A scanning Kelvin probe for synchrotron investigations: the in situ detection of radiation-induced potential changes.

A wide range of high-performance X-ray surface/interface characterization techniques are implemented nowadays at every synchrotron radiation source. However, these techniques are not always `non-destructive' because possible beam-induced electronic or structural changes may occur during X-ray irradiation. As these changes may be at least partially reversible, an in situ technique is required for assessing their extent. Here the integration of a scanning Kelvin probe (SKP) set-up with a synchrotron hard X-ray interface scattering instrument for the in situ detection of work function variations resulting from X-ray irradiation is reported. First results, obtained on bare sapphire and sapphire covered by a room-temperature ionic liquid, are presented. In both cases a potential change was detected, which decayed and vanished after switching off the X-ray beam. This demonstrates the usefulness of a SKP for in situ monitoring of surface/interface potentials during X-ray materials characterization experiments.

Integrated scanning Kelvin probe-scanning electrochemical microscope system: development and first applications.

The integration of a scanning Kelvin probe (SKP) and a scanning electrochemical microscope (SECM) into a single SKP-SECM setup, the concept of the proposed system, its technical realization, and first applications are presented and discussed in detail. A preloaded piezo actuator placed in a grounded stainless steel case was used as the driving mechanism for oscillation of a Pt disk electrode as conventionally used in SECM when the system was operated in the SKP mode. Thus, the same tip is recording the contact potential difference (CPD) during SKP scanning and is used as a working electrode for SECM imaging in the redox-competition mode (RC-SECM). The detection of the local CPD is established by amplification of the displacement current at an ultralow noise operational amplifier and its compensation by application of a variable backing potential (V(b)) in the external circuit. The control of the tip-to-sample distance is performed by applying an additional alternating voltage with a much lower frequency than the oscillation frequency of the Kelvin probe. The main advantage of the SKP-SECM system is that it allows constant distance measurements of the CPD in air under ambient conditions and in the redox-competition mode of the SECM in the electrolyte of choice over the same sample area without replacement of the sample or exchange of the working electrode. The performance of the system was evaluated using a test sample made by sputtering thin Pt and W films on an oxidized silicon wafer. The obtained values of the CPD correlate well with known data, and the electrochemical activity for oxygen reduction is as expected higher over Pt than W.

An in situ tensile tester for studying electrochemical repassivation behavior: fabrication and challenges.

An in situ tensile rig is proposed, which allows performing electrochemical (repassivation) experiments during dynamic mechanical testing of wires. Utilizing the basic components of a conventional tensile tester, a custom-made minitensile rig was designed and fabricated. The maximal force that can be measured by the force sensor is 80 N, with a sensitivity of 0.5 mV/V. The maximum travel range of the crosshead induced by the motor is 10 mm with a minimum step size of 0.5 nm. The functionality of the tensile test rig was validated by investigating Cu and shape memory NiTi wires. Wires of lengths between 40 and 50 mm with varying gauge lengths can be tested. An interface between wire and electrochemical setup (noncontact) with a smart arrangement of electrodes facilitated the electrochemical measurements during tensile loading. Preliminary results on the repassivation behavior of Al wire are reported.

Ureteral complications in the renal transplant recipient after laparoscopic living donor nephrectomy.

OBJECTIVES: We report on ureteral and surgical complications in our first 110 consecutive recipients of kidneys procured with laparoscopic living donor nephrectomy (LLDN). METHODS: The records of all living donor transplants with LLDN performed between February 1999 and December 2004, including 10 pediatric transplants, were reviewed retrospectively. Three urologists performed LLDN using a pure laparoscopic non-hand-assisted transperitoneal technique. Kidney transplantation was performed in a standard fashion. For ureteroneocystostomy, the intravesical Politano-Leadbetter (P-L) technique was used. RESULTS: Two-year patient and graft survival was 99% and 98%, respectively. Serum creatinine at 12 months was 1.36+/-0.1mg/dl in adult and 0.99+/-0.23 mg/dl in pediatric recipients. Nineteen right donor kidneys were transplanted into adult recipients. Surgical complications included three symptomatic lymphoceles, one peritransplant haematoma and one kinking of a lower pole artery. All five (4.5%) ureteral complications occurred in adult recipients with a mean age of 33.2+/-2.8 years. The incidence of ureteral complications was not clustered around the early phase of our LLDN experience. Of the three (2.7%) patients diagnosed with ureteral obstruction, two required ureteral reimplantation, and one was managed conservatively. Another two patients (1.8%) with a urinary leak received a double J stent and a cystostomy catheter for 3 and 5 months, respectively. Of the five patients with a ureteral complication, three had received a donor kidney with more than one renal artery. CONCLUSIONS: LLDN combined with the intravesical (P-L) ureteral implantation technique provides excellent graft outcomes with low recipient morbidity. Renal artery multiplicity may increase the risk of ureteral complications.

