Laparoscopic Versus Open Renal Procurement for Pediatric Recipients of Living Donor Renal Transplantation

Despite reports demonstrating the safety of laparoscopic donor nephrectomy (LDN) for pediatric recipients of renal transplants, recent evidence has challenged using LDN for recipients 5 years of age or younger. We retrospectively reviewed the records of all pediatric recipients of living donor renal transplants from September 2000 through August 2004. We compared those who received allografts recovered by LDN (n = 34) with those recovered by open donor nephrectomy (ODN, n = 26). Outcomes of interest included operative complications, postoperative renal function, the incidence of delayed graft function or episodes of acute rejection and long-term graft function. Donor and recipient demographic data were similar for the LDN and ODN groups. Serum creatinine and calculated creatinine clearance were not significantly different between groups both in the early postoperative period and at long-term follow-up (p > 0.142). Rates of delayed graft function and acute rejection did not differ between groups. Among recipients aged 5 years old or younger stratified by donor technique (9 LDN, 5 ODN recipients), no difference was noted in graft outcomes both early and long-term (p > 0.079). At our center, pediatric LDN recipients have graft outcomes comparable to those of ODN recipients. At experienced centers, we recommend continued use of LDN for pediatric recipients of all ages.     

Mutation of the surface-exposed amino acid Trp to Ala in the FVIII C2 domain results in defective secretion of the otherwise functional protein

The C2 domain of factor VIII (FVIII) is important for FVIII-phospholipid (PL) and FVIII-von Willebrand factor (VWF) interactions. A FVIII structural model, derived by electron crystallography, suggests four hydrophobic loops at the FVIII C2 domain-PL interface. Within loop four, the solvent-exposed amino acid, Trp(2313), is believed to contribute to FVIII-PL binding. To analyse this interaction, the amino-acid exchange Trp(2313) to Ala (W2313A) was introduced into the C2 domain of B-domain-deleted FVIII (dBFVIII). Both proteins, dBFVIII and W2313A, were expressed in a mammalian expression system. Labelling experiments showed that the mutation W2313A resulted in reduced secretion but did not affect intracellular synthesis of the protein. Specific activity, kinetic parameters, binding to VWF and haemostatic potential in a murine model of haemophilia A were found to be similar for both proteins. Binding studies to synthetic 4% phosphatidyl-l-serine vesicles showed, however, a 28-fold higher K(D) for W2313A, indicating the important role of Trp(2313) in the FVIII-PL interaction. In conclusion, the C2-domain-surface-exposed residue Trp(2313), is critical for secretion of the protein. The W2313A mutation weakens binding to phosphatidyl-l-serine vesicles but the mutant protein has the same effector function as dBFVIII in vitro and in vivo.     

Evaluation of the haemostatic potential of factor VIII-heparin cofactor II hybrid proteins in a mouse model

We constructed factor VIII-heparin cofactor II (FVIII-HCII) hybrid molecules, which are more readily activated by thrombin in vitro than the respective wild-type molecules. The hybrid proteins were tested in a murine model of haemophilia A to investigate their haemostatic efficacy in vivo. Bleeding characteristics, measured using standard tail-tip cutting techniques, were total blood loss, bleeding time and survival rate. FVIII-HCII hybrids were found to be effective in preventing bleeding in FVIII knockout mice. While in vitro experiments showed that the chimaeric molecules had higher haemostatic functions than the wild-type proteins, the variables analysed in vivo were similar for both proteins.     

Use of heparin and protamine sulfate during laparoscopic donor nephrectomy

BACKGROUND: Our aim was to evaluate the necessity of heparin and protamine administration during laparoscopic donor nephrectomy. METHODS: Data from 52 consecutive living-related laparoscopic donor nephrectomies performed at University of California Los Angeles between August 1999 and August 2001 were used for this analysis. For the purpose of this analysis, the patients were divided into three cohorts: group A received both heparin and protamine; group B received heparin only; and group C received neither. Intraoperative blood loss, length of admission, recipient creatinine at follow-up, and intraoperative and postoperative complications were compared between the groups. Statistical analysis was performed using a two-tailed test. RESULTS: There were no significant differences between the groups with regard to patient age and gender. Intraoperative blood loss did not differ between group B (99+/-73 mL) and group C (82+/-54 mL) ( =0.4). None of the patients required blood transfusion. No graft loss occurred in any group. Length of hospital stay, excluding any preoperative days, was similar (2.8+/-0.7, 2.9+/-1.6, and 2.5+/-0.8 days, for groups A, B, and C, respectively, ( >0.05). No systemic thromboembolic complications were noted in any of the groups. One patient in group B was converted to an open procedure because of a difficult dissection unrelated to heparin administration. The mean recipient creatinine levels at follow-up in the recipients of kidneys from groups A, B, and C were not significantly different (1.1, 1.3, and 1.3; >0.05) through the extended follow-up period of 691, 286, and 97 days, respectively. CONCLUSIONS: According to our experience, there is no apparent benefit in the administration of heparin alone or in the administration of protamine sulfate to reverse heparin anticoagulation during laparoscopic donor nephrectomy if heparin is given. This is not only in terms of bleeding complications but is also true in regard to recipient renal function through the follow-up period. It is important to note that our warm ischemic times were less than 2 minutes, because longer warm ischemic times may make the use of heparin a more important consideration. This is the first time that these questions have been studied in the laparoscopic donor nephrectomy population.     

