The use of venous jump grafts in pancreatic transplantation - no difference in patient or allograft outcomes - an update of the UNOS database

Venous jump grafts are used in pancreas transplantation to salvage a pancreas with a short portal vein or to facilitate an easier anastomosis. There have been no large studies evaluating the safety of venous jump grafts in pancreas transplantation. We analyzed the UNOS database to determine whether venous jump grafts are associated with graft loss or patient death. Data from UNOS on all adult pancreas transplant recipients 1996-2012 were analyzed. Venous extension grafts were used in 2657 cases; they were not in 18 124. Kaplan-Meier/product-limit estimates analysis demonstrated similar patient survival (p < 0.641) and death-censored graft survival (p < 0.351) at one, three, five,10, and 15 yr between subjects with and without venous jump grafts. There was a statistically significant difference in one-yr unadjusted patient survival between the venous extension graft (94.9%) and the no-venous extension graft (95.8%) groups (p < 0.045) and a borderline difference in one-yr graft survival between the venous extension graft (84.1%) and the no-venous extension graft (82.6%) groups (p < 0.055). There was no significant difference in patient survival or allograft survival at the three-, five-, 10-, and 15-yr intervals. The use of venous jump grafts is not associated with increased graft loss or mortality.

MicroRNAs: history, biogenesis, and their evolving role in animal development and disease

The discovery of microRNAs (miRNAs) in 1993 followed by developments and discoveries in small RNA biology have redefined the biological landscape by significantly altering the longstanding dogmas that defined gene regulation. These small RNAs play a significant role in modulation of an array of physiological and pathological processes ranging from embryonic development to neoplastic progression. Unique miRNA signatures of various inherited, metabolic, infectious, and neoplastic diseases have added a new dimension to the studies that look at their pathogenesis and highlight their potential to be reliable biomarkers. Also, altering miRNA functionality and the development of novel in vivo delivery systems to achieve targeted modulation of specific miRNA function are being actively pursued as novel approaches for therapeutic intervention in many diseases. Here we review the current body of knowledge on the role of miRNAs in development and disease and discuss future implications.

Terahertz reflectarray as a polarizing beam splitter

A reflectarray is designed and demonstrated experimentally for polarization-dependent beam splitting at 1 THz. This reflective component is composed of two sets of orthogonal strip dipoles arranged into interlaced triangular lattices over a ground plane. By varying the length and width of the dipoles a polarization-dependent localized phase change is achieved on reflection, allowing periodic subarrays with a desired progressive phase distribution. Both the simulated field distributions and the measurement results from a fabricated sample verify the validity of the proposed concept. The designed terahertz reflectarray can efficiently separate the two polarization components of a normally incident wave towards different predesigned directions of ±30°. Furthermore, the measured radiation patterns show excellent polarization purity, with a cross-polarization level below -27 dB. The designed reflectarray could be applied as a polarizing beam splitter for polarization-sensitive terahertz imaging or for emerging terahertz communications.

Extended-spectrum-beta-lactamase producing bacteria related urinary tract infection in renal transplant recipients and effect on allograft function

Background

Urinary tract infection (UTI) is a well-recognized early complication in renal transplant recipients (RTR) and can have significant bearing on their outcome. The recent rise in incidence of extended spectrum beta lactamase (ESBL) producing bacteria causing UTI among RTR poses new and significant challenges in terms of management and outcome. Our aim is to analyze the effect of ESBL producing bacteria causing UTI in these patients and its impact on allograft function.

Methods

We reviewed the medical records of 147 RTR who were followed at a tertiary care hospital affiliated transplant center between January 2007 and May 2013 and noted five RTR who developed episodes of ESBL producing bacteria related UTI during follow up. Multiple patient characteristics including demographics, immunosuppression, recurrences, allograft function and outcome were analyzed.

Results

Five patients (3.4%) out of 147 had ESBL producing bacteria related UTI. We found all patients to be above 60 years of age, with three out of five being females, and all five patients had diabetes mellitus. We identified a total of 37 episodes of UTI among these five patients during this period. Two of these patients had elevated creatinine values during the episodes of UTI and three of them developed bacteremia. Of the five patients, four of them had a favorable outcome except for one patient who developed persistent allograft dysfunction.

Conclusion

RTR are at a higher risk for developing ESBL producing bacteria associated UTI. Early diagnosis along with appropriate and judicious use of antibiotics will ensure long term success in allograft and patient outcome.

