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In this study, the viscoelastic properties of porcine kidney in the upper, middle and lower poles were investigated using oscillatory shear tests. The viscoelastic properties were extracted in the form of the storage modulus and loss modulus in the frequency and time domain. Measurements were taken as a function of frequency from 0.1 Hz to 6.5 Hz at a shear strain amplitude of 0.01 and as function of strain amplitude from 0.001 to 0.1 at a frequency of 1 Hz. Measurements were also taken in the time domain in response to a step shear strain. Both the frequency and time domain data were fitted to a conventional Standard Linear Solid (SLS) model and a semi-fractional Kelvin–Voigt (SFKV) model with a comparable number of parameters. The SFKV model fitted the frequency and time domain data with a correlation coefficient of 0.99. Although the SLS model well fitted the time domain data and the storage modulus data in the frequency domain, it was not able to capture the variation in loss modulus with frequency with a correlation coefficient of 0.53. A five parameter Maxwell–Wiechert model was able to capture the frequency dependence in storage modulus and loss modulus better than the SLS model with a correlation of 0.85. [ABSTRACT FROM AUTHOR]

In this study, the viscoelastic properties of porcine kidney in the upper, middle and lower poles were investigated using oscillatory shear tests. The viscoelastic properties were extracted in the form of the storage modulus and loss modulus in the frequency and time domain. Measurements were taken as a function of frequency from 0.1 Hz to 6.5 Hz at a shear strain amplitude of 0.01 and as function of strain amplitude from 0.001 to 0.1 at a frequency of 1 Hz. Measurements were also taken in the time domain in response to a step shear strain. Both the frequency and time domain data were fitted to a conventional Standard Linear Solid (SLS) model and a semi-fractional Kelvin–Voigt (SFKV) model with a comparable number of parameters. The SFKV model fitted the frequency and time domain data with a correlation coefficient of 0.99. Although the SLS model well fitted the time domain data and the storage modulus data in the frequency domain, it was not able to capture the variation in loss modulus with frequency with a correlation coefficient of 0.53. A five parameter Maxwell–Wiechert model was able to capture the frequency dependence in storage modulus and loss modulus better than the SLS model with a correlation of 0.85.

Introduction: Ureteral access sheath (UAS) and irrigation are used in flexible ureteroscopy (fURS). Both conventional UAS (cUAS) and vacuum-assisted UAS (vaUAS) are currently available. Irrigation increases the intrarenal pressure (IRP). Our objectives were to study the effects of various irrigation rates on IRP using different sizes of fURS in different sizes and functions of UAS. Materials and methods: Ten freshly harvested porcine kidneys served as the study subjects. 11/13F and 12/14F cUAS and vaUAS with 2.8 mm and 3.2 mm fURS were experimented on in various scope/sheath combinations. 6F pressure monitor catheters were placed into upper, middle, and lower calyces. IRPs were recorded under different irrigation rates in cUAS and vaUAS, with either 150 or 300 mmHg aspiration pressures, and with air vent either open or closed. Results: 12/14F cUAS with 2.8 mm fURS could maintain IRPs below 35 mmHg with irrigation rates up to 200 cc/min. With 3.2 mm fURS, the rate dropped to 110–120 cc/min. With 12/14F vaUAS and vent closed, the IRP remained less than 5 mmHg at 200 cc/min irrigation for both fURS. For 11/13F cUAS, the < 35 mmHg threshold for 2.8 mm fURS was 80–90 cc/min; for 3.2 mm fURS, it was 30–40 cc/min. For 11/13F vaUAS with vent closed, IRPs remained < 5 mmHg at 200 cc/min irrigation for both scopes. Conclusion: Both 12F cUAS and vaUAS can be used safely with 2.8 mm fURS up to 200 cc/min irrigation. With either a smaller sheath or a larger scope, vaUAS with vent closed can maintain IRP in a safe range up 200 cc/min irrigation. vaUAS with vent open performed marginally better than cUAS. