Physikalische Modellversuche zu erodierbaren Überlaufstrecken

Aufsatz veröffentlicht in: "Wasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel, Zurich, Switzerland, September 15-17, 2021, Band 2" veröffentlicht unter: https://doi.org/10.3929/ethz-b-00049975

β2-Adaptin is constitutively de-phosphorylated by serine/threonine protein phosphatase PP2A and phosphorylated by a staurosporine-sensitive kinase

AbstractClathrin-mediated endocytosis includes cycles of assembly and disassembly of the clathrin-coated vesicle constituents. How these cycles are regulated is still not fully known but previous studies have indicated that phosphorylation of coat subunits may play a role. Here we describe that β2-adaptin undergoes cycles of phosphorylation/de-phosphorylation in intact cells. Thus, β2-adaptin was constitutively de-phosphorylated by serine/threonine protein phosphatase 2A and phosphorylated by a staurosporine-sensitive kinase in vivo. Confocal laser scanning microscopy demonstrated that phosphorylated AP2 complexes were found more evenly distributed at the plasma membrane compared to non-phosphorylated AP2 complexes which were found in aggregates. Finally, we found that phosphorylation of β2-adaptin correlated with inhibition of clathrin-mediated endocytosis. Our results support the hypothesis that phosphorylation/de-phosphorylation of coat proteins plays a regulatory role in the assembly/disassembly cycle of clathrin-coated vesicles

Senescence and quiescence in adipose-derived stromal cells:Effects of human platelet lysate, fetal bovine serum and hypoxia

AbstractBackground aims. Adipose-derived stromal cells (ASCs) are attractive sources for cell-based therapies. The hypoxic niche of ASCs in vivo implies that cells will benefit from hypoxia during in vitro expansion. Human platelet lysate (hPL) enhances ASC proliferation rates, compared with fetal bovine serum (FBS) at normoxia. However, the low proliferation rates of FBS-expanded ASCs could be signs of senescence or quiescence. We aimed to determine the effects of hypoxia and hPL on the expansion of ASCs and whether FBS-expanded ASCs are senescent or quiescent. Methods. ASCs expanded in FBS or hPL at normoxia or hypoxia until passage 7 (P7), or in FBS until P5 followed by culture in hPL until P7, were evaluated by proliferation rates, cell cycle analyses, gene expression and β-galactosidase activity. Results. hPL at normoxia and hypoxia enhanced proliferation rates and expression of cyclins, and decreased G0/G1 fractions and expression of p21 and p27, compared with FBS. The shift from FBS to hPL enhanced cyclin levels, decreased p21 and p27 levels and tended to decrease G0/G1 fractions. Conclusion. Hypoxia does not add to the effect of hPL during ASC expansion with regard to proliferation, cell cycle regulation and expression of cyclins, p21 and p27. hPL rejuvenates FBS-expanded ASCs with regard to cell cycle regulation and expression of cyclins, p21 and p27. This indicates a reversible arrest. Therefore, we conclude that ASCs expanded until P7 are not senescent regardless of culture conditions

The inflammatory biomarker YKL-40 decreases stepwise after exercise stress test

BACKGROUND: Serum YKL-40 is an inflammatory biomarker associated with disease activity and mortality in diseases characterized by inflammation such as coronary artery disease (CAD). Exercise has a positive effect on CAD, possibly mediated by a decreased inflammatory activity. This study aimed to compare serial measurements of serum YKL-40 before and after exercise in patients with stable CAD versus controls. MATERIALS AND METHODS: Eleven patients with stable CAD verified by coronary angiography (>70% stenosis) and 11 patients with a computer tomography angiography with no stenosis or calcification (calcium score=0) (controls) performed a standard clinical maximal exercise test. Serum YKL-40 was measured before exercise, immediately after exercise, and every hour for 6 h. RESULTS: Cardiovascular risk factors were more prevalent among the CAD patients compared with the controls. CAD patients had higher serum concentration of YKL-40 at baseline compared with controls, median (interquartile range) 94 (52–151) versus 57 (45–79) μg/l. Serum YKL-40 decreased stepwise after exercise, with a median decrease of 16 (13–39) μg/l for the CAD patients and 13 (10–22) μg/l for the controls from baseline to the lowest value. Thereafter, values increased again toward baseline level. Time after exercise was a significant factor for decrease in serum YKL-40 (P<0.0001), but no difference in YKL-40 decrease over time could be demonstrated between the groups (P=0.12). CONCLUSION: Serum YKL-40 is elevated in patients with documented CAD compared with controls, and it decreases stepwise after exercise in both groups, indicating an anti-inflammatory effect of exercise independent of the presence of coronary atherosclerosis

Overlap between angina without obstructive coronary artery disease and left ventricular diastolic dysfunction with preserved ejection fraction

<div><p>Background</p><p>A link between angina with no obstructive coronary artery disease (CAD) and heart failure with preserved left ventricular ejection fraction has been proposed, but evidence in support of this is lacking. In a cross-sectional study, we investigated whether left ventricular diastolic function in women with angina pectoris and no obstructive CAD differed from a reference population.</p><p>Methods</p><p>We included 956 women with angina and <50% coronary artery stenosis at invasive coronary angiography. Women with cardiovascular risk factors, but no history of chest pain or cardiac disease served as controls (n = 214). Left ventricular diastolic function was assessed by transthoracic echocardiography.</p><p>Results</p><p>The women with angina were slightly older, had higher body mass index, higher heart rate, and more had diabetes compared with controls while systolic blood pressure was lower. In age-adjusted analyses, angina patients had significantly lower E/A (Estimated difference -0.13, 95% CI: -0.17; -0.08), higher left ventricular mass index (5.73 g/m², 95% CI: 3.71; 7.75), left atrial volume index (2.34 ml/m², 95% CI: 1.23; 3.45) and E/e’ (0.68, 95% CI: 0.30; 1.05) and a larger proportion had higher estimated left ventricular filling pressure (17% versus 6%, p = 0.001). No between group differences were seen for e’ or deceleration time. After adjustment for known cardiovascular risk factors, between group differences for echocardiographic parameters remained statistically significant.</p><p>Conclusions</p><p>Patients with angina and no obstructive CAD had a more impaired left ventricular diastolic function compared with an asymptomatic reference population. This suggests some common pathophysiological pathway between the two syndromes.</p></div