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Biomedical subjects

P N Bretan

Publications and source records attributed to P N Bretan.

At least 19 recordsLinked to original sources
PubMed2000

Successful long-term outcome using existing native cutaneous ureterostomy for renal transplant drainage.

PURPOSE: We report our long-term experience with a preexisting native cutaneous ureterostomy via an ipsilateral transplant ureteral native ureterostomy for transplant drainage without native nephrectomy. MATERIALS AND METHODS: Between 1993 and 1998, 5 patients without a usable bladder had undergone previously urinary diversion via cutaneous ureterostomy. All patients had a well functioning cutaneous ureterostomy for a mean plus or minus standard deviation of 18+/-12 years before renal transplantation. No patient had a history of stomal stenosis, recent urinary tract infection or pyelonephritis. RESULTS: All 5 patients continued to have a functioning renal transplant at last mean followup of 36+/-6.6 months. Complications included stomal retraction due to postoperative weight gain requiring revision in 2 cases and ureteroureteral anastomotic stenosis treated with endopyelotomy in 1. Mean serum creatinine at last followup was 1.5+/-0.6 mg./dl. CONCLUSIONS: Of the complications that we present only 1 may be attributed to the singularity of our procedure. Our experience suggests that a preexisting native cutaneous ureterostomy may serve as a receptacle for transplant ureteral drainage in select patients with excellent long-term function.

Adult↗
PubMed1999

Complex renal reconstruction.

This article provides a complete review of current renal reconstructive techniques. The techniques described include partial nephrectomy, intrasinusal surgery, anatrophic nephrolithotomy, nonvascular bench procedures with autotransplantation, and allograft partial nephrectomy in renal transplantation. A detailed discussion on renovascular and collecting system anatomy and current indications for these procedures is presented.

Humans↗
PubMed1999

Complex posttransplantation abnormalities of renal allografts: evaluation with MR imaging.

PURPOSE: To assess the efficacy of magnetic resonance (MR) imaging in the evaluation of complex abnormalities of renal allografts. MATERIALS AND METHODS: Clinical and radiologic findings were retrospectively reviewed in 24 patients who underwent MR imaging of a renal allograft because ultrasonographic (US) findings were inconclusive or discordant with clinical findings. The final diagnoses were established with histopathologic analysis (n = 16) or clinical and imaging follow-up (n = 8). RESULTS: MR imaging diagnoses were correct in 16 patients (67%), whereas US diagnoses were correct in six patients (25%) (P < .05). Five cases of allograft involvement by posttransplantation lymphoproliferative disorder (PTLD) were found at histopathologic analysis; at MR imaging, PTLD appeared as hypointense masses on T1-and T2-weighted images with minimal enhancement. In four of the five cases of PTLD, the masses occurred at the renal hilum and encased hilar vessels. Normal morphology was correctly diagnosed with MR imaging in five patients in whom a mass was suspected at US. CONCLUSION: MR imaging results are often diagnostic in cases of complex abnormalities of renal allografts. Renal allograft involvement by PTLD appears to have a relatively characteristic MR imaging appearance. Normal MR imaging findings in cases of suspected masses at US may obviate biopsy.

Female↗
PubMed1999

Urolithiasis in renal and combined pancreas/renal transplant recipients.

PURPOSE: Urological complications in renal transplant recipients will become more common with increasing numbers of transplantations as well as increased graft survival secondary to improvements in immunosuppression. Urinary stone disease may be one of those complications. We determine the current incidence of urinary stone disease in renal transplant patients based on contemporary immunosuppressive regimens. MATERIALS AND METHODS: We reviewed the records of 1,730 renal and 83 pancreas/renal transplantations performed during the cyclosporine era and identified 8 recipients (0.4%) with urinary stone disease, including 3 with renal pelvic stones, 1 with multiple ureteral stones and 4 with bladder calculi. RESULTS: Treatment ranged from conservative observation to open pyelolithotomy, and included percutaneous nephrolithotomy and extracorporeal shock wave lithotripsy. The ureteral stones were removed with antegrade and retrograde ureteroscopy. The 4 bladder stones were treated with cystolithalopaxy. No case had significant permanent graft damage. Mean followup was 68.6 months. Mean serum creatinine was 1.5 mg./dl. (normal 0.5 to 1.3) at baseline and 2.38 after followup. CONCLUSIONS: While the incidence of upper tract urinary stone disease in renal (0.23%) and pancreas/renal (1.2%) transplant recipients is not statistically significant (p <0.45), the latter have significantly higher rates of bladder stones (4.8 versus 0%, p <0.001). The diagnosis of urinary stone disease in transplant recipients can be challenging because of the lack of symptoms but the treatment approach is the same as in the normal population.

