Vascular anastomosis model: relation between competency in a laboratory-based model and surgical competency.

BACKGROUND: Previously, we presented a new, laboratory-based, vascular anastomosis model as a tool to objectively quantify surgical skill. The purpose of the present study was to determine the relation between the outcomes of vascular anastomosis in the laboratory and technical competency, when performing similar vascular anastomoses, in the operating room. MATERIALS AND METHODS: Twenty-nine resident surgeons-in-training participated in the present study. All residents had at least one previous laboratory training session using the vascular anastomosis model. Then residents had to create a forearm arterio-venous bridge graft in the operating room (OR). Three measures were used to assess technical competency in the OR: completion time of the graft to vein anatomosis, leakage grade across the anastomosis, and the mini-objective structured assessment of technical skills (MOSAT) score. Similar outcomes obtained in the laboratory were used as predictors of OR outcomes. Significant predictors were identified using multiple linear regression and multiple ordinal logistic regression modelling. RESULTS: Worse leakage in the laboratory predicted worse leakage in the OR, longer completion time and worse MOSAT score in the OR. Longer completion time in the laboratory was associated with longer OR completion time, but less leakage. Higher year of training and greater laboratory exposure were related to higher MOSAT score and shorter completion time in the OR, respectively. CONCLUSIONS: Completion time and grade of anastomosis leakage measured in the laboratory were predictive of technical competency in the OR. The vascular anastomosis model may be useful for training in clinical surgery.

Impact of recipient obesity on living donor kidney transplant outcomes: a single-center experience.

The number of overweight and obese patients undergoing renal transplantation has drastically increased in the last two decades. Studies on graft survival and complication rates of these obese patients have had conflicting results, with some reporting a significant risk and others reporting relatively good outcomes. We examined 1-year outcomes in obese and nonobese patients who underwent living donor transplants at our transplant program, a slightly different approach than prior studies of deceased donor transplants into patients with high body mass index (BMI). The mean serum creatinine clearance by the modified MDRD equation at the end of 1 year in the nonobese group was 58.9 mL/min whereas the mean creatinine clearance in the obese group was 48.9 mL/min (P = .09). The length of stay, incidence of delayed graft function, and 1-year graft survival did not differ between the obese and nonobese groups. The results of this single-center experience with living donor transplant into obese subjects suggest no differences in outcomes with regard to surgical or wound complications, delayed graft function, or serum creatinine at 1 year.

A new vascular anastomosis model: relation between outcome and experience.

BACKGROUND: Vascular anastomosis is a complex task that requires multiple skills. Existing training methods lack the ability to objectively quantify surgical skill. In this study we tested a new vascular anastomosis model for bench training. MATERIALS AND METHODS: Surgical performance was assessed based on the new vascular anastomosis training model. Thirty- eight subjects were asked to (1) close the end of a 6-mm polytetrafluoroethylene (PTFE) graft, using a continuous suturing technique with 6-0 polypropylene; (2) perform end-to-end and (3) end-to-side anastomosis using the same materials and techniques. RESULTS: The mean age (sd) of all participants was 28.3 (2.1) years. More surgically experienced trainees did better in all measures of technical skill. Although there was a tendency for those with previous experience with the training model to do better in terms of the technical outcomes, these differences were not statistically significant. Multivariable analysis revealed that level of surgical training and type of anastomosis were the only significant factors related to completion time. CONCLUSIONS: Our study confirmed the impact of increasing surgical experience on the technical skills of surgical trainees. Trainees with higher levels of training made fewer errors and completed the procedures faster than those with lower levels of training.

Angiocidal effect of Cyclosporin A: a new therapeutic approach for pathogenic angiogenesis.

AIM: Angiogenesis is essential in the development of several disorders such as cancer, arthritis, and autoimmune diseases. Several agents prevent angiogenesis but only a few destroy established angiogenesis. In this study we tested whether local or systemic administration of Cyclosporin A (CyA) would inhibit as well as destroy established angiogenesis in an in vivo assay of angiogenesis. METHODS: We utilized an in vivo assay of angiogenesis in which an angiogenic mixture of Matrigel, FGF, VEGF, and heparin was injected subcutaneously into mice. Angiogenesis in the subcutaneous plugs was quantified by ANOVA. CyA or the vehicle for CyA was administered to the experimental or the control groups by three routes: by addition to the angiogenic mixture, by local injection into the angiogenic plug at various time points or by systemic administration at high doses. Angiogenesis was quantified by pointing method and expressed as an angiogenic index (AI). RESULTS: In control animals the subcutaneous plug of Matrigel with the angiogenic mixture revealed exuberant angiogenesis at day 4 and day 7. This angiogenesis was completely inhibited when CyA was included in the angiogenic mixture; the vehicle for CyA had no such effect. Angiogenesis that had progressed was found to regress after local subcutaneous injection of CyA at day 4 and 7. Similar regression of angiogenesis was noted when CyA was administered systemically after allowing angiogenesis to proceed for 4 days. CONCLUSIONS: Our experiments strongly suggest that CyA is both angiocidal and angiostatic in vivo. These results provide a basis for future therapy directed against established angiogenesis in malignancies and autoimmune diseases.

