Knowing and acting in the clinical workplace: trainees' perspectives on modelling and feedback.

In this article we discuss clinical workplace learning using a dual approach: a theoretical one and an empirical one. Drawing on the philosophical work of Aristotle, Polanyi and Schön we posit that the 'knowing and acting' underpinning day-to-day medical practice is personal and embraces by nature a tacit dimension. Consequently, imparting and acquiring this knowledge type necessitates personal interaction between trainer and trainee. The tacit dimension particularly influences modelling and feedback. In our empirical exploration we explore these educational routes in two disparate disciplines: surgery and paediatrics. We use a longitudinal design with in-depth interviewing. Our conclusion on modelling is: modelling is a dynamic and fragmented process reflecting discipline bound characteristics and working styles. On feedback it is: 'feedback' serves as vehicle for three distinctive forms of commenting on performance, each holding a specific power of expression for learning. We propose to view clinical workplace learning as: an interactive master-apprenticeship model encompassing modelling and feedback as natural educational routes. We conceptualise modelling and feedback as 'function' of interaction (developing grounded theory). Modelling function and feedback function may serve to study these routes as didactical components of ongoing interaction between trainer and trainee rather than an educator-driven series of unrelated events.

Presence of hyperemic islets in human donor-pancreata results in reduced islet isolation yield.

When studying histological characteristics of human donor-pancreata, a remarkably high number of hyperemic islets (HIs) were encountered. The abnormalities in these HIs ranged from single/multiple dilated vessels to hemorrhages extending into the exocrine tissue. We aimed to determine the relevance of the presence of HIs in human donor-pancreata for isolation outcome and to identify donor and procurement factors associated with the occurrence of HIs. The presence of HIs was scored semi-quantitatively (HI-, HI+) in 102 human donor-pancreata. Islet isolation was performed in 40 cases. Donor and procurement factors were retrospectively analyzed in 94 donors. HIs were found in 54.6% of all donor-pancreata. However, only 4.5% of all islets in the affected pancreata was hyperemic. The affected pancreata contained slightly more endocrine tissue, but produced significantly lower yields. When corrected for other factors known to influence isolation outcome, the presence of HIs and endocrine content were the only factors significantly influencing isolation outcome. Prolonged ICU stay and pre-procurement hypertension were associated with the presence of HIs. This study is a first indication that the presence of HIs in human donor-pancreata are associated with reduced isolation outcomes and suggest an impact of the procurement procedure and pre-procurement hemodynamic status of the donor on the islet quality. It is tempting to speculate that this contributes to the generally experienced difficulties in obtaining sufficient amounts of human islets.

Reduced porcine islet isolation yield in the presence of hyperemic islets.

When studying histological characteristics of porcine pancreata in relation to islet isolation, a remarkably high number of hyperemic islets (HIs) was encountered. The abnormalities observed in these HIs ranged from a single dilated vessel to hemorrhages extending into the surrounding exocrine tissue. The aim of the present study was to compare pancreata with and without HI on islet isolation outcomes. This study involved a histological examination of 143 purebred (74 juvenile and 69 adult) and 47 crossbred (only juvenile) porcine pancreata. Islet isolation was performed in 48 purebred adult pigs and in 25 crossbred pigs. Tissue samples were stained with Aldehyde Fuchsine. The presence of HIs was scored semi-quantitatively (HI-, HI+). We observed HIs in 48% of the purebred and in 68% of the crossbred pigs. However, only 3.3±3.1% and 3.1±4.7% of all assessed islets was hyperemic in HI+ pancreata in purebred and crossbred pigs, respectively. In both groups, significantly higher endocrine cell mass was found in the HI+ pancreata (p<0.01). When the higher endocrine cell mass was taken into account, we found significantly lower yields in the HI+ pancreata in both purebred and crossbred pigs (p=0.03 in both groups). The presence of HIs occurs frequently in porcine donor-pancreata and is associated with reduced isolation outcomes.

More than 25 years of surgical treatment of hydatid cysts in a nonendemic area using the "frozen seal" method.

