Improvement of right ventricular function with transcatheter aortic valve implantation

Background and aim. It has been demonstrated that right ventricular systolic dysfunction develops soon after surgical aortic valve replacement (s-AVR). While the impact of s-AVR or TAVI on the function of the left ventricle has been studied with various imaging modalities, little is known about the impact on right ventricular function (RVF). In the current study, we evaluated the impact of TAVI on RVF using conventional echocardiography parameters. Methods and results. Echocardiography was performed prior to 24 h, 1 month and 6 months after TAVI. RVF was assessed using (1) tricuspid annular plane systolic excursion (TAPSE); (2) RV Tissue Doppler Imaging (S’); (3) right ventricular systolic pressure (RVSP); (4) Fractional area change (FAC); and (5) RV ejection fraction (RVEF). TAVI was performed through the subclavian artery in two patients and femoral artery in 48 patients with an Edwards Sapien XT valve. TAVI was performed on 50 patients between the dates of December 2012 and June 2013. After TAVI, a statistically significant improvement was observed for all parameters related to RVF (RVSP, RVEF, TAPSE, FAC, RVTDI S’). During the 1st and 6th months this statistically significant improvement continued in TAPSE and FAC, and there was no deterioration in RVSP, RVEF, and RVTDI S during the 1st month but a statistically significant improvement continued in the 6th month. Conclusion. RVF assessed by conventional echocardiography did not deteriorate after TAVI in early and midterm follow-up. Further, TAVI provides improvement of RVF and can safely and efficiently be performed in patients with impaired RVF.     

Cytokinin signaling regulates cambial development in poplar

Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula × tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXIDASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.     

The significance of elevated troponin T in patients with nondialysis-dependent renal insufficiency: a validation with coronary angiography

BACKGROUND: Patients with elevated troponin are at high risk of adverse outcomes, future cardiac events, and are more likely to have hemodynamically significant coronary artery stenoses. Elevated troponin T (cTnT) in patients with poor renal function portends a poor prognosis; however, findings of significant coronary artery disease (CAD) by coronary angiography have not been demonstrated in patients with poor renal function and elevated cTnT. HYPOTHESIS: The purpose of this study was to correlate the angiographic findings of patients with elevated cTnT with respect to renal function in patients with nondialysis-dependent renal insufficiency. METHODS: We retrospectively identified 342 patients with elevated cTnT who underwent coronary angiography in the setting of acute coronary syndrome. Patients were divided into poor (< 40 ml/min) and normal (> 40 ml/min) renal function by measuring their glomerular filtration rate. Our primary outcome was CAD stenosis, defined as epicardial stenosis > or = 70%. Secondary outcomes were rates of contrast nephropathy, initiation of hemodialysis, revascularization, length of stay (LOS), and in-hospital mortality. RESULTS: There was no significant difference in the prevalence of CAD between patients who had positive cTnT with poor renal function versus patients with positive cTnT and normal renal function (87.1 vs. 89.7%, p = 0.54). This finding persisted after stratifying by age. Patients with impaired renal function had a higher mortality, longer LOS, and a higher rate contrast nephropathy requiring hemodialysis. CONCLUSION: The association between elevated cTnT and significant CAD stenosis does not vary with renal function.     

How do tutors intervene when conflicts on knowledge arise in tutorial groups?

Recent research on problem-based learning (PBL) has shown that students need support when dealing with conflicting ideas in PBL-tutorial discussions. In the present study, we examined tutor facilitation during tutorial discussions, and particularly how the facilitation helped students to collaboratively resolve conflicts on knowledge. The study involved four PBL-tutorial sessions that included altogether 33 first-year medical and dental students. The sessions were videotaped and analysed using qualitative interaction analysis. Our aim was to find out how the tutor interventions encouraged students to elaborate on conflicting ideas, and how the interventions differed between conflict and non-conflict situations. We also examined how the tutors intervened during conflicts about factual or conceptual knowledge. The tutorial discussions included 92 tutor intervention episodes and 43 conflict episodes. The tutors intervened during 24 of the conflict episodes and resolved 13 of these episodes. Generally, the tutors often intervened by confirming what the students had said or by giving explanations, but they rarely asked questions that would stimulate the elaboration of knowledge. During conflicts on knowledge the tutors gave more explanations, but did little to encourage the students to deal with conflicting ideas. The tutors more often resolved conflicts on factual knowledge than conceptual knowledge. The findings suggest that tutor training should focus on promoting tutors’ understanding on when to give direct explanations, and when and how to encourage students to collaboratively elaborate on conflicting ideas.     

Elderly deaths in Ankara,Turkey

According to World Health Organization, the life expectancy at birth is increasing. An increase in life expectancy might result in increased morbidity and mortality in elderly. The increase in the elderly population also leads to an increase in medico-legal problems, as well. Autopsy is of high importance for determination of cause of death in clinical and forensic cases. The purpose of this study was to find out general characteristics elderly deaths by examining forensic autopsy records.     

Left Main Coronary Artery Obstruction by Dislodged Native-Valve Calculus after Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement can be an effective, reliable treatment for severe aortic stenosis in surgically high-risk or ineligible patients. However, various sequelae like coronary artery obstruction can occur, not only in the long term, but also immediately after the procedure. We present the case of a 78-year-old woman whose left main coronary artery became obstructed with calculus 2 hours after the transfemoral implantation of an Edwards Sapien XT aortic valve. Despite percutaneous coronary intervention in that artery, the patient died. This case reminds us that early recognition of acute coronary obstruction and prompt intervention are crucial in patients with aortic stenosis who have undergone transcatheter aortic valve replacement.     

NF‐κB activation mediates LPS‐or zymosan‐induced hypotension and inflammation reversed by BAY61‐3606, a selective Syk inhibitor,in rat models of septic and non‐septic shock

We have previously demonstrated that the activation of the spleen tyrosine kinase (Syk)/inhibitory‐κB (IκB)‐α/nuclear factor‐κB (NF‐κB) p65 signalling pathway contributes to hypotension and inflammatory response in a rat models of zymosan (ZYM)‐induced non‐septic shock. The purpose of this study was to further examine the possible mechanism underlying the effect of inhibition of Syk by BAY61‐3606 via NF‐κB activity at the level of nuclear translocation regarding the production of vasodilator and proinflammatory mediators in lipopolysaccharide (LPS) (septic)‐ and ZYM (non‐septic)‐induced shock. Administration of LPS (10 mg/kg, ip) or ZYM (500 mg/kg, ip) to male Wistar rats decreased mean arterial pressure and increased heart rate that was associated with an increase in the activities of cyclooxygenase and nitric oxide synthase, tumour necrosis factor‐α, and interleukin‐8 levels, and NF‐κB activation and nuclear translocation in sera and/or cardiovascular and renal tissues. BAY61‐3606 (3 mg/kg, ip), the selective Syk inhibitor, given 1 hour after LPS‐ or ZYM injection reversed all the above‐mentioned effects. These results suggest that Syk contributes to the LPS‐ or ZYM‐induced hypotension and inflammation associated with transactivation of NF‐κB in septic and non‐septic shock.