily chemically modified onto the thread channel using dithizone (DTZ) as a ligand to bind to Zn2+ with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as well as 2,2-azobisisobutyronitrile (AIBN) as cross-linking agents to enhance the selectivity for Zn2+ detection. The imprinted polymer was characterized using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Under optimization, the linear detection range was from 1.0 to 20.0 mg L-1 (R2 = 0.9992) with a limit of detection (LOD) of 1.0 mg L-1. Other potentially interfering metal ions and molecules did not interfere with this approach, leading to high selectivity. Furthermore, our technique exhibits a remarkable recovery ranging from 100.48% to 103.16%, with the highest relative standard deviation (% RSD) of 5.44% for monitoring Zn2+ in human control urine samples, indicating high accuracy and precision. Similarly, there is no significant statistical difference between the results obtained using our method and standards on zinc supplement sample labels. The proposed method offers several advantages in detecting trace Zn2+ for point-of-care (POC) medical diagnostics and environmental sample analysis, such as ease of use, instrument-free readout, and cost efficiency. Overall, our developed dTAD-based IIP method holds potential for simple, affordable, and rapid detection of Zn2+ levels and can be applied to other metal ions' analysis.

Strategies for inducing and validating zinc deficiency and zinc repletion.

Given the growing interest in the role of zinc in the onset and progression of diseases, there is a crucial demand for reliable methods to modulate zinc homeostasis. Using a dietary approach, we provide validated strategies to alter whole-body zinc in mice, applicable across species. For confirmation of zinc status, animal growth rates as well as plasma and urine zinc levels were evaluated. The accessible and cost-effective methodology outlined will increase scientific rigor, ensuring reproducibility in studies exploring the impact of zinc deficiency and repletion on the onset and progression of diseases.NEW & NOTEWORTHY This methods paper details dietary approaches to alter zinc homeostasis in rodents and qualitative and quantitative methods to ensure the zinc status of experimental animals. The outlined accessible and cost-effective protocol will elevate scientific rigor, ensuring reproducibility in studies exploring the impact of zinc deficiency and repletion on the onset and progression of a multitude of health conditions and diseases.

Association between urinary zinc excretion and isoflavone-metabolizing enterotypes among Japanese females: a cross-sectional study.

BACKGROUND: Zinc absorption and competition among gut bacteria have been reported in animal studies. Thus, gut bacteria may modify zinc availability in humans. Metabolism of intestinal bacteria is known to be necessary for the activation of several phytoconstituents in the body. For example, equol, a typical substance of soybean isoflavone, is produced by intestinal bacteria metabolizing daidzein and the enterotype is one of distinct ones among Japanese population. The difference in the intestinal microflora can modify the bioavailability of zinc. In this study, we examined urinary zinc concentrations in adult female equol producers (EQPs). METHODS: Urine samples from women participating in health examinations in Miyagi, Okinawa, Kyoto, Kochi, and Hokkaido prefectures were used; from total 17,484 samples, approximately 25 samples were randomly selected for each age group from 30 to 60 years per region (subsample: n = 520), and 520 samples with available urinary zinc concentration (determined by flame atomic absorption analysis) and enterobacterial type were analyzed. EQP was defined as log(equol/daidzein) ≥ -1.42, and urinary concentrations were corrected for creatinine concentration. Urinary zinc concentrations were compared by Student's t-test and multiple regression analyses. RESULTS: The geometric mean urinary zinc concentration (µg/g-Cr) was lower in EQP than in non-EQP (p = 0.0136 by t-test after logarithm transformation). On the other hand, there was no correlation between urinary zinc concentration with daidzein (r = -0.0495, P = 0.436) and equol concentrations (r = -0.0721, P = 0.256). There was a significant negative association between urinary zinc concentration and EQP (ß = -0.392, P = 0.0311) after adjusting with other potential confounding variables, such as daidzein intake. CONCLUSIONS: The results suggest that gut bacteria that produce equol are involved in the metabolism of zinc. Based on previous studies, the bacteria that affect the metabolism of both substances are thought to be Enterococcus. Future studies are expected to identify specific intestinal bacteria for zinc availability and understand individual differences in the effects of micronutrients.

