PubMed Health⌕ Search

Biomedical subjects

Richard V Perez

Publications and source records attributed to Richard V Perez.

At least 19 recordsLinked to original sources
PubMed2005

Upper arm arteriovenous fistula versus forearm looped arteriovenous graft for hemodialysis access: a comparative analysis.

If an autogenous wrist radiocephalic arteriovenous fistula cannot be created, the next choice for chronic hemodialysis access may be a prosthetic forearm looped arteriovenous graft (FAL-AVG) or a native upper arm arteriovenous fistula (UA-AVF). We reviewed our experience with these two forms of dialysis access to determine which is preferable. Patient medical records were retrospectively reviewed. The main outcomes were time to first use, complications, and reinterventions as well as primary and assisted primary patency. Eighty-six patients underwent creation of UA-AVF, and 60 patients underwent placement of FAL-AVG. Time to first use was 3.8 months for UA-AVFs vs. 1.8 months for FAL-AVGs (p < 0.018). Complication rates were 42% vs. 65% for UA-AVFs vs. FAL-AVGs, respectively (p = 0.006). Thrombosis was more common in FAL-AVGs than UA-AVFs (42% vs. 17%, p = 0.001), as was nonelective reintervention (50% vs. 30%, p = 0.016). Patency rates were similar at 1 and 2 years. Although UA-AVFs and FAL-AVGs share similar early patency rates, UA-AVFs may be a better choice for chronic hemodialysis access because of a lower incidence of complications and nonelective reinterventions. To maximize the benefits of UA-AVFs, however, early surgical referral is required.

Aged↗
PubMed2005

Assessment of pretransplant inflammation in pediatric renal allograft recipients.

Pretransplant (Tx) inflammation is linked to adverse outcomes in adult Tx recipients but no such data exist for children. Our study evaluated the predictive value of three pre-Tx inflammatory markers: serum C-reactive protein (CRP), Neopterin (Neo) and interleukin (IL) 12, in determining outcome. Pre-Tx serum on 51 children (mean age 11 years) transplanted between 1985 and 2000 was analyzed. Data on other variables were abstracted from patient records. Primary end-points were graft survival and acute rejection (AR). Kaplan-Meier and log-rank statistics compared endpoints in patients at different quartiles for each marker. Cox regression analysis was used to determine the independent effect of the markers on the end-points. The mean CRP, Neo, and IL-12 were 1.3 mg/l, 1.78 ng/ml, and 123 pg/ml, respectively. The mean CRP, Neo, and IL-12 were not different between the patients with and without AR or graft loss (P > 0.4 for all). Neither rejection-free survival nor graft survival was affected by CRP, Neo, or IL-12 quartiles. Cox-regression analysis demonstrated no predictive value of any marker on outcome. Unlike adults, a single pre-Tx determination of inflammatory markers was not predictive of AR or graft loss in children, indicating that the pathogenesis of AR may be different in children.

Adolescent↗
PubMed2005

Laparoscopic live donor nephrectomy: a risk factor for delayed function and rejection in pediatric kidney recipients? A UNOS analysis.

The impact of laparoscopic (vs. open) donor nephrectomy on early graft function and survival in pediatric kidney recipients (< or =18 years) is unknown. We studied 995 pediatric live donor txs reported to UNOS from January 2000 to June 2002, in two recipient age groups: 0-5 years (n = 212, 44% laparoscopic donors [LapD]) and 6-18 years (n = 783, 50% LapD). Delayed graft function (DGF) rates were higher for LapD versus open donor (OpD) txs (0-5 years, 12.8% vs. 2.5% [p = 0.004]; 6-18 years, 5.9% vs. 2.8% [p = 0.03]). Acute rejection incidence for LapD versus OpD txs was higher at 6 months for recipients 0-5 years (18.6% vs. 5.9%, p = 0.01) and 6-18 years (22.5% vs. 15.6%, p = 0.03), and 1 year for recipients 0-5 years (24.3% vs. 7.9%, p = 0.004). In multivariate analyses, significant independent risk factors for rejection at 6 months and 1 year were recipient age 6-18 years, pretx dialysis, LapD nephrectomy and DGF. Graft survival was similar for LapD versus OpD txs. In this retrospective UNOS database analysis, LapD procurement was associated with increased DGF and an independent risk factor for rejection during the first year, particularly for recipients 0-5-years old. Future investigations must confirm these findings and identify strategies to optimize procurement and pediatric recipient outcome.