Factors associated with completion of pre-kidney transplant evaluations

This study sought to examine various factors that may prevent transplant candidates from completing their transplant workup prior to listing. We reviewed the records of 170 subjects (cases = 100, controls 70) who were either on dialysis or had less than 20 mL/min creatinine clearance and were therefore candidates for preemptive transplantation. Approximately, 56% of preemptive patients completed their workup, while only 36% of patients on dialysis completed their workup. Our data revealed that factors contributing toward completion of workup included intrinsic motivation (four times more likely), lack of specific medical comorbidities (three times more likely), and preemptive status (two times more likely). Among patients on dialysis, intrinsic motivation (five times more likely) and absence of cardiovascular complications (four times more likely) were associated with completion. When comparing patients on dialysis to patients not on dialysis, there were significant differences between the two groups in distance from home to the transplant center, level of education, and presence of medical comorbidities. We believe that targeted interventions such as timely referral, providing appropriate educational resources, and development of adequate support systems, have the potential to improve workup compliance of patients with advanced chronic kidney disease, including those on dialysis.

Arterio-enteric fistula in failed enteric-drained pancreas transplants: an impending danger

Enteric drainage is the preferred method of exocrine diversion in simultaneous kidney-pancreas transplantation. Because of improvements in immunosuppression, enteric drainage has become the preferred method of pancreas transplantation in general. Although associated with less potential complications than bladder-drained pancreas, potentially lethal arterio-enteric fistulas in the setting of nonfunctioning allografts represent a constant threat. We herein present a case report, a review of the literature, and a call for caution.

Shortened length of stay improves financial outcomes in living donor kidney transplantation

Kidney transplantation is the preferred clinical and most cost-effective option for end-stage renal disease. Significant advances have taken place in the care of the transplant patients with improvements in clinical outcomes. The optimization of the costs of transplantation has been a constant goal as well. We present herein the impact in financial outcomes of a shortened length of stay after kidney transplant.

Removal of foley catheters in live donor kidney transplant recipients on postoperative day 1 does not increase the incidence of urine leaks

Catheterization of the urinary bladder during kidney transplantation is essential. The optimal time to remove the Foley catheter postoperatively is not universally defined. It is our practice to remove the Foley catheter on postoperative day 1 in live donor kidney transplant recipients who meet our standardized protocol criteria. We believe that early removal of Foley catheters increases patient comfort and mobility, decreases the risk of catheter associated urinary tract infections, and allows for decreased hospital length of stay. The hypothetical risk of early removal of Foley catheters would be the increased risk of urine leak. We reviewed 120 consecutive live donor kidney transplant recipients and found that there was not an increased incidence of urine leaks in patients whose Foley catheters were removed on postoperative day 1.

Elevated human chorionic gonadotropin levels in patients with chronic kidney disease: Case series and review of literature

Women are often subjected to serum human chorionic gonadotropin (HCG) testing prior to diagnostic and therapeutic interventions. A positive result leads to further testing to rule out pregnancy and avoid possible fetal teratogenicity. The impact of chronic kidney disease (CKD) on HCG testing has not been studied. We report a series of 5 women out of 62 with CKD, who had a positive HCG test on routine pre-transplant screening at a single transplant center. We analyzed their case records retrospectively. Despite aggressive investigation, their elevated HCG levels remained unexplained. The positive test contributed to delays in transplantation and increased overall cost of treatment.

Field effect biosensing platform based on 2D α-MoO(3)

Electrical-based biosensing platforms offer ease of fabrication and simple sensing solutions. Recently, two-dimensional (2D) semiconductors have been proven to be excellent for the fabrication of field effect transistors (FETs) due to their large transconductance, which can be efficiently used for developing sensitive bioplatforms. We present a 2D molybdenum trioxide (MoO3) FET based biosensing platform, using bovine serum albumin as a model protein. The conduction channel is a nanostructured film made of 2D α-MoO3 nanoflakes, with the majority of nanoflake thicknesses being equal to or less than 2.8 nm. The response time is impressively low (less than 10 s), which is due to the high permittivity of the 2D α-MoO3 nanoflakes. The system offers a competitive solution for future biosensing applications.

