Using energy to go downhill—a genoprotective role for ATPase activity in DNA topoisomerase II

Type II topoisomerases effect topological changes in DNA by cutting a single duplex, passing a second duplex through the break, and resealing the broken strand in an ATP-coupled reaction cycle. Curiously, most type II topoisomerases (topos II, IV and VI) catalyze DNA transformations that are energetically favorable, such as the removal of superhelical strain; why ATP is required for such reactions is unknown. Here, using human topoisomerase IIβ (hTOP2β) as a model, we show that the ATPase domains of the enzyme are not required for DNA strand passage, but that their loss elevates the enzyme's propensity for DNA damage. The unstructured C-terminal domains (CTDs) of hTOP2β strongly potentiate strand passage activity in ATPase-less enzymes, as do cleavage-prone mutations that confer hypersensitivity to the chemotherapeutic agent etoposide. The presence of either the CTD or the mutations lead ATPase-less enzymes to promote even greater levels of DNA cleavage in vitro, as well as in vivo. By contrast, aberrant cleavage phenotypes of these topo II variants is significantly repressed when the ATPase domains are present. Our findings are consistent with the proposal that type II topoisomerases acquired ATPase function to maintain high levels of catalytic activity while minimizing inappropriate DNA damage

Role of invasive mechanical ventilation and ECMO in the management of COVID-19: a systematic review

Objectives: This systematic review aims to provide insight into the outcome of extracorporeal membrane oxygenation (ECMO) and invasive mechanical ventilation use in critically ill COVID-19 patients. Data sources: Electronic databases PubMed Central and PubMed were searched from January 2020 to June 2020 for published studies about ECMO and/or invasive mechanical ventilation use in COVID-19 patients. Data Extraction and Study Selection: The search strategy retrieved 766 articles, of which 19 studies consisting of 204 patients fulfilled the inclusion criteria and were included in the analysis. Data synthesis: Primary outcomes evaluated were discharge and/or clinical improvement and mortality rate. Secondary outcomes evaluated included reported complications and the mean number of days of hospitalization for survivors. Weighted averages of included studies were calculated, and data were pooled in forest plots. Nearly, 68.1% of the patients received invasive mechanical ventilation without ECMO support, and 31.9% were placed on ECMO. Also, 22.5% of the patients were discharged and/or clinically improved and 51.5% died. Twenty-six percent of the study population deteriorated but remained alive or experienced no improvement in clinical condition. And 75.2% of those who died belonged to the non-ECMO group and 24.8% to the ECMO group. The mortality rate in the non-ECMO group was 56.8% compared to 40% in the ECMO group. Conclusion: The utility of ECMO during a pandemic is uncertain as it is a resource-intensive modality, especially when the mortality rate in severely ill patients infected with COVID-19 virus is already known to be high

Activation of Rho-associated coiled-coil protein kinase 1 (ROCK-1) by caspase-3 cleavage plays an essential role in cardiac myocyte apoptosis

Rho-associated coiled-coil protein kinase 1 (ROCK-1) is a direct cleavage substrate of activated caspase-3, which is associated with heart failure. In the course of human heart failure, we found marked cleavage of ROCK-1 resulting in a 130-kDa subspecies, which was absent in normal hearts and in an equivalent cohort of patients with left ventricular assist devices. Murine cardiomyocytes treated with doxorubicin led to enhanced ROCK-1 cleavage and apoptosis, all of which was blocked by a caspase-3 inhibitor. In addition, a bitransgenic mouse model of severe cardiomyopathy, which overexpresses Gq protein and hematopoietic progenitor kinase-/germinal center kinase-like kinase, revealed the robust accumulation of the 130-kDa ROCK-1 cleaved fragment. This constitutively active ROCK-1 subspecies, when expressed in cardiomyocytes, led to caspase-3 activation, indicating a positive feed-forward regulatory loop. ROCK-1-dependent caspase-3 activation was coupled with the activation of PTEN and the subsequent inhibition of protein kinase B (Akt) activity, all of which was attenuated by siRNA directed against ROCK-1 expression. Similarly, ROCK-1-null mice (Rock-1(−/−)) showed a marked reduction in myocyte apoptosis associated with pressure overload. These data suggest an obligatory role for ROCK-1 cleavage in promoting apoptotic signals in myocardial hypertrophy and/or failure

LEARN: A multi-centre, cross-sectional evaluation of Urology teaching in UK medical schools

OBJECTIVE: To evaluate the status of UK undergraduate urology teaching against the British Association of Urological Surgeons (BAUS) Undergraduate Syllabus for Urology. Secondary objectives included evaluating the type and quantity of teaching provided, the reported performance rate of General Medical Council (GMC)-mandated urological procedures, and the proportion of undergraduates considering urology as a career. MATERIALS AND METHODS: LEARN was a national multicentre cross-sectional study. Year 2 to Year 5 medical students and FY1 doctors were invited to complete a survey between 3rd October and 20th December 2020, retrospectively assessing the urology teaching received to date. Results are reported according to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). RESULTS: 7,063/8,346 (84.6%) responses from all 39 UK medical schools were included; 1,127/7,063 (16.0%) were from Foundation Year (FY) 1 doctors, who reported that the most frequently taught topics in undergraduate training were on urinary tract infection (96.5%), acute kidney injury (95.9%) and haematuria (94.4%). The most infrequently taught topics were male urinary incontinence (59.4%), male infertility (52.4%) and erectile dysfunction (43.8%). Male and female catheterisation on patients as undergraduates was performed by 92.1% and 73.0% of FY1 doctors respectively, and 16.9% had considered a career in urology. Theory based teaching was mainly prevalent in the early years of medical school, with clinical skills teaching, and clinical placements in the later years of medical school. 20.1% of FY1 doctors reported no undergraduate clinical attachment in urology. CONCLUSION: LEARN is the largest ever evaluation of undergraduate urology teaching. In the UK, teaching seemed satisfactory as evaluated by the BAUS undergraduate syllabus. However, many students report having no clinical attachments in Urology and some newly qualified doctors report never having inserted a catheter, which is a GMC mandated requirement. We recommend a greater emphasis on undergraduate clinical exposure to urology and stricter adherence to GMC mandated procedures

Excision of rare adult cervical thymic cyst

Cervical thymic cysts (CTCs) represent 1% of all cervical cystic masses. A review of the literature found that CTCs are typically asymptomatic, with a propensity to be left sided. CTCs often require histological evaluation for diagnosis. A 27-year-old male patient presented to an outpatient otolaryngology clinic with worsening bilateral jaw and neck pain and an incidental right-sided neck mass found on cervical MRI. Preoperative differential diagnosis included venolymphatic malformation versus branchial cleft cyst. Histological examination of the excised specimen provided diagnosis of a CTC. Postoperatively, the patient reported improvement in cervical pain. CTCs are a rare cause of lateral neck mass in young adults. Typical presentation included neck enlargement with no symptoms or in some cases compressive symptoms. It is important to consider CTCs when formulating a differential for a lateral neck mass