Late abscess formation after spilled gallstones masquerading as a liver mass.

The most common complication during laparoscopic cholecystectomy is the spillage of stones into the abdominal cavity. Although spillage occurs in 30% of cases, the potential adverse effects of this event are rare and generally manifest within months. When complications do occur, however, they may cause significant morbidity for the patient. We report an unusual case in which an inflammatory mass mimicking a liver tumor developed 5 years after the stones had been lost during a laparoscopic cholecystectomy. We therefore urge all surgeons to make every attempt to retrieve gallstones from the abdominal cavity once they have been accidentally dropped.

Laparoscopic live donor nephrectomy: the recipient.

BACKGROUND: Laparoscopic live donor nephrectomy offers advantages to the donor in terms of decreased pain and shorter recuperation. Heretofore no detailed analysis of the recipient of laparoscopically procured kidneys has been performed. The purpose of this study was to determine whether laparoscopic donor nephrectomy had any deleterious effect on the recipient. METHODS: A retrospective review was conducted of all live donor renal transplantations performed from January 1995 through April 1998. The control group received kidneys procured via a standard flank approach (Open). Rejection was diagnosed histologically. Creatinine clearance was calculated using the Cockroft-Gault formula. RESULTS: A total of 110 patients received kidneys from laparoscopic (Lap) and 48 from open donors. One-year recipient (100% vs. 97.0%) and graft (93.5% vs. 91.1%) survival rates were similar for the Open and Lap groups, respectively. A similar incidence of vascular thrombosis (3.4% vs. 2.1%, P=NS) and ureteral complications (9.1% vs. 6.3%, P=NS) were seen in the Lap and Open groups, respectively. The incidence of acute rejection for the first month was 30.1% for the Lap group and 31.9% for the Open group (P=NS). The rate of decline of serum creatinine level in the early posttransplantation period was initially greater in the Open group, but by postoperative day 4 no significant difference existed. No difference was observed in allograft function long-term. The median length of hospital stay was 7.0 days for both groups. CONCLUSIONS: Laparoscopic live donor nephrectomy does not adversely effect recipient outcome. The previously demonstrated benefits to the donor, and the increased willingness of individuals to undergo live kidney donation, coupled with the acceptable outcomes experienced by recipients of laparoscopically procured kidneys justifies the continued development and adoption of this operation.

Intravenous mycophenolate mofetil: safety, tolerability, and pharmacokinetics.

An intravenous (i.v.) formulation of mycophenolate mofetil (MMF; CellCept, Roche Pharmaceuticals, Inc., Palo Alto, CA) that will enable its administration to patients unable to tolerate oral medication is available. Two separate studies, an open-labeled pharmacokinetic (PK) study and a double-blind safety study, were performed. Within 24 h after transplant, 153 (safety study) and 45 (PK study) first or second renal transplant recipients were started on i.v. MMF 1 g Q12h or placebo (used in the safety study only, 2:1 MMF:placebo), given over 2 h via a dedicated peripheral venous catheter. In the safety study, per os (p.o.) MMF (1g Q12h) or placebo was administered, starting within 72 h after transplant, whereas in the PK study, p.o. MMF was started on the evening of day 5. Sequential blood samples obtained on study days 5 (i.v. MMF) and 6 (p.o. MMF) before and up to 12 h after the AM dose were analyzed for mycophenolic acid (MPA) and MPA glucuronide (MPAG) concentrations by high-performance liquid chromatography. The area under the concentration curve (AUC) was calculated using the linear trapezoidal rule. The MPA AUC(0-12) was higher for i.v. MMF than p.o. MMF (40.8 +/- 11.4 microg x h/ mL vs. 32.9 +/- 15, p < 0.001). There were no other significant PK differences for plasma MPA or MPAG. In the safety study (n = 98 i.v. MMF vs. n = 55 placebo), 11 patients (11%, i.v. MMF) and 4 patients (7%, placebo) discontinued their use of the drug because of an adverse event (AE). Overall, AEs were similar between i.v. MMF and placebo. Injection site phlebitis (4%) and thrombosis (4%) were observed only with i.v. MMF. MMF i.v. 1 g twice daily (b.i.d.) should provide efficacy at least equivalent to p.o. MMF without increased toxicity, and it provides an acceptable alternative dose form in the immediate period after transplant.

