First-pass metabolism of midazolam by the human intestine.

The in vivo intestinal metabolism of the CYP3A probe midazolam to its principal metabolite, 1'-hydroxymidazolam, was investigated during surgery in 10 liver transplant recipients. After removal of the diseased liver, five subjects received 2 mg midazolam intraduodenally, and the other five received 1 mg midazolam intravenously. Simultaneous arterial and hepatic portal venous blood samples were collected during the anhepatic phase; collection of arterial samples continued after reperfusion of the donor liver. Midazolam, 1'-hydroxymidazolam, and 1'-hydroxymidazolam glucuronide were measured in plasma. A mass balance approach that considered the net change in midazolam (intravenously) or midazolam and 1'-hydroxymidazolam (intraduodenally) concentrations across the splanchnic vascular bed during the anhepatic phase was used to quantitate the intestinal extraction of midazolam after each route of administration. For the intraduodenal group, the mean fraction of the absorbed midazolam dose that was metabolized on transit through the intestinal mucosa was 0.43 +/- 0.18. For the intravenous group, the mean fraction of midazolam extracted from arterial blood and metabolized during each passage through the splanchnic vascular bed was 0.08 +/- 0.11. Although there was significant intersubject variability, the mean intravenous and intraduodenal extraction fractions were statistically different (p = 0.009). Collectively, these results show that the small intestine contributes significantly to the first-pass oxidative metabolism of midazolam catalyzed by mucosal CYP3A4 and suggest that significant first-pass metabolism may be a general phenomenon for all high-turnover CYP3A4 substrates.

Renal disease in hepatitis C-positive liver transplant recipients.

Glomerular abnormalities are frequent in patients undergoing liver transplantation; however, renal dysfunction following transplantation is mainly attributed to cyclosporine toxicity. Membranoproliferative glomerulonephritis (MPGN) is seen in patients infected with hepatitis C virus (HCV), the virus responsible for 30% of the end-stage liver disease leading to liver transplantation. To determine the incidence of renal abnormalities in liver transplant recipients and the association with HCV, we undertook a longitudinal study in HCV-positive (n=91) and HCV-negative (n=106) liver transplant recipients. Mean creatinine clearance before transplantation was 94 ml/min/1.73 m2 in HCV+ patients and 88 ml/min/1.73 m2 in HCV- patients. By 3 months after transplantation, the mean creatinine clearance decreased by approximately one third in both groups. A greater proportion of HCV+ patients excreted >2 g protein/day after transplantation (P=0.05) and had renal biopsies showing MPGN than did HCV- recipients (4/10 HCV+ patients vs. 0/7 HCV- patients; P=0.1). In the HCV+ group, proteinuria was not associated with recurrent HCV hepatitis, DQ matching, posttransplant diabetes, or hypertension. Treatment of HCV-related MPGN with interferon-alpha2b appeared to stabilize proteinuria and renal function but did not reverse renal dysfunction nor cause liver allograft rejection. After transplantation, HCV+ patients had similar renal function over 3 years after transplantation, compared with HCV- patients, but they had an increased risk of proteinuria and occurrence of MPGN that was only partially responsive to interferon.

Recombinant human tumor necrosis factor receptor Fc fusion protein therapy in kidney transplant recipients undergoing OKT3 induction therapy.

BACKGROUND: Initial doses of OKT3 are associated with a cytokine-induced acute clinical syndrome (ACS). This study assessed the safety of a recombinant human tumor necrosis factor receptor fusion protein (TNFR:Fc) given to minimize OKT3-ACS symptoms in renal allograft recipients undergoing induction therapy. METHODS: Sixteen patients were randomized into treatment or control groups. Treated patients received TNFR:Fc 1 hr before OKT3 on days 0 and 3. Patients were monitored after transplant for OKT3-ACS symptoms. Levels of cytokines, serum creatinine, and C-reactive protein were followed. RESULTS: Patients receiving TNFR:Fc had lower OKT3-ACS symptoms as measured by a scoring system. There was a higher incidence of infection in treated patients (10/12) compared to controls (1/4) in the 3 months after transplant, but the etiology of this difference was unclear. There were no significant differences in cytokine profiles. CONCLUSIONS: TNFR:Fc is well tolerated by renal transplant patients receiving OKT3 induction therapy and modestly decreases the symptoms associated with OKT3-ACS.

Pretransplant systemic inflammation and acute rejection after renal transplantation.