BACKGROUND: Hydatid disease of the liver remains endemic in the world and is an imported disease in The Netherlands. The aim of this study was to evaluate the treatment and outcome of surgically treated patients for hydatid disease in a single center in The Netherlands. METHODS: This retrospective study included 112 consecutive patients surgically treated for hydatid disease between 1981 and 2007. The primary outcome was relapse of the disease. Secondary outcomes were infections, complications, reoperations, length of hospital stay, and mortality. RESULTS: In all cases, echinococcosis was diagnosed by computed tomography or ultrasonography (US). Serology (enzyme-linked immunosorbent assay, immunofluorescence) confirmed the diagnosis in 92.9%. Most of the cysts were seen only in the liver (73.5%). All cysts were operated on with the frozen seal technique. Relapse of disease was seen in 9 (8.0%) cases. Five (4.5%) required surgical treatment at a later stage. Twenty (17.9%) complications were recorded. Four (3.6%) needed radiological drainage and three (2.7%) a reoperation. Follow-up was performed with US and/or serology at a mean of 24 months (range 0.5-300 months). All but one complication were seen in the liver-operated group, this proved not to be of statistical significance (P = 0.477). Patients with complications stayed significantly longer in hospital than did the patients without complications (P < 0.001). No mortality was observed in this study. CONCLUSIONS: The present study suggests that the frozen seal method of surgery for hydatid disease is safe and effective. Future studies are needed to prove its position in the treatment of hydatid disease as new developments show promising results.

Hyperemic islets: a possible explanation for poor yields in human and porcine islet isolation.

When studying histological characteristics of human and porcine pancreata in relation to islet isolation, we encountered a remarkably high number of hyperemic islets. The abnormalities observed in these islets ranged from a single dilated vessel through multiple widely dilated vessels to hemorrhages extending into the surrounding exocrine tissue. We determined their possible relevance for outcomes of islet isolation. This study involved a histological examination of 143 porcine pancreata (72 juvenile and 71 adult) and islet isolation from 48 adult pancreata. Human pancreata obtained from 71 multiple organ donors yielded islet isolation in 24 cases. To determine their endocrine content, tissue samples were stained with Aldehyde Fuchsin. The presence of hyperemic islets was scored semiquantitatively with pancreata allotted to categories based on the severity. In humans and pigs we observed hyperemic islets in 48% of pancreata, but only 4.0 +/- 2.4% of the islets were hyperemic. In both humans and pigs, significantly higher endocrine content was found in the most severely affected pancreata. When the higher endocrine content was taken into account and isolation results were expressed as ratios of yield and content, we observed significantly lower yields in the most affected pancreata in pigs with a trend toward lower yields in humans. A substantial proportion of human and porcine pancreata contain hyperemic islets. Although the results in humans are preliminary, our data suggest that this phenomenon may contribute to the unpredictable, highly variable islet yields in pigs and humans.

Amount and distribution of collagen in the pancreas have no effect on porcine islet isolation outcome.

Xenotransplantation of porcine islets of Langerhans is considered to be a possible alternative for clinical islet transplantation. However, porcine islet isolation procedures have been shown to produce highly variable yields between pigs with similar backgrounds. One of the variables that could account for this is the collagen substrate within the pancreas. We determined the amount and distribution of collagen within porcine pancreata as they determined islet isolation outcomes. This study involved the histological examination of 140 porcine pancreata (64 juvenile and 76 adult) and islet isolation from 58 adult organs. To quantify the amount of collagen, tissue samples were stained with Sirius Red. Collagen distribution was determined by assessing the presence of collagen in the endocrine-exocrine interface (the "islet capsule"), in tissue samples double-stained with Sirius Red and anti-insulin. Strong variation in total collagen was observed in both adult and juvenile pigs. The mean collagen content in the juvenile group was significantly lower than that in the adult group. Apparently, the pancreas undergoes a process of fibrosis as pigs age. The vast majority of islets from both adult and juvenile pancreata had no or only a limited collagen capsule. However, islet encapsulation was highly variable between pancreata. We observed no significant correlation between total collagen content or the percentage islet encapsulation and islet yield. Although total collagen content and islet encapsulation show great variability between pancreata, neither the amount nor the distribution of collagen affected porcine islet isolation outcome.

