Carnosine Prevents Apoptosis of Glomerular Cells and Podocyte Loss in STZ Diabetic Rats

Background/Aims: We identified carnosinase-1 (CN-1) as risk-factor for diabetic nephropathy (DN). Carnosine, the substrate for CN-1, supposedly is a protective factor regarding diabetic complications. In this study, we hypothesized that carnosine administration to diabetic rats might protect the kidneys from glomerular apoptosis and podocyte loss. Methods: We examined the effect of oral L-carnosine administration (1g/kg BW per day) on apoptosis, podocyte loss, oxidative stress, AGEs and hexosamine pathway in kidneys of streptozotocin-induced diabetic Wistar rats after 3 months of diabetes and treatment. Results: Hyperglycemia significantly reduced endogenous kidney carnosine levels. In parallel, podocyte numbers significantly decreased (-21% compared to non-diabetics,

Qualitative and Quantitative Imaging Evaluation of Renal Cell Carcinoma Subtypes with Grating-based X-ray Phase-contrast CT

Current clinical imaging methods face limitations in the detection and correct characterization of different subtypes of renal cell carcinoma (RCC), while these are important for therapy and prognosis. The present study evaluates the potential of grating-based X-ray phase-contrast computed tomography (gbPC-CT) for visualization and characterization of human RCC subtypes. The imaging results for 23 ex vivo formalin-fixed human kidney specimens obtained with phase-contrast CT were compared to the results of the absorption-based CT (gbCT), clinical CT and a 3T MRI and validated using histology. Regions of interest were placed on each specimen for quantitative evaluation. Qualitative and quantitative gbPC-CT imaging could significantly discriminate between normal kidney cortex (54 +/- 4 HUp) and clear cell (42 +/- 10), papillary (43 +/- 6) and chromophobe RCCs (39 +/- 7), p < 0.05 respectively. The sensitivity for detection of tumor areas was 100%, 50% and 40% for gbPC-CT, gbCT and clinical CT, respectively. RCC architecture like fibrous strands, pseudocapsules, necrosis or hyalinization was depicted clearly in gbPC-CT and was not equally well visualized in gbCT, clinical CT and MRI. The results show that gbPC-CT enables improved discrimination of normal kidney parenchyma and tumorous tissues as well as different soft-tissue components of RCCs without the use of contrast media

X-Ray Phase-Contrast Tomography of Renal Ischemia-Reperfusion Damage

Purpose: The aim of the study was to investigate microstructural changes occurring in unilateral renal ischemia-reperfusion injury in a murine animal model using synchrotron radiation. Material and Methods: The effects of renal ischemia-reperfusion were investigated in a murine animal model of unilateral ischemia. Kidney samples were harvested on day 18. Grating-Based Phase-Contrast Imaging (GB-PCI) of the paraffin-embedded kidney samples was performed at a Synchrotron Radiation Facility (beam energy of 19 keV). To obtain phase information, a two-grating Talbot interferometer was used applying the phase stepping technique. The imaging system provided an effective pixel size of 7.5 mu m. The resulting attenuation and differential phase projections were tomographically reconstructed using filtered back-projection. Semi-automated segmentation and volumetry and correlation to histopathology were performed. Results: GB-PCI provided good discrimination of the cortex, outer and inner medulla in non-ischemic control kidneys. Post-ischemic kidneys showed a reduced compartmental differentiation, particularly of the outer stripe of the outer medulla, which could not be differentiated from the inner stripe. Compared to the contralateral kidney, after ischemia a volume loss was detected, while the inner medulla mainly retained its volume (ratio 0.94). Post-ischemic kidneys exhibited severe tissue damage as evidenced by tubular atrophy and dilatation, moderate inflammatory infiltration, loss of brush borders and tubular protein cylinders. Conclusion: In conclusion GB-PCI with synchrotron radiation allows for non-destructive microstructural assessment of parenchymal kidney disease and vessel architecture. If translation to lab-based approaches generates sufficient density resolution, and with a time-optimized image analysis protocol, GB-PCI may ultimately serve as a non-invasive, non-enhanced alternative for imaging of pathological changes of the kidney

X-Ray Dark-field Imaging to Depict Acute Lung Inflammation in Mice

Abstract The aim of this study was to evaluate the feasibility of early stage imaging of acute lung inflammation in mice using grating-based X-ray dark-field imaging in vivo. Acute lung inflammation was induced in mice by orotracheal instillation of porcine pancreatic elastase. Control mice received orotracheal instillation of PBS. Mice were imaged immediately before and 1 day after the application of elastase or PBS to assess acute changes in pulmonary structure due to lung inflammation. Subsequently, 6 mice from each group were sacrificed and their lungs were lavaged and explanted for histological analysis. A further 7, 14 and 21 days later the remaining mice were imaged again. All images were acquired with a prototype grating-based small-animal scanner to generate dark-field and transmission radiographs. Lavage confirmed that mice in the experimental group had developed acute lung inflammation one day after administration of elastase. Acute lung inflammation was visible as a striking decrease in signal intensity of the pulmonary parenchyma on dark-field images at day 1. Quantitative analysis confirmed that dark-field signal intensity at day 1 was significantly lower than signal intensities measured at the remaining timepoints, confirming that acute lung inflammation can be depicted in vivo with dark-field radiography

Quantitative differentiation of minimal-fat angiomyolipomas from renal cell carcinomas using grating-based x-ray phase-contrast computed tomography: An ex vivo study.