Dose-dependant preventive effect of a herbal compound on crystal formation in rat model.

INTRODUCTION: To analyze the dose-dependent preventive effect of a plant-based herbal product on the new crystal formation in a rat model. MATERIALS AND METHODS: A total of 42 rats were divided into 7 groups and zinc discs were placed into the bladder of rats to provide a nidus for the development of new crystal formation: Group 1: control, Group 2: 0.75 percent ethylene glycol (EG); Group 3: 0.75 percent EG plus 0.051 ml of the compound; Group 4: 0.75 percent EG plus 0.179 ml of the compound; Group 5: 0.75 percent EG plus 0.217 ml of the compound; Group 6: 0.75 percent EG plus 0.255 ml of the compound; Group 7 0.75 percent EG plus 0.332 of the compound). The analysis and comparison focused on the disc weights, changes in urinary oxalate and calcium levels, urinary pH, and the histopathologic evaluation of the inflammatory changes in the bladder after 14 days. RESULTS: According to the evaluation of discs placed in the bladders of the animals, animals receiving the herbal compound on a dose-dependent basis showed a limited increase in the disc weights values after 14 days, despite a considerable increase in animals receiving EG alone (p = 0.001). Further evaluation of the increase in disc weights on a dose-dependent basis in different subgroups (from Groups 3 to 7) demonstrated that the limitation of crystal deposition began to be more prominent as the dose of herbal compound increased. This effect was more evident particularly in comparisons between group 7 and others, according to LSD multiple comparison tests (p = 0.001). As anticipated, there has been no discernible change in the weight of the discs in the control group. Although urinary calcium levels in animals of Groups 2, 6, and 7 were significantly higher than the other groups, we were not able to demonstrate a close correlation between urinary oxalate levels and the increasing dose levels. Even though mean urine pH levels were statistically considerably higher in Group 3, there was no statistically significant correlation between the oxalate and calcium levels between all groups, and no association was seen with the administration of herbal agents. The transitional epithelium between the three groups of animals' bladder samples did not exhibit any appreciable difference according to pathological analysis. CONCLUSIONS: In this animal model, the treatment of the compound was successful in lowering the amount of crystal deposition surrounding the zinc discs, most noticeably at a dosage of 0.332 ml, three times per day.

Association of CYP19A1 Gene, Plasma Zinc, and Urinary Zinc with the Risk of Type 2 Diabetes Mellitus in a Chinese Population.

To explore the effects of CYP19A1 gene polymorphisms, plasma zinc, and urinary zinc levels and their interactions on type 2 diabetes mellitus (T2DM) in residents of Gongcheng County, Guangxi, China. The case-control study was used for the investing. The MassARRAY System was applied to genotype the CYP19A1 genes rs752760, rs10046, rs10459592, and rs700518 in 540 study subjects. Plasma and urinary zinc concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS). Conditional logistic regression showed that rs752760 and plasma zinc were associated with T2DM risks with ORs of 0.593 (95% CI: 0.371-0.948) and 0.563 (95% CI: 0.356-0.889), respectively. Unconditional logistic regression analysis showed an association between urinary zinc levels and the risk of T2DM as well, with an OR of 0.352 (95% CI: 0.212-0.585). The results of the multiplicative interaction model showed that the rs752760 T allele was associated with a significantly reduced risk of T2DM with moderate/low plasma zinc levels, with ORs of 0.340 (95% CI: 0.161-0.715) and 0.583 (95% CI: 0.346-0.981), respectively, and the rs752760 T allele was also associated with a significantly decreased risk of T2DM with moderate/low urinary zinc levels, with ORs of 0.358 (95% CI: 0.201-0.635) and 0.321 (95% CI: 0.183-0.562), respectively. CYP19A1 rs752760 T allele and moderate/low plasma/urinary zinc levels reduce the risk of T2DM.

The impact of essential and toxic elements on cardiometabolic risk factors in adults and older people.