Heterogeneity of human pancreata in perspective of the isolation of the islets of langerhans.

The success of human islet isolation is hampered by the varied and unpredictable outcomes of the islet isolation procedure. Pancreata which meet well-defined criteria are no guarantee for success. Interindividual variations may contribute to the differences in isolation outcomes. The present study examined several structural elements in the anatomy of the human pancreas for possible relevance for islet isolation. Sixty pancreata were used for histochemical and immunochemical analyses. We assessed the total percentage of endocrine tissue and the size distribution of the islets. Sirius Red staining quantified total collagen content; the degree of islet encapsulation with collagen was correlated with total collagen. We analyzed the percentage of pancreatic edema and amount of intraparenchymal fat. The percentage of endocrine tissue varied 5-fold with wide variations in islet size distribution. A strong variation was observed for total collagen; its content increased slightly with age. The number of islets totally encapsulated with collagen varied strongly with no relation to age or to total collagen. Pancreatic edema and intraparenchymal fat also showed great differences. These differences justifies continued study to evaluate the correlation of these variables with isolation outcomes.

Isolation of the islets of Langerhans from the human pancreas with magnetic retraction.

Low yield and insufficient purity limit the transplantation of human islets of Langerhans. In the rat, a new technique to isolate the islets of Langerhans was developed by intraarterial infusion of iron particles into the islet capillaries. After digestion the iron-loaded islets were purified with magnetic retraction (MR). In the present study, 10 human pancreata not suitable for clinical use were arterially injected with an iron-oxide suspension. After injection a small piece was used for histological analysis, and the tail was intraductally perfused with collagenase and manually digested. The yield was compared with 11 pancreata processed in the standard way. Nine of 10 pancreata were successfully injected with iron-oxide and digested. After MR, enrichment was achieved but the purity was not more than 50%. Similar results between the 2 groups were obtained regarding digestion times (23 +/- 1.1 vs 22.7 +/- 1.5 minutes) and purification yields (1749 +/- 502.1 vs 2111 +/- 501.8 IE/g, P = .6) for the MR vs control groups, respectively. Histological analysis revealed that 60% to 88% of the islets contained iron aggregations with substantially higher concentrations compared with the exocrine tissue. In conclusion, iron-oxide did not influence the isolation outcome before purification. Islet purification with MR gave enrichment but no pure fractions.

Integrin signaling via RGD peptides and anti-beta1 antibodies confers resistance to apoptosis in islets of Langerhans.

Islet transplantation is associated with a high rate of early graft failure caused by early immune attack and poor functionality of islets. Apoptosis of islet cells appears soon after islet isolation and primarily involves the beta-cell. The purpose of this study was to determine the effect of ligation to extracellular matrix (ECM) proteins on survival of the islets of Langerhans following islet isolation. Islets that had been cultured for 24 h on collagen type I showed an islet survival of 59.7 +/- 8.7%, while islets that had been cultured on collagen type IV and laminin showed an islet survival of 88.6 +/- 10.3 and 94.3 +/- 5.6%, respectively. Islets that had been pretreated with anti-beta1 antibodies and argenin-glycin-aspartic acid (RGD) peptides showed a decrease in the level of apoptosis by a factor of 2.5 and 3.1, respectively, and an increase of phospho-Akt Ser 473 activity by a factor of 3.1 and 2.9, respectively, compared with untreated islets. When detached from their natural ECM surrounding in the pancreas, islet cells undergo apoptosis, unless islets are cultured on collagen IV or laminin or treated with anti-beta1 integrin antibodies or RGD peptides to mimic ECM ligation. These results indicate that inhibition of anoikis may offer opportunities to improve function and viability of islet cells.