BackgroundThe differentiation of minimal-fat-or low-fat-angiomyolipomas from other renal lesions is clinically challenging in conventional computed tomography. In this work, we have assessed the potential of grating-based x-ray phase-contrast computed tomography (GBPC-CT) for visualization and quantitative differentiation of minimal-fat angiomyolipomas (mfAMLs) and oncocytomas from renal cell carcinomas (RCCs) on ex vivo renal samples.Materials and methodsLaboratory GBPC-CT was performed at 40 kVp on 28 ex vivo kidney specimens including five angiomyolipomas with three minimal-fat (mfAMLs) and two high-fat (hfAMLs) subtypes as well as three oncocytomas and 20 RCCs with eight clear cell (ccRCCs), seven papillary (pRCCs) and five chromophobe RCC (chrRCC) subtypes. Quantitative values of conventional Hounsfield units (HU) and phase-contrast Hounsfield units (HUp) were determined and histogram analysis was performed on GBPC-CT and grating-based attenuation-contrast computed tomography (GBAC-CT) slices for each specimen. For comparison, the same specimens were imaged at a 3T magnetic resonance imaging (MRI) scanner.ResultsWe have successfully matched GBPC-CT images with clinical MRI and histology, as GBPC-CT presented with increased soft tissue contrast compared to absorption-based images. GBPC-CT images revealed a qualitative and quantitative difference between mfAML samples (58±4 HUp) and oncocytomas (44±10 HUp, p = 0.057) and RCCs (ccRCCs: 40±12 HUp, p = 0.012; pRCCs: 43±9 HUp, p = 0.017; chrRCCs: 40±7 HUp, p = 0.057) in contrast to corresponding laboratory attenuation-contrast CT and clinical MRI, although not all differences were statistically significant. Due to the heterogeneity and lower signal of oncocytomas, quantitative differentiation of the samples based on HUp or in combination with HUs was not possible.ConclusionsGBPC-CT allows quantitative differentiation of minimal-fat angiomyolipomas from pRCCs and ccRCCs in contrast to absorption-based imaging and clinical MRI

Comparison of Histological Slices of Clamped Kidney.

<p>(a) PAS histological slice of the clamped kidney. (b) HE-stained histological slice of the clamped kidney, with a similar slice of the phase-contrast volume (c). For both histology slices a respective zoom view of the inner medulla is given. Scarring and beginning tubular atrophy as well proteinaceous casts could be detected correlating with increasing medullary density in PCI.</p

Contralateral Control Kidney and Ischemic Kidney in three Different Contrast Modalities.

<p>(a), (d) Phase contrast. (b), (e) Dark-field contrast. (c), (f) Attenuation contrast. All images are scaled individually for best visual appearance. (a) Phase-contrast images of the contralateral kidney allow to differentiate the functional compartments of the kidney. (d) Phase-contrast images of I/R kidneys show considerably less variation in gray value between the different compartments. Stripes of the outer medulla cannot be distinguished. The number of visible tubular structure or voids is highly reduced. In dark-field contrast, (b) control kidneys show scattering at interfaces, which is reduced in (e) I/R kidneys. Conventional absorption-based images show considerably lower contrast and relatively higher noise in both (c) control and (f) ischemic kidney. CO – cortex; OM – outer medulla; OSOM – outer stripe outer medulla; ISOM – inner stripe outer medulla; IM – inner medulla.</p

Photograph of the Interferometer Setup at Beamline ID19, ESRF, Grenoble, France.

<p>Monochromatic, coherent X-rays travel through the sample and introduce distortions in the interference pattern created by the phase grating. Those are evaluated by a lateral movement of the phase grating located behind the sample. Photograph adapted from I. Zanette, <i>Interférometrie X à réseaux pour l'imagerie et l'analyse de front d'ondes au synchrotron</i>, PhD thesis, University of Grenoble, 2011.</p

Mean Gray Values of Kidney Compartments.

<p>Mean value and standard deviations of phase gray values of the respective compartment. Note that OSOM and cortex were assessed together in healthy kidneys and OSOM and ISOM together in I/R kidneys. OSOM – outer stripe outer medulla ISOM – inner stripe outer medulla.</p