Enriched stable 204Pb as tracer at ultra-low levels in clinical investigations.

The potential of enriched Pb (204Pb) was assessed to monitor pathways of trace levels of Pb in the pg range within the human body via isotope pattern variation in situations where natural lead cannot be used as a tracer due to regulatory limitations. Isotope ratio measurements were accomplished by means of (multi-collector) inductively coupled plasma mass spectrometry including a comparison of single and multi-collector ICP-MS for low-level 204Pb assessment. Isotopic pattern results from a blend of a large quantity of the element with a natural isotopic composition and an enriched stable isotope at orders of magnitude lower levels pose a nontrivial analytical problem. Isotope pattern deconvolution was successfully applied as mathematical tool based on multiple linear regressions. The method allowed for deconvolving the isotope pattern from measured isotope ratios without knowing the quantities of different isotope sources incorporated and mixed into the sample at levels of < 1 pg 204Pb/g blood. The objective of this manuscript is to evaluate and summarize the analytical aspects for Pb isotope pattern deconvolution based on the results of a clinical trial, where a 204Pb-enriched isotope tracer was applied to investigate the bioavailability of orally applied Pb along with purified clinoptilolite tuff as potential supplement. This unique approach allows to reduce tracer amounts to harmless levels to human health, which are in accordance with the legal regulative to study enrichment levels of < 0.01% in human blood.

A combined chemical imaging approach using (MC) LA-ICP-MS and NIR-HSI to evaluate the diagenetic status of bone material for Sr isotope analysis.

This paper presents a combination of elemental and isotopic spatial distribution imaging with near-infrared hyperspectral imaging (NIR-HSI) to evaluate the diagenetic status of skeletal remains. The aim is to assess how areas with biogenic n(87Sr)/n(86Sr) isotope-amount ratios may be identified in bone material, an important recorder complementary to teeth. Elemental (C, P, Ca, Sr) and isotopic (n(87Sr)/n(86Sr)) imaging were accomplished via laser ablation (LA) coupled in a split stream to a quadrupole inductively coupled plasma mass spectrometer (ICP-QMS) and a multicollector inductively coupled plasma mass spectrometer (MC ICP-MS) (abbreviation for the combined method LASS ICP-QMS/MC ICP-MS). Biogenic areas on the bone cross section, which remained unaltered by diagenetic processes, were localized using chemical indicators (I(C)/I(Ca) and I(C) × 10/I(P) intensity ratios) and NIR-HSI at a wavelength of 1410 nm to identify preserved collagen. The n(87Sr)/n(86Sr) isotope signature analyzed in these areas was in agreement with the biogenic bulk signal revealed by solubility profiling used as an independent method for validation. Elevated C intensities in the outer rim of the bone, caused by either precipitated secondary minerals or adsorbed humic materials, could be identified as indication for diagenetic alteration. These areas also show a different n(87Sr)/n(86Sr) isotopic composition. Therefore, the combination of NIR-HSI and LASS ICP-QMS/MC ICP-MS allows for the determination of preserved biogenic n(87Sr)/n(86Sr) isotope-amount ratios, if the original biogenic material has not been entirely replaced by diagenetic material. Graphical abstract ᅟ.

Fungicide application increased copper-bioavailability and impaired nitrogen fixation through reduced root nodule formation on alfalfa.

Copper-based fungicides have been used for a long time in viticulture and have accumulated in many vineyard soils. In this study, incrementing Cu(OH)2-based fungicide application from 0.05 to 5 g Cu kg-1 on two agricultural soils (an acidic sandy loam (L, pH 4.95) and an alkaline silt loam (D, pH 7.45)) resulted in 5 times more mobile Cu in the acidic soil. The most sensitive parameters of alfalfa (Medicago sativa) growing in these soils were the root nodule number, decreasing to 34% and 15% of the control at 0.1 g Cu kg-1 in soil L and at 1.5 g Cu kg-1 in soil D, respectively, as well as the nodule biomass, decreasing to 25% and 27% at 0.5 g Cu kg-1 in soil L and at 1.5 g Cu kg-1 in soil D, respectively. However, the enzymatic N2-fixation was not directly affected by Cu in spite of the presence of Cu in the meristem and the zone of effective N2-fixation, as illustrated by chemical imaging. The strongly different responses observed in the two tested soils reflect the higher buffering capacity of the alkaline silt loam and showed that Cu mitigation and remediation strategies should especially target vineyards with acidic, sandy soils.