Laparoscopy for living donor nephrectomy--particularities of the currently applied techniques.

Today, laparoscopic donor nephrectomy (LDN) in many centers features the standard approach for kidney retrieval in living donors. More than 60% of the centers in the USA currently perform LDN and numbers are rising in Europe as well. Today's variety of laparoscopic approaches reflects the evolution in the field of LDN. Multiple modifications have been made for the laparoscopic approach, with consequences for intraoperative handling of the kidney, operating and ischemic times and with impact on donor, organ, and recipient. We reviewed the literature from 1995 to 2004 and critically evaluated the different technical modifications, their specific advantages and disadvantages and their impact for the operation. The article aims to help the surgeon choose the technique he feels most safe with for performing laparoscopic kidney retrieval safely and with good results for donor and recipient.

Quality of life of living kidney donors in Germany: a survey with the Validated Short Form-36 and Giessen Subjective Complaints List-24 questionnaires.

BACKGROUND: Most studies evaluating the impact of kidney donation on donors' quality of life (QOL) have limitations such as small cohort size, unmatched references, use of nonstandardized and nonvalidated questionnaires, or low response rates. METHODS: We performed a study on donors' QOL that was designed to avoid these limitations. All available living renal donors in our department in the last 18 years were included in the study. QOL was assessed with two validated, standardized questionnaires (Short Form-36, Giessen Subjective Complaints List [Giessener Beschwerdebogen]-24) and compared with gender- and age-matched references. In addition, specific questions relating to kidney donation were asked. RESULTS: The response rate (89.8%) is one of the highest reported for studies on QOL of living kidney donors. Most donors had an equal or better QOL than the healthy population. Donors' willingness to donate again (93.4%) or recommend living-donor kidney transplantation (92.4%) was high, irrespective of complications. A small number of donors experienced financial drawbacks or occupational disadvantages. Donors aged 31 to 40 years were found to be at risk of QOL deterioration after organ donation. Donor and recipient complications had a significant impact on donors' QOL. One third of the donors found that the psychologic care preceding and after kidney donation was insufficient. CONCLUSIONS: Our findings support the practice of living-donor kidney transplantation as a good means to meet the persisting organ shortage. Further effort must be put into minimizing donor and recipient complications. The specific demands of younger donors should be further elucidated. In addition to medical follow-up, living kidney donors should also be offered lifelong psychologic counseling.

Laparoscopic dismembered pyeloplasty--the method of choice in the presence of an enlarged renal pelvis and crossing vessels.

OBJECTIVE: Herein we report our experience of 49 consecutive pyeloplasties that were all laparoscopically performed with an intracorporeally sutured anastomosis. We describe the operative technique, complications and outcomes during a follow-up period of 1-53 months (mean 23.2 months). PATIENTS AND METHODS: Forty-nine patients (28 women and 21 men) with a mean age of 34 years (range 6-65 years) underwent a laparoscopic dismembered pyeloplasty because of primary ureteropelvic junction (UPJ) obstruction with hydronephrosis in each case. The preoperative evaluation included an evaluation for pain, an excretory urography (IVP), renal scan and sometimes CT angiography to evaluate for crossing vessels. Follow-up studies included an IVP, renal scan and renal ultrasound 4 weeks postoperatively and every 3 months thereafter. Success was considered as improvement of the pain score and IVP (less hydronephrosis, visible UPJ and/or normalization of drainage) or absence of an obstructive pattern during the washout phase of a renal scan. RESULTS: There was no conversion to open surgery. The mean operative time was 165 min (range 90-240 min). Blood loss was negligible. Crossing vessels were noted in 57.1% of the patients (28/49). Postoperative hospital stay was 3.7 days (range 3-6 days). One patient had a leakage of the anastomosis on postoperative day 1 and needed to undergo laparoscopic repair. The mean follow-up is 23.2 months (range 1-53 months). There was one single late failure. This patient later underwent an open revision of the laparoscopic pyeloplasty. In all other patients (48/49), the obstruction was resolved or significantly improved. The long-term success rate is 97.7%. CONCLUSIONS: The results of dismembered laparoscopic pyeloplasties compare favorably with those achieved by open pyeloplasties with less perioperative morbidity and discomfort. We do believe that laparoscopic dismembered pyeloplasty with an intracorporeal anastomosis is the method of choice in the treatment of the UPJ obstruction in the presence of an enlarged renal pelvis and crossing vessels.

