Preliminary Report on Stone Breakage and Lesion Size Produced by a New Extracorporeal Electrohydraulic (Sparker Array) Discharge Device.

OBJECTIVE: To determine if an innovative extracorporeal electrohydraulic shock wave (SW) device (sparker array [SPA]) can effectively fracture artificial stones in vitro and in vivo, and if SPA treatment produces a renal lesion in our pig model of lithotripsy injury. Results of these experiments will be used to help evaluate the suitability of this device as a clinical lithotripter. MATERIALS AND METHODS: Ultracal-30 artificial stones were placed in a holder at the focus of the SPA and treated with 600 SWs (21.6 kV, 60 shocks/min). Stone fragments were collected, dried, and weighed to determine stone breakage. In vivo stone breakage entailed implanting stones into pigs. These stones were treated with 600 or 1200 SWs and the fragments were collected for analysis. Lesion analysis consisted of treating the left kidney of pigs with 1200 or 2400 SWs and quantitating the hemorrhagic lesion. RESULTS: In vitro, 71% ± 2% of each artificial stone was fractured to <2 mm in size. In vivo stone breakage averaged 63%. Renal injury analysis revealed that only 1 of 7 kidneys showed evidence of hemorrhagic injury in the treated area. CONCLUSION: The SPA consistently comminuted artificial stones demonstrating its ability to fracture stones like other lithotripters. Also, the SPA caused little to no renal injury at the settings used in this study. These findings suggest further research is warranted to determine the potential of this device as a clinical lithotripter.

Detection and Evaluation of Renal Injury in Burst Wave Lithotripsy Using Ultrasound and Magnetic Resonance Imaging.

PURPOSE: Burst wave lithotripsy (BWL) is a transcutaneous technique with potential to safely and effectively fragment renal stones. Preclinical investigations of BWL require the assessment of potential renal injury. This study evaluates the capabilities of real-time ultrasound and MRI to detect and evaluate BWL injury that was induced in porcine kidneys. MATERIALS AND METHODS: Ten kidneys from five female farm pigs were treated with either a 170 or 335 kHz BWL transducer using variable treatment parameters and monitored in real-time with ultrasound. Eight kidneys were perfusion fixed and scanned with a 3-Tesla MRI scanner (T1-weighted, T2-weighted, and susceptibility-weighted imaging), followed by processing via an established histomorphometric technique for injury quantification. In addition, two kidneys were separately evaluated for histologic characterization of injury quality. RESULTS: Observed B-mode hyperechoes on ultrasound consistent with cavitation predicted the presence of BWL-induced renal injury with a sensitivity and specificity of 100% in comparison to the histomorphometric technique. Similarly, MRI detected renal injury with a sensitivity of 90% and specificity of 100% and was able to identify the scale of lesion volumes. The injuries purposefully generated with BWL were histologically similar to those formed by shock wave lithotripsy. CONCLUSIONS: BWL-induced renal injury can be detected with a high degree of sensitivity and specificity by real-time ultrasound and post-treatment ex vivo MRI. No injury occurred in this study without cavitation detected on ultrasound. Such capabilities for injury detection and lesion volume quantification on MRI can be used for preclinical testing of BWL.

Development of a novel magnetic resonance imaging acquisition and analysis workflow for the quantification of shock wave lithotripsy-induced renal hemorrhagic injury.

The current accepted standard for quantifying shock wave lithotripsy (SWL)-induced tissue damage is based on morphometric detection of renal hemorrhage in serial tissue sections from fixed kidneys. This methodology is time and labor intensive and is tissue destructive. We have developed a non-destructive magnetic resonance imaging (MRI) method that permits rapid assessment of SWL-induced hemorrhagic lesion volumes in post-mortem kidneys using native tissue contrast to reduce cycle time. Kidneys of anesthetized pigs were targeted with shock waves using the Dornier Compact S lithotripter. Harvested kidneys were then prepared for tissue injury quantification. T1 weighted (T1W) and T2 weighted (T2W) images were acquired on a Siemens 3T Tim Trio MRI scanner. Images were co-registered, normalized, difference (T1W - T2W) images generated, and volumes classified and segmented using a Multi-Spectral Neural Network (MSNN) classifier. Kidneys were then subjected to standard morphometric analysis for the measurement of lesion volumes. Classifications of T1W, T2W and difference image volumes were correlated with morphometric measurements of whole kidney and parenchymal lesion volumes. From these relationships, a mathematical model was developed that allowed predictions of the morphological parenchymal lesion volume from MRI whole kidney lesion volumes. Predictions and morphology were highly correlated (R = 0.9691, n = 20) and described by the relationship y = 0.84x + 0.09, and highly accurate with a sum of squares difference error of 0.79%. MRI and the MSNN classifier provide a semi-automated segmentation approach, which provide a rapid and reliable means to quantify renal injury lesion volumes due to SWL.

