An Improved Method for Determining Urease Activity from Electrical Conductivity Measurements.

We present an improved approach to evaluating the activity of urease from electrical conductivity (EC) measurements. In this approach, chemical equilibrium modeling via PHREEQC is used in conjunction with empirical equations for computing EC to develop a function that relates the increase in EC during urea hydrolysis in a closed reactor to the concentration of ammonium species present (and concentration of urea remaining) in the reaction solution. By applying this function to data from continuous measurement of EC during urea hydrolysis, we obtain a profile of the concentration of the urea substrate with time, which is then used to determine the urease activity. The activity of commercially available urease extracted from jack beans was determined using this method and compared well to the activity determined using Nessler's reagent, a commonly used colorimetric assay. This EC-based method is inexpensive and can be used for accurate determination of urease activity for a variety of applications.

Imaging volumes during COVID-19: A Victorian health service experience.

BACKGROUND: The World Health Organisation declared the coronavirus disease 2019 (COVID-19) a pandemic on March 11, 2020. While globally, the relative caseload has been high, Australia's has been relatively low. During the pandemic, radiology services have seen significant changes in workflow across modalities and a reduction in imaging volumes. AIM: To investigate differences in modality imaging volumes during the COVID-19 pandemic across a large Victorian public health network. METHODS: A retrospective analysis from January 2019 to December 2020 compared imaging volumes across two periods corresponding to the pandemic's first and second waves. Weekly volumes across patient class, modality and mobile imaging were summed for periods: wave 1 (weeks 11 to 16 for 2019; weeks 63 to 68 for 2020) and wave 2 (weeks 28 to 43 for 2019; weeks 80 to 95 for 2020). Microsoft Power Business Intelligence linked to the radiology information system was used to mine all completed examinations. RESULTS: Summed weekly data during the pandemic's first wave showed the greatest decrease of 29.8% in adult outpatient imaging volumes and 46.3% in paediatric emergency department imaging volumes. Adult nuclear medicine demonstrated the greatest decrease of 37.1% for the same period. Paediatric nuclear medicine showed the greatest decrease of 47.8%, with angiography increasing by 50%. The pandemic's second wave demonstrated the greatest decrease of 23.5% in adult outpatient imaging volumes, with an increase of 18.2% in inpatient imaging volumes. The greatest decrease was 28.5% in paediatric emergency department imaging volumes. Nuclear medicine showed the greatest decrease of 37.1% for the same period. Paediatric nuclear medicine showed the greatest decrease of 36.7%. Mobile imaging utilisation increased between 57.8% and 135.1% during the first and second waves. A strong correlation was observed between mobile and non-mobile imaging in the emergency setting (Spearman's correlation coefficient = -0.743, P = 0.000). No correlation was observed in the inpatient setting (Spearman's correlation coefficient = -0.059, P = 0.554). CONCLUSION: Nuclear medicine was most impacted, while computed tomography and angiography were the least affected by the pandemic. The impact was less during the pandemic's second wave. Mobile imaging shows continuous growth during both waves.