BACKGROUND AND AIM: Evidence suggests an association between essential and toxic elements and the worsening of cardiometabolic risk factors. This study aimed to investigate the concentrations of zinc, copper, selenium, arsenic, cadmium, and mercury and their relationship with cardiometabolic risk factors in adults and older people. METHODS: This cross-sectional study was carried out with 112 adults with a mean age of 59 (sd 14) years old and a BMI of 29.30 (sd 5.11) Kg/m2. The subject's weight and height were measured for body mass index (BMI) calculation, classified according to the cut-off points recommended by the World Health Organization (WHO). We evaluated sociodemographic, clinical, lifestyle, waist circumference - WC, visceral adiposity index - VAI, glycemic lipid profile, blood pressure, and high-sensitive C-reactive protein (hs-CRP). Cardiovascular risk was defined by The Global Risk Score (GRS) score. Plasma zinc, selenium, copper levels, urinary arsenic, cadmium, and mercury levels were measured using the inductively coupled plasma mass spectrometry technique (ICP-MS). RESULTS: There was a negative association between urinary arsenic and VAI (ß - 0.03, p < 0.01), triglycerides (ß - 1.10, p < 0.01), and VLDL cholesterol (ß - 0.14, p = 0.02). Plasma copper and copper/zinc ratio were positively associated with fasting glucose and hs-CRP (ß 0.38, p < 0.01; ß 36.02, p = 0.01, ß 0.004, p < 0.01, ß 0.68, p < 0.001, respectively). Urinary arsenic (ß - 0.14, p = 0.04) and cadmium (ß - 36.42, p = 0.04) were negatively associated with systolic blood pressure. Also, urinary cadmium was negatively associated with diastolic blood pressure (ß - 21.55, p = 0.03), and urinary mercury showed an opposite behavior (ß 1.45, p = 0.03). CONCLUSION: Essential and toxic elements in urine and plasma could be potential biomarkers for cardiovascular risk factors. A healthy lifestyle should be adopted; in addition, government policies should be developed to guarantee sustainable production and a safe environment.

Effects of the chelating agent DTPA on naturally accumulating metals in the body.

Diethylenetriaminepentaacetate (DTPA) is the most widely used chelating agent for Pu and Am. Volunteers were assigned to receive intravenous injections or aerosol inhalations of 1 g of DTPA on days 1-4; volunteers received once daily injections of CaDTPA or ZnDTPA, CaDTPA inhalation as an aerosol, or CaDTPA injection on day 1 and ZnDTPA on days 2-4. CaDTPA injection or inhalation increased the excretion rates of Zn in urine with concomitantly reduced levels of serum Zn. Injection of CaDTPA reduced activities of serum alkaline phosphatase (AP) in parallel with the kinetics of Zn, whereas CaDTPA and ZnDTPA injection reduced activities of lactate dehydrogenase (LDH), and reduced activities of creatinine kinase (CK) were observed upon CaDTPA injection and its inhalation. Intravenous administration of CaDTPA and ZnDTPA enhanced excretion rates of Mn in urine, whereas transient reduction of Mn levels in serum was detected only via CaDTPA injection. Both CaDTPA and ZnDTPA transiently reduced levels of Mg in serum without affecting the excretion rates. On the other hand, both DTPAs increased excretion rates of toxic metals such as Pb and Cd, and CaDTPA also increased the rates of Hg. These results suggest that DTPA, and especially CaDTPA, removes essential metals and that the activities of these metalloenzymes are good indicators for the imbalance of essential metals during the DTPA administration. Our results also show that CaDTPA injection is more potent for removing these metals than ZnDTPA and inhalation of CaDTPA, and DTPA may be useful for the treatment of acute heavy metal poisoning with Pb, Cd, or Hg.

Spatial analysis of urine zinc (Zn) concentration for women of reproductive age and school age children in Malawi.