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to prove the vacuum-assisted ureteral access sheath (vaUAS) is more effective in maintaining a lower IRP than conventional ureteral access sheath (cUAS). Materials: The model consisted of 12 freshly harvested adult porcine kidneys. Methods: Either a 12/14F cUAS or vaUAS was alternately inserted into the ureter to one cm below the renal pelvis. Upper, middle, and lower calyces were punctured, and 6F pressure monitor catheters were introduced. IRP with cUAS was monitored using various irrigation rates. IRP with vaUAS was monitored with the same irrigation rates; various aspiration pressures; and vent fully closed, 50% closed, and fully open. Results: cUAS with irrigation rate of 50 cc/min resulted in IRP < 30 mmHg. 50 to 100 cc/min should be used with caution. When irrigation rate exceeded 100 cc/min, IRP rose to ≥ 30 mmHg in most instances. With vent closed, vaUAS with vacuum pressure ≥ 150 mmHg and irrigation rate of 50 cc, 100 cc, and 150 cc/min generally resulted in IRPs < 5 mmHg. With vent half closed, vaUAS with vacuum pressure ≥ 300 mmHg and irrigation rate of ≤ 100 cc/min avoided IRP > 30 mmHg. vaUAS with vent open showed limited advantages over cUAS. Conclusion: vaUAS maintains lower IRP than cUAS under same parameters. Both vaUAS and cUAS can be used when irrigation is ≤ 50 cc/min vaUAS showed clear advantages over cUAS in maintaining lower pressure when irrigation rate is ≥ 100 cc/min. [ABSTRACT FROM AUTHOR]

Background: Xenotransplantation of genetically engineered porcine organs has the potential to address the challenge of organ donor shortage. Two cases of porcine-to-human kidney xenotransplantation were performed, yet the physiological effects on the xenografts and the recipients' immune responses remain largely uncharacterized., Methods: We performed single-cell RNA sequencing (scRNA-seq) and longitudinal RNA-seq analyses of the porcine kidneys to dissect xenotransplantation-associated cellular dynamics and xenograft-recipient interactions. We additionally performed longitudinal scRNA-seq of the peripheral blood mononuclear cells (PBMCs) to detect recipient immune responses across time., Findings: Although no hyperacute rejection signals were detected, scRNA-seq analyses of the xenografts found evidence of endothelial cell and immune response activation, indicating early signs of antibody-mediated rejection. Tracing the cells' species origin, we found human immune cell infiltration in both xenografts. Human transcripts in the longitudinal bulk RNA-seq revealed that human immune cell infiltration and the activation of interferon-gamma-induced chemokine expression occurred by 12 and 48 h post-xenotransplantation, respectively. Concordantly, longitudinal scRNA-seq of PBMCs also revealed two phases of the recipients' immune responses at 12 and 48-53 h. Lastly, we observed global expression signatures of xenotransplantation-associated kidney tissue damage in the xenografts. Surprisingly, we detected a rapid increase of proliferative cells in both xenografts, indicating the activation of the porcine tissue repair program., Conclusions: Longitudinal and single-cell transcriptomic analyses of porcine kidneys and the recipient's PBMCs revealed time-resolved cellular dynamics of