Differential inhibition of autoreactive memory- and alloreactive naive T cell responses by soluble cytotoxic T lymphocyte antigen 4 (sCTLA4), CTLA4Ig and LEA29Y.

Cytotoxic T lymphocyte antigen 4 (CTLA4) is a potent inhibitory co-stimulatory molecule believed to be involved in type 1 diabetes and other autoimmune diseases. An association has been reported of both mRNA expression and serum levels of the soluble splice variant of CTLA4 (sCTLA4) with type 1 diabetes. Furthermore, recombinant fusion proteins CTLA4Ig and LEA29Y have been proposed as therapies for type 1 diabetes. We studied the role of (s)CTLA4 in islet autoimmunity. Binding capacity of the proteins to antigen-presenting cells was determined by flow cytometry in competition and binding assays. Functionality of sCTLA4 as well as the therapeutic inhibitory fusion proteins CTLA4Ig and LEA29Y was measured in a dose-response lymphocyte stimulation test, using a panel of diabetes-associated T cell clones reactive to islet autoantigens. As controls, mixed lymphocyte reactions (MLR) were performed to assess functionality of these proteins in a primary alloreactive setting. All three CTLA4 molecules were able to bind to antigen-presenting cells and inhibit the expression of CD80/CD86. sCTLA4 was able to suppress proliferation of different committed autoreactive T cell clones in a dose-dependent manner, whereas CTLA4Ig and LEA29Y were not. Conversely, CTLA4Ig and LEA29Y, rather than sCTLA4, were able to suppress naive alloreactive proliferation in a MLR. Our results indicate a differential role for sCTLA4, CTLA4Ig and LEA29Y proteins in memory versus primary immune responses with implications for efficacy in intervention therapy.

Life-saving therapy for haemorrhaging liver adenomas using selective arterial embolization.

BACKGROUND: Emergency treatment for patients with a ruptured hepatocellular adenoma is controversial. The aim of this study was to evaluate management with selective arterial embolization. METHODS: The study included 11 consecutive patients treated for ruptured hepatocellular adenomas between 2001 and 2006. After initial haemodynamic support, all patients received selective embolization of branches of the hepatic artery. The primary outcome was effectiveness in stopping the bleeding. Secondary outcomes were complications and changes in tumour size after embolization. RESULTS: A single embolization brought haemorrhaging under control in ten patients; one patient needed three embolizations. None of the patients required emergency surgery. In the follow-up of 19 (range 7-49) months, no general or hepatobiliary complications were observed. All 25 adenomas, including those without signs of haemorrhaging in the same liver lobe, were either smaller or not detectable on computed tomography or magnetic resonance imaging after embolization, with the median diameter decreasing from 7.0 to 2.5 cm (P < 0.001). CONCLUSION: Selective embolization of the hepatic artery is a safe and adequate first approach in the management of patients with haemorrhaging hepatocellular adenomas. Furthermore, arterial embolization reduces the size of adenomas in the liver.

Contrasting effects of subtotal enteric bypass, enterectomy, and colectomy on azoxymethane-induced intestinal carcinogenesis.

Compensatory hyperplasia after extensive loss of functioning small or large intestine might predispose to the development of neoplasia in the residual adapted bowel. To test this hypothesis, male Fischer rats were randomized to receive 85 to 90% jejunoileal resection or bypass, subtotal colectomy, or no operation (controls). One week later, the first of six weekly s.c. injections of azoxymethane (15 mg/kg/week) was given. At the 36th week postoperatively, mean body weight after enterectomy or colectomy it was 78 to 79% of control. Adaptation after all three operations was characterized by 22 to 84% increments in villous height and crypt depth in the residual functioning ileum (p = 0.05 to 0.001); the depth of colonic crypts was unchanged. Fewer rats developed intestinal tumors after enteric bypass (36%) than after any of the other treatments (80 to 91%) (p = 0.01 to 0.001); the depth of colonic crypts was unchanged. Fewer rats developed intestinal tumors after enteric bypass (36%) than after any of the other treatments (80 to 91%) (p = 0.01 to 0.001). Compared with controls, bypass reduced the number of colonic tumors by 77% (p less than 0.001). Although resection did not affect colonic tumor yield, it tripled the incidence of tumors in the duodenum and jejunum (p = 0.025). Colectomy promoted rectal carcinogenesis (p less than 0.05). Anastomotic tumors were commoner after intestinal resection. the lower frequency of tumors after jejunoileal bypass contrasts with enhanced carcinogenesis after enterectomy or colectomy. Profound reduction in body weight may prevent the promotional effect of adaptive hyperplasia.