Zinc (Zn) is an essential micronutrient, and Zn deficiency remains a major global public health challenge. Recognised biomarkers of population Zn status include blood plasma or serum Zn concentration and proxy data such as dietary Zn intake and prevalence of stunting. Urine Zn concentration is rarely used to assess population Zn status. This study assessed the value of urine Zn concentration as a biomarker of population Zn status using a nationally representative sample of non-pregnant women of reproductive age (WRA) and school-aged children (SAC) in Malawi. Spot (casual) urine samples were collected from 741 WRA and 665 SAC. Urine Zn concentration was measured by inductively coupled plasma mass spectrometry with specific gravity adjustment for hydration status. Data were analysed using a linear mixed model with a spatially correlated random effect for between-cluster variation. The effect of time of sample collection (morning or afternoon), and gender (for SAC), on urine Zn concentration were examined. There was spatial dependence in urine Zn concentration between clusters among SAC but not WRA, which indicates that food system or environmental factors can influence urine Zn concentration. Mapping urine Zn concentration could potentially identify areas where the prevalence of Zn deficiency is greater and thus where further sampling or interventions might be targeted. There was no evidence for differences in urine Zn concentration between gender (P = 0.69) or time of sample collection (P = 0.85) in SAC. Urine Zn concentration was greater in afternoon samples for WRA (P = 0.003). Relationships between urine Zn concentration, serum Zn concentration, dietary Zn intake, and potential food systems covariates warrant further study.

High-Performance Flexible Electrochemical Heavy Metal Sensor Based on Layer-by-Layer Assembly of Ti3C2Tx/MWNTs Nanocomposites for Noninvasive Detection of Copper and Zinc Ions in Human Biofluids.

A flexible electrochemical heavy metal sensor based on a gold (Au) electrode modified with layer-by-layer (LBL) assembly of titanium carbide (Ti3C2Tx) and multiwalled carbon nanotubes (MWNTs) nanocomposites was successfully fabricated for the detection of copper (Cu) and zinc (Zn) ions. An LBL drop-coating process was adopted to modify the surface of Au electrodes with Ti3C2Tx/MWNTs treated via ultrasonication to fabricate this novel nanocomposite electrode. In addition, an in situ simultaneous deposition of "green metal" antimony (Sb) and target analytes was performed to improve the detection performance further. The electrochemical measurement was realized using square wave anodic stripping voltammetry (SWASV). Moreover, the fabricated sensor exhibited excellent detection performance under the optimal experimental conditions. The detection limits for Cu and Zn are as low as 0.1 and 1.5 ppb, respectively. Furthermore, Cu and Zn ions were successfully detected in biofluids, that is, urine and sweat, in a wide range of concentration (urine Cu: 10-500 ppb; urine Zn: 200-600 ppb; sweat Cu: 300-1500 ppb; and sweat Zn: 500-1500 ppb). The fabricated flexible sensor also possesses other advantages of ultra-repeatability and excellent stability. Thus, these advantages provide a great possibility for the noninvasive smart monitoring of heavy metals in the future.

Cross-sectional and longitudinal associations between urinary zinc and lung function among urban adults in China.

BACKGROUND: Exposure to zinc was suggested to be associated with pulmonary damage, but whether zinc exposure affects lung function remains unclear. OBJECTIVES: To quantify the association between urinary zinc and lung function and explore the potential mechanisms. METHODS: Urinary zinc and lung function were measured in 3917 adults from the Wuhan-Zhuhai cohort and were repeated after 3 years of follow-up. Indicators of systemic inflammation (C reactive protein), lung epithelium integrity (club cell secretory protein-16) and oxidative damage (8-hydroxy-2'-deoxyguanosine and 8-isoprostane) were measured at baseline. Linear mixed models were used to estimate the exposure-response relationship between urinary zinc and lung function. Mediation analyses were conducted to assess mediating roles of inflammation and oxidative damage in above relationships. RESULTS: Each 1-unit increase in log-transformed urinary zinc values was associated with a 35.72 mL decrease in forced vital capacity (FVC) and a 24.89 mL decrease in forced expiratory volume in 1 s (FEV1) in the baseline analyses. In the follow-up analyses, there was a negative association between urinary zinc and FVC among participants with persistent high urinary zinc levels, with an estimated change of -93.31 mL (95% CI -178.47 to -8.14). Furthermore, urinary zinc was positively associated with restrictive ventilatory impairment. The mediation analyses suggested that C reactive protein mediated 8.62% and 8.71% of the associations of urinary zinc with FVC and FEV1, respectively. CONCLUSION: Urinary zinc was negatively associated with lung function, and the systemic inflammation may be one of the underlying mechanisms.

