The carboxyproxyl-derived spin trap (CP-H) is an appropriate detector-compound for oxidative stress

Hemodialysis raises oxidative stress through carbon-centered radicals despite improved biocompatibility

Leukocyte activation and the resulting oxidative stress induced by bioincompatible materials during hemodialysis impact the prognosis of patients. Despite multiple advances in hemodialysis dialyzers, the prognosis of hemodialysis patients with complications deeply related to oxidative stress, such as diabetes mellitus, remains poor. Thus, we re-evaluated the effects of hemodialysis on multiple reactive oxygen species using electron spin resonance-based methods for further improvement of biocompatibility in hemodialysis. We enrolled 31 patients in a stable condition undergoing hemodialysis using high-flux polysulfone dialyzers. The effects of hemodialysis on reactive oxygen species were evaluated by two methods: MULTIS, which evaluates serum scavenging activities against multiple hydrophilic reactive oxygen species, and i-STrap, which detects lipophilic carbon-center radicals. Similar to previous studies, we found that serum hydroxyl radical scavenging activity significantly improved after hemodialysis. Unlike previous studies, we discovered that scavenging activity against alkoxyl radical was significantly reduced after hemodialysis. Moreover, patients with diabetes mellitus showed a decrease in serum scavenging activity against alkyl peroxyl radicals and an increase in lipophilic carbon-center radicals after hemodialysis. These results suggest that despite extensive improvements in dialyzer membranes, the forms of reactive oxygen species that can be eliminated during dialysis are limited, and multiple reactive oxygen species still remain at increased levels during hemodialysis.

Usefulness of Thulium-Doped Fiber Laser and Diode Laser in Zero Ischemia Kidney Surgery-Comparative Study in Pig Model

Background: The aim of this study was to evaluate the usefulness of a thulium-doped fiber laser and a diode laser in zero ischemia kidney surgery, by carrying out a comparative study in a pig model. Material and methods: Research was carried out on 12 pigs weighing 30 kg each. A thulium-doped fiber laser (TDFL) and a diode laser (DL) operating at wavelengths of 1940 and 1470 nm, respectively, were used. The cut sites were assessed both macroscopically and microscopically. The zone of thermal damage visible in the histopathological preparations was divided into superficial and total areas. Results: During partial nephrectomy, moderate to minimal bleeding was observed, which did not require additional hemostatic measures. All animals survived the procedure. On day 0, the total thermal damage depth was 837.8 µm for the TDFL and 1175.0 µm for the DL. On day 7, the depths were 1556.2 and 2301.7 µm, respectively. On day 14, the overall thermal damage depth for the DL was the greatest (6800 µm). The width of the superficial zone was significantly reduced on days 7 and 14 after TDFL application. Conclusion: Both lasers are suitable for partial wedge nephrectomy without ischemia in pigs. The TDFL produced similar or better hemostasis than the DL, with a smaller zone of thermal damage and, therefore, seems more suitable for application in human medicine.

Non-ischemic laparoscopic partial nephrectomy using 1318-nm diode laser for small exophytic renal tumors

Purpose

Warm ischemia (WI) and bleeding constitute the main challenges for surgeons during laparoscopic partial nephrectomy (LPN). Current literature on the use of lasers for cutting and coagulation remains scarce and with small cohorts. We present the largest case series to date of non-ischemic LPN using a diode laser for small exophytic renal tumors.

Methods

We retrospectively evaluated 29 patients with clinically localized exophytic renal tumors who underwent non-ischemic laser–assisted LPN with a 1318-nm wavelength diode laser. We started applying the laser 5 mm beyond the visible tumor margin, 5 mm away from the tissue in a non-contact fashion for coagulation and in direct contact with the parenchymal tissue for cutting. 

Results

The renal vessels were not clamped, resulting in a WIT (warm ischaemic time) of 0 min, except for one case that required warm ischemia for 12 min and parenchymal sutures. No transfusion was needed, with a mean Hemoglobin drop of 1,4 mg/dl and no postoperative complications. The eGFR did not significantly change by 6 months. Histologically, the majority of lesions (n = 22/29) were renal-cell carcinoma stage pT1a. The majority of malignant lesions (n = 13/22) had a negative margin. However, margin interpretation was difficult in 9 cases due to charring of the tumor base. A mean follow-up of 1.8 years revealed no tumor recurrence. The mean tumor diameter was 19.4 mm.