Adolescent↗
PubMed2004

Occult pretransplantation systemic inflammation and posttransplantation vascular changes in a primate arterial allograft model.

BACKGROUND: Occult systemic inflammation, as manifested by increased levels of C-reactive protein (CRP), identify patients at increased risk for renal allograft rejection. The mechanisms linking occult systemic inflammation to these adverse outcomes remain unclear. The purpose of this study was to examine the anatomic and physiologic effects of occult pretransplantation systemic inflammation on posttransplantation allograft outcome in a nonhuman primate model. METHODS: Seventy-one healthy male Rhesus macaques were stratified into quartiles based on serum CRP. Five high quartile and six low quartile animals underwent common iliac artery transplantation from male donors. Duplex ultrasound measured graft flow at 3 weeks postoperatively; luminal narrowing was assessed by graft/femoral peak systolic velocity ratio. At 6 weeks, the grafts were harvested and morphometry studies were performed. Vessel wall changes were assessed by measuring the intimal medial area. RESULTS: The allografts placed in high CRP quartile animals had more luminal narrowing by 3 weeks than those placed in low quartile animals, as evidenced by a higher mean graft/femoral peak systolic velocity ratio (1.6 vs. 0.90, P=0.006). Morphometry studies after graft harvest showed increased vessel wall area in the high quartile group versus the low quartile group (1.39 mm vs. 1.03 mm, P=0.018). CONCLUSIONS: Occult pretransplantation systemic inflammation is associated with increased intimal thickening and stenosis after arterial allograft transplantation in a primate model. Additional studies are needed to confirm these results and to further investigate potential mechanisms linking pretransplantation systemic inflammation to adverse outcomes after transplantation.

Animals↗
PubMed2004

Pretransplant recipient cytomegalovirus seropositivity and hemodialysis are associated with decreased renal allograft and patient survival.

BACKGROUND: Pretransplant systemic inflammation has been associated with decreased renal allograft survival, and infectious agents such as cytomegalovirus (CMV) may play a role. We hypothesized that pretransplant CMV seropositivity is a risk factor for decreased patient and allograft survival after cadaveric renal transplantation and that other factors believed to modulate systemic inflammation, such as dialysis modality, might act synergistically with CMV to decrease patient and allograft survival. METHODS: The United Network for Organ Sharing database was reviewed to identify all patients undergoing cadaveric renal transplantation in the United States from 1988 to 1997. Outcomes for CMV seropositive and seronegative recipients of organs from CMV seronegative donors were analyzed. Subgroup analysis was performed to identify any synergistic influence on outcome between CMV serostatus and known determinants of risk, including degree of human leukocyte antigen mismatch, pretransplant dialysis, and cold ischemia time. RESULTS: Of 29,875 patients who underwent transplantation, 12,239 were CMV seronegative and 17,636 were CMV seropositive. Patient survival was decreased by pretransplant seropositivity (relative risk [RR] 1.11, P =0.001). In addition, this group demonstrated worse overall allograft survival (RR 1.05, P =0.029), although this adverse effect disappeared when patients who died with a functioning graft were censored. Decreased allograft survival was most pronounced in patients who were on hemodialysis before transplantation (RR 1.62, P =0.004). CONCLUSIONS: Pretransplant CMV seropositivity is associated with decreased patient survival. Pretransplant CMV seropositivity and hemodialysis have a synergistic adverse effect on graft survival, independent of patient mortality. Additional studies are required to define mechanisms by which pretransplant CMV infection and dialysis modality may contribute to decreased allograft survival.