xenograft-recipient interactions during xenotransplantation. These cues can be leveraged for designing gene edits and immunosuppression regimens to optimize xenotransplantation outcomes., Funding: This work was supported by NIH RM1HG009491 and DP5OD033430., Competing Interests: Declaration of interests J.D.B. is a founder and director of CDI Labs, Inc.; a founder of and consultant to Opentrons LabWorks/Neochromosome, Inc.; and serves or served on the scientific advisory boards of the following: CZ Biohub New York, LLC; Logomix, Inc.; Modern Meadow, Inc.; Rome Therapeutics, Inc.; Sangamo, Inc.; Tessera Therapeutics, Inc.; and the Wyss Institute. R.A.M. is on scientific advisory boards for eGenesis, Sanofi, Regeneron, CareDx, and Hansa Biopharma; is a consultant to Recombinetics; reports consulting fees from Hansa Medical, Regeneron, Thermo Fisher Scientific, Genentech, CareDx, One Lambda, ITB Med, Sanofi, and PPD Development; and reports grant support from Hansa Biopharma, all unrelated to the present work. R.A.M. also reports grant support from United Therapeutics Corporation, PBC. All other authors have no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the impact of the fiber–tissue distance on histological parameters in a porcine kidney model. Methods: Four lasers were tested at 60 W using a 600-µm bare-ended fiber: a continuous wave (cw) thulium fiber laser (TFL), a super pulsed (SP) TFL, a Ho:YAG laser, and a blue diode laser (BDL). All tissue samples were mounted on a motorized XY-translation stage. The fiber–tissue distance was changed within a range from 0to 6 mm. Ten incisions were made with each laser at each distance. Afterwards, the tissue samples were sliced with a microtome for lactate dehydrogenase staining to determine zones of thermal damage. Results: In contact mode, the largest incision depth was found for the cw TFL (1.7 ± 0.1 mm) compared to the SP TFL (1.0 ± 0.1 mm), BDL (0.9 ± 0.1 mm) and HoYAG laser (1.1 ± 0.1 mm), respectively. With regard to the coagulative properties, the SP TFL and the Ho:YAG laser showed comparable coagulation depths with 0.7 ± 0.1 and 0.6 ± 0.1 mm, respectively. At 2 mm fiber–tissue distance, the Ho:YAG laser was the only laser that vaporized tissue (incision depth: 0.2 ± 0.1 mm). The BDL was the only laser that caused coagulation at a distance of 3–5 mm. Conclusion: Our results support the clinical observation that cw TFL must be defocused for best coagulation, while the coagulation depth of the SP TFL remains nearly constant within the range of 0–3 mm. Increasing the distance of the laser fiber to the tissue up to 5 mm did not cause significant differences with regard to coagulation depth using the BDL. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the ablation capacity using two Thulium fiber lasers (TFL) in a porcine kidney model. Methods: All tissue samples were mounted on a motorized stage for a precise speed of cutting. A continuous wave (cw) TFL and a super pulsed (SP) TFL were used at power settings of 60 and 120 W with 200 and 600 µm laser fibers. After lactate dehydrogenase staining, histological evaluation was performed to measure the vaporization volume (VV), ablation depth (AD), thermo-mechanical damage zones (TMZ), coagulation zones (CZ) and the carbonization grade (CG). Results: At 120 W, no significant differences were seen between 200 and 600 µm fibers utilizing the cw TFL regarding VV (24.6 vs. 28.2 mm3/s), AD (5.6 vs. 5.7 mm), TMZ (0 vs. 0 mm2) and CZ (18.1 vs. 12.3 mm2). Using the SP TFL, no significant differences between both fiber diameters with regard to VV (4 vs. 6.2 mm3/s), AD (2.7 vs. 3.4 mm), TMZ (1 vs. 2.6 mm2) and CZ (3.1 vs. 2.2 mm2) at 120 W were found, respectively. However, the VV of the cw TFL at 60 W was significantly less compared to 120 W using 200 and 600 µm fibers, respectively, whereas the SP TFL did not show significant differences between 60 and 120 W with regard to VV. SP TFL showed a consistently lower CG compared to cw TFL. Conclusions: This experiment suggests that there is no significant difference using 200 or 600 µm laser fibers in cw or SP TFLs. However, the cw TFL produces a coagulation zone three to five times larger than the SP TFL regardless of the fiber diameter. [ABSTRACT FROM AUTHOR]