Obesity as a barrier to living kidney donation: a center-based analysis

BACKGROUND

Obesity is a major epidemic and may present a significant barrier to living kidney donation. The purpose of our study was to determine the frequency of obesity as an exclusion factor and assess how often these donors lose weight and donate.

METHODS

A single center, retrospective analysis of 104 potential living kidney donors between 2008 and 2012.

RESULTS

Of the 104 donors, 19 (18%) had a normal body mass index (BMI) of <25. Eighty-five of the 104 (82%) donors spanned the overweight to morbidly obese classifications. Thirty-eight (37%) were overweight (BMI 25-29.9). Twenty-four (23%) were categorized as class I obesity (BMI 30-34.9), 17 (16%) as class II obesity (BMI 35-39.9), and six (6%) as class III obesity (BMI >40). There were a total of 23 donors (22%) who were considered moderately and morbidly obese (BMI >35). Of these, only three (13%) succeeded at losing weight and donating.

CONCLUSIONS

Obesity may be a frequent barrier to living kidney donation, directly leading to exclusion as a potential kidney donor in about one in five instances. Successful weight loss leading to donation appears to be infrequent, suggesting need to address obesity in the donor population.

Engineering electrodeposited ZnO films and their memristive switching performance

We report the influence of zinc oxide (ZnO) seed layers on the performance of ZnO-based memristive devices fabricated using an electrodeposition approach. The memristive element is based on a sandwich structure using Ag and Pt electrodes. The ZnO seed layer is employed to tune the morphology of the electrodeposited ZnO films in order to increase the grain boundary density as well as construct highly ordered arrangements of grain boundaries. Additionally, the seed layer also assists in optimizing the concentration of oxygen vacancies in the films. The fabricated devices exhibit memristive switching behaviour with symmetrical and asymmetrical hysteresis loops in the absence and presence of ZnO seed layers, respectively. A modest concentration of oxygen vacancy in electrodeposited ZnO films as well as an increase in the ordered arrangement of grain boundaries leads to higher switching ratios in Ag/ZnO/Pt devices.

Partial closure of skin wounds after kidney transplantation decreases the incidence of postoperative wound infections

Wound infections are a major cause of morbidity after kidney transplantation. The purpose of our study was to evaluate an improved technique of wound closure. Data corresponding to 104 consecutive live donor kidney recipients were prospectively collected and analyzed. Our routine standard technique involved closure of the abdominal wall muscle and fascia in one layer with interrupted nonabsorbable full thickness sutures. No drains were used. The skin was closed with interrupted 2-0 nylon sutures 4 to 5 cm apart, leaving the skin and subcutaneous tissue in between partially open. Patients were allowed to shower starting on the first postoperative day. Examination of the wounds was continued for at least 1 month postoperatively, and then routinely as needed. All patients were thoroughly informed preoperatively of our technique. There were no immediate postoperative wound infections. There were no instances of dehiscence, evisceration, or need for revision. All patients were able to continue with their routine daily activities. Cosmetic results were satisfactory in all cases. We did not experience any patient complaints with respect to our technique. Patient satisfaction scores conducted by Press Ganey and Associates ranked in the 99 percentile with respect to peers undergoing kidney transplantation. Three patients returned six months postoperatively with suture granulomas which were treated nonoperatively. Partial closure of the skin wound with no associated drains is an effective and cosmetically desirable way to decrease the incidence of postoperative infections in kidney transplantation.

Treatment of Late Class II Antibody-Mediated Rejection Status Postkidney Transplantation: Two Case Reports

We are describing the successful treatment of two cases of late Class II antibody mediated rejection status postkidney transplantation. The first patient was treated with a combination of plasmapheresis, intravenous immunoglobulin (IVIG), and stenting of the transplanted renal artery. The second was treated with IVIG and pulse steroids.

Forty-eight hour kidney transplant admissions

Forty-eight hour kidney transplantation admissions are a feasible option in selected recipients of live-donor allografts through the use of standardized post-operative protocols, multidisciplinary team patient care, and intensive follow-up at outpatient centers. Age, gender, and pre-transplant dialysis status did not impact the ability to achieve 48-hour admissions. We did not identify any other pre-operative risk factors that contributed to increased length of stay. Although ABO and highly sensitized recipients had longer lengths of stay, the subgroup was too small to achieve statistical significance. We did not encounter any readmissions within the first seven post-operative days. Further improvements in clinical management will enhance the potential to shorten the length of hospital stay for all kidney transplant recipients.