Adult↗
PubMed1998

Ureteral obstructions and leaks after renal transplantation: outcome of percutaneous antegrade ureteral stent placement in 44 patients.

PURPOSE: To analyze the outcome of percutaneous antegrade ureteral stent placement for treatment of ureteral stenoses and leaks after renal transplantation. MATERIALS AND METHODS: Antegrade pyelography and percutaneous ureteral stent placement were performed in 45 patients with ureteral obstruction (n = 40), leak (n = 3), or both (n = 2). Obstructions were graded as mild, moderate, or complete, and as early (< or = 3 months after transplantation) or late (> 3 months). RESULTS: The outcome of stent placement was successful in 25 (57%) patients (average follow-up, 30 months). The ureteroneocystostomy (UNC) was the most common site of obstructions (22 of 41), leaks (four of five), and successful outcomes (16 of 22). Moderate obstructions were most common (29 of 41) and responded best to treatment (17 of 29). Eighteen (69%) of 26 early obstructions and five (33%) of 15 late obstructions were successfully managed percutaneously. All complications (12 of 45 patients) were minor, with infections the most common (n = 7). No mortality or allograft loss was attributable to stent placement. CONCLUSION: Ureteral stents are safe and effective for the treatment of obstructions and leaks and are particularly effective for early and UNC obstructions. These stents may also be useful for temporary drainage.

Adolescent↗
PubMed1997

Immunologic and patient selection strategies for successful utilization of less than 15 kg pediatric donor kidneys--long term experiences with 40 transplants.

Renal transplantation using infant donors is associated with significantly less graft survival (GS) and increased morbidity, especially from very young and small donors. We report our results using specific strategies to determine which age and size donor require en bloc renal transplant reconstruction and associated immunologic protocols for optimization of subsequent GS. Forty cadaveric pediatric en bloc renal transplants were performed. Mean donor age was 23.6+/-18.4 months with subgroups: 2-12 months, n=14; 13-24 months, n=19; and 25-60 months, n=7. Mean donor weight was 14.4+/-4.5 kg. All kidneys were placed in primary, nonsensitized (peak PRA = 7.9+/-5.6%) adult (41.6+/-16 years) recipients. Low weight was preferred (62.4+/-12.8 kg). Mean cold ischemia time was 26.9+/-8.6 hr. Immunosuppression consisted of quadruple immunosuppression (QI) with OKT3 induction. All patients had ureteral stents placed intraoperatively. Mean follow-up was 16.9 months. Actuarial GS at 12, 24, and 33 months were 100% (n=13), 85% (n=20), and 71% (n=7), respectively. Total GS was 35/40=88%. All grafts functioned immediately and there were no technical losses. Biopsy proven rejections occurred in 12 (30%) patients, developing at 16-167 days postoperatively (mean = 50.3 days). Mean serum creatinine at one week and 1, 6, 12, and 18 months were 2.1+/-2.0, 1.5+/-0.8, 1.3+/-0.5, 1.1+/-0.4, and 0.9+/-0.4 mg/dl, respectively. Functional isotopic renography, as well as sonographic monitoring reflected rapid initial and continued growth in these kidneys. Mean BP at 12 and 24 months postoperatively were 145/83+/-18/13 and 122/76+/-20/10 mmHg, respectively, with no significant proteinuria noted. Excellent results with minimal complications utilizing very small and young infant donors can be achieved with QI immunosuppression, and selection of low immune reactive and noncomplicated adult recipients. Additionally, maximal renal dosing by minimizing recipient weight may prevent future hyperfiltration damage.

Actuarial Analysis↗
PubMed1997

Assessment of preservation induced reperfusion injury via intraoperative renal transplant blood flow and endothelin concentration studies.

