Variation in landmarks for the rectum: an MRI study

AIM

This study aimed to assess the reliability of measurements and bony landmarks for the rectosigmoid junction on MRI.

METHOD

The staging MRI scans for 100 patients were reviewed. The junction of the mesorectum and mesocolon was used to identify the rectum and sigmoid. The performance of current metric measurements or bony landmarks was then compared against the actual anatomical bowel segment.

RESULTS

The mean distance of the sigmoid take-off from the anal verge was 12.6 cm (SD 1.8 cm, range 9.4-19.0 cm). At a cutoff of 12 cm, the anatomical bowel segment was found to be sigmoid colon rather than rectum in 35% of patients. At 15 and 16 cm the bowel segment was sigmoid in 84% and 96% of patients, respectively. At the sacral promontory and the third sacral segment, the bowel segment was sigmoid in 28% and 100% of patients, respectively.

CONCLUSION

Current definitions of the rectum that rely on arbitrary measurements or bony landmarks will not locate the correct point of transition between the rectum and sigmoid in the majority of patients. The sigmoid take-off offers an alternative, anatomically bespoke, landmark.

Deep urban groundwater vulnerability in India revealed through the use of emerging organic contaminants and residence time tracers

Demand for groundwater in urban centres across Asia continues to rise with ever deeper wells being drilled to avoid shallow contamination. The vulnerability of deep alluvial aquifers to contaminant migration is assessed in the ancient city of Varanasi, India, using a novel combination of emerging organic contaminants (EOCs) and groundwater residence time tracers (CFC and SF₆). Both shallow and intermediate depth private sources (<100 m) and deep (>100 m) municipal groundwater supplies were found to be contaminated with a range of EOCs including pharmaceuticals (e.g. sulfamethoxazole, 77% detection frequency, range <0.0001-0.034 μg L^-1), perfluoroalkyl substances (e.g. PFOS, range <0.0001-0.033 μg L^-1) as well as a number of pesticides (e.g. phenoxyacetic acid, range <0.02-0.21 μg L^-1). The profile of EOCs found in groundwater mirror those found in surface waters, albeit at lower concentrations, and reflect common waste water sources with attenuation in the subsurface. Mean groundwater residence times were found to be comparable between some deep groundwater and shallow groundwater sources with residence times ranging from >70 to 30 years. Local variations in aquifer geology influence the extent of modern recharge at depth. Both tracers provide compelling evidence of significant inputs of younger groundwater to depth >100 m within the aquifer system.

Rapid disease progression in a patient with mismatch repair-deficient and cortisol secreting adrenocortical carcinoma treated with pembrolizumab

CONTEXT

Metastatic adrenocortical carcinoma (ACC) is an aggressive malignancy with a poor prognosis and limited therapeutic options. A subset of ACC is due to Lynch syndrome, an inherited tumor syndrome resulting from germline mutations in mismatch repair (MMR) genes. It has been demonstrated that several cancers characterized by MMR deficiency are sensitive to immune checkpoint inhibitors that target PD-1. Here, we provide the first report of PD-1 blockade with pembrolizumab in a patient with Lynch syndrome and progressive cortisol-secreting metastatic ACC.

CASE REPORT

A 58-year-old female with known Lynch syndrome presented with severe Cushing's syndrome and was diagnosed with a cortisol-secreting ACC. Three months following surgical resection and adjuvant mitotane therapy the patient developed metastatic disease and persistent hypercortisolemia. She commenced pembrolizumab, but her second cycle was delayed due to a transient transaminitis. Computed tomography performed after 12 weeks and 2 cycles of pembrolizumab administration revealed significant disease progression and treatment was discontinued. After 7 weeks, the patient became jaundiced and soon died due to fulminant liver failure.

CONCLUSION

Treatment of MMR-deficient cortisol-secreting ACC with pembrolizumab may be ineffective due to supraphysiological levels of circulating corticosteroids, which may in turn mask severe drug-induced organ damage.

The Pathophysiology of Cardiac Surgery-Associated Acute Kidney Injury (CSA-AKI)

Cardiac surgery associated acute kidney injury (CSA-AKI) is a significant clinical problem. Its pathogenesis is complex and multifactorial. It likely involved at least six major injury pathways: exogenous and endogenous toxins, metabolic factors, ischemia and reperfusion, neurohormonal activation, inflammation and oxidative stress. These mechanisms of injury are likely to be active at different times with different intensity and probably act synergistically. Because of such complexity and the small number of randomised controlled investigations in this field only limited recommendations can be made. Nonetheless, it appears important to avoid nephrotoxic drugs and desirable to avoid hyperglycemia in the peri-operative period. The duration of cardiopulmonary bypass should be limited whenever possible. Off-pump surgery, when indicated, may decrease the risk of AKI. Invasive hemodynamic monitoring focussed on attention to maintaining euvolemia, an adequate cardiac output and an adequate arterial blood pressure is desirable. Echocardiography may be useful in minimizing atheroembolic complications. The administration of N-acetylcysteine to protect the kidney from oxidative stress is not recommended. There is marked lack of randomised controlled trials in this field.

The fate of plasma-generated oxygen atoms in aqueous solutions: non-equilibrium atmospheric pressure plasmas as an efficient source of atomic O(aq)

It is demonstrated with help of ¹⁸O₂ labeling that O_(aq) is stable in water and can directly react with dissolved molecules.