D. Kahn

Temporary closure of open abdominal wounds by the modified sandwich–vacuum pack technique

A 5‐year experience with the modified sandwich–vacuum pack technique, using an opened 3‐litre urological irrigation bag and continuous high‐pressure suction, for temporary abdominal wall closure is presented.

Characterization of a CD46 transgenic pig and protection of transgenic kidneys against hyperacute rejection in non-immunosuppressed baboons

Abstract:  Human membrane cofactor protein (CD46) controls complement activation and when expressed sufficiently as a transgene protects xenografts against complement‐mediated rejection, as shown here using non‐immunosuppressed baboons and heterotopic CD46 transgenic pig kidney xenografts. This report is of a carefully engineered transgene that enables high‐level CD46 expression. A novel CD46 minigene was validated by transfection and production of a transgenic pig line. Pig lymphocytes were tested for resistance to antibody and complement‐mediated lysis, transgenic tissues were characterized for CD46 expression, and kidneys were transplanted to baboons without immunosuppression. Absorption of anti‐Galα(1,3)Gal epitope (anti‐GAL) serum antibodies was measured. Transgenic pigs expressed high levels of CD46 in all tissues, especially vascular endothelium, with stable expression through three generations that was readily monitored by flow cytometry of transgenic peripheral blood mononuclear cells (PBMC). Transgenic PBMC pre‐sensitized with antibody were highly resistant to human complement‐mediated lysis which readily lysed normal pig PBMC. Normal pig kidneys transplanted without cold ischemia into non‐immunosuppressed adult baboons survived a median of 3.5 h (n = 7) whereas transgenic grafts (n = 9), harvested at ∼24‐h intervals, were either macroscopically normal (at 29, 48 and 68 h) or showed limited macroscopic damage (median > 50 h). Microscopic assessment of transplanted transgenic kidneys showed only focal tubular infarcts with viable renal tissue elsewhere, no endothelial swelling or polymorph adherence and infiltration by lymphocytes beginning at 3 days. Coagulopathy was not a feature of the histology in four kidneys not rejected and assessed at 48 h or later after transplantation. Baboon anti‐GAL serum antibody titers were high before transplantation and, in one extensively analyzed recipient, reduced ∼8‐fold within 5.5 h. The data demonstrate that a single CD46 transgene controls hyperacute kidney graft rejection in untreated baboons despite the presence of antibody and complement deposition. The expression levels, tissue distribution and in vitro functional tests indicate highly efficient CD46 function, controlling both classical and alternative pathway complement activation, which suggests it might be the complement regulator of choice to protect xenografts.

Selective non-operative management of liver gunshot injuries†

In contrast to non‐surgical treatment of blunt liver trauma, non‐operative management (NOM) of liver gunshot injuries (LGSIs) is not widely accepted. This prospective study evaluated an experience of NOM of gunshot wounds to the liver.

Liver blood flow after partial hepatectomy in the pig

The role of liver blood flow in liver regeneration remains controversial. This study in 17 pigs documents the total hepatic blood flow, and portal and arterial components measured with an electromagnetic flowmeter, the portal pressure, and the cardiac output for 6 days after partial hepatectomy (PH) or sham operation. There was a twofold increase in total flow immediately after PH which rose to three- to fourfold by the second postoperative day. Thereafter values decreased but remained elevated above preoperative values; no similar increase was noted in sham animals. The increase in flow was both absolute as well as relative to the proportion of liver remnant remaining. The portal component increased from 74 +/- 3% preoperatively to 84 +/- 3% (P less than 0.05) on the second postoperative day, and portal pressure was apparently increased. These changes in flow precede the previously documented maximum regeneration response between Days 3 and 4. The factors resulting in the increased flow may be responsible in part, for regeneration.

