Assessing the impact of immobilisation on the bioavailability of PFAS to plants in contaminated Australian soils

Per- and polyfluoroalkyl substances (PFAS) have become a key concern to both environmental and human health due to their extreme persistence in the environment and their ability to bioaccumulate in plants, animals, and humans. In this mesocosm study, Australian PFAS-contaminated soil with a mean total concentration of 8.05 mg/kg and a mean combined PFHxS + PFOS concentration of 7.89 mg/kg was treated with an immobilisation sorbent (RemBind®) at different application rates (0.5, 1, 1.5, 2, 3, 4, and 5% w/w). To assess the efficacy of this immobilisation treatment, PFAS leachability, PFAS plant uptake, and ecotoxicity tests were conducted. Leachability testing was performed according to the Australian Standard Leaching Procedure (ASLP) at pH 5 and 7. A grass species (Dactylis glomerata) was used to measure plant uptake of PFAS from untreated and treated contaminated soil. In addition, the Microtox test was used to assess the associated ecotoxicity. The immobilisation treatment resulted in a significant reduction of 88.5-99.8% in the total PFAS leachability and 88.7-99.8% in the combined PFOS and PFHxS leachability at pH 5. Similarly, significant reductions (5-12-fold) were observed in the plant uptake of total PFAS and combined PFOS and PFHxS in all treated soil samples. In addition, although the Microtox test showed relatively low ecotoxicity in all the experimental samples, including the untreated soil, a significant decrease in the ecotoxicity of treated soil samples was observed. The results from this study highlight that this treatment approach has the potential to reduce both PFAS leachability and plant bioavailability with a relatively low associated ecotoxicity. This is likely to reduce the risk of the transfer of PFAS into higher trophic levels. This immobilisation treatment may, therefore, reduce the risk associated with PFAS-contaminated soils and may be an important remediation tool for managing certain PFAS-contaminated soils.

Monitoring calf circumference: changes during prolonged constrained sitting

Prolonged sitting has been associated with negative health effects; however, short-term time-varying exposure and response data is lacking. Twenty-two young and healthy participants were seated for 2 hours with the instruction to avoid the confounding effects of large leg movements while calf circumference, perceived discomfort, and lower limb muscle activity were collected. Calf circumference increased significantly (0.90 ± 0.32 cm) during sitting with no statistical differences between sexes. Perceived discomfort increased significantly over time in the low back and gluteal regions (p = 0.001-0.072, η_p²=0.080-0.360). On average, it took 20.31 ± 10.87 minutes of walking for calf measures to return to pre-sitting baseline. These results suggest that sitting for 2 hours without activity breaks may not be advisable and that recovery may take longer than expected. The exposure/response data from this study may be helpful in the design of future studies, with a larger and more general population, aiming to better define recommended duration/activity ratios for sitting-focused occupations. Practitioner summary: Leg swelling is a concern in prolonged sitting. In this study of young, healthy participants, we found a 2 hour constrained sitting exposure (controlling for large leg movements) induced significant increases in calf circumference that took an average of 20.31 ± 10.87 min of walking to return to baseline.Abbreviations: FMD: flow-mediated dilation, GSC: gastrocnemius; TA: tibialis anterior; EMG: electromyography; VAS: visual analog scale; MVC: maximum voluntary contractions.

The contribution of rapid KATP channel gene mutation analysis to the clinical management of children with congenital hyperinsulinism

OBJECTIVE

In children with congenital hyperinsulinism (CHI), K(ATP) channel genes (ABCC8 and KCNJ11) can be screened rapidly for potential pathogenic mutations. We aimed to assess the contribution of rapid genetic testing to the clinical management of CHI.

DESIGN

Follow-up observational study at two CHI referral hospitals.

METHODS

Clinical outcomes such as subtotal pancreatectomy, (18)F-Dopa positron emission tomography-computed tomography (PET-CT) scanning, stability on medical treatment and remission were assessed in a cohort of 101 children with CHI.

RESULTS

In total, 32 (32%) children had pathogenic mutations in K(ATP) channel genes (27 in ABCC8 and five in KCNJ11), of which 11 (34%) were novel. In those negative at initial screening, other mutations (GLUD1, GCK, and HNF4A) were identified in three children. Those with homozygous/compound heterozygous ABCC8/KCNJ11 mutations were more likely to require a subtotal pancreatectomy CHI (7/10, 70%). Those with paternal heterozygous mutations were investigated with (18)F-Dopa PET-CT scanning and 7/13 (54%) had a focal lesionectomy, whereas four (31%) required subtotal pancreatectomy for diffuse CHI. Those with maternal heterozygous mutations were most likely to achieve remission (5/5, 100%). In 66 with no identified mutation, 43 (65%) achieved remission, 22 (33%) were stable on medical treatment and only one child required a subtotal pancreatectomy.