BACKGROUND: There are presently no established pre-transplant tests that consistently identify patients who may be at increased risk for acute rejection episodes after renal transplantation. We studied whether pretransplant serum levels of C-reactive protein (CRP), a marker for the presence of systemic inflammation, would predict the occurrence of acute rejection episodes after renal transplantation. METHODS: Pretransplant serum was tested for CRP level in 97 consecutive renal transplant recipients. Time to acute rejection after transplantation was stratified by CRP level and compared using the Kaplan-Meier method. In addition, Cox regression multivariate analysis was performed to assess whether any pretransplant covariates could independently predict the subsequent occurrence of acute rejection episodes. RESULTS: Pretransplant mean CRP levels were higher in patients who subsequently had a rejection episode versus those who had no rejection (22.2+/-2.9 vs. 11.7+/-1.8 microg/ml, respectively, P=0.003). Patients less than the median CRP value had a significantly longer time to rejection compared to those with higher CRP levels (P=0.002). Similarly, patients within the lowest CRP quartile had longer times to rejection when compared with the highest quartile (P=0.006). Cox proportional hazards regression multivariate analysis identified CRP level as the only independent pretransplant risk factor for rejection identified (P=0.044). CONCLUSIONS: Pretransplant systemic inflammation as manifested by elevated serum CRP level independently predicts the risk of acute rejection after renal transplantation and may be useful in stratifying patients at the time of transplantation according to immunological risk. Thus, assessment of pretransplant systemic inflammatory status may be helpful in prospective individualization of immunosuppression therapy after renal transplantation.

Increased transplantation of kidneys with multiple renal arteries in the laparoscopic live donor nephrectomy era: surgical technique and surgical and nonsurgical donor and recipient outcomes.

BACKGROUND: For anatomical and technical reasons, many transplant centers restrict laparoscopic live donor nephrectomy (in contrast with open live donor nephrectomy) to left kidneys. HYPOTHESIS: This change in surgical practice increases procurement and transplantation rates of live donor kidneys with multiple renal arteries (RAs), without affecting donor and recipient outcomes. DESIGN AND SETTING: Retrospective review at an academic tertiary care referral center comparing laparoscopically procured single vs multiple-RA kidney grafts (April 1997 to October 2000). PATIENTS: Seventy-nine consecutive left laparoscopic live kidney donors and 78 transplant recipients. MAIN OUTCOME MEASURES: Donor and recipient complications and postoperative length of stay; cold and warm ischemia time; operating time; short-term and long-term graft function; and survival. RESULTS: We noted multiple RAs in 21 (27%) of all kidneys. The proportion of donors with 1 or more perioperative complications was 19% in the single-RA group vs 10% in the multiple-RA group (P was not significant). For the recipients, we noted no significant differences between groups with respect to surgical complications, quality of early and late graft function, rejection rates, graft losses (all immunologic), and graft survival. Cold and warm ischemia time and length of stay were similar for donors and recipients in both groups. Median operating times were significantly longer for the multiple-RA vs single-RA group (difference, 41 minutes for donors and 45 minutes for recipients; P<.02). CONCLUSIONS: While the introduction of laparoscopic live donor nephrectomy has significantly increased the number of grafts with multiple RAs (compared with historical open controls), this change in practice is safe for both donors and recipients from a patient outcome-based perspective. However, from an economic perspective, the longer operating time associated with multiple-RA grafts provides strong added rationale for optimization of surgical instruments and techniques to make right-sided laparoscopic nephrectomy a routine intervention.

Management of spinal cord injury in the critical care setting.

Approximately 12,000 Americans suffer traumatic spinal cord injuries each year. This article discusses the management of their neurologic, respiratory, cardiovascular, gastroenterologic, and genitourinary complications in the critical care setting.

Characteristics of human lipoproteins isolated by selected-affinity immunosorption of apolipoprotein A-I.