Flexible terahertz metamaterials for dual-axis strain sensing

Utilizing an elastic polymer, we design and experimentally demonstrate a four-fold symmetric flexible metamaterial operating at terahertz frequencies. The fabricated metamaterials exhibit good stretchability and recoverability. Two independent resonances can be observed when the structure is probed with linearly polarized terahertz waves in two orthogonal axes. Applying a stretching force along a main axis causes an observable frequency shift in the corresponding resonance, with minimal effect on the other. This study suggests a possible application of flexible metamaterials for dual-axis strain sensing.

Experimental demonstration of reflectarray antennas at terahertz frequencies

Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase distribution is implemented on the patch array to create a reflector able to deflect an incident beam towards a predefined angle off the specular direction. In order to confirm the validity of the design, a set of reflectarrays each with periodically distributed 360 × 360 patch elements are fabricated and measured. The experimental results obtained through terahertz time-domain spectroscopy (THz-TDS) show that up to nearly 80% of the incident amplitude is deflected into the desired direction at an operation frequency close to 1 THz. The radiation patterns of the reflectarray in TM and TE polarizations are also obtained at different frequencies. This work presents an attractive concept for developing components able to efficiently manipulate terahertz radiation for emerging terahertz communications.

Dielectric resonator nanoantennas at visible frequencies

Drawing inspiration from radio-frequency technologies, we propose a realization of nano-scale optical dielectric resonator antennas (DRAs) functioning in their fundamental mode. These DRAs operate via displacement current in a low-loss high-permittivity dielectric, resulting in reduced energy dissipation in the resonators. The designed nonuniform planar DRA array on a metallic plane imparts a sequence of phase shifts across the wavefront to create beam deflection off the direction of specular reflection. The realized array clearly demonstrates beam deflection at 633 nm. Despite the loss introduced by field interaction with the metal substrate, the proposed low-loss resonator concept is a first step towards nanoantennas with enhanced efficiency. The compact planar structure and technologically relevant materials promise monolithic circuit integration of DRAs.

Enhanced charge carrier mobility in two-dimensional high dielectric molybdenum oxide

We demonstrate that the energy bandgap of layered, high-dielectric α-MoO(3) can be reduced to values viable for the fabrication of 2D electronic devices. This is achieved through embedding Coulomb charges within the high dielectric media, advantageously limiting charge scattering. As a result, devices with α-MoO(3) of ∼11 nm thickness and carrier mobilities larger than 1100 cm(2) V(-1) s(-1) are obtained.

Elevated temperature anodized Nb2O5: a photoanode material with exceptionally large photoconversion efficiencies

Here, we demonstrate that niobium pentoxide (Nb(2)O(5)) is an ideal candidate for increasing the efficiencies of dye-sensitized solar cells (DSSCs). The key lies in developing a Nb(2)O(5) crisscross nanoporous network, using our unique elevated temperature anodization process. For the same thicknesses of ∼4 μm, the DSSC based on the Nb(2)O(5) layer has a significantly higher efficiency (∼4.1%) when compared to that which incorporates a titanium dioxide nanotubular layer (∼2.7%). This is the highest efficiency among all of the reported photoanodes for such a thickness when utilizing back-side illumination. We ascribe this to a combination of reduced electron scattering, greater surface area, wider band gap, and higher conduction band edge, as well as longer effective electron lifetimes.

Sub-diffraction thin-film sensing with planar terahertz metamaterials

Planar metamaterials consisting of subwavelength resonators have been recently proposed for thin dielectric film sensing in the terahertz frequency range. Although the thickness of the dielectric film can be very small compared with the wavelength, the required area of sensed material is still determined by the diffraction-limited spot size of the terahertz beam excitation. In this article, terahertz near-field sensing is utilized to reduce the spot size. By positioning the metamaterial sensing platform close to the sub-diffraction terahertz source, the number of excited resonators, and hence minimal film area, are significantly reduced. As an additional advantage, a reduction in the number of excited resonators decreases the inter-cell coupling strength, and consequently the resonance Q factor is remarkably increased. The experimental results show that the resonance Q factor is improved by more than a factor of two compared to the far-field measurement. Moreover, for a film with a thickness of λ/375 the minimal area can be as small as 0.2λ × 0.2λ. The success of this work provides a platform for future metamaterial-based sensors for biomolecular detection.