Acute Disease↗
PubMed2004

Outcomes of upper arm arteriovenous fistulas for maintenance hemodialysis access.

HYPOTHESIS: Radiocephalic fistulas for maintenance hemodialysis access are not feasible in all patients with end-stage renal disease. Our aim was to review our experience with 3 types of upper arm arteriovenous fistula (AVF) to ascertain whether they are reasonable alternatives to radiocephalic fistulas and which, if any, have superior performance. PATIENTS AND METHODS: Patient medical records were retrospectively reviewed. The main outcomes were maturation rate, time to maturation, assisted maturation rate, complication rates, reintervention rates, primary and assisted primary patency rates, and effects of comorbidities. RESULTS: Eighty-six patients with end-stage renal disease underwent creation of a brachiocephalic, brachiobasilic, or brachial artery-to-median antecubital vein AVF. Overall, 80% matured, with 23% requiring an intervention to achieve maturity. The mean time to maturation was 3.8 months; 47% had a complication (inability to access, thrombosis, and so on), and 43% required additional interventions. The overall primary patency and assisted primary patency rates at 12 months were 50% and 74%, respectively. Brachiobasilic AVFs not superficialized immediately often needed a second operation. There were no significant differences in patency rates among the 3 AVF types. The AVFs in patients with diabetes took 2 months longer to mature than did those in patients without diabetes. CONCLUSIONS: An upper arm AVF is a reasonable alternative for maintenance hemodialysis access when a radiocephalic AVF is not possible. There are 3 valid options from which to choose to best accommodate each patient's antecubital anatomy. Diabetes may adversely affect outcomes. Our data suggest that brachiobasilic AVFs should be superficialized at the initial procedure, if feasible.

Adult↗
PubMed2004

The unrecognized posterior gastric artery: a potential cause of surgical complications in pancreas transplantation.

BACKGROUND: Our report describes, for the first time, a pre-transplant vascular complication in a pancreas graft related to the posterior gastric artery - a major, but relatively unknown side branch of the splenic artery. The posterior gastric artery that was overlooked by a surgical procurement team during donor pancreatectomy led to distortion of the peripancreatic vascular anatomy and set the stage for a splenic artery injury. METHODS: We identified the transected, partially resected graft splenic artery during backtable preparation of the pancreas, and repaired it using standard vascular surgical techniques. RESULTS: The recipient's post-operative course was uncomplicated. At 9-yr post-transplant, the recipient is alive with good pancreas graft function. CONCLUSIONS: The relevance of the posterior gastric artery with regard to general surgical procedures was only recently recognized. Our case demonstrates that the posterior gastric artery is also important in transplant surgery. Awareness of this anatomical structure during organ procurement would help minimize pre-transplant vascular complications.

Adult↗
PubMed2004

Acute renal transplant injury and interaction between antithymocyte globulin and pooled human immunoglobulin.

The increasing number of highly sensitized patients awaiting renal transplantation has prompted the use of induction immunosuppression regimens including pooled human intravenous immunoglobulin (IVIG) combined with polyclonal anti-lymphocyte sera. We report a case of a patient who received a live donor transplant after abrogation of donor-specific positive cytotoxic crossmatch by IVIG. She developed early acute tubular injury associated with IVIG, mannitol, and hypertonic saline infusion. Furthermore, a possible interaction between IVIG and rabbit antithymocyte globulin (ATG) occurred, suggested by an increased number of peripheral CD3(+) lymphocytes after initial rapid lymphodepletion. We suggest that IVIG-associated nephrotoxicity should be considered in the differential diagnosis of early allograft dysfunction, and furthermore, that IVIG may interact with polyclonal antilymphocyte serum to affect the amount of lymphodepletion achieved.

Antilymphocyte Serum↗
PubMed2004

Pre-transplant elevations of interleukin-12 and interleukin-10 are associated with acute rejection after renal transplantation.