Dual kidneys from marginal adult donors as a source for cadaveric renal transplantation in the United States

The current organ shortage has led to the utilization of double kidney transplants from marginal adult donors, but outcomes data are limited. The United Network for Organ Sharing registry database was used to compare the outcomes of 403 dual adult kidney transplantations (DKT) and 11,033 single kidney transplantations (SKT) from 1997 to 2000. Graft and patient survival and the effect of multiple risk factors were evaluated. It was found that DKT patients were older, less sensitized, and received grafts from older, more mismatched donors with longer cold ischemia times. There was also a greater percentage of donors with a history of diabetes or hypertension and African-American recipients and donors in the DKT group. Graft survival was inferior in the DKT group, with a 7% lower graft survival rate at 1 yr. There was a higher incidence of primary nonfunction in the DKT group, although the incidence of delayed graft function, early rejection treatment, and graft thrombosis did not differ. Multivariate analysis was used to identify African-American recipient ethnicity and retransplant as risk factors for graft loss. Graft survival was comparable in DKT and SKT with donors over 55 yr of age. DKT resulted in inferior graft outcomes compared with SKT. When compared with SKT with donors over 55 yr of age, DKT resulted in similar graft outcomes. These otherwise discarded kidneys should be cautiously considered as a source of marginal donors.     

Continuous infusion of FVIII and FIX concentrates: in vitro analysis of clinically relevant parameters.

A high purity factor VIII/von Willebrand Factor (FVIII/vWF) concentrate (IMMUNATE [STIM plus]) (n = 6 batches), and a high purity factor IX (FIX) concentrate (IMMUNINE [STIM plus]) (n = 7 batches), were assessed in vitro for their applicability to continuous infusion. Parameters pertinent to continuous infusion were investigated and included stability, sterility and, in the case of FIX, the generation of potentially thrombogenic components. Four stationary or transportable mini infusion pumps, equipped with polyethylene, polypropylene or polyvinylchloride plastic components were used. The concentrates were reconstituted without extra filling volume and perfused at 12.5 mL h-1 and 1 mL h-1; sampling was carried out at the start of the experiment and for up to 48 h. The FVIII procoagulant activity (FVIII:C) was assayed by amidolytic, 1-stage and 2-stage assays; vWF was examined for ristocetin cofactor activity, antigen and multimers. The FIX coagulation activity (FIX:C) was determined by a 1-stage coagulation assay; thrombogenicity potential was assessed in vivo (Wessler stasis model in rabbits) and in vitro (FIXa and nonactivated thromboplastin time). Reconstituted concentrate incubated under the same conditions served as a control. Both concentrates remained sterile throughout the testing period. The perfused and control samples remained stable, retaining over 95% of activity for FVIII:C and over 90% for FIX:C for up to 48 h. Intermittent decrease of FVIII:C or FIX:C was not observed, suggesting no adsorption of FVIII or FIX onto plastic surfaces during either short or long-term exposure. No thrombogenic components were detected in the high purity FIX concentrate. Thus, under the in vitro conditions used, FVIII/vWF and FIX were found to be suitable for administration by continuous infusion.     

FEIBA®: mode of action

Summary.  FEIBA^® (factor eight inhibitor bypassing activity) has a history of more than 30 years of successful use in controlling bleeding in haemophilic patients who have developed inhibitory antibodies against factor (F)VIII or FIX. Recently it was shown that FEIBA^® contains the proenzymes of the prothrombin complex factors, prothrombin, FVII, FIX and FX, but only very small amounts of their activation products, with the exception of FVIIa, which is contained in FEIBA^® in greater amounts. FEIBA^® controls bleeding by induction and facilitation of thrombin generation, a process for which FV is crucial. A number of biochemical in vitro and in vivo studies have shown that FXa and prothrombin play a critical role in the activity of FEIBA^®. Consequently, they are considered to be key components of this product. The prothrombinase complex has been found to be a major target site for FEIBA^®. Apart from prothrombin and FXa, FEIBA^® contains other proteins of the prothrombin complex, which could also facilitate haemostasis in haemophilia patients with inhibitors.