We have isolated high density lipoproteins (HDL) from human serum by a new strategy, selected-affinity immunosorption, avoiding perturbation from ultracentrifugation or polyanion precipitation. The principle of this strategy is to utilize a subpopulation of monospecific antibodies directed against apolipoprotein A-I (apo A-I), which was preselected for dissociation under mild conditions of elution. Particles containing more than 90% of the apo A-I contained in serum were isolated uncontaminated by any other serum proteins. The immunoaffinity columns have been cycled over 300 times without apparent diminution in capacity. The apo A-I-containing particles sequestered from serum by immunosorption were more polydisperse in diameter and contained more protein than in ultracentrifugally isolated HDL. They also contained minor apolipoproteins that were not observed in ultracentrifuged HDL. Furthermore, the apo A-I-containing particles had different electrophoretic mobilities from those of ultracentrifugally isolated HDL when run under nondenaturing conditions in polyacrylamide gels. The apo A-I-containing particles isolated by our procedure separate into discrete bands similar to the subspecies visualized when whole serum is subjected to electrophoresis, whereas ultracentrifuged HDL migrate as two broad featureless zones. This suggests that selected affinity immunosorption does not subject the lipoproteins to structural disruption like that which occurs during ultracentrifugation. The principle of selected-affinity immunosorption should be of widespread utility in the isolation of fragile biological complexes.

Antiviral prophylaxis and the Epstein Barr virus-related post-transplant lymphoproliferative disorder.

Epstein Barr virus (EBV) infection has been associated with the post-transplant lymphoproliferative disorder (PTLD) in up to 8% of transplant recipients. Primary EBV infection and the use of antilymphocyte preparations appear to increase the incidence of PTLD. Experimental evidence suggests that the antiviral prophylaxis used by many transplant programs may influence the development of this post-transplant complication. In order to investigate the influence of antiviral prophylaxis (intravenous ganciclovir followed by high-dose oral acyclovir) on the development of PTLD in kidney-pancreas and liver allograft recipients from the University of Washington Medical Center, records were reviewed for pretransplant EBV status, antilymphocyte preparation use and for histologic documentation of PTLD. Two of 83 kidney-pancreas recipients (1 EBV-seronegative, 1 EBV-seropositive) and 1 of 123 liver recipients (EBV-seropositive) has developed PTLD. Six of 83 kidney-pancreas patients were EBV-seronegative prior to transplantation and 4 of these patients received at least two courses of an antilymphocyte preparation. Thirty-eight (49%) of the 77 EBV-seropositive kidney-pancreas recipients received at least two courses of an antilymphocyte globulin without the development of PTLD. Both the EBV-seronegative kidney-pancreas and the liver recipient who developed PTLD had received multiple courses of antilymphocyte globulins. One EBV-seropositive kidney-pancreas recipient had only received one course of OKT3 1 year prior to the development of PTLD. The incidence of PTLD reported here in patients receiving intravenous ganciclovir followed by high-dose oral acyclovir antiviral prophylaxis is lower than previously recorded when consideration is given for patient's EBV status and the use of antilymphocyte preparations.

Dissection of an iliac artery conduit to liver allograft: treatment with an endovascular stent.

Hepatic artery thrombosis remains one of the most serious complications after orthotopic liver transplantation. Sepsis, biliary leakage and strictures, and retransplantation are often the result of this devastating complication. Because retransplantation or reoperation is sometimes not possible or advisable, other means of reestablishing hepatic artery continuity are desirable. We describe a liver transplant recipient who developed a dissection of an iliac artery conduit after retransplantation that was treated with fibrinolytic therapy followed by successful placement of an endovascular stent.

Infection complicating percutaneous liver biopsy in liver transplant recipients.

There is controversy about the frequency of and risk factors for infectious complications of percutaneous liver biopsy in liver transplant recipients. The aim of this study was to identify the incidence and nature of complications associated with liver biopsy after orthotopic liver transplantation (OLT), with particular emphasis on infection. The medical records of all patients undergoing OLT between January 1990 and August 1994 were reviewed retrospectively to identify complications requiring hospitalization within one week of percutaneous liver biopsy. The nature and severity of complications were recorded and possible risk factors for infectious complications were examined. One hundred ninety-eight patients underwent 1,136 percutaneous liver biopsies. There were eleven complications (0.96%), including as follows: 7 infections, 3 bleeding episodes, and 1 vasovagal reaction. Infections after percutaneous liver biopsy included fever and bacteremia (n = 6), and fever without bacteremia (n = 1). All infections developed only in patients with underlying biliary tract abnormalities; the frequency of infection was higher (9.8%) in patients with choledochojejunostomy when compared with those with choledochocholedochostomy (1.4%). Bacteremia was more likely caused by skin flora in patients with choledochocholedochostomy (CDC) and by enteric bacteria in patients with choledochojejunostomy (CDJ). All infections were treated successfully with parenteral antibiotics. We conclude that biliary tract abnormalities are the primary risk factors for infection after percutaneous liver biopsy, although the risk is higher in patients with CDJ than with CDC. These data support the use of antibiotic prophylaxis before percutaneous liver biopsy in OLT recipients with biliary tract abnormalities.