Using 300 Pretreatment Shock Waves in a Voltage Ramping Protocol Can Significantly Reduce Tissue Injury During Extracorporeal Shock Wave Lithotripsy.

PURPOSE: Pretreating a pig kidney with 500 low-energy shock waves (SWs) before delivering a clinical dose of SWs (2000 SWs, 24 kV, 120 SWs/min) has been shown to significantly reduce the size of the hemorrhagic lesion produced in that treated kidney, compared with a protocol without pretreatment. However, since the time available for patient care is limited, we wanted to determine if fewer pretreatment SWs could be used in this protocol. As such, we tested if pretreating with 300 SWs can initiate the same reduction in renal lesion size as has been observed with 500 SWs. MATERIALS AND METHODS: Fifteen female farm pigs were placed in an unmodified Dornier HM-3 lithotripter, where the left kidney of each animal was targeted for lithotripsy treatment. The kidneys received 300 SWs at 12 kV (120 SWs/min) followed immediately by 2000 SWs at 24 kV (120 SWs/min) focused on the lower pole. These kidneys were compared with kidneys given a clinical dose of SWs with 500 SW pretreatment, and without pretreatment. Renal function was measured both before and after SW exposure, and lesion size analysis was performed to assess the volume of hemorrhagic tissue injury (% functional renal volume, FRV) created by the 300 SW pretreatment regimen. RESULTS: Glomerular filtration rate fell significantly in the 300 SW pretreatment group by 1 hour after lithotripsy treatment. For most animals, low-energy pretreatment with 300 SWs significantly reduced the size of the hemorrhagic injury (to 0.8% ± 0.4%FRV) compared with the injury produced by a typical clinical dose of SWs. CONCLUSIONS: The results suggest that 300 pretreatment SWs in a voltage ramping treatment regimen can initiate a protective response in the majority of treated kidneys and significantly reduce tissue injury in our model of lithotripsy injury.

Percutaneous Renal Access: Surgical Factors Involved in the Acute Reduction of Renal Function.

INTRODUCTION AND OBJECTIVE: Studies in patients and experimental animals have shown that percutaneous nephrolithotomy (PCNL) can acutely impair glomerular filtration and renal perfusion, but the factors contributing to this decline in renal function are unknown. The present study assessed the contribution of needle puncture of the kidney vs dilation of the needle tract to the acute decline in renal hemodynamic and tubular transport function associated with PCNL surgery. MATERIALS AND METHODS: Acute experiments were performed in three groups of anesthetized adult farm pigs: sham-percutaneous access (PERC), that is, no surgical procedure (n = 7); a single-needle stick to access the renal collecting system (n = 8); expansion of the single-needle access tract with a 30F NephroMax balloon dilator and insertion of a nephrostomy sheath (n = 10). The glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and renal extraction of para-amino hippurate (EPAH, estimates tubular organic anion transporter [OAT] activity) were assessed before and 1 to 4.5 hours after sham-PERC or PERC surgical procedures. RESULTS: Overall, GFR responses were similar in all three groups. Sham-treated PERC pigs showed no significant change in ERPF over the experimental observation period, whereas a single-needle stick to access the renal collecting system resulted in renal vasoconstriction (∼30% reduction in ERPF, p < 0.05). Dilation of the single-needle access tract to create the nephrostomy did not lead to a further decline in ERPF. PERC surgical procedure-mediated renal vasoconstriction was most evident at the 1-hour posttreatment time point. A reduction in EPAH was only observed in pig kidneys with a nephrostomy. CONCLUSIONS: Needle puncture of the kidney for percutaneous access to the renal collecting system is the major driving force for the renal vasoconstriction observed after PCNL surgery, whereas creation of the nephrostomy appears to be largely responsible for decreasing tubular OAT activity.