Evaluation of peripheral blood CD4 and CD8 lymphocyte subsets, CD69 expression and histologic rejection grade as diagnostic markers for the presence of cardiac allograft rejection

We investigated the dynamics of the CD4+ and CD8+ lymphocyte subsets, and the expression of activation markers in cardiac transplant recipients. We tested 132 peripheral blood samples from 62 cardiac transplant recipients using fluorescent staining and flow cytometry analysis. The results were correlated with histological rejection grade of concurrently taken biopsies, and 5-year survival of the recipients. A decrease in the total T lymphocyte subset, and in CD4+ lymphocytes was associated with higher rejection grade and lesser survival. An increase (5-11%) of double positive CD4+ CD8+ lymphocytes was observed; these were mostly CD4brightCD8dim. The CD4/CD8 ratio was significantly (P < 0.00) lower in the transplant recipients than in normal individuals. CD69 expression was higher than CD54 and CD154 expression on CD4 and CD8 lymphocytes of cardiac transplant recipients; correlation between these activation markers was excellent (P < 0.001). Fluorescent staining for CD69 was often of low intensity. Multiple regression for % CD8+ CD69+ cells and survival, and for % CD69+ T cells and rejection grade yielded a significant correlation (P < 0.050). Both % CD8+ CD69+ and % CD69+ T cells were significantly higher in samples with severe and moderate rejection grade (grades 3A, 3B and 4) than in samples which showed no, minimal or mild rejection (grades < or = 2); P-values were 0.052 and 0.003, respectively. Preliminary results indicated that false negative results could be contributed to increased immunosuppression. We conclude that CD69 expression on circulating CD4 and CD8 lymphocytes is a useful parameter for the diagnosis of moderate and severe rejection.

Tumour necrosis factor levels during acute rejection and acute tubular necrosis in renal transplant recipients.

Plasma tumour necrosis factor levels were measured serially in 16 patients following renal transplantation, and in 10 patients on haemodialysis and in 12 patients on peritoneal dialysis. The patients on peritoneal dialysis had lower plasma TNF levels than the patients on haemodialysis. There was a decrease in TNF levels immediately following renal transplantation; this is probably related to the bolus doses of methylprednisolone administered intra-operatively. Patients with acute rejection had higher levels of TNF than non-rejecting patients. The increase in TNF levels in rejecting patients was observed 2 days before the clinical manifestation of acute rejection. There was a marked decrease in TNF levels in rejecting patients in response to treatment with steroids. Patients with delayed graft function had higher levels of TNF on the first post-operative day compared to patients with immediate function. These changes in plasma TNF levels following renal transplantation have important clinical and therapeutic implications.

A tale of two kidneys – how long can a kidney transplant wait?

This paper compares early graft function (EGF) of the first transplanted kidney (group 1) with the kidney transplanted second (group 2) in kidney pairs from the same cadaver donor. Thirty‐one pairs of kidneys were harvested from cadaver donors between January 1997 and October 1998. 
Each pair was transplanted using a standard technique by the same team of surgeons, one after the other, as a result of limitations in theatre time and staff availability. Incidence of acute rejection (AR), acute tubular necrosis (ATN) and need for post‐transplant dialysis was recorded for both groups, and was compared using the relevant statistical methods. 
Patients in both groups were well matched for age, gender and mode of dialysis pre‐transplant. Human leucocyte antigen (HLA) matching and panel reactive antibody (PRA) status were similar in the two groups (p>0.05). Cold ischaemia time (CIT) in the two groups was 14.1±5.7 and 19.2±6.9 h, respectively, the difference being statistically significant (p<0.05). The incidence of AR was similar in the two groups. However, ATN (on renogram) was significantly more common in group 2 (p<0.05; 12 patients versus 5 patients in group 1). All patients with ATN required post‐transplant dialysis. Hospital stay was significantly prolonged in group 2 patients (p<05; 20±10.6 versus 16.3±6.2 d for group 1). 
Even a relatively short increase in CIT can cause the second transplanted kidney of a pair to have a significantly higher incidence of ATN, resulting in need for dialysis and prolongation of hospital stay. Simultaneous transplantation, in areas lacking organ sharing networks, would not only improve EGF, but also improve long term graft survival. In addition, the reduced requirement for post‐transplant dialysis and a shorter hospital stay would balance any increased demand on resources.

