Transcription termination factor Rho prefers catalytically active elongation complexes for releasing RNA

RNA polymerase pauses at different DNA sequences during transcription elongation, and this pausing is associated with distinct conformational state(s) of the Elongation Complex (EC). Transcription termination by the termination factor Rho, an RNA-dependent molecular motor, requires pausing of the EC in the termination zone of Rho-dependent terminators. We hypothesized that the conformational state(s) of the EC associated with this pausing would influence the action of Rho. Analyses of the pausing behavior of the EC at the termination points of two well known Rho-dependent terminators revealed that Rho prefers actively transcribing complexes for termination. RNA release kinetics from stalled ECs showed that the rate of RNA release by Rho was reduced if the EC was irreversibly backtracked, if its RNA exit channel was modified by an RNA hairpin, or the bridge helix/trigger loop movement in its active site was perturbed. These defects were overcome significantly by enhancing the rate of ATP hydrolysis either by increasing the concentration of ATP or by using a Rho mutant with higher ATPase activity. We propose that the force generated from ATP hydrolysis of Rho is the key factor in dislodging the EC through its molecular motor action, and this process is facilitated when the EC is in a catalytically competent state, undergoing rapid “Brownian ratchet” motion

Transoesophageal Echocardiographic - Defined Valvular Strands in Acute Ischaemic Stroke: A Prospective Study

Background: Transoesophageal echocardiographic (TOE)-defined mobile, thread-like valvular strands (VS) have been associated with acute ischaemic stroke (AIS). The relationship between VS as a possible embolic substrate and the risk of recurrent stroke remains unclear. Our primary aims were to measure the prevalence of VS and explore their association with AIS in a case-control study and then, compare the risk of subsequent poor vascular outcome (vascular events and vascular death) in the stroke cohort patients with or without VS in a follow-up study. Our secondary aims were to determine the relationship of VS to other potential cardiac sources of emboli in TOE, relationship of VS to diastolic dysfunction in stroke cohort on comparison with controls. In addition, we sought to evaluate the relationship of VS to ischaemic stroke subtype and infarct topography on neuroimaging, and also to determine the relationship of hypercoagulable states in young patients with VS in the stroke cohort. Methods: In the case-control study, the prevalence of VS was estimated from patients consecutively admitted with AIS and from patients underwent TOE for cardiac conditions (those with infective endocarditis and stroke were excluded) in our institution over a two year period. In the follow-up study, patients with AIS were followed to evaluate the risk of poor vascular outcome, including risk of recurrent stroke. Results: We recruited 170 patients with AIS and of those, 78 underwent TOE. In our case-control study, we found TOE-defmed VS in approximately half of the patients with AIS (38/78, 48.7%) compared to one-third of controls (29/89, 32.6%). VS were more commonly seen in stroke patients over the age of 60 years (21/34, 61.8%). Univariate analysis found an association between the presence of VS and risk of AIS (OR = 3.85 ,p = 0.05), but multivariate analysis reduced the strength of the association (OR = 2.15,p= 0.06). In stroke subtypes, high prevalence of VS was seen in cardioembolic stroke but it did not reach statistical significance (p = 0.52) and there was no increased frequency of VS in cryptogenic stroke subtype. Diastolic dysfunction was seen in 78.9 % of cases with VS and there was a strong association between diastolic dysfunction and VS in the case-control study (OR 7.75,/) = 0.005). There was no statistically significant association between infarct location (cortical, subcortical, brainstem or cerebellar) in neuroimaging and the presence of VS. There were only few young cases with abnormalities in laboratory testing for hypercoagulable conditions. The risk of recurrent stroke and survival without poor vascular outcome was not statistically different between cases with or without VS in our study (OR = 1.45, 95 % Cl 0.30 - 6.96,p = 0.64). Conclusion: We were able to demonstrate an association between valvular strands and acute ischaemic stroke in our case-control study, however, the strength of the association was reduced after multivariate analysis. We did not find any increased risk of poor vascular outcome or increased recurrent stroke risk in cases with or without VS. Our findings do not support the embolic potential of valvular strands and it may not be a risk factor for stroke