Baseline glomerular size as a predictor of function in human renal transplantation.

BACKGROUND: Nonimmune mechanisms have been implicated in chronic renal allograft injury. In experimental studies, a strong correlation exists between glomerular size and the degree of glomerular sclerosis that develops after subtotal nephrectomy. Therefore, we assessed the impact of glomerular maximal planar area (MPA) in baseline biopsy specimens of human renal allografts on later graft function. METHODS: The MPA was measured, by point counting and by computer planimetry, in postperfusion biopsy specimens from 96 allograft kidneys from nonhypertensive donors that had functioned for at least 2 years. Clinical data were analyzed throughout a follow-up period averaging 7.46+/-2.46 years. RESULTS: Both methods produced equivalent estimates of MPA. MPA proved to be a strong predictor of late renal allograft function, with a significant correlation (P = 0.02 to P < 0.01) between MPA at baseline and later serum creatinine level and creatinine clearance, beginning at 6 months after transplantation and persisting through follow-up. Creatinine level at discharge and occurrence of rejection were also independent predictors, whereas donor age, gender and race, cold ischemia time, cadaveric versus living donor, delay in initial function, and HLA mismatch did not predict clinical outcome. CONCLUSION: Larger glomeruli at baseline, measured by a simple point-counting technique, provide an early predictor of risk for late allograft dysfunction and may identify a subpopulation of patients in whom treatment to prevent/ameliorate glomerular enlargement and/or hypertension may be efficacious.

Heterogeneity of glomerular size in normal donor kidneys: impact of race.

Glomerular size has been the subject of many studies and, in a number of settings, has a direct association with the development of glomerular sclerosis. However, the normal distribution of glomerular size has not been thoroughly evaluated in the general population in the United States. To address this issue, we analyzed the baseline biopsy specimens of 103 human donor kidneys to determine the maximal planar area (MPA) of the glomerular tuft in a heterogeneous human population. The MPA of each glomerulus was determined by measurement of sections through the vascular pole and/or origin of the proximal tubule, and was determined on each section by two methods: point counting and computer planimetry. There was very high agreement between these two methods. Multivariate analysis was used to identify significant correlates with MPA. Overall, younger donors had smaller glomeruli (P < 0.0001). Black donors had a larger MPA (23.4+/-8.6 mm2 x 10(-3)) than white donors (17.9+/-6.7 mm2 x 10(-3); P < 0.001), independent of donor age. MPA was not significantly different between genders. This heterogeneity in glomerular size may confound clinical studies if not recognized and may help explain differences in glomerular structure and function in response to injurious processes.

CTLA4Ig inhibits alloantibody responses to repeated blood transfusions.

Allosensitization is a fundamental problem that limits the effectiveness of blood transfusions. Patients who receive multiple transfusions of blood or blood components frequently develop alloantibodies against donor alloantigens. Allosensitized patients are refractory to further transfusion and difficult to transplant successfully. CTLA4Ig fusion protein, which blocks the CD28-B7 costimulatory pathway in T-lymphocyte activation, was tested for its capacity to inhibit allosensitization to blood transfusions. Groups of LEW (RT1') rats were transfused with ACI blood (RT1a) together with L6 (a human immunoglobulin G1 [IgG1] antibody as isotype control) or CTLA4Ig in different doses (0.004, 0.02, 0.1, and 0.5 mg). Rats were retransfused with ACI blood after 28 and 84 days without any additional CTLA4Ig therapy. Weekly sera samples were tested for alloantibody against donor leukocytes using flow cytometry. CTLA4Ig caused a dose-dependent decrease in the IgM alloantibody response against donor major histocompatibility complex (MHC) class I antigens. In addition, 0.02-, 0.1-, and 0.50-mg doses of CTLA4Ig totally inhibited the IgG responses to the first transfusion, and this immunosuppressive effect persisted for the second and third transfusions. To study the capacity of CTLA4Ig to prevent a secondary immune response, three groups of LEW rats were transfused with ACI blood with no accompanying treatment. Animals were retransfused 28 days later with ACI blood together with L6 control antibody or 0.5 or 2.5 mg CTLA4Ig. CTLA4Ig, but not L6, prevented an increase in IgG alloantibody response despite repeated transfusions. The effects of CTLA4Ig treatment on helper T-lymphocyte proliferation was tested by limiting dilution analysis (LDA). Peripheral blood cells taken 30 days after blood transfusion and CTLA4Ig treatment contained significantly decreased donor-specific T-lymphocyte precursors compared with L6-treated rats. These data support the idea that blocking the B7/CD28 signal of T-lymphocyte activation by CTLA4Ig treatment at the time of transfusion may be an important therapeutic tool to inhibit alloantibody responses to blood transfusions.