Locoregional therapies of liver metastases in a rat CC531 coloncarcinoma model results in increased resistance to tumour rechallenge.

BACKGROUND: Locoregional treatments like photodynamic therapy (PDT), radiofrequency ablation (RFA) or hepatic artery infusion (HAI) of chemotherapeutics may be applied for unresectable colorectal liver metastases. We evaluated the effect of these treatments on the immune response in a rat colon tumour liver metastases model. METHOD: Wag/Rij rats were inoculated at day 0 with CC531 tumour cells at two sites in the liver. At day 15, one of two tumours was treated with RFA or PDT, or the liver was treated by HAI. Twelve days later (day 27), rats were rechallenged locally with CC531 cells in the liver or systemically with CC531 cells in the femoral vein. At day 42, tumour growth in liver and lungs was determined. RESULTS: RFA, PDT and HAI were very effective in liver tumour eradication, but following RFA or PDT there was no inhibitory effect on untreated nearby liver tumours. Outgrowth after local rechallenge was, however, significantly inhibited in RFA-, PDT- and HAI-treated rats, whereas all control rats showed outgrowth of a third liver tumour. After systemic rechallenge, control rats developed lung metastases whereas treated rats did not, but this difference was not statistically significant. CONCLUSION: These results show that following PDT, RFA and HAI resistance to local and possibly systemic tumour rechallenge is increased. This may be partly due to the induction or enhancement of a cellular immune response.

[Transplantation of the islets of Langerhans in patients with diabetes mellitus type 1]. / Transplantatie van eilandjes van Langerhans bij patiënten met diabetes mellitus type 1.

Since 1921 and until recently, insulin by injection has been the only treatment for patients with diabetes mellitus type 1. After pancreas transplantation, which became possible in 1977, the next logical step to cure patients with diabetes mellitus type 1 is the transplantation of the islets of Langerhans. In the last few years, the results of islet transplantation are markedly improved thanks to developments in the isolation technique and better immunosuppressive protocols. Ongoing problems in islet transplantation are allo-immunity, auto-immunity and the growing shortage of donor pancreases. Alternatives to pancreas donation, be it post-mortem or from a living donor, could be: sources for islets are xenotransplantation with the aid of pig islets and beta-cell neogenesis from embryonic stem cells or pancreatic duct cells.

Deiodination of thyroid hormone by human liver.

Liver is an important site for the peripheral production of T3 by outer ring deiodination (ORD) of T4 as well as for the clearance of plasma rT3, which is produced by inner ring deiodination (IRD) of T4 in other tissues. However, little is known about the underlying enzymatic reactions, and current concepts about thyroid hormone deiodination are largely based on studies in rat tissue. Here we describe the results of detailed studies of the catalytic properties of the iodothyronine deiodinase activity of human liver. The results demonstrated a high degree of similarity with the type I deiodinase of rat liver. The enzyme activity was found in the microsomal fraction. rT3 was the preferred substrate, since its ORD was catalyzed roughly 400 times more efficiently than the ORD or IRD of T4 or the IRD of T3. The deiodination of sulfated substrates was more rapid, as demonstrated by the roughly 30-fold increase in the IRD of T3 sulfate (T3S) compared with T3. The deiodinations exhibited ping-pong-type kinetics with dithiothreitol as the cofactor. Inhibition by propylthiouracil was uncompetitive with substrate and competitive with dithiothreitol, and PTU was an equally effective inhibitor of the ORD of rT3 and the IRD of T3S (Ki, 0.10-0.16 mumol/L). Various compounds with widely different inhibitory potencies had similar effects on ORD (rT3) and IRD (T3S). These results suggest that in human liver microsomes a single enzyme catalyzes the deiodination of the outer as well as the inner ring of iodothyronines by the same catalytic mechanism and with the same substrate specificity as the type I deiodinase of rat liver.