Efficient in vitro transduction of epithelial cells and keratinocytes with improved adenoviral gene transfer for the application in skin tissue engineering.

The adenovirus-mediated transfer of therapeutic genes into keratinocytes may be a useful approach to treat several skin diseases or to improve the graft take of in vitro generated skin equivalents used for wound coverage. However, in contrast to many other tissues, keratinocytes are relatively difficult to transduce by adenoviral vectors. To achieve high efficiency of adenoviral transduction into epithelial cells we investigated the effects of the polycation polybrene on the infection process. The human (HaCaT, A549) and rat (NBT II, MHICI) epithelial cell lines, as well as human and rat primary keratinocytes, were transduced with recombinant Ad(beta)-gal adenovirus, encoding for the reporter gene E. coli beta-galactosidase, in the presence of various polybrene concentrations. We determined the amount of beta-gal positive cells by X-gal staining and the beta-gal expression by ONPG-assay after 24 h. In all tested human and rat epithelial cell lines, as well as in human and rat primary keratinocytes, the addition of polybrene during adenoviral transduction of Ad(beta)-gal resulted in a marked increase of beta-gal positive cells and beta-gal protein expression. The efficacy of polybrene showed a clear dose dependency. The improvement of adenoviral gene transfer into various types of human and rat epithelial cells by polybrene allows us to reduce the amount of recombinant virus particles resulting in a decreased inflammation induced by this therapeutic agent. In addition, the efficient transduction and expression with enhanced adenoviral transfer of therapeutic genes into primary keratinocytes provides a powerful tool for analysing the functions and the regulation of a gene of interest in vitro.

Laparoscopic live donor right nephrectomy: a new technique with preservation of vascular length.

PURPOSE: We report our initial experience with right laparoscopic live donor nephrectomy using a modified vascular clamp for achieving maximal length of the renal vein. MATERIALS AND METHODS: Since 1999, 34 patients have undergone laparoscopic live donor nephrectomy at Charité Hospital in Berlin, including 30 on the left and 4 on the right side. The right technique involves a 4-port transperitoneal laparoscopic approach with a muscle splitting lumbar incision for kidney extraction. To duplicate completely the comparable open operation a modified Satinsky atraumatic vascular clamp (Aesculap, Inc., Center Valley, Pennsylvania) was introduced through a 1 cm. lateral incision and placed across the vena cava, enabling harvest of the full length of the renal vein flush with the vena cava. The vena cavotomy is closed with a running suture placed in intracorporeal fashion. RESULTS: All procedures were successfully accomplished without technical or surgical complications. Mean operative time was 170 minutes. Mean renal warm ischemia time from endoscopic cross clamping of the renal vessels to cold perfusion on the bench was 2.1 minutes. In all 4 kidneys it was possible to harvest the whole length of the renal vein, so that the recipient operation was performed under optimal vascular conditions. All 4 kidneys were transplanted successfully in the recipients and showed immediate function. CONCLUSIONS: Right laparoscopic live donor nephrectomy is technically feasible, safe and a viable option for minimally invasive organ donation when left kidney donation is not desired. The Satinsky atraumatic vascular clamp enabled harvest of the whole right renal vein. We believe that this laparoscopic technique effectively duplicates the open operation with less morbidity.