Intraluminal measurement of papillary duct urine pH, in vivo: a pilot study in the swine kidney.

We describe the in vivo use of an optic-chemo microsensor to measure intraluminal papillary duct urine pH in a large mammal. Fiber-optic pH microsensors have a tip diameter of 140-µm that allows insertion into papillary Bellini ducts to measure tubule urine proton concentration. Anesthetized adult pigs underwent percutaneous nephrolithotomy to access the lower pole of the urinary collecting system. A flexible nephroscope was advanced towards an upper pole papilla with the fiber-optic microsensor contained within the working channel. The microsensor was then carefully inserted into Bellini ducts to measure tubule urine pH in real time. We successfully recorded tubule urine pH values in five papillary ducts from three pigs (1 farm pig and 2 metabolic syndrome Ossabaw pigs). Our results demonstrate that optical microsensor technology can be used to measure intraluminal urine pH in real time in a living large mammal. This opens the possibility for application of this optical pH sensing technology in nephrolithiasis.

Shock wave lithotripsy does not impair renal function in a Swine model of metabolic syndrome.

PURPOSE: To determine whether shock wave lithotripsy (SWL) may be a risk factor for renal functional impairment in a swine model of metabolic syndrome (MetS). MATERIALS AND METHODS: Nine-month-old female Ossabaw pigs were fed an excess calorie atherogenic diet to induce MetS. At 15 months of age, the MetS pigs were treated with 2000 SWs or an overtreatment dose of 4000 SWs targeted at the upper pole calyx of the left kidney (24 kV at 120 SWs/min using the unmodified Dornier HM3 lithotripter; n=5-6 per treatment group). Serum creatinine (Cr) and blood urea nitrogen (BUN) levels were measured in conscious pigs before and ∼60 days after SWL to provide a qualitative assessment of how well both kidneys were filtering (glomerular filtration rate [GFR]). Bilateral renal function was assessed at ∼65 days post-SWL in anesthetized pigs with GFR and effective renal plasma flow (ERPF) quantified by the renal clearance of inulin and para-amino hippurate, respectively. RESULTS: Cr and BUN values were within normal limits before SWL and remained unchanged after lithotripsy in both the 2000 SW- and 4000 SW-treated pigs. GFR and ERPF of kidneys treated with SWL at either SW dose were similar to the contralateral nontreated kidney. Chronic histological changes in the SW-treated pole of the kidney included interstitial fibrosis, sclerotic glomeruli, and dilated and atrophic tubules. CONCLUSIONS: Our results are consistent with the view that a single SWL session does not result in renal impairment, even in the presence of MetS.

Shock wave lithotripsy targeting of the kidney and pancreas does not increase the severity of metabolic syndrome in a porcine model.

PURPOSE: We determined whether shock wave lithotripsy of the kidney of pigs with metabolic syndrome would worsen glucose tolerance or increase the risk of diabetes mellitus. MATERIALS AND METHODS: Nine-month-old female Ossabaw miniature pigs were fed a hypercaloric atherogenic diet to induce metabolic syndrome. At age 15 months the pigs were treated with 2,000 or 4,000 shock waves (24 kV at 120 shock waves per minute) using an unmodified HM3 lithotripter (Dornier MedTech, Kennesaw, Georgia). Shock waves were targeted to the left kidney upper pole calyx to model treatment that would also expose the pancreatic tail to shock waves. The intravenous glucose tolerance test was done in conscious fasting pigs before lithotripsy, and 1 and 2 months after lithotripsy with blood samples taken for glucose and insulin measurement. RESULTS: Pigs fed the hypercaloric atherogenic diet were obese, dyslipidemic, insulin resistant and glucose intolerant, consistent with metabolic syndrome. Assessments of insulin resistance, glucose tolerance and pancreatic ß cell function from fasting plasma glucose and insulin levels, and the glucose and insulin response profile to the intravenous glucose tolerance test were similar before and after lithotripsy. CONCLUSIONS: The metabolic syndrome status of pigs treated with shock wave lithotripsy was unchanged 2 months after kidney treatment with 2,000 high amplitude shock waves or overtreatment with 4,000 high amplitude shock waves. These findings do not support a single shock wave lithotripsy treatment of the kidney as a risk factor for the onset of diabetes mellitus.