BACKGROUND: Methods for predicting patients at higher risk for rejection before transplantation may help improve outcomes. We hypothesized that pre-transplant elevations of serum interleukin-12 (IL-12), a pro-inflammatory cytokine, would predict acute rejection, while pre-transplant IL-10, an immunoregulatory cytokine, would be down-regulated in patients subsequently experiencing acute rejection. MATERIALS AND METHODS: Thirty patients experiencing acute rejection after cadaveric renal allograft transplantation and a control group of 30 patients, undergoing the same procedure but without the occurrence of rejection, were identified. Serum samples taken before transplantation from each patient were then analyzed quantitatively for IL-12 and IL-10 using ELISA assays. RESULTS: The mean pre-transplant serum IL-12 level was higher in patients who subsequently underwent acute rejection vs. those who did not (181 +/- 143 pg/mL vs. 81.2 +/- 71.5 pg/mL, respectively, p = 0.007). Unexpectedly, pre-transplant serum IL-10 levels were also elevated in patients who underwent rejection (559 +/- 293 pg/mL vs. 332 +/- 163 pg/mL, respectively, p = 0.002). Multivariate analysis demonstrated that elevations of IL-12 and IL-10 were independent risk factors for rejection when adjusted for confounding variables. CONCLUSIONS: Pre-transplant elevations of IL-12 and, unexpectedly, IL-10 are associated with acute rejection after cadaveric renal transplantation and may be useful in predicting which patients are at increased immunological risk at the time of transplantation. Further studies are necessary to assess the role of occult systemic inflammation in contributing to poor outcomes after transplantation.

Case-Control Studies↗
PubMed2004

Impact of portal venous pancreas graft drainage on kidney graft outcome in simultaneous pancreas-kidney recipients reported to UNOS.

Clinical data on the potential immunologic impact of portal (PD) vs. systemic (SD) venous pancreas graft drainage on outcome remains controversial. We reviewed the UNOS database to study the effect of PD vs. SD on the incidence of kidney graft rejection and survival in first cadaveric simultaneous pancreas-kidney (SPK) recipients transplanted 1994-2001. We studied three groups: all SPK (n=6629, 13% PD) (group I), SPK on tacrolimus (n=3563, 17% PD) (group II), and SPK on tacrolimus performed at centers with significant PD experience (n=948, 46% PD) (group III). The cumulative kidney graft rejection incidence for PD vs. SD was only significantly different in group I (for PD vs. SD, respectively: at 6 months, 31% vs. 36% [p=0.015]; at 1 year, 37% vs. 43% [p=0.006]). Kidney graft survival was similar in all groups for PD vs. SD. Multivariate analysis of group III showed only transplantation during the earlier era (1994-96), but not SD, to be an independent risk factor for kidney graft rejection. Portal venous pancreas graft drainage does not affect kidney graft rejection and survival in SPK recipients on tacrolimus. Our data suggests that the efficacy of current immunosuppressive protocols and increasing center experience are clinically much more relevant than any potential immunologic advantage of portal venous drainage in SPK recipients.

Adult↗
PubMed2004

Disseminated microsporidiosis in a pancreas/kidney transplant recipient.

Human microsporidiosis has been described most commonly in patients with acquired immunodeficiency syndrome and only rarely in those with other forms of immunosuppression. Only 11 cases of microsporidiosis have been reported previously in solid transplant recipients. To our knowledge, this is the first report to describe a case of microsporidiosis in a pancreas/kidney transplant recipient in whom multi-organ system dissemination was observed. This infection was not detected until postmortem examination of stained tissue sections revealed microsporidian spores that were identified as Encephalitozoon species by transmission electron microscopy. It is suspected that leakage from the duodenal anastomosis to the bladder may have contributed to the dissemination of this infection.

Adult↗
PubMed2004

Intra-access blood flow in patients with newly created upper-arm arteriovenous native fistulae for hemodialysis access.