PURPOSE: We investigated a possible relationship between levels of the vasoconstrictive peptide endothelin and renal transplant reperfusion injury, and modified a technique for measuring renal blood flow with an ultrasonic perivascular transit time flow probe. MATERIALS AND METHODS: Renal grafts in a swine transplant model were cold flushed with either Collins-2 or University of Wisconsin solution. Renal blood flow and renal vein endothelin levels after reperfusion of transplanted grafts, as well as histological parameters within the transplanted kidney were measured. The 5-minute post-reperfusion renal blood flow was used as the baseline allograft flow. The definition of reperfusion injury was a decrease in flow from baseline with no recovery within 1 hour of reperfusion. In 9 human recipients reperfusion injury was further verified by monitoring subsequent serum creatinine, urine output, graft survival and rejection episodes. RESULTS: In the swine model and human transplant recipients no evidence of post-reperfusion ischemia was noted by histological examination, supporting that moderate to mild reperfusion injury or ischemic injury cannot be clinically determined with this method. In the swine model the decrease flow from baseline in allograft post-reperfusion renal blood flow was significantly greater in kidneys preserved in Collins'-2 than in University of Wisconsin solution (41.75 +/- 5.69 versus 11.18 +/- 13.99 ml. per minute, p = 0.005), supporting that this technique can assess mild to moderate reperfusion injury. The increase in serum endothelin in the allografts from the swine model and in humans was not significantly different from baseline. Clinically, post-reperfusion renal blood flow changes correlated well with subsequent function. The 4 patients with renal transplant reperfusion injury had significantly higher serum creatinine values and lower urine output 1 week postoperatively than 5 patients with no evidence of injury (serum creatinine: 6.75 +/- 3.03 versus 2.08 +/- 1.28 mg./dl., p = 0.015). Reperfusion injury patients had more rejections (2 versus 1) and less graft survival (75% versus 100%) at 1-year followup compared to the nonreperfusion injury patients. CONCLUSIONS: Vasoactive factors other than endothelin most likely contribute to reperfusion injury. Furthermore, the ultrasonic transit time flow probe accurately measures post-reperfusion renal blood flow and offers a practical method for assessing acute reperfusion injury, which may help to optimize immunosuppressive strategies to decrease allograft loss associated with delayed graft function.

Animals↗
PubMed1997

Improved survival of en bloc renal allografts from pediatric donors.

PURPOSE: We developed a technical and immunological protocol to increase survival of renal transplants from pediatric donors. MATERIALS AND METHODS: En bloc kidneys (22) were procured from donors weighing 2 to 14 kg. (1 to 60 months old) and transplanted into adult recipients. In group 1 (12 patients) sequential therapy was used for kidneys with more than 35 hours of cold storage and immediate triple therapy (cyclosporine, azathioprine and prednisone) was used for those with less than 35 hours of cold storage. In group 2 (10 patients) OKT3 induction therapy was used. Mean followup was 4.7 years. RESULTS: Mean blood pressure at 1 and 4 years was not significantly different between the groups. Mean serum creatinine was not significantly different between the groups at 1 year but it was significantly less in group 2 at 4 years (1.9 +/- 1.0 versus 1.2 +/- 0.24 mg./dl., p <0.05). At 1 year of followup the complication rate was 75% in 9 of 12 patients in group 1, including 4 infections or leaks (2 lost), 6 rejections (3 lost) and 3 cases of thrombosis or hemorrhage, and 20% (p <0.01) in group 2 (1 patient had the hemolytic uremic syndrome leading to graft loss). Graft survival was significantly greater in group 2 at all 4 years of followup (p = 0.05). CONCLUSIONS: The success of pediatric en bloc renal transplantation can be enhanced by induction therapy in healthy recipients.

Child, Preschool↗
PubMed1996

[Effect of HLA compatibility on the transplanted kidney in relation to recipient age].

Donor-recipient histocompatibility, as evaluated by the HLA matching results, plays an important role in the outcome of renal transplants, although much controversy surrounds the benefit of kidney allocation based on HLA typing. In this report HLA matching and survival data on 1,342 transplants performed at the University of California at San Francisco between 1984 and 1992 and treated uniformly by quadruple immunosuppression were analyzed in relation to the recipient's age. With respect to the influence of the increasing number of mismatches from 0 to 6, the analysis revealed decreasing 3-year graft survival rates as follows: 85.4%; 87.3%; 71.3%; 78.2%; 75.8%; 70.9% and 67.5%. Whereas the impact of cold ischemia time and histocompatibility was equally important during the 3-year postoperative period, the essential positive influence of good HLA matching on the long-term graft survival was demonstrated. The children aged between 5 and 18 years were identified as a high-risk group by the analysis, HLA-A incompatibility being attributed to poor graft survival in this age group. With respect to the effect of HLA-A histoincompatibility, the data provide evidence that HLA-A matching results seem to play an important role in graft survival in children, whereas transplants well matched in terms of HLA-B did well in adult recipients. No age difference in the impact of HLA-DR could be detected. In conclusion, HLA matching is still essential. It seems that there are differences in the impact of HLA loci in relation to the recipient's age.

Adolescent↗
PubMed1996

[Improved organ survival in transplantation of pediatric kidneys by optimizing donor-recipient size relation].

