DT diaphorase is a flavoprotein that enzymatically transfers two electrons from quinones as intermediate substrates and has been reported to increase its activity in the liver after exposure to toxicants. In this series of experiments, we tested the hypothesis that DT diaphorase also increases its activity after exposure to oxidants following gradient ischemia in skin. Using dorsal rat flaps, oxidant stress was induced immediately or during a 7-day period of preconditioning as a bipedicle flap before the distal attachment was divided. DT diaphorase activity (delta Abs/min/100 g) or expression of message was measured during the period of preconditioning to determine the relationship between skin survival, enzyme activity, and expression of message. There was 4.7 +/- 0.8 cm of skin necrosis in the distal end of acute flaps while the preconditioned flaps had no skin necrosis after the distal attachment was divided. In the acute flaps, the DT diaphorase activity was equal throughout the flap for the first 6 hr. After 24 hr of ischemia, the DT diaphorase activity was significantly higher in the proximal end of the flap (1.83 +/- 0.21 delta Abs/min/100 g) than that in the distal end (0.005 +/- 0.01 delta Abs/min/100 g), which was significant (P < 0.05). In the preconditioned flaps, enzyme activity did not increase but there was as 50-fold increase in DT diaphorase activity at the distal end 24 hr after they were divided (P < 0.05). Maximal enzyme induction of DT diaphorase activity occurred after 4 days of preconditioning and correlated with the maximal expression of mRNA. These studies provide the first evidence that DT diaphorase enzyme activity is inducible after oxidant stress. The data also suggests that DT activity remains elevated for at least 6 hr of ischemia and may be a potential source of anti-oxidant activity in ischemic skin.

Background/Aims: Intensive haemodialysis (HD) sometimes causes hypophosphataemia, but phosphate-containing dialysate is not readily available. We examined the effectiveness of extemporaneously producing a phosphate-rich dialysate for use in HD. Methods: Incremental volumes of Fleet® were added to acid concentrate and predicted to deliver dialysate phosphate concentrations of 0.19–1.1 mmol/l, following mixture with ultrapure water and base concentrate by the HD machine. Results: The achieved concentrations were close to predicted values (p = 0.77) and remained stable throughout an 8-hour ‘treatment’ time (p = 0.99). The dialysate phosphate concentration had a linear relationship with the Fleet® volume added, defined by the regression equation y = 172.79 x – 1.47 (R² = 0.99, r = 0.99, p = 0.003). The dialysate pH, calcium, magnesium and bicarbonate concentrations did not change over the study period (p = 0.28–0.99). Microscopic analysis under polarised light showed no evidence of crystal formation. Conclusion: The study validates a simple, reliable and cost-effective protocol for phosphate supplementation in conventional and extended HD.

Rationale and Objectives We aimed to assess early COVID-19 pandemic-associated changes in brain MRI examination frequency and acuity of imaging findings acuity. Methods Using a natural language processing model, we retrospectively categorized reported findings of 12,346 brain MRI examinations performed during 6-month pre-pandemic and early pandemic time periods across a large metropolitan health system into three acuity levels: 1, normal or near normal; 2, incidental or chronic findings not requiring a management change; and 3, new or progressive findings requiring a management change. Brain MRI frequency and imaging finding acuity level were compared over time. Results Between March and August of 2019 (pre-pandemic) and 2020 (early pandemic), our health system brain MRI examination volumes decreased 17.0% (6,745 vs. 5,601). Comparing calendar-matched 6-month periods, the proportion of higher acuity findings increased significantly (p <0.001) from pre-pandemic (22.5%, 43.6% and 34.0% in acuity level 1, 2, and 3, respectively) to early pandemic periods (19.1%, 40.9%, and 40.1%). During the second three months of the early pandemic period, as MRI volumes recovered to near baseline, the proportion of higher acuity findings remained high (42.6% vs. 34.1%) compared with a similar pre-pandemic period. In a multivariable analysis, Black (B coefficient, 0.16) and underinsured population (B coefficient, 0.33) presented with higher acuity findings (p < 0.05). Conclusion As the volume of brain MRI examinations decreased during the early COVID-19 pandemic, the relative proportion of examinations with higher acuity findings increased significantly. Pandemic-related changes in patient outcomes related to reduced imaging access merits further attention.

Background and Purpose: Percutaneous trigeminal tractotomy is an ablative procedure that can be used to treat trigeminal neuralgia in patients who have failed prior pharmacologic and surgical treatments. Using perioperative computed tomography (CT) guidance, ablation of the descending spinal trigeminal nucleus and trigeminal tract can be performed precisely to mitigate damage to surrounding structures. These patients are subsequently followed with postoperative imaging and clinical visits to assess long-term pain relief. Methods:In this report, we present a series of four patients with trigeminal neuralgia who were had refractory disease after prior medical and surgical interventions. These patients underwent CT-guided percutaneous trigeminal tractotomy for pain relief. The patients underwent postoperative MRI and were followed for up to 6 months for long-term clinical outcomes. Results:For intraoperative CT, we find that preprocedure lumbar contrast injection enables better visualization of the cord during placement of the ablation probe. On postoperative imaging, we find that all four patients have hyperintense lesions on T2-weighted MRI that correspond with the location of the trigeminal nucleus and tract. Three patients had short-term pain relief, one of which continued to have long-term relief. Conclusion:Intraoperative CT and postoperative MRI serve as useful modalities for confirming localization, evaluating complications, and can be used as a metric for quality control.

Tetralogy of Fallot (TOF) is a congenital heart defect (CHD) found in 1 of 3600 live births and represents 3.5% to 7% of all CHD's in infants. TOF is characterised by a ventricular septal defect (VSD), overriding aorta astride of the VSD and pulmonary stenosis or atresia with or without right ventricular hypertrophy. It is well documented that prenatal diagnosis of TOF improves neonatal outcomes; however, ultrasound successfully detects it in only 30% to 60% of cases. Lack of skill and expertise by sonographers has been cited as a contributing factor to the relatively poor prenatal detection rates of TOF. This literature review was performed to provide a comprehensive resource for sonographers with the aim of improving awareness and understanding of the prenatal diagnosis of TOF with obstetric ultrasound. Emphasis has been placed on imaging protocols, sonographic appearances of TOF, and technological and best practice advancements in fetal cardiac ultrasound.