Endoscopic management of biliary strictures in liver transplant recipients: effect on patient and graft survival.

BACKGROUND: Biliary strictures in liver transplant recipients cause significant morbidity and can lead to reduced patient and graft survival. METHODS: Of 251 liver transplant recipients, 22 patients with biliary strictures were categorized into two groups: donor hepatic duct (n = 12) or anastomotic (n = 10). Strictures were dilated and stented. Endoscopic therapy was considered successful if a patient did not require repeat stenting or dilation for 1 year. RESULTS: Patient and graft survival did not differ significantly in the 22 patients compared with patients without strictures (relative risk of death and graft survival 1.8 and 1.3). Donor hepatic duct strictures required significantly longer therapy than anastomotic strictures (median days 185 versus 67, p = 0.02). Twenty-two months after the first endoscopic treatment, 73% of the donor hepatic duct stricture group were stent free compared with 90% of the anastomotic group (p = 0.02). The former group had significantly more (p < 0.05) hepatic artery thrombosis (58.3% versus 10%), cholangitis (58.3% versus 30%), choledocholithiasis (91% versus 10%), and endoscopic interventions. No patient undergoing endoscopic treatment required retransplantation or biliary reconstruction during a median follow-up of 35.7 months. CONCLUSION: Endoscopic therapy of biliary strictures after liver transplantation is effective and is not accompanied by reduced patient or graft survival.

The natural history of untreated focal allograft rejection in liver transplant recipients.

Focal rejection involves less than 20% of portal tracts in liver allograft biopsy results. The clinical significance of "focal" rejection on protocol liver biopsy results is unknown. The purpose of this study was to prospectively determine the incidence of clinically significant rejection in patients with focal rejection after orthotopic liver transplantation. Biopsy specimens from 165 consecutive transplantations in 149 patients were analyzed. After protocol biopsy specimens were obtained, patients with focal or mild rejection were observed. Fifty of 583 (8.6%) protocol biopsy results in 41 patients showed focal or mild rejection. None were treated on the basis of this histological finding. Six patients subsequently developed abnormal liver function tests and required treatment with additional immunosuppression. We conclude that focal or mild rejection is a relatively common finding on protocol liver biopsy results and only rarely progresses to a clinically significant problem. Patients with this finding can safely be observed without treatment.

Induction immunosuppressive therapy is associated with a low rejection rate after liver transplantation.

Despite advances in immunosuppression, allograft rejection occurs frequently after liver transplantation. The use of induction therapy with cytolytic antibodies may decrease the frequency of rejection in liver transplant recipients, but may also increase the rate of cytomegalovirus (CMV) infection. It has been our center's strategy to use induction therapy in our liver transplant recipients. To determine the outcome of our strategy, we retrospectively reviewed all liver transplants performed in the first 5 yr of our liver transplant program. The frequency of acute rejection in the first year after liver transplantation was only 34% in patients who received induction therapy. The type of induction therapy antibody did not affect the rejection rate. Clinically significant CMV infection (requiring treatment) occurred in 22% of patients. These results suggest that use of induction therapy with cytolytic antibodies does not lead to a high incidence of CMV infection and decreases the incidence of rejection after liver transplantation.

Use of ultrasound and cystoscopically guided pancreatic allograft biopsies and transabdominal renal allograft biopsies: safety and efficacy in kidney-pancreas transplant recipients.