The role of radiotherapy in the treatment of bile duct carcinoma.

Forty-two patients with irresectable bile duct carcinoma (n = 31) or with microscopic evidence of tumor rest after aggressive surgery for bile duct carcinoma (n = 11) were given radiotherapy consisting intentionally of external-beam therapy and intraluminal 192Iridium (192Ir) wire application(s) following bile drainage procedures. The treatment was well tolerated; complications were mainly infectious and related to the success of the drainage. A median survival of 10 months was achieved for the group as a whole. Patients treated following microscopically incomplete resection survived longer than patients with an irresectable tumor (15 vs 8 months median survival, p = 0.06). Gross lymph node involvement also proved to be a prognostic factor.

The effects of long-term graft preservation and prostaglandin E1 on intraoperative hemodynamic changes in liver transplantation. A comparison between orthotopic and heterotopic transplantation in the pig.

The study aimed to compare the intraoperative hemodynamic changes during orthotopic liver transplantation (OLT) with those during heterotopic liver transplantation (HLT) after different durations of cold storage of the graft. The effect of prostaglandin E1 (PGE1) on these parameters was also studied. Sixty-nine female Yorkshire pigs underwent either OLT (n = 32) or HLT (n = 37) with a graft stored for 2 hr (n = 31), 24 hr (n = 16), 48 hr (n = 7), or 72 hr (n = 15). In 16 transplantations in the various groups, PGE1 was given intravenously to both donor and recipient animals and it was added to the preservation and flushing solutions. Univariate nonparametric tests (Mann-Whitney and Wilcoxon rank-sum) were used for analysis of cardiac output (CO), mean arterial pressure (MAP), left and right ventricular minute work (LVMW, RVMW), pulmonary capillary wedge pressure (PCWP), and systemic and pulmonary vascular resistance (SVR, PVR), at different intervals during the operative procedure. For the three main variables--i.e., the type of transplantation, the use of PGE1, and the preservation time, multiple regression analysis was performed. During HLT, portal vein clamping lowered MAP and CO, while during the anhepatic phase in OLT, SVR increased and CO dropped. After recirculation of the graft, an increase in PVR and a decrease in SVR were found in both OLT and HLT. At different stages of the surgical procedure, longer graft storage time diminished CO and MAP (P less than 0.001), especially in OLT. PGE1 appeared to reduce the cardiovascular reserves needed to compensate the changes after recirculation of the graft. The observed differences in intraoperative hemodynamics between OLT and HLT can partly be attributed to differences in operative techniques. Extension of the graft preservation period resulted in poor cardiac performance, more so in OLT than HLT. The native liver in HLT might be able to metabolize the presumed myocardial depressant factors, released by the graft upon reperfusion. Prostaglandin E1 did not protect against the reperfusion syndrome.

The effect of aprotinin on renal function in orthotopic liver transplantation.

BACKGROUND: In the European Multicenter Study on the Use of Aprotinin in Liver Transplantation (EMSALT), a randomized, double-blind, placebo-controlled, prospective study, we demonstrated that aprotinin significantly reduces intraoperative blood loss during orthotopic liver transplantation (OLT). Aprotinin is metabolized in the kidney and potentially nephrotoxic at high concentrations. Renal insufficiency is a common and serious complication after OLT. It is unknown whether aprotinin increases the risk of renal failure after OLT. METHODS: We analyzed intraoperative urine output, need for postoperative dialysis, perioperative serum creatinine levels, and creatinine clearance in 93 patients enrolled in EMSALT, receiving a high dose of aprotinin, a regular dose, or placebo. RESULTS: Peak increase in serum creatinine exceeding 0.5 mg/dl during one of the postoperative days occurred in 11 (35%) patients in the placebo group, in 11 (34%) patients in the high-dose group, but only in 1 (3%) patient in the regular-dose group (P=0.007). Furthermore, a perioperative decrease in creatinine clearance was seen in the placebo group (-23.9+/-10.1 ml/min) but not in both high-dose (-1.6+/-13.3 ml/min) and regular-dose (9.7+/-10.3 ml/min) groups (P<0.02 comparing regular-dose and placebo group). CONCLUSIONS: Despite its potential nephrotoxicity, the use of aprotinin for reducing blood loss during OLT does not lead to a higher incidence of postoperative renal insufficiency. In combination with the observed reduction in blood loss, these findings support the prophylactic use of regular-dose aprotinin during OLT.

