Further investigation of lead exposure as a potential threatening process for a scavenging marsupial species.

There is a growing recognition of the harmful effects of lead exposure on avian and mammalian scavengers. This can lead to both lethal and non-lethal effects which may negatively impact wildlife populations. Our objective was to assess medium-term lead exposure in wild Tasmanian devils (Sarcophilus harrisii). Frozen liver samples (n = 41), opportunistically collected in 2017-2022, were analysed using inductively coupled plasma mass spectrometry (ICP-MS) to determine liver lead concentrations. These results were then used to calculate the proportion of animals with elevated lead levels (>5 mg/kg dry weight) and examine the role of explanatory variables that may have influenced the results. The majority of samples analysed were from the south-east corner of Tasmania, within 50 km of Hobart. No Tasmanian devil samples were found to have elevated lead levels. The median liver lead concentration was 0.17 mg/kg (range 0.05-1.32 mg/kg). Female devils were found to have significantly higher liver lead concentrations than males (P = 0.013), which was likely related to lactation, but other variables (age, location, body mass) were not significant. These results suggest that wild Tasmanian devil populations currently show minimal medium-term evidence of exposure to lead pollution, although samples were concentrated in peri-urban areas. The results provide a baseline level which can be used to assess the impact of any future changes in lead use in Tasmania. Furthermore, these data can be used as a comparison for lead exposure studies in other mammalian scavengers, including other carnivorous marsupial species.

Determination of copper in infant formula by graphite furnace atomic absorption spectroscopy with a L'vov platform.

A rapid method for the determination of sub-part-per-million levels of copper in infant formula, which does not require decomposition of the sample matrix before analysis, has been developed. The method uses L'vov platform graphite furnace atomic absorption spectroscopy (GFAAS), a technique that greatly reduces matrix interferences limiting the applicability of normal GFAAS. The sample preparation consists of dilution of a weighed sample of infant formula to a known volume with a 0.5% solution of Triton X-100 in deionized water. The accuracy of the method, as assessed from the results of overspike recovery studies (96.5-101.3% recovery) for different matrix types and comparison to results generated with alternative methodologies, can be considered excellent. The overall precision of the method ranges from 2.5 to 4.3% RSD for different matrix types.

Metabolism and selective effects of 1-beta-D-arabinofuranosylcytosine in L1210 and Host tissues in vivo.

The selectivity of action of 1-beta-D-arabinofuranosylcytosine (ara-C) against leukemic cells was studied in vivo. Dynamic state tissue levels of ara-C and of its mono-, di-, and triphosphate (ara-CTP) were measured in L1210 leukemic cells and in C57BL x DBA/2 F1 host tissues at different times after various doses of the agent. The levels were correlated with inhibition of thymidine incorporation into DNA and with cytocidal effects as measured by loss of isotopically prelabeled DNA. ara-CTP levels, but not those of the mono- and diphosphates of ara-C, were higher in leukemic cells and in host cell renewal systems than in other host tissues. DNA synthesis was equally inhibited by similar levels of ara-CTP in ascitic L1210 cells, in leukemic infiltrates in liver, and in small intestine. However, L1210 cells accumulated higher levels of ara-CTP for longer periods than did small intestine, and correspondingly the inhibition of DNA synthesis was greater and more prolonged in leukemic cells. ara-C caused greater losses of prelabeled DNA in ascites cells and in infiltrated liver than in host small intestine. It appears that the differential net tissue level of ara-CTP and its duration are the determinants of chemotherapeutic efficacy of ara-C against L1210 leukemia. ara-C was the predominant nucleoside present in hydrolysates of ara-CTP fractions. By contrast, 1-beta-D-arabinofuranosyluracil predominated in hydrolysates of monophosphate nucleotide fractions from ascites cells, liver, small intestine, and blood. Monophosphate nucleotide was also present in ascites fluid and plasma.