The risk for renal allograft failure in pediatric renal transplantation (donor age below 3 years) is still high, although it has been reduced by the use of potent immunosuppressive therapies. In this study we report on experience with 80 kidneys of donors below 3 years of age (PD) transplanted at the University of California at San Francisco Hospital in accordance with the policy of minimizing donor-recipient size differences. The graft survival rates were comparable with the results for adult donors, 18-50 years of age (AD, n = 891): at 1 year PD 74.1% vs AD 85.5%, at 2 years PD 70.5% vs AD 80.2%, at 3 years PD 63.5% vs AD 76%; there were no significant differences. The policy of minimizing donor-recipient size differences seems to improve graft survival rates, avoiding the tendency for hyperfiltration phenomena and possibly being responsible for this salutary effect. We conclude that the use of pediatric donor kidneys can yield excellent long-term results independent of primary disease if the donor-recipient size difference is minimized and a potent immunosuppressive regimen is employed.

Adolescent↗
PubMed1995

The risk of transmission of hepatitis B from HBsAg(-), HBcAb(+), HBIgM(-) organ donors.

Liver allografts from HBcAb(+), IgM(-), HBsAg(-) donors can transmit HBV to uninfected recipients. We currently no longer accept these livers for transplantation while continuing to accept the kidneys. The purpose of this study is to determine the risk of donor-transmitted HBV infections from HBcAb(+), HBIgM(-), HBsAg(-) organ donors and determine if the risk of donor-transmitted HBV infections and their severity is dependent on the organ being transplanted. This study consists of a retrospective review of the posttransplant course of recipients of HBcAb(+), HBIgM(-), HBsAg(-) donors accepted at UCSF from 6/85 to 12/93. Transmitted HBV infection was defined as one in which the recipient changed from HBsAg(-) prior to transplantation to HBsAg(+) posttransplant, with no other source. There were 25 of 1190 donors who were HBcAb(+), HBIgM(-), HBsAg(-); 1/42 kidney, 3/6 liver, and 0/7 heart HBsAg(-) transplant recipients of organs from these donors became HBsAg(+) after transplantation. This difference in infection rate (liver vs. kidney and heart) is statistically significant. The clinical course of the liver recipients was also more severe. All of the patients who became infected were HBsAb(-) and HBcAb(-) prior to transplant. We conclude that (1) HBV can be transmitted from HBcAb(+), HBIgM(-), HBsAg(-) organ donors, (2) the rate of transmission is highest and severity of infection is worst in the liver recipients; and (3) we will continue to transplant kidneys from these donors, preferably into immunized recipients.

Adolescent↗
PubMed1995

Renal transplantation in patients with posterior urethral valves: favorable long-term outcome.

PURPOSE: We assessed the long-term efficacy of renal transplantation in patients with posterior urethral valves. MATERIALS AND METHODS: We reviewed the outcome in 23 patients with posterior urethral valves who underwent renal transplantation since 1979. RESULTS: Graft survival was 69% at 5 years and 63% at 10 years. Seven patients with followup of 7 years or longer had a mean serum creatinine level of 1.5 mg/dl. Three patients (13%) demonstrated significant bladder dysfunction postoperatively. CONCLUSIONS: Renal transplantation into a valve bladder is not associated with an abnormally high rate of failure. Deterioration of graft function secondary to lower urinary tract dysfunction is uncommon, with the majority of patients able to use the unmodified native bladder as a receptacle for the transplanted kidney.

Adolescent↗
PubMed1994

Characterization of improved renal transplant preservation mechanisms using PB-2 flush solution by HPLC assay.

Renal flush solutions have been found to be beneficial for extending organ viability, but their mechanisms of action are poorly understood. In order to delineate these mechanisms we studied the addition of mannitol and adenosine to a modified simple hypothermic intracellular flush solution (PB-2), and the relationships of renal adenine nucleotide (AN) concentrations with ischemia, reperfusion and viability. A significant (P < 0.05) and progressive decay in AN and increase in total degradation products (DP; hypoxanthine and xanthine) was noted during warm ischemia. Total AN and AMP were significantly higher after 50 h of cold storage in the PB-2 compared to the C-2 control cold flush group. Viability was associated with a significant (P < 0.01) regeneration of AN within 45 min of reperfusion. HPLC assay indicated that PB-2 cold flush solution enhances renal viability by both diminution of reperfusion injury enabling better reflow and primary preservation of AN. The latter process may appreciably contribute to the former process.

Adenine Nucleotides↗