Monitoring engraftment of transplanted hepatocytes in recipient liver with 5-bromo-2'-deoxyuridine.

For studies on the intrahepatic engraftment of transplanted hepatocytes, labeling of donor cells is necessary. Current labeling techniques enable only short-term monitoring of engraftment. In the present study, we describe the use of 5-bromo-2'-deoxyuridine (BrdU) for a more permanent hepatocyte labeling. BrdU is stably incorporated into replicating DNA; consequently, BrdU labeling was performed in regenerating livers. In 10 Lewis rats, a two-thirds partial hepatectomy was performed, followed by continuous, low-dose BrdU administration. This approach provided a fraction of 89+/-1.5% BrdU-labeled donor hepatocytes, without influencing the efficacy of the ensuing isolation of donor hepatocytes. Subsequently, +/-1 x 10(7) isolated hepatocytes were transplanted either intraportally or intrasplenically into syngeneic recipients, and the engraftment of transplanted cells was evaluated in liver lobes at successive time intervals after transplantation. BrdU-positive hepatocytes could be identified and quantitated in recipient livers up to 180 days after transplantation. Repetitive quantitative assessments over time revealed an initial, drastic loss of transplanted cells (<24 hr), followed by a stabilization at approximately 7% of the injected cells. Histological monitoring showed that during this period (<48 hr) the transplanted cells migrate from the portal venules to the liver parenchyma. In recipient livers a homogeneous lobe distribution of hepatocyte engraftment was found 30 days after both intraportal and intrasplenic transplantation. Moreover, no significant difference between the intrahepatic liver cell engraftment of the two transplantation routes was demonstrated. In conclusion, the BrdU-labeling technique of donor hepatocytes enables long-term histological monitoring and quantitative evaluation of the engraftment of transplanted liver cells in recipient livers.

Evidence of metabolic activity of adult and fetal rat hepatocytes transplanted into solid supports.

This study was undertaken to assess the metabolic effect of fetal and adult hepatocyte transplantation in the Gunn rat, genetically incapable of bilirubin conjugation. A comparison was made between fetal and adult hepatocytes transplanted into the spleen, and those injected into polytetrafluoroethylene (PTFE) solid supports that had previously been implanted intraperitoneally. Between 4 and 12 weeks after intrasplenic transplantation of adult liver cells, serum bilirubin was significantly decreased when compared with control animals (39.6 +/- 5.6%; P less than 0.01 vs. controls). Intrasplenic transplantation of fetal hepatocytes resulted in a maximal decrease of 33.2 +/- 9.1% at 8 weeks postoperatively (P less than 0.02 vs. controls). Similar declines of serum bilirubin levels were found after transplantation of adult or fetal liver cells into the solid supports. At 12 weeks after transplantation, bilirubin conjugates were detectable in the bile of all animals that underwent intrasplenic hepatocyte transplantation and in 60% of those that underwent the solid support procedure, whereas none could be detected in control animals. Histological evidence of surviving cells was obtained in all but one animal at 12 weeks, and confirmed at 12 months postoperatively. It is concluded that the PTFE solid support technique offers an attractive alternative to the intrasplenic route, and that both fetal and adult hepatocytes, transplanted in either way still exert their conjugating activity after 12 weeks.