Intervention Strategies and Agents Mediating the Prevention of Xenorejection

Xenotransplantation, the transplantation of cells, tissues, and/or organs across species, has proven to be an enormous challenge, resulting in only limited achievements over the last century. Unlike allotransplantation, the immunologic barriers involved in xenotransplant rejection are aggressive and usually occur within minutes in a hyperacute fashion. The use of organs from phylogenetically related concordant species may not be practical. Discordant xenotransplantation is characterized by hyperacute graft rejection, and to use nonprimate discordant organs for human benefit will require manipulation of the taxonomic differences. The hyperacute rejection process is primarily due to the attachment of preformed xenoreactive antibodies to the donor vascular endothelium, which results in hyperactivation of the complement system beyond the control of the natural complement regulatory proteins. Understanding the complex and diverse immune components involved in hyperacute, acute, and accelerated rejections has resulted in the development of different hematologic and molecular strategies. Plasmapheresis has been used to remove xenoantibodies, and xenoperfusion techniques are used to create a suitable and familiar environment for the xenograft. Various molecular approaches, such as the development of transgenic animals expressing human complement regulatory proteins such as CD59 or decay accelerating factor (DAF), to downregulate complement activation or the production of pigs lacking the xenoreactive antigen by knockout of the Galα‐1,3‐galactosyl transferase gene have also been attempted. A combination of these techniques together with the administration of soluble complement inhibitors such as the vaccinia virus complement control protein (VCP) may well contribute to prolong graft survival. However, various issues including the possible emergence of new viral infections have confounded the topic of xenotransplantation. Here the different modulatory approaches and agents mediating interventions in xenorejection are discussed.

Liver transplantation at Red Cross War Memorial Children's Hospital.

UNLABELLED The liver transplant programme for infants and children at Red Cross War Memorial Childrens Hospital is the only established paediatric service in sub-Saharan Africa. Referrals for liver transplant assessment come from most provinces within South Africa as well as neighbouring countries. PATIENTS AND METHODS Since 1987, 81 children (range 6 months-14 years) have had 84 liver transplants with biliary atresia being the most frequent diagnosis. The indications for transplantation include biliary atresia (48), metabolic (7), fulminant hepatic failure (10), redo transplants (3) and other (16). Four combined liver/kidney transplants have been performed. Fifty-three were reduced-size transplants with donor/recipient weight ratios ranging from 2:1 to 11:1 and 32 children weighed less than 10 kg. RESULTS Sixty patients (74%) survived 3 months-14 years post-transplant. Overall cumulative 1- and 5-year patient survival figures are 79% and 70% respectively. However, with the introduction of prophylactic intravenous ganciclovir and the exclusion of hepatitis B virus (HBV) IgG core Ab-positive donors, the 1-year patient survival is 90% and the projected 5-year paediatric survival is > 80%. Early (< 1 month) post-liver-transplant mortality was low. Causes include primary malfunction (1), inferior vena cava thrombosis (1), bleeding oesophageal ulcer (1), sepsis (1) and cerebral oedema (1). Late morbidity and mortality was mainly due to infections: de novo hepatitis B (5 patients, 2 deaths), Epstein-Barr virus (EBV)- related post-transplantation lymphoproliferative disease (12 patients, 7 deaths) and cytomegalovirus (CMV) disease (10 patients, 5 deaths). Tuberculosis (TB) treatment in 3 patients was complicated by chronic rejection (1) and TB-drug-induced subfulminant liver failure (1). CONCLUSION Despite limited resources, a successful paediatric programme has been established with good patient and graft survival figures and excellent quality of life. Shortage of donors because of infection with HBV and human immunodeficiency virus (HIV) leads to significant waiting-list mortality and infrequent transplantation.

Molecular Characterization of Duck Hepatitis B Virus Isolates from South African Ducks

The objective of the study was to characterize the genome of duck hepatitis B virus (DHBV) isolates from South African Pekin ducks. Duck serum and liver samples were collected from two commercial duck farms from geographically distinct regions of South Africa. In total, 498 duck serum samples were tested for the presence of DHBV DNA using either sub-genomic or full-length polymerase chain reaction (PCR) assays. The overall prevalence of DHBV infection in South African ducks was 47%. In addition, 30% of 59 liver tissues tested were DHBV DNA-positive. Six randomly selected serum or liver samples were used to clone and sequence the genomes of the South African DHBV strains. All six isolates had DHBV genomes of 3,021 nucleotides with three characteristic overlapping reading frames encoding the polymerase, surface and core gene products. No X-like gene with a traditional start codon was found. Following phylogenetic analysis, the South African DHBV isolates clustered with DHBV isolates from other “Western” countries, including United States of America, Canada, Germany and India. On translation of the open reading frames, the South African isolates were found to share signature amino acids in the polymerase and surface genes with the “Western” country isolates as opposed to those of Chinese DHBV isolates.