Evaluation of shock wave lithotripsy injury in the pig using a narrow focal zone lithotriptor.

UNLABELLED: What's known on the subject? and What does the study add? Of all the SW lithotriptors manufactured to date, more research studies have been conducted on and more is known about the injury (both description of injury and how to manipulate injury size) produced by the Dornier HM-3 than any other machine. From this information have come suggestions for treatment protocols to reduce shock wave (SW)-induced injury for use in stone clinics. By contrast, much less is known about the injury produced by narrow-focus and high-pressure lithotriptors like the Storz Modulith SLX. In fact, a careful study looking at the morphology of the injury produced by the SLX itself is lacking, as is any study exploring ways to reduce renal injury by manipulating SW delivery variables of this lithotriptor. The present study quantitates the lesion size and describes the morphology of the injury produced by the SLX. In addition, we report that reducing the SW delivery rate, a manoeuvre known to lower injury in the HM-3, does not reduce lesion size in the SLX. OBJECTIVE: • To assess renal injury in a pig model after treatment with a clinical dose of shock waves using a narrow focal zone (≈3 mm) lithotriptor (Modulith SLX, Karl Storz Lithotripsy). MATERIALS AND METHODS: • The left kidney of anaesthetized female pigs were treated with 2000 or 4000 shock waves (SWs) at 120 SWs/min, or 2000 SWs at 60 SWs/min using the Storz SLX. • Measures of renal function (glomerular filtration rate and renal plasma flow) were collected before and 1 h after shock wave lithotripsy (SWL) and the kidneys were harvested for histological analysis and morphometric quantitation of haemorrhage in the renal parenchyma with lesion size expressed as a percentage of functional renal volume (FRV). • A fibre-optic probe hydrophone was used to determine acoustic output and map the focal width of the lithotriptor. • Data for the SLX were compared with data from a previously published study in which pigs of the same age (7-8 weeks) were treated (2000 SWs at 120 or 60 SWs/min) using an unmodified Dornier HM3 lithotriptor. RESULTS: • Treatment with the SLX produced a highly focused lesion running from cortex to medulla and often spanning the full thickness of the kidney. Unlike the diffuse interstitial haemorrhage observed with the HM3, the SLX lesion bore a blood-filled core of near-complete tissue disruption devoid of histologically recognizable kidney structure. • Despite the intensity of tissue destruction at the core of the lesion, measures of lesion size based on macroscopic determination of haemorrhage in the parenchyma were not significantly different from kidneys treated using the HM3 (2000 SWs, 120 SWs/min: SLX, 1.86 ± 0.52% FRV; HM3, 3.93 ± 1.29% FRV). • Doubling the SW dose of the SLX from 2000 to 4000 SWs did not significantly increase lesion size. In addition, slowing the firing rate of the SLX to 60 SWs/min did not reduce the size of the lesion (2.16 ± 0.96% FRV) compared with treatment at 120 SWs/min, as was the case with the HM3 (0.42 ± 0.23% FRV vs 3.93 ± 1.29% FRV). • Renal function fell significantly below baseline in all treated groups but was similar for both lithotriptors. • Focal width of the SLX (≈2.6 mm) was about one-third that of the HM3 (≈8 mm) while peak pressures were higher (SLX at power level 9: P+≈90 MPa, P-≈-12 MPa; HM3 at 24 kV: P+≈46 MPa, P-≈-8 MPa). CONCLUSIONS: • The lesion produced by the SLX (narrow focal width, high acoustic pressure) was a more focused, more intense form of tissue damage than occurs with the HM3. • Slowing the SW rate to 60 SWs/min, a strategy shown to be effective in reducing injury with the HM3, was not protective with the SLX. • These findings suggest that the focal width and acoustic output of a lithotriptor affect the renal response to SWL.

Renal functional effects of simultaneous bilateral single-tract percutaneous access in pigs.

