Search

Expression of the alcohol dehydrogenase gene (ADH) of Arabidopsis is known to be induced by environmental stresses and regulated developmentally. We used a negative-selection approach to isolate mutants that were defective in regulating the expression of the ADH gene during seed germination; we then characterized three recessive mutants, aar1-1, aar1-2, and aar2-1, which belong to two complementation groups. In addition to their defects during seed germination, mutations in the AAR1 and AAR2 genes also affected anoxic and hypoxic induction of ADH and other glycolytic genes in mature plants. The aar1 and aar2 mutants were also defective in responding to cold and osmotic stress. The two allelic mutants aar1-1and aar1-2 exhibited different phenotypes under cold and osmotic stresses. Based on our results we propose that these mutants are defective in a late step of the signaling pathways that lead to increased expression of the ADH gene and glycolytic genes.

The interactions of Aspergillus flavus uricase with the substrates O2 and urate and the inhibitors xanthine, cyanide, periodate and hydroxylamine were investigated. Under equilibrium conditions O2 does not bind directly to the enzyme, and the absence of O2 had no effect on either the binding stoicheiometry or binding constant for xanthine, as measured by equilibrium dialysis and microcalorimetry. Cyanide, periodate and hydroxylamine inhibit uricase in a non-classical manner. A decrease in initial velocity to a steady-state inhibited velocity can be observed on a time scale of minutes. The time-dependence, which is unaltered by prior incubation with the inhibitors, is consistent with a first-order transition. Rate constants for induction of inhibition are linearly dependent on inhibitor concentration, but independent of urate and O2 concentrations. Radioactively labelled urate forms a stable but reversible complex with uricase in the presence of cyanide and O2. These results were used to deduce the nature of enzyme-bound intermediates and thus for the proposal of a novel mechanism for cyanide inhibition.

The subunit composition, metal content, substrate-analogue binding and thermal stability of Aspergillus flavus uricase were determined. A. flavus uricase is a tetramer and contains no copper, iron or any other common prosthetic group. Analytical-gel-filtration and equilibrium-dialysis experiments showed one binding site per subunit for urate analogues. The free energy of xanthine binding was −30.5 kJ (-7.3 kcal)/mol of subunit by equilibrium dialysis and −30.1 kJ (-7.2 kcal)/mol of subunit by microcalorimetry. The enthalpy change for xanthine binding was −15.9 kJ (-3.8 kcal)/mol of subunit when determined from the temperature-dependence of the equilibrium constant and −18.0 kJ (-4.3 kcal)/mol of subunit when measured microcalorimetrically. The thermal inactivation rate of A. flavus uricase increases as protein concentration is decreased. This concentration-dependent instability is not due to subunit dissociation.

IntroductionAcute upper GI bleeding (AUGIB) presents with a spectrum of severity. Current NICE guidance recommends risk-stratifying patients using the Glasgow-Blatchford score (GBS) and considering early discharge for patients with a pre-endoscopy Blatchford score of 01. STHK Teaching Hospitals has developed an ambulatory pathway to manage low-risk (GBS ≤2) patients with suspected AUGIB. Patients are commenced on the pathway by a Medical StR, then discharged home with a pre-arranged endoscopy (OGD) and a post-OGD medical review. Our aim was to assess the safety of this strategy.MethodData between May 2016 and Jan 2017 was retrospectively collected from e-case notes. A standard audit tool was used and included GBS, endoscopy findings, readmission, re-bleeding, transfusion, surgery and death. Local audit data was used to estimate total bed days saved.Results68 patients (M:F 34:34) were referred via the Low Risk GI Bleed Ambulatory Pathway. The mean age was 42, range 18–79. Median time to OGD was 1 day, range 0–10. 2 patients elected to defer their endoscopy by 10 days for non-clinical reasons. All patients were discharged after post-OGD medical review. 26 had a normal OGD, 6 had peptic ulcer disease.5 patients had a delay in the decision to ambulate, mean stay 1.2 days. 1 patient re-presented after 3 months with a suspected AUGIB, GBS was 1 and repeat OGD revealed oesophagitis. 6 patients were inappropriately referred and had GBS>2. No patients had stigmata of recent or active bleeding, none required endotherapy or surgery and no patients died. 1 patient recieved a blood transfusion.ConclusionOur data shows that patients with GBS ≤2 can potentially be managed safely with an ambulatory pathway and this supports previously published findings2,3. Using local audit data, median and mean length of stay for patients with GBS ≤2 is 2 and 3 days respectively. Between May 2016 and Jan 2017 we estimate to have saved 138–204 bed days. At an estimated cost of £400 per day, this equates to a saving of £55,200–81,6004.References. National Institute for Health and Care Excellence, June 2012. Acute upper gastrointestinal bleeding in over 16s: Management[CG141]. London: NICE.. Stewart RF, Murphy RFE, Church NI. “An ambulatory care protocol for managing low-risk patients with non-variceal upper GI bleeding”. Society of Acute Medicine Conference, Manchester, England, 30th Dec 2012.. Stanley AJ, et al. Outpatient management of patients with low-risk upper-gastrointestinal haemorrhage: multicentre validation and prospective evaluation. The Lancet, vol 373, No. 9657, p42–47, 3rd Jan 2009.. https://data.gov.uk/data-request/nhs-hospital-stay. Department of Health. Data.gov.uk. NHS Hospital Stay, 24/08/2015.Accessed:17/02/17.Disclosure of InterestNone Declared

Presents letters to the editor referencing articles and topics discussed in previous issues. "Brown at 50," which focused on the Brown versus Board of Education case and lawyers; "Are Schools Returning to the 1950s," which addressed the segregation issue in public schools; "Marching Orders," which discussed management techniques to encourage pro bono.