CONCLUSIONS

Rapid genetic analysis is important in the management pathway of CHI; it provides aetiological confirmation of the diagnosis, indicates the likely need for a subtotal pancreatectomy and identifies those who require (18)F-Dopa PET-CT scanning. In the absence of a mutation, reassurance of a favourable outcome can be given early in the course of CHI.

Alteration in p53 modulates glial proteins in human glial tumour cells

In transformed human glial cells, abnormalities of the p53 gene and altered expression of glial-specific properties (GSPs) have been observed. We therefore investigated whether (i) expression of the altered p53 protein is involved in the reduced expression of GSPs; and (ii) expression of the wild-type p53 (wt-p53) gene leads to induction of GSPs. We first determined that the p53 gene is mutated in human glioblastoma U-373MG cells. In these cells, and in human T-98G glioblastoma cells reported to possess a mutated p53 (m-p53) gene, nuclear m-p53 expression was intense while GSP expression was low in the same cell as revealed by double labelling immunocytochemistry. Conversely, glial fibrillary acidic protein (GFAP) and glutamate synthase (GS) were expressed in cells devoid of nuclear m-p53 immnunoreactivity. Therefore, a mutually exclusive relationship exists between the cytoplasmic GSPs and nuclear m-p53. Upon treatment with retinoic acid (RA) and dibutyryl cyclic AMP (dbcAMP), overall GSP staining were increased concomitant with suppression of nuclear m-p53. Their mutually exclusive expression pattern was maintained suggesting a functional relationship. This is supported by the observation of a similar mutually exclusive expression pattern for p53 and GSPs in pathologic specimens of human glioblastoma tissues. We then explored the role of the wt-p53 gene in the induction of GSPs using a wt-p53 tetracycline-regulated conditional expression system in human LN-Z308 glioblastoma cells. These cells normally express no p53 and no appreciable levels of GS or GFAP. Induced expression of wt-p53 lead to induction of GSP. These observations are consistent with the hypotheses that (i) nuclear m-p53 expression and cytoplasmic expression of GFAP and GS are inversely correlated, and (ii) expression of the wt-p53 gene leads to the expression of GSPs.

Mutant p53 may selectively suppress glial specific proteins in pluripotential human neuroectodermal tumor cells

The p53 gene is mutated in pluripotential human neuroectodermal tumor DAOY cells which express both glial and neuronal markers. In most cells, nuclear m-p53 immunostaining was intense while cytoplasmic glial specific proteins (GSPs) were present at low levels. Conversely, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) were expressed in the few cells devoid of nuclear m-p53 immunoreactivity. The level of neuron specific enolase (NSE) staining was low and not different between p53 positive and p53 negative cells. Therefore, a selective, mutually exclusive expression relationship exists between cytoplasmic GSPs and nuclear m-p53. Upon treatment with epidermal growth factor (EGF) and dibutyrylcyclic AMP, overall cytoplasmic GFAP and GS levels were increased while nuclear p53 was suppressed but a mutually exclusive expression pattern between these proteins was maintained. In cells which also express NSE, GFAP was selectively stimulated suggesting that nuclear expression of m-p53 and cytoplasmic expression of GSPs may be functionally related.

Conformal radiotherapy of the pelvis: assessment of acute toxicity

During the last 3 years the Royal Marsden Hospital (RMH) has conducted a prospective randomised trial of conformal pelvic radiotherapy in which dose/volume data and acute toxicity scores have been determined prospectively. Pending completion of the trial, a preliminary analysis has been undertaken of the volume reductions achieved, and of some of the symptom scores. The average symptom score increased during radiotherapy, more markedly for bowel than bladder symptoms. In comparing total doses of 30-38 Gy with 56-65 Gy, watery bowel motions were more frequent with the higher doses (p = 0.013) but in the high-dose group neither this symptom nor tenesmus correlated with volume of rectum treated to at least 90% of the prescribed dose. We conclude that the assessment of the impact of volume on the level of acute symptoms in pelvic radiotherapy is complex, and requires analysis of a range of symptoms, dose levels and normal-tissue volumes. The degree of symptom reduction from conformal radiotherapy will emerge from the RMH randomised trial within the next 12 months.