OBJECTIVE: To present our findings of simultaneous bilateral percutaneous nephrolithotomy (sbPCNL) on bilateral renal haemodynamic and excretory function in an in vivo pig model, as despite sbPCNL being a treatment strategy for patients with bilateral renal stones, the functional response of both kidneys to such a procedure is unknown. MATERIALS AND METHODS: Nine anaesthetized female pigs ( approximately 70 kg) had a single-tract PCNL procedure in the left kidney and then the right kidney in one session (sbPCNL). Percutaneous access was achieved by a 30 F balloon dilator system. Bilateral renal function was measured before, 1.5 and 4.5 h after sbPCNL and included glomerular filtration rate (GFR), effective renal plasma flow (RPF), renal extraction of para-aminohippurate (EPAH, a measure of the efficiency of tubular organic anion transport), urine flow (UV), absolute sodium excretion (UNaV) and fractional sodium excretion (FENa). RESULTS: Both kidneys had similar baseline haemodynamic and excretory function, and showed comparable changes after sbPCNL. Bilateral GFR and RPF decreased by approximately 35% at 1.5 and 4.5 h after sbPCNL; EPAH was reduced to a similar degree in both kidneys at 1.5 h after sbPCNL and remained depressed throughout the observation period; bilateral UV and UNaV progressively decreased by approximately 30% and approximately 60% at 1.5 and 4.5 h after sbPCNL, respectively; bilateral FENa did not significantly change at 1.5 h after sbPCNL but decreased significantly by approximately 50% at 4.5 h. CONCLUSIONS: Both kidneys responded in a similar fashion after sbPCNL, with declines in haemodynamic and excretory function. These bilateral functional responses were comparable to those previously reported after unilateral PCNL, and help to reduce concerns that PCNL of both kidneys in one session could lead to greater functional complications, at least acutely.

Renal functional effects of multiple-tract percutaneous access.

INTRODUCTION: Percutaneous nephrolithotomy (PCNL) can involve establishing more than one access into the urinary collecting system. The present study examined whether multiple percutaneous accesses results in a more severe reduction in renal function than that after single-percutaneous access. METHODS: Adult female pigs were anesthetized, and percutaneous access to the left urinary collecting system was achieved by puncturing the lower pole calyx (single-tract access, n = 16) or serially puncturing the lower pole, interpolar region, and upper pole calyces [multiple (three)-tract access, n = 11]. Renal function measurements included glomerular filtration rate and effective renal plasma flow, and were taken immediately before and 1.5 and 4.5 hours after percutaneous access. We also examined glomerular function in a group of adult patients with normal preoperative serum creatinine (Cr) levels (

Protein geranylgeranyltransferase I is involved in specific aspects of abscisic acid and auxin signaling in Arabidopsis.

Arabidopsis (Arabidopsis thaliana) mutants lacking a functional ERA1 gene, which encodes the beta-subunit of protein farnesyltransferase (PFT), exhibit pleiotropic effects that establish roles for protein prenylation in abscisic acid (ABA) signaling and meristem development. Here, we report the effects of T-DNA insertion mutations in the Arabidopsis GGB gene, which encodes the beta-subunit of protein geranylgeranyltransferase type I (PGGT I). Stomatal apertures of ggb plants were smaller than those of wild-type plants at all concentrations of ABA tested, suggesting that PGGT I negatively regulates ABA signaling in guard cells. However, germination of ggb seeds in response to ABA was similar to the wild type. Lateral root formation in response to exogenous auxin was increased in ggb seedlings compared to the wild type, but no change in auxin inhibition of primary root growth was observed, suggesting that PGGT I is specifically involved in negative regulation of auxin-induced lateral root initiation. Unlike era1 mutants, ggb mutants exhibited no obvious developmental phenotypes. However, era1 ggb double mutants exhibited more severe developmental phenotypes than era1 mutants and were indistinguishable from plp mutants lacking the shared alpha-subunit of PFT and PGGT I. Furthermore, overexpression of GGB in transgenic era1 plants partially suppressed the era1 phenotype, suggesting that the relatively weak phenotype of era1 plants is due to partial redundancy between PFT and PGGT I. These results are discussed in the context of Arabidopsis proteins that are putative substrates of PGGT I.