Intestinal diamine oxidase (DAO) acts as a protective barrier against exogenous histamine. A deficit of DAO activity can lead to the appearance of histamine intolerance, a clinical condition that may be treated by a low-histamine diet and oral DAO supplementation to enhance intestinal histamine degradation. As sources of DAO, porcine kidneys and certain legume seedlings are suitable components for the formulation of a DAO supplement. The aim of this work was to develop a rapid and reliable methodology for the in vitro determination of DAO activity in food matrices based on an enzymatic assay coupled to UHPLC-FL. The proposed method showed a satisfactory linearity and sensitivity and provided a relative standard deviation lower than 3%, guaranteeing method precision, and a mean recovery greater than 99% both for lyophilized pea sprouts and porcine kidney protein extracts. A high specificity is a key attribute of this method due to the use of histamine as the reaction substrate and the direct quantification of its degradation. Moreover, the lack of interference of catalase and hydrogen peroxide is another advantage in comparison with previously published methods. Lyophilized pea sprouts showed the greatest histamine-degrading activity (0.40 ± 0.01 mU/mg), followed by porcine kidney protein extracts (0.23 ± 0.01 mU/mg) and commercial DAO supplements (0.09 ± 0.06 mU/mg). This technique could be used as a tool to validate the DAO activity of food matrices of potential interest for the treatment of histamine intolerance. [ABSTRACT FROM AUTHOR]

Shiga toxin (Stx) producing Escherichia coli (STEC) cause the edema disease in pigs by releasing the swine-pathogenic Stx2e subtype as the key virulence factor. Stx2e targets endothelial cells of animal organs including the kidney harboring the Stx receptor glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer, Galα1-4Galβ1-4Glcβ1-1Cer) and globotetraosylceramide (Gb4Cer, GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer). Since the involvement of renal epithelial cells in the edema disease is unknown, in this study, we analyzed the porcine kidney epithelial cell lines, LLC-PK1 and PK-15, regarding the presence of Stx-binding GSLs, their sensitivity towards Stx2e, and the inhibitory potential of Gb3- and Gb4-neoglycolipids, carrying phosphatidylethanolamine (PE) as the lipid anchor, towards Stx2e. Immunochemical and mass spectrometric analysis revealed various Gb3Cer and Gb4Cer lipoforms as the dominant Stx-binding GSLs in both LLC-PK1 and PK-15 cells. A dihexosylceramide with proposed Galα1-4Gal-sequence (Gal2Cer) was detected in PK-15 cells, whereas LLC-PK1 cells lacked this compound. Both cell lines were susceptible towards Stx2e with LLC-PK1 representing an extremely Stx2e-sensitive cell line. Gb3-PE and Gb4-PE applied as glycovesicles significantly reduced the cytotoxic activity of Stx2e towards LLC-PK1 cells, whereas only Gb4-PE exhibited some protection against Stx2e for PK-15 cells. This is the first report identifying Stx2e receptors of porcine kidney epithelial cells and providing first data on their Stx2e-mediated damage suggesting possible involvement in the edema disease.