Influence of a high-temperature programme on serum, urinary and sweat levels of selenium and zinc.

INTRODUCTION: The effect of hyperthermia on the antioxidant system in the human organism is well known. AIM: The objective of this study was to observe the effects of heat on the concentration of Se and Zn, elements related to antioxidant systems. METHODS: Twenty-nine subjects voluntarily participated in this study. They were divided into a control group (CG; n = 14) and an experimental group (EG; n = 15). All of them underwent two incremental tests until exhaustion in normothermia (22 °C, 20-40%RH) and hyperthermia (42 °C, 20-40%RH). EG experienced nine sessions of repeated heat exposure at high temperatures (100 °C, 20%RH) for three weeks (HEHT). After the intervention, the initial measurements were repeated. Urine and blood samples were collected before and after each test. Additionally, sweat samples were collected after tests in hyperthermia. RESULTS: There were no significant changes in serum. An increase in the elimination of Zn and Se in EG was observed in urine after HEHT (p < .05). The elimination of Zn by sweating decreased after HEHT in EG (p < .05). CONCLUSIONS: Exposure to heat at high temperatures increases the urinary excretion of Se and Zn.

Assessment of copper, iron, zinc and manganese status and speciation in patients with Parkinson's disease: A pilot study.

BACKGROUND: The objective of this pilot study was to assess iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn) status (hair, serum, and urine) and speciation (serum) in Parkinson's disease (PD) patients. METHODS: A pilot study involving a total of 27 subjects (13 PD patients, 14 controls) was performed. Serum, urine, and hair metal content was assessed using ICP-MS. Speciation analysis of Cu, Zn, Fe, and Mn was performed using a hybrid HPLC-ICP-MS system. RESULTS: Group comparisons did not reveal any significant group difference in serum Cu, Zn, Fe, and Mn total metal level between PD patients and controls. Speciation analysis revealed a significant decrease in Cu/ceruloplasmin copper in association with elevation of low-molecular weight species (amino acids)-bound copper. It is proposed that in PD, binding of Cu(II) ions to ceruloplasmin is reduced and free copper ions coordinate with low molecular weight ligands. The level of Mn-albumin complexes in PD patients was more than 4-fold higher as compared to the respective value in the control group. The observed difference may be considered as a marker of redistribution between high and low molecular weight ligands. CONCLUSIONS: Metal speciation is significantly affected in serum of PD-patients. These findings are indicative of the potential role of metal metabolism and PD pathogenesis, although the exact mechanisms of such associations require further detailed studies.

Association between Urinary Cadmium to Zinc Intake Ratio with Adult Mortality in a Follow-Up Study of NHANES 1988-1994 and 1999-2004.

Cadmium (Cd) is a toxic heavy metal associated with increased mortality, but the effect of zinc (Zn) intake on the association between Cd and mortality is unknown. The objective of this study was to examine the association of urinary Cd to Zn intake ratio (Cd/Zn ratio) and mortality risk. In total, 15642 US adults in NHANES 1988-1994 and 1999-2004 were followed until 2011 (15-year mean follow-up). Of the 5367 total deaths, 1194 were attributed to cancer and 1677 were attributed to CVD. After adjustment for potential confounders, positive associations were observed between urinary Cd and all-cause mortality (HR for highest vs. lowest quartile: 1.38; 95% CI: 1.14-1.68) and cancer mortality (HR: 1.54; CI: 1.05-2.27). Urinary Cd was positively associated with cancer mortality among the lowest Zn consumers, and the association diminished among the highest Zn consumers. Positive relationships were observed between the Cd/Zn ratio and all-cause mortality (HR: 1.54; CI: 1.23-1.93), cancer mortality (HR: 1.65; CI: 1.11-2.47) and CVD mortality (HR: 1.49; CI: 1.18-1.88). In conclusion, these findings indicate that Zn intake may modify the association between Cd and mortality. Furthermore, the Cd/Zn ratio, which was positively associated with mortality from all causes, cancer, and CVD, may be an important predictor of mortality.

