Intravital imaging of hemodynamic glomerular effects of enalapril or/and empagliflozin in STZ-diabetic mice

Background: Diabetic kidney disease is the leading cause of end-stage renal disease. Administration of ACE inhibitors or/and SGLT2 inhibitors show renoprotective effects in diabetic and other kidney diseases. The underlying renoprotective mechanisms of SGLT2 inhibition, especially in combination with ACE inhibition, are incompletely understood. We used longitudinal intravital microscopy to directly elucidate glomerular hemodynamics on a single nephron level in response to the ACE inhibitor enalapril or/and the SGLT2 inhibitor empagliflozin. Methods: Five weeks after the induction of diabetes by streptozotocin, male C57BL/6 mice were treated with enalapril, empagliflozin, enalapril/empagliflozin or placebo for 3 days. To identify hemodynamic regulation mechanisms, longitudinal intravital multiphoton microscopy was employed to measure single nephron glomerular filtration rate (snGFR) and afferent/efferent arteriole width. Results: Diabetic mice presented a significant hyperfiltration. Compared to placebo treatment, snGFR was reduced in response to enalapril, empagliflozin, or enalapril/empagliflozin administration under diabetic conditions. While enalapril treatment caused significant dilation of the efferent arteriole (12.55 ± 1.46 µm vs. control 11.92 ± 1.04 µm, p < 0.05), empagliflozin led to a decreased afferent arteriole diameter (11.19 ± 2.55 µm vs. control 12.35 ± 1.32 µm, p < 0.05) in diabetic mice. Unexpectedly under diabetic conditions, the combined treatment with enalapril/empagliflozin had no effects on both afferent and efferent arteriole diameter change. Conclusion: SGLT2 inhibition, besides ACE inhibition, is an essential hemodynamic regulator of glomerular filtration during diabetes mellitus. Nevertheless, additional mechanisms—independent from hemodynamic regulation—are involved in the nephroprotective effects especially of the combination therapy and should be further explored in future studies

A new analysis approach for single nephron GFR in intravital microscopy of mice [version 3; peer review: 2 approved, 2 not approved]

Background: Intravital microscopy is an emerging technique in life science with applications in kidney research. Longitudinal observation of (patho-)physiological processes in living mice is possible in the smallest functional unit of the kidney, a single nephron (sn). In particular, effects on glomerular filtration rate (GFR) - a key parameter of renal function - can be assessed. Methods: After intravenous injection of a freely filtered, non-resorbable, fluorescent dye in C57BL/6 mice, a time series was captured by multiphoton microsopy. Filtration was observed from the glomerular capillaries to the proximal tubule (PT) and the tubular signal intensity shift was analyzed to calculate the snGFR. Results: Previously described methods for snGFR analysis relied on two manually defined measurement points in the PT and the tubular volume was merely estimated in 2D images. We present an extended image processing workflow by adding continuous measurement of intensity along the PT in every frame of the time series using ImageJ. Automatic modelling of actual PT volume in a 3D dataset replaced 2D volume estimation. Subsequent data analysis in R, with a calculation of intensity shifts in every frame and normalization against tubular volume, allowed exact assessment of snGFR by linear regression. Repeated analysis of image data obtained in healthy mice showed a striking increase of reproducibility by reduction of user interaction. Conclusions: These improvements in image processing and data analysis maximize the reliability of a sophisticated intravital microscopy technique for the precise assessment of snGFR, a highly relevant predictor of kidney function

Mentalitätengeschichte

Kessel M. Mentalitätengeschichte. In: Cornelißen C, Budde G-F, eds. Geschichtswissenschaften : Eine Einführung. Frankfurt a.M.: Fischer-Taschenbuch-Verlag; 2000: 235-246

A quantitative 3D intravital look at the juxtaglomerular renin-cell-niche reveals an individual intra/extraglomerular feedback system

The juxtaglomerular niche occupied by renin cells (RCN) plays an important role in glomerular repair but the precise temporal and spatial interrelations remain unclear. This study proposes the hypothesis of a local intra-extraglomerular regenerative feedback system and establishes a new quantifiable system for RCN responses in individual glomeruli in vivo. A strictly intraglomerular twophoton laser-induced injury model was established. Labeled renin cells (RC) in transgenic renin reporter mice were fate-traced in healthy and injured glomeruli over several days by intravital microscopy and quantified via new three-dimensional image processing algorithms based on ray tracing. RC in healthy glomeruli demonstrated dynamic extraglomerular protrusions. Upon intraglomerular injury the corresponding RCN first increased in volume and then increased in area of dynamic migration up to threefold compared to their RCN. RC started migration reaching the site of injury within 3 hours and acquired a mesangial cell phenotype without losing physical RCN-contact. During intraglomerular repair only the corresponding RCN responded via stimulated neogenesis, a process of de novo differentiation of RC to replenish the RCN. Repeated continuous intravital microscopy provides a state-of-the-art tool to prove and further study the local intraglomerular RCN repair feedback system in individual glomeruli in vivo in a quantifiable manner

A trend towards a more intense adjuvant treatment of low-grade-gliomas in tertiary centers in Germany after RTOG 9802 – results from a multi-center survey

Abstract Background The treatment recommendations for Low-grade Gliomas (LGG) underwent profound changes due to results from RTOG 9802 published in April 2016. This work aims to investigate whether the results from the trial were already incorporated into the treatment recommendations at German oncology centers before an update of the official guidelines. Methods An online based questionnaire with questions covering all aspects of adjuvant treatments of LGGs was generated, including three cases with distinct clinical situations. We contacted all members of the neuro-oncologic working group (NOA) of the German Cancer Society (DKG) as well as all German-speaking members of the European Low-Grade Glioma Network via E-mail. Results We collected 38 responses. All responders were at least specialists; they predominantly worked at tertiary hospitals with a high volume of LGGs treated annually (75% with more than 10 cases per year). All responders stated to consent treatment recommendation for LGGs within interdisciplinary oncologic boards. The treatment recommendations for LGGs changed profoundly between 2015 and 12/2016. There is a trend towards PCV-based multimodal treatments, especially for oligodendroglial LGGs, as well as a trend away from watchful-waiting-policies for astrocytic LGGs. Conclusion Neurooncologists do adapt results from clinical trials quickly. None the less, there is still an immense heterogeneity within the treatment recommendations, predominantly for astrocytic LGGs. Well planned clinical trials and concise treatment recommendations are warranted; additionally, individual counseling of patients is essential

Correction: Cytosolic Hsp70 as a biomarker to predict clinical outcome in patients with glioblastoma.

[This corrects the article DOI: 10.1371/journal.pone.0221502.]