Conclusion

The 1318-nm diode laser has the advantages of excellent cutting and sealing properties when applied to small vessels in the renal parenchyma, reducing the need for parenchymal sutures. However, excessive smoke, charring of the surgical margin, and inability to seal large blood vessels are encountered with this technique.

A high precision method for quantitative measurements of reactive oxygen species in frozen biopsies

OBJECTIVE

An electron paramagnetic resonance (EPR) technique using the spin probe cyclic hydroxylamine 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH) was introduced as a versatile method for high precision quantification of reactive oxygen species, including the superoxide radical in frozen biological samples such as cell suspensions, blood or biopsies.

MATERIALS AND METHODS

Loss of measurement precision and accuracy due to variations in sample size and shape were minimized by assembling the sample in a well-defined volume. Measurement was carried out at low temperature (150 K) using a nitrogen flow Dewar. The signal intensity was measured from the EPR 1st derivative amplitude, and related to a sample, 3-carboxy-proxyl (CP•) with known spin concentration.

RESULTS

The absolute spin concentration could be quantified with a precision and accuracy better than ±10 µM (k = 1). The spin concentration of samples stored at -80°C could be reproduced after 6 months of storage well within the same error estimate.

CONCLUSION

The absolute spin concentration in wet biological samples such as biopsies, water solutions and cell cultures could be quantified with higher precision and accuracy than normally achievable using common techniques such as flat cells, tissue cells and various capillary tubes. In addition; biological samples could be collected and stored for future incubation with spin probe, and also further stored up to at least six months before EPR analysis, without loss of signal intensity. This opens for the possibility to store and transport incubated biological samples with known accuracy of the spin concentration over time.

Laser-supported partial laparoscopic nephrectomy for renal cell carcinoma without ischaemia time

Background

To date, elective nephron-sparing surgery is an established method for the exstirpation of renal tumors. While open partial nephrectomy remains the reference standard of the management of renal masses, laparoscopic partial nephrectomy (LPN) continues to evolve. Conventional techniques include clamping the renal vessels risking ischaemic damage of the clamped organ. Thus, new techniques are needed that combine a sufficient tissue incision for exstirpation of the tumor with an efficient coagulation to assure haemostasis and abandon renal vessel clamping in LPN. Laser-excision of renal tumors during laparoscopic surgery seems to be a logical solution.

Methods

We performed nephron-sparing surgery without clamping of the renal vessels in 11 patients with a renal tumor in exophytic position (mean size 32 mm, ranging 8–45 mm) by laser-supported LPN.

Results

Regular ultrasound monitoring and insertion of a temporary drainage showed no evidence of postoperative hemorrhage. All tumors were removed with a histopathologically confirmed surrounding margin of normal renal tissue (R0 resection). Serum creatinine, hemoglobin, and hematocrit were nearly unaltered before and after surgery.

Conclusions

The experience won in these patients have confirmed that laser-assisted LPN without clamping of the renal vessels could be a safe and gentle alternative to classic partial nephrectomy in patients with exophytic position of renal tumors.

[Laser now also to be used in organ-preserving kidney surgery?]

Kidney surgery is subject to continuous change. Partial nephrectomy is the prevailing method for small and medium-sized tumours and proven to be superior to radical nephrectomy. The conventional technique usually includes clamping the renal vessels. The duration of the ischaemia caused determines the outcome of the remaining renal function. The shorter the ischaemic time the more likely the renal function will be preserved. Thus, new techniques are needed to abandon renal vessel clamping. Essential is a combination of good cutting abilities and assured haemostasis. To date, the commonly used techniques for cutting in partial nephrectomy only partially fulfil these requirements. Establishment of laser in urology offers a new surgical technique that combines both. In spite of the still limited data on laser use in kidney surgery, this method can be assessed favourably. Laser offers a possibility of both open and laparoscopic partial nephrectomy avoiding renal vessel clamping without additional risks or complications.