Downregulation of the Escherichia coli guaB promoter by upstream-bound cyclic AMP receptor protein

The Escherichia coli guaB promoter (P-guaB) is responsible for directing transcription of the guaB and guaA genes, which specify the biosynthesis of the nucleotide GMP. P-guaB is subject to growth rate-dependent control (GRDC) and possesses an UP element that is required for this regulation. In addition, PguaB contains a discriminator, three binding sites for the nucleoid-associated protein FIS, and putative binding sites for the regulatory proteins DnaA, PurR, and cyclic AMP receptor protein (CRP). Here we show that the CRP-cyclic AMP (cAMP) complex binds to a site located over 100 bp upstream of the guaB transcription start site, where it serves to downregulate P-guaB. The CRP-mediated repression of P-guaB activity increases in media that support lower growth rates. Inactivation of the crp or cyaA gene or ablation/translocation of the CRP site relieves repression by CRP and results in a loss of GRDC of P-guaB. Thus, GRDC of P-guaB involves a progressive increase in CRP-mediated repression of the promoter as the growth rate decreases. Our results also suggest that the CRP-cAMP complex does not direct GRDC at P-guaB and that at least one other regulatory factor is required for conferring GRDC on this promoter. However, PurR and DnaA are not required for this regulatory mechanism

Comparison of three wet-alkaline methods of digestion of biogenic silica in water

Methods for determination of low levels of biogenic silica (0.2–0.4 mg SiO 2 ) in aqueous samples after digestion with three wetalkaline extraction procedures compared favourably in both precision of replicates and recovery of silica utilized by diatoms in budgeted cultures. Leaching samples with 0.2 M NaOH for 10–15 min at 100°C was the least time consuming procedure. Also interference from silicate minerals was lower for this method than leaching with either 0.5 or 5% Na 2 CO 3 for 2 h at 85°C. The use of filters to concentrate samples enables detection of low levels of biogenic silica with colorimetric procedures. Polycarbonate filters are recommended in preference to cellulose acetate or polyvinyl chloride filters for sample collection. Time-course experiments are recommended for establishing digestion times and determining the presence of mineral silicate interference. Wet-alkaline digestion methods are recommended for routine analysis of biogenic silica in suspended matter in preference to infra-red analysis, alkaline fusion and hydrofluoric acid/nitric acid methods.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74725/1/j.1365-2427.1983.tb00658.x.pd

A Randomized Trial of Real-Time Geriatric Assessment Reporting in Nonelectively Hospitalized Older Adults with Cancer

Background: Hospitalized older adults have significant geriatric deficits that may lead to poor outcomes. We conducted a randomized trial to investigate the effectiveness of providing clinicians with a real-time geriatric assessment (GA) report in nonelectively hospitalized older patients with cancer. Subjects, Materials, and Methods: We developed a web-based software platform for administering a modified GA (Cancer 2005; 104:1998–2005) to older (>70 years) nonelectively hospitalized patients with pathologically confirmed malignancy. Patients were randomized to have their GA report provided to their treating clinicians (Intervention arm) or not provided (Control arm). Results: Our study included 135 patients, median age 76 years, 52% female, 75% white, 21% black, 79% greater than high school education, 59% married, and 17% living alone. All patients had at least one GA-identified deficit, including physical function deficits (90%), cognitive impairment (22%), >5 comorbidities (28%), polypharmacy (>9 medications; 38%), weight loss ≥10% in the past 6 months (40%), anxiety (32%), or depression (30%). There was no difference between the Intervention (6%) and Control arms (9%) in the proportion of patients who were referred by their clinical team for an intervention to address a deficit (p =.53). Conclusion: Many older nonelectively hospitalized patients with cancer have geriatric deficits that are amenable to evidence-based interventions. Real-time GA reports provided to the care team prior to discharge did not influence provider referral for such interventions. There is a need for systems-level interventions to address deficits in this vulnerable patient population. Implications for Practice: Geriatric deficits are common in hospitalized older adults with cancer and lead to poor outcomes. Addressing modifiable deficits represents an appealing way to improve outcomes. Widespread geriatrician consultation is impractical owing to resource and personnel constraints. This work tested whether prompt delivery of a mostly self-administered, web-based geriatric assessment report to clinicians improved referral rates for evidence-informed interventions. It confirmed frequent geriatric deficits and high readmission rates in this population but found that real-time geriatric assessment reporting did not influence provider referral for evidence-informed interventions on geriatric assessment identified deficits. These findings highlight the need for systems-level intervention to improve outcomes in this vulnerable patient population

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

Background: Many patients with COVID-19 have been treated with plasma containing anti-SARS-CoV-2 antibodies. We aimed to evaluate the safety and efficacy of convalescent plasma therapy in patients admitted to hospital with COVID-19. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]) is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. The trial is underway at 177 NHS hospitals from across the UK. Eligible and consenting patients were randomly assigned (1:1) to receive either usual care alone (usual care group) or usual care plus high-titre convalescent plasma (convalescent plasma group). The primary outcome was 28-day mortality, analysed on an intention-to-treat basis. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936. Findings: Between May 28, 2020, and Jan 15, 2021, 11558 (71%) of 16287 patients enrolled in RECOVERY were eligible to receive convalescent plasma and were assigned to either the convalescent plasma group or the usual care group. There was no significant difference in 28-day mortality between the two groups: 1399 (24%) of 5795 patients in the convalescent plasma group and 1408 (24%) of 5763 patients in the usual care group died within 28 days (rate ratio 1·00, 95% CI 0·93–1·07; p=0·95). The 28-day mortality rate ratio was similar in all prespecified subgroups of patients, including in those patients without detectable SARS-CoV-2 antibodies at randomisation. Allocation to convalescent plasma had no significant effect on the proportion of patients discharged from hospital within 28 days (3832 [66%] patients in the convalescent plasma group vs 3822 [66%] patients in the usual care group; rate ratio 0·99, 95% CI 0·94–1·03; p=0·57). Among those not on invasive mechanical ventilation at randomisation, there was no significant difference in the proportion of patients meeting the composite endpoint of progression to invasive mechanical ventilation or death (1568 [29%] of 5493 patients in the convalescent plasma group vs 1568 [29%] of 5448 patients in the usual care group; rate ratio 0·99, 95% CI 0·93–1·05; p=0·79). Interpretation: In patients hospitalised with COVID-19, high-titre convalescent plasma did not improve survival or other prespecified clinical outcomes. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research