BACKGROUND: The upper-arm native arteriovenous fistula for hemodialysis (HD) vascular access is an important option in the long-term HD population. This single-center cohort study evaluated intra-access blood flow (Q AC) in 3 variants of newly created upper-arm fistulae. METHODS: Fifty-three patients with mature, working, upper-arm fistulae composed of brachial artery to cephalic vein (n = 27), brachial artery to basilic vein (n = 13), and brachial artery to median antecubital vein (n = 13) fistulae were included. Nine of 13 brachio-median antecubital fistulae were of the Gracz type and used the deep perforating vein. Q AC was measured by means of ultrasound velocity dilution during HD. In brachio-median antecubital fistulae, additional flow in the alternate draining vein was measured by means of duplex ultrasound, with 9 of 11 studied patients showing a patent alternate outflow, of whom 7 patients showed substantial flow (median, 0.7 L/min). RESULTS: Q AC in the HD-used primary vein in brachio-median antecubital fistulae (0.85 L/min) was significantly less than those of brachiocephalic and brachiobasilic fistulae (1.4 and 1.7 L/min, respectively). However, when the additional flow provided by the patent alternate vein in brachio-median antecubital fistulae was considered, flow rates provided by all 3 variants of fistulae appeared similar. The inverse correlation between alternate-vein and primary-vein flows (r = -0.70; P = 0.017) suggested there was competitive flow between the 2 venous outlets. There was no instance of access recirculation. CONCLUSION: Upper-arm fistulae, regardless of type, provide excellent blood flows and should be considered routinely if a wrist fistula is not feasible. The patent alternate vein in the brachio-median antecubital or Gracz fistula may continue to drain a substantial amount of blood.

Adult↗
PubMed2003

Higher surgical wound complication rates with sirolimus immunosuppression after kidney transplantation: a matched-pair pilot study.

Sirolimus, a potent new immunosuppressant, has been anecdotally associated with surgical wound complications. We studied postoperative surgical wound complications in 15 kidney recipients receiving sirolimus, prednisone, and tacrolimus or cyclosporine (study group) compared with 15 recipients receiving tacrolimus, prednisone, and mycophenolate mofetil who were pair-matched for surgical wound complication risk factors. Surgical wound complications were defined as any complication related to the surgical transplant wound requiring reintervention. Fifty-three percent of the study group and 7% of the control group experienced more than one surgical wound complication (P=0.014), and the relaparotomy incidence was 33% and 7%, respectively. Four graft losses have occurred since the beginning of the study: one chronic rejection and two deaths with function in the study group, and one death with function in the control group. At 1 year, graft survival for study recipients compared with control recipients was 87% and 93%, respectively; patient survival was 93% in both groups. Recipients receiving sirolimus demonstrated a significantly higher surgical wound complication rate, but graft and patient survival were not affected. Peritransplant immunosuppression with sirolimus and steroids warrants careful consideration, particularly in recipients with surgical complication risk factors.

Adult↗
PubMed2003

Amelioration of tacrolimus-induced nephrotoxicity in rats using juniper oil.

BACKGROUND: Calcineurin-inhibitor nephrotoxicity plays a role in the pathogenesis of chronic allograft nephropathy by causing renal ischemia mediated by vasoconstrictive metabolites of the prostanoid pathway. The purpose of our study was to evaluate whether altering the prostanoid profile using juniper oil (JO) would afford renoprotection in rats treated with tacrolimus. METHODS: Diets supplemented with biologic oils (no supplementation, JO, fish oil [FO], safflower oil [SO], and arachidonic acid [AA]) were fed to five groups of rats for 5 weeks; during the last 2 weeks, tacrolimus was administered to all groups except for a control group of animals. At week 5, urinary prostaglandin (PG)F(2-alpha) and inulin clearances were measured. The rat kidneys were harvested to determine the renal cell membrane composition for arachidonic, eicosatrienoic, and eicosapentaenoic acids. RESULTS: Both JO and FO completely reversed the decrease in inulin clearance seen with tacrolimus, the greatest effect being with JO (inulin clearance 15.1+/-3 vs. 6.0+/-1.1 ml/min in the nonsupplemented group; P<0.001); urinary PGF(2-alpha) excretion was also highest in the JO group (328+/-23 pg/mL, P<0.001 vs. the nonsupplemented group). Fatty acid membrane analysis showed greatest incorporation of eicosapentaenoic and eicosatrienoic acids in the JO- (5.7+/-0.6% and 3.1+/-0.4%, respectively) and FO- (8.1+/-0.7% and 2.8+/-0.6%, respectively) treated animals. CONCLUSIONS: JO supplementation in tacrolimus-treated rats was associated with incorporation of vasodilatory prostanoids in the renal-cell membrane and elevated urinary PGF(2-alpha) excretion, and the precipitous fall in inulin clearance induced by tacrolimus was completely prevented. Whether this benefit will translate into a reduction in chronic allograft nephropathy remains to be determined. However, our preliminary data point towards the need for human trials.