Organ donors and nondonors. An American dilemma.

The principal motive for organ donation in the United States remains altruism. Surveys suggest that if the life-threatening and critical shortage of cadaveric donor organs were appropriately understood by the public, an altruistic response would lead to increased donation. However, despite intense educational efforts appealing to altruism, cadaveric organ donation has not increased substantially while the number of patients in need of a life-saving organ has grown markedly. To understand why organ donation has not increased, a telephone survey and focus group sessions of volunteers who were either for or against donation (donors and nondonors, respectively) were reviewed. The focus group nondonors demonstrated a remarkable lack of trust in the fairness of organ allocation and in the success of transplantation; indeed, this mistrust extended to the entire medical profession. The donors in the focus groups, on the other hand, believed that the system worked equitably, although their knowledge about organ donation and transplantation was equivalent to that of nondonors. For organ donation to increase, efforts must be directed toward those who are not convinced that donation is for the common welfare. One way to increase organ donation is for physicians to educate their patients better regarding the equity and success of transplantation.

Does high MHC class II gene expression in normal lungs account for the strong immunogenicity of lung allografts?

Clinical experience has demonstrated that lung allografts are considerably more immunogenic than liver allografts although both organs contain equivalent amounts of lymphoreticular tissue. Northern blot analysis of MHC class II gene expression in various murine organs with I-AB and I-EB gene-specific oligonucleotide probes revealed that MHC class II expression in lungs is semiquantitatively higher than in the liver and other organs with the exception of the spleen. We conclude that this high MHC class II expression strongly suggests that the lymphoreticular tissue in the lungs is in a state of activation. This may be an important reason for the strong immunogenicity of lung allografts.

Transplantation of half kidneys in swine: I. Long-term survivors of hemirenal autotransplants.

We describe a novel model of hemirenal transplantation in swine wherein one-half of one kidney is autotransplanted by modifications of standard vascular anastomoses and ureteropyelostomy. Two pigs with hemirenal transplants performed in this manner have not only survived but have grown normally and had decreased but stable renal function for more than 1 year. The model confirms that one-fourth of the total renal mass is sufficient to sustain life and growth in pigs. It is anticipated that this model could be used to study the effects of renal ablation on remnant nephrons in pigs.

Prolonged ambulatory monitoring of colonic motor activity in the pig.

The aim of this study was to develop a chronic model suitable for repeated, long-term studies of the interaction of behavior and colonic function in unrestrained pigs. Cecostomies were created in three 20-30 kg micropigs under general anesthesia. Fistulas were created by suturing the bowel to the abdominal wall. Recordings were made by passing a small (8F) solid-state pressure transducer through the fistula into the proximal bowel and connecting it to a battery-operated data logger worn in a vest on the pig's back. Cecostomies have remained patent and trouble-free for over 18 months. No serious infections have occurred. Preliminary data from a total of thirteen 24-h recording sessions showed 54% of all contractile activity to be in the 2-4 cpm frequency range. Increased motility was seen following meals and upon morning awakening. Motility was minimal during the night. Infrequent (10.31 +/- 2.05/24 h; mean +/- SD) propagated contractions were also noted. These contractions were generally of low amplitude (33.24 +/- 3.81 mmHg). These techniques allow prolonged, intraluminal recordings to be made from the colon of the unrestrained pig.

Graft-specific MHC class II gene expression in response to allogeneic stimulus in heterotopic murine cardiac allografts.

Although, major histocompatibility complex (MHC) class II antigen expression in allografts is thoroughly studied, regulation of the genes for these antigens is not fully understood. The graft-specific MHC class II genes are potentially important in determining the immunogenicity of graft but their detection in a mixed-cell population such as in the allograft would require unambiguous differentiation of graft-specific class II expression from those in host lymphoid cells. With an oligonucleotide probe that specifically hybridizes to I-Ab mRNA from H-2k haplotype mice, we have studied I-A gene expression in cardiac allografts heterotopically transplanted from B10.Br (H-2k) to B10.D2 (H-2d) mice. Normal B10.Br hearts do not have appreciable I-Ab transcripts as determined with this probe, but 4 days after allografting, a substantial increase in I-Abk messenger RNA (mRNA) content was noted in the allografted hearts which persisted for the next 2 days and then decreased concomitant with destruction of the heart. The increase in I-Abk mRNA preceded the expression of surface Iak antigens on dendritic and endothelial cells in the allograft. These data indicate increased transcription of the I-Ab gene in cells of graft origin suggesting that transcriptional regulation is the initial mechanism for expression of class II genes in allografts. The sustained rise in graft-specific class II mRNA also seen in these allografts suggests that increased mRNA stability may be another mechanism for the increased density of class II antigens in allografts undergoing rejection.