All Sugars Ain’t Sweet: Selection of Particular Mono-, Di- and Trisaccharides by Western Carpenter Ants and European Fire Ants

Ants select sustained carbohydrate resources, such as aphid honeydew, based on many factors including sugar type, volume and concentration. We tested the hypotheses (H1– H3) that western carpenter ants, Camponotus modoc, seek honeydew excretions from Cinara splendens aphids based solely on the presence of sugar constituents (H1), prefer sugar solutions containing aphid-specific sugars (H2) and preferentially seek sugar solutions with higher sugar content (H3). We further tested the hypothesis (H4) that workers of both Ca. modoc and European fire ants, Myrmica rubra, selectively consume particular mono-, di- and trisaccharides. In choice bioassays with entire ant colonies, sugar constituents in honeydew (but not aphid-specific sugar) as well as sugar concentration affected foraging decisions by Ca. modoc. Both Ca. modoc and M. rubra foragers preferred fructose to other monosaccharides (xylose, glucose) and sucrose to other disaccharides (maltose, melibiose, trehalose). Conversely, when offered a choice between the aphid-specific trisaccharides raffinose and melezitose, Ca. modoc and M. rubra favoured raffinose and melezitose, respectively. Testing the favourite mono-, di- and trisaccharide head-to-head, both ant species favoured sucrose. While both sugar type and sugar concentration are the ultimate cause for consumption by foraging ants, strong recruitment of nest-mates to superior sources is probably the major proximate cause

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

4D-Printed Tool for Compressing a Shape Memory Polyurethane Foam during Programming

Although several force application concepts are known that can be used to deform shape memory polymers (SMPs) within the scope of programming, controlled deformation is challenging in the case of samples with a cylinder-like shape, which need to be homogeneously compressed starting from the lateral surface. To solve this problem, this contribution follows a material approach that takes advantage of four-dimensional (4D) printing. Fused filament fabrication (FFF) was used as an additive manufacturing (AM) technique to produce a thermoresponsive tool in a cylindrical shape from a polyether urethane (PEU) having a glass transition temperature (Tg) close to 55 °C, as determined by differential scanning calorimetry (DSC). Once it was 4D-printed, a sample of laser cut polyester urethane urea (PEUU) foam with a cylindrical wall was placed inside of it. Subsequent heating to 75 °C and keeping that temperature constant for 15 min resulted in the compression of the foam, because the internal stresses of the PEU were transferred to the PEUU, whose soft segments were completely molten at 65 °C as verified by DSC. Upon cooling to −15 °C and thus below the offset temperature of the soft segment crystallization transition of the PEUU, the foam was fixed in its new shape. After 900 days of storage at temperatures close to 23 °C, the foam recovered its original shape upon reheating to 75 °C. In another experiment, a 4D-printed cylinder was put into hibernation for 900 days before its thermoresponsiveness was investigated. In the future, 4D-printed tools may be produced in many geometries, which fit well to the shapes of the SMPs to be programmed. Beyond programming SMP foams, transferring the forces released by 4D-printed tools to other programmable materials can further expand technical possibilities

Invasive Aspergillosis and Candidiasis in a Patient with Supraglottic Carcinoma undergoing Chemoradiotherapy: A Case Report

The incidence of Invasive Aspergillosis (IA) is increasing. Early diagnosis and treatment are very important to improve patient survival, especially in immunocompromised patients. The diagnosis of IA is challenging as clinical indicators are limited, and early microbiological confirmation of the infection is infrequent. Here, the authors present the case of a 43-year-old male who was undergoing radiotherapy along with concurrent chemotherapy for carcinoma supraglottis. He developed Invasive Pulmonary Aspergillosis (IPA) along with candidiasis within two weeks of therapy. Voriconazole remains the recommended therapy for patients with IA, which also acts against fluconazole-resistant Candida species