Animals↗
PubMed2003

The presence of a local lung transplant center increases lung procurement rates.

BACKGROUND: The availability of cadaveric organs is the major problem in transplantation today. METHODS: A retrospective review of donors in a single organ procurement organization (OPO) was performed. Donors were divided into three eras: before, during, and after the presence of a local lung transplant program. Lung procurement rates by OPO in the United States in 1999 and 2000 were also retrospectively reviewed. RESULTS: Lung transplant rates were higher in the presence of a local lung program: 4.9% at baseline, 19.1% with a local program, and 7.1% after closure of the local lung program (P<0.01). In the United States, 12.4% of lungs available in OPOs with local lung programs are transplanted, versus 8.9% in OPOs without a local program (P<.001). CONCLUSIONS: Even if donor management protocols are maintained, closure of a local lung program decreases lung recovery rates. This observation supports the importance of maintaining local programs to maximize organ recovery rates.

ABO Blood-Group System↗
PubMed2003

Pretransplantation soluble adhesion molecule expression predicts outcome after living donor renal transplantation.

HYPOTHESIS: Occult pretransplantation systemic inflammation will identify patients at risk for poor outcomes after renal transplantation. DESIGN: Retrospective cohort study. Adhesion molecule levels were measured in pretransplantation serum samples from 86 recipients. Univariate and multivariate analyses were conducted to assess a possible correlation between serum adhesion molecule level and outcome. SETTING: University referral center. MAIN OUTCOME MEASURES: Allograft rejection and survival. RESULTS: Patients with low levels of vascular cell adhesion molecule 1 had less graft rejection (P=.007). Low levels of vascular cell adhesion molecule 1 independently predicted decreased rejection (relative risk, 0.17; P=.01), and high levels of vascular cell adhesion molecule 1 independently predicted graft loss (relative risk, 3.83; P=.02). Similar correlations were observed for intercellular adhesion molecule 1. CONCLUSIONS: Decreased pretransplantation adhesion molecule expression correlates with less rejection, and increased levels correlate with graft loss. Assessment of pretransplantation inflammatory status may be useful in optimizing immunosuppression therapy.

Adult↗
PubMed2003

Laparoscopic (vs open) live donor nephrectomy: a UNOS database analysis of early graft function and survival.

The impact of laparoscopic (lap) live donor nephrectomy on early graft function and survival remains controversial. We compared 2734 kidney transplants (tx) from lap donors and 2576 tx from open donors reported to the U.S. United Network for Organ Sharing from 11/1999 to 12/2000. Early function quality (>40 mL urine and/or serum creatinine [creat] decline >25% during the first 24 h post-tx) and delayed function incidence were similar for both groups. Significantly more lap (vs. open) txs, however, had discharge creats greater than 1.4 mg/dL (49.2% vs. 44.9%, p = 0.002) and 2.0 mg/dL (21.8% vs. 19.5%, p = 0.04). But all later creats, early and late rejection, as well as graft survival at 1 year (94.4%, lap tx vs. 94.1%, open tx) were similar for lap and open recipients. Our data suggests that lap nephrectomy is associated with slower early graft function. Rejection rates and short-term graft survival, however, were similar for lap and open graft recipients. Further prospective studies with longer follow up are necessary to assess the potential impact of the laparoscopic procurement mode on early graft function and long-term outcome.

Adult↗