Background/Aim: The global shortage of donor organs for transplantation has necessitated the expansion of the organ pool through increased use of organs from less ideal donors. Venous systemic oxygen persufflation (VSOP) and oxygenated machine perfusion (OMP) have previously demonstrated beneficial results compared to cold storage (CS) in the preservation of warm-ischemia-damaged kidney grafts. The aim of this study was to compare the efficacy of VSOP and OMP for the preservation of warm-ischemia-damaged porcine kidneys using the recently introduced Ecosol preservation solution compared to CS using Ecosol or histidinetryptophan- ketoglutarate solution (HTK). Materials and Methods: Kidneys from German Landrace pigs (n = 5/group) were retrieved and washed out with either Ecosol or HTK after 45 min of clamping of the renal pedicle. As controls, kidneys without warm ischemia, cold stored for 24 h in HTK, were employed. Following 24 h of preservation by VSOP, OMP, CS-Ecosol, or CS-HTK, renal function and damage were assessed during 1 h using the isolated perfused porcine kidney model. Results: During reperfusion, urine production was significantly higher in the VSOP and OMP groups than in the CS-HTK group; however, only VSOP could demonstrate lower urine protein concentrations and fractional excretion of sodium, which did not differ from the non-warm-ischemia-damaged control group. VSOP, CS-Ecosol, and controls showed better maintenance of the acid-base balance than CS-HTK. Reduced lipid peroxidation, as reflected in postreperfusion tissue thiobarbituric acid-reactive substance levels, was observed in the VSOP group compared to the OMP group, and the VSOP and CS-Ecosol groups had concentrations similar to the controls. The ratio of reduced to oxidized glutathione was higher in the VSOP, OMP, and CS-Ecosol groups than in the CS-HTK group and controls, with a higher ratio in the VSOP than in the OMP group. Conclusion: VSOP was associated with mitigation of oxidative stress in comparison to OMP and CS. Preservation of warm-ischemia-damaged porcine kidneys by VSOP was improved compared to OMP and CS, and was comparable to preservation of non-warm-ischemia-damaged cold-stored kidneys. [ABSTRACT FROM AUTHOR]

Background: To evaluate the feasibility of flexible ureteroscopy training by using isolated porcine kidneys and ureters in vitro. Methods: Twenty young urologists were randomly divided into four groups. Overall performance was assessed based on a global rating scale, pass/fail rating, total time to complete task, learning curve, incidence of trauma, and perforations. The effect of training was determined by comparing their performance in baseline with that in the post-test. Results: After the training, average operation time significantly decreased from 18 ± 3.4 min to 11 ± 1.2 min (P< 0.05). The urologists exhibited a relatively stable performance level after the sixth operation. Significant differences were observed between pre-test and post-test with respect to the global rating scale and the pass/fail rating (P < 0.05). However, the incidence of mucosal trauma and perforations did not change significantly (P = 0.26 and 0.35, respectively). Conclusions: The isolated porcine kidneys are convenient and intuitive models for young urologists to practice flexible ureteroscopy on. [ABSTRACT FROM AUTHOR]

Background: The isolated perfused porcine kidney (IPPK) model has been the method of choice for the early preclinical evaluation of kidney graft preservation techniques. The preferred reperfusion conditions have not yet been determined. Here, we examined the effects of pressure- or flow-controlled perfusion and oxygenation by pure oxygen or carbogen (95% O2/5% CO2) on normothermic reperfusion in the IPPK model. Methods: Porcine kidneys were cold-stored for 24 h in histidine-tryptophan-ketoglutarate solution and reperfused for 1 h with normothermic whole blood/Krebs-Henseleit buffer medium (20/80%). Kidneys (n = 5/group) were flow-controlled reperfused with pure oxygen (1 ml/min/g; Flow-O2) or pressure-controlled reperfused (85 mm Hg mean arterial pressure) and oxygenated with either pure oxygen (Pressure-O2) or carbogen (Pressure-O2/CO2). Renal function and damage were assessed during reperfusion and NGAL and HIF-1α levels were analyzed using an ELISA. Results: Pressure-O2 and Pressure-O2/CO2 were associated with significantly better renal hemodynamics and acid-base homeostasis compared to Flow-O2. Urine protein concentrations and the fractional excretion of sodium were lower with both Pressure-O2 and Pressure-O2/CO2 than with Flow-O2. NGAL and HIF-1α levels were also lower with Pressure-O2 and Pressure-O2/CO2 than with Flow-O2. Only Pressure-O2/CO2 could demonstrate a significantly increased urine production compared to Flow-O2. The structural integrity was well preserved in the Pressure-O2 and Pressure-O2/CO2 groups, whereas diffuse and global glomerular destruction was observed in the Flow-O2 group. Conclusion: In the IPPK model, the application of pressure-controlled reperfusion with carbogen oxygenation, and to a lesser extent with pure oxygen, maintained physiological renal function for 1 h, thus providing a reliable and reproducible ex vivo evaluation of kidney preservation quality. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]