Factors affecting the hydrolysis of the antibiotic amoxicillin in the aquatic environment.

The environmental fate of the frequently used broad-spectrum ß-lactam antibiotic amoxicillin (AMX) is of high concern regarding the potential evolution of antimicrobial resistance (AMR). Moreover, it is known that AMX is prone to hydrolysis, yielding a variety of hydrolysis products (HPs) with yet unknown effects. Studies to identify those HPs and investigate their formation mechanisms have been reported but a long-term study on their stability in real water samples was missing. In this regard, we investigated the hydrolysis of AMX at two concentration levels in four distinct water types under three different storage conditions over two months. Concentrations of AMX and four relevant HPs were monitored by an LC-MS/MS method revealing pronounced differences in the hydrolysis rate of AMX in tap water and mineral water on the one hand (fast) and surface water on the other (slow). In this context, the occurrence, relative intensities, and stability of certain HPs are more dependent on the water type than on the storage condition. As clarified by ICP-MS, the main difference between the water types was the content of the metals copper and zinc which are supposed to catalyze AMX hydrolysis demonstrating an effective method to degrade AMX at ambient conditions.

Concomitant oral intake of purified clinoptilolite tuff (G-PUR) reduces enteral lead uptake in healthy humans.

Lead exposure can cause substantial organ damage. Enteral lead absorption may be reduced by concomitant intake of clinoptilolite tuff, a zeolite from natural sources. This study aimed to assess the effect of purified clinoptilolite tuff (G-PUR) on enteral lead uptake in adults using stable lead isotope 204Pb as a tracer. In this randomized, placebo-controlled, double-blind, parallel-group study, 42 healthy participants were randomized to receive oral G-PUR 2.0 g, 2 * 2.0 g, or placebo, together with 2.5 µg of 204Pb in water. The enrichment of 204Pb caused by the tracer in blood and urine was measured by mass spectrometry. G-PUR was well tolerated. The mean maximum 204Pb enrichment of 0.505% of total blood lead was significantly higher (p < 0.0001) in the placebo group compared to G-PUR 2.0 g (0.073%) or G-PUR 2 * 2.0 g (0.057%) group. Normalized 204Pb AUC0-192 was 86.5, 11.9, and 8.5% * h without and with G-PUR 2.0 g, and G-PUR 2 * 2.0 g, respectively (p < 0.0001 vs. placebo). This smaller 204Pb exposure was paralleled by a reduced urinary excretion in subjects receiving G-PUR. Concomitant oral intake of purified clinoptilolite tuff reduced enteral uptake of 204Pb in healthy humans by approximately 90%. The reduced bioavailability is demonstrable by a decrease of 204Pb tracer enrichment in blood and urine.Trial registration: clinicaltrials.gov identifier: NCT04138693, registered 24/10/2019.

Ancient DNA reveals monozygotic newborn twins from the Upper Palaeolithic.

The Upper Palaeolithic double burial of newborns and the single burial of a ca. 3-month-old infant uncovered at the Gravettian site of Krems-Wachtberg, Austria, are of paramount importance given the rarity of immature human remains from this time. Genome-wide ancient DNA shows that the male infants of the double grave are the earliest reported case of monozygotic twins, while the single grave´s individual was their 3rd-degree male relative. We assessed the individuals´ age at death by applying histological and µCT inspection of the maxillary second incisors (i2) in conjunction with C- and N-isotope ratios and Barium (Ba) intake as biomarker for breastfeeding. The results show that the twins were full-term newborns, and that while individual 2 died at birth, individual 1 survived for about 50 days. The findings show that Gravettian mortuary behaviour also included re-opening of a grave and manipulation of its layout and content.