Self-Reported Health and Metal Body Burden in an Electronic Waste Recycling Community in Northeastern Thailand.

OBJECTIVE: This study aims to summarize electronic waste (e-waste) worker health; examine associations between health and sociodemographic characteristics; and metal body burden. METHODS: In 2016, 131 e-waste recycling workers were enrolled in the study, completed a questionnaire, and gave blood and urine samples for heavy metal concentration assessment (lead, cadmium, copper, zinc, nickel). The relationship between symptoms, general health, and metals is assessed via generalized estimating equation models (adjusted for age, education, sex, and village). RESULTS: Cadmium in blood and copper in serum were most consistently associated with higher odds of poor health and prevalence of symptoms. We found inconsistent results between general health, symptom severity, and urinary nickel. Higher blood lead levels (BLL) were associated with fewer self-reported symptoms. CONCLUSIONS: Exposure to certain metals in e-waste recycling communities may adversely impact health status.

Assessment of coupled Zn concentration and natural stable isotope analyses of urine as a novel probe of Zn status.

Zinc is a common trace metal in the human body, present in about 10% of proteins. Despite numerous roles of Zn in health and disease, there is still a need for a robust biomarker of Zn status. Many parameters have been proposed, with varying levels of success, with plasma Zn often favoured. This study investigates if Zn status can be assessed from the natural stable Zn isotope composition of urine. To this end, 60 urine samples were analysed from ten healthy participants. Remarkably, samples with lower Zn concentrations are systematically enriched in heavy Zn isotopes. Most of the low-Zn urine originated from individuals who omitted dairy, meat or both from their diets. When data for blood serum from age-matched, healthy individuals are compared with the urine results, the former plot at the extension of the urine trend at higher Zn concentrations and lighter isotope compositions. The observed co-variation of Zn isotope compositions with concentrations is indicative of an isotope fractionation system where both properties are controlled by the same processes. It is interpreted as arising from filtration and/or reabsorption processes within the kidney, which are associated with absorbed dietary Zn. The data suggest that the Zn in blood serum that is bound to low molecular weight molecules has an isotope composition distinct from total serum, due to the different affinities of molecular Zn-binding residues to heavy and light Zn isotopes. This technique provides additional information into an individual's Zn status compared to urine or plasma Zn levels alone.

Reproducibility of essential elements chromium, manganese, iron, zinc and selenium in spot samples, first-morning voids and 24-h collections from healthy adult men.

Evaluation of Cr, Mn, Fe, Zn and Se in humans is challenged by the potentially high within-individual variability of these elements in biological specimens, which are poorly characterised. This study aimed to evaluate their within-day, between-day and between-month variability in spot samples, first-morning voids and 24-h collections. A total of 529 spot urine samples (including eighty-eight first-morning voids and 24-h collections) were collected from eleven Chinese adult men on days 0, 1, 2, 3, 4, 30, 60 and 90 and analysed for these five elements using inductively coupled plasma-MS. Intraclass correlation coefficients (ICC) were utilised to characterise the reproducibility, and their sensitivity and specificity were analysed to assess how well a single measurement classified individuals' 3-month average exposures. Serial measurements of Zn in spot samples exhibited fair to good reproducibility (creatinine-adjusted ICC = 0·47) over five consecutive days, which became poor when the samples were gathered months apart (creatinine-adjusted ICC = 0·33). The reproducibility of Cr, Mn, Fe and Se in spot samples was poor over periods ranging from days to months (creatinine-adjusted ICC = 0·01-0·12). Two spot samples were sufficient for classifying 60 % of the men who truly had the highest (top 33 %) 3-month average Zn concentrations; for Cr, Mn, Fe and Se, however, at least three specimens were required to achieve similar sensitivities. In conclusion, urinary Cr, Mn, Fe, Zn and Se concentrations showed a strong within-individual variability, and a single measurement is not enough to efficiently characterise individuals' long-term exposures.