The use of allograft biopsies to guide treatment after solid organ transplantation is a valuable tool in the detection and treatment of rejection. Prior development and use of the cystoscopically guided pancreatic allograft biopsy have allowed for more accurate and timely diagnosis of pancreatic allograft dysfunction, possibly contributing to our 1-year pancreas graft, renal allograft and patient survival rates of 87.1%, 88.5% and 96.8%, respectively. We reviewed our experience, examining efficacy and complication rates of pancreas and kidney biopsies in 31 cadaveric pancreas or combined kidney and pancreas transplants performed between June 1990 and February 1992 with at least 1 year of followup. There were 94 pancreas, 54 kidney and 53 duodenal mucosal biopsies in 29 evaluable patients. This biopsy technique uses a 24.5F side-viewing nephroscope to view the cystoduodenostomy, with the duodenum acting as a portal for biopsy needles into the pancreas. Pancreatic tissue is obtained with either an 18 gauge, 500 mm. Menghini aspiration/core needle or an 18 gauge, 500 mm. Roth core needle. Percutaneous renal allograft biopsies are performed independently or simultaneously with the pancreas biopsies using a 16 gauge spring loaded needle. Pancreas biopsies were prompted by clinical indications of rejection (decreased urinary amylase, increased serum amylase or increased serum creatinine) or by protocol (10, 21 and 40 days postoperatively). Among the biopsies 30% were required by protocol, of which 10 (36%) revealed abnormal pathological findings and 5 (18%) showed evidence of occult cellular rejection. Renal biopsies demonstrated rejection in 69% of the cases. Of simultaneous pancreas/kidney biopsies 33% revealed concomitant rejection. A total of 88 Menghini needles with 170 passes was used in 73 biopsy attempts, yielding 126 tissue cores with a 16% complication rate. A total of 41 Roth needles was used with 73 passes in 34 biopsy attempts, yielding 55 tissue cores with a complication rate of 21%. Complications included self-limited bleeding from the biopsy site in 13% of the cases, bleeding requiring clot evacuation and fulguration in 1% and asymptomatic hyperamylasemia in 12%. Renal biopsy complications included 1 arteriovenous fistula (2%). We conclude that ultrasound and cystoscopically guided pancreatic allograft biopsy and percutaneous renal allograft biopsies are safe and essential methods of obtaining tissue for histological diagnosis without serious sequelae. The Menghini and Roth needles in cystoscopically guided pancreatic allograft biopsy have similar yield and complication rates in obtaining pancreatic tissue, although they require different performance techniques. In some cases both needles are necessary and are complementary in obtaining adequate tissue.(ABSTRACT TRUNCATED AT 400 WORDS)

Impact of double helical CT and three-dimensional CT arteriography on surgical planning for hepatic transplantation.

BACKGROUND: To assess the impact of preliver transplant double helical computed tomography (DHCT) and three-dimensional computed tomography arteriography (3D-CTA) on surgical planning for hepatic transplantation. METHODS: Vascular findings detected on DHCT/3D-CTAs of 80 patients were shown to the transplant surgeon in a blinded fashion. These findings included hepatic arterial anatomy, diameters of the major vessels that supplied the liver, celiac axis stenosis, splenic artery (SA) aneurysms, and portal vein thrombosis (PVT). The surgeon was asked to state the "planned" surgical approach for each case based on scan findings. These results were subsequently compared with what "actually" occurred at transplantation by review of surgical records. RESULTS: Fifty-five patients had conventional and 25 patients had nonconventional hepatic arterial anatomy. Three patients had PVT, three patients had celiac axis stenosis, and three patients had SA aneurysms. Correlation between the "actual surgical technique" and the "planned surgical approach" was seen in 50/55 (91%) patients with conventional and in 23/25 (92%) patients with nonconventional anatomy. Five patients requiring aortohepatic interposition grafts for arterial anastomoses had either severe celiac axis stenoses or arterial inflow vessels that were 3 mm or smaller. Three patients with PVT underwent successful surgical resection of the thrombosed segment and standard PV anastomoses as planned. Patients with complete replacement of hepatic arterial supply to the superior mesenteric artery required alteration of the sequence of the vascular anastomoses. Patients with SA aneurysms had surgical ligation of the splenic artery. CONCLUSIONS: DHCT/3D-CTA provides noninvasive means to identify findings that have significant impact on surgical planning for hepatic transplantation including celiac axis stenosis, diameter of inflow arterial vessel

Expression of vascular cell adhesion molecule (VCAM-1) in liver and pancreas allograft rejection.

VCAM-1, a leukocyte adhesion molecule expressed by cytokine-activated endothelial cells in culture, may mediate mononuclear leukocyte infiltration in vessels and interstitium in solid organ allograft rejection. Using the avidin-biotin immunoperoxidase technique and two different antibodies--4B9, a murine monoclonal antibody, and rabbit polyclonal antisera to recombinant human VCAM (rVCAM Ab), which work in methacarn-fixed tissues--we studied the expression of this molecule in biopsies of transplanted liver and pancreas with and without features of rejection as well as nontransplant control tissues. The rVCAM Ab, but not 4B9, showed a population of reactive endothelial cells limited to sites of prominent subendothelial leukocytic cell infiltration in arteries and veins in rejecting allografts. VCAM-1 expression by sinusoidal endothelium in rejecting liver allografts was also observed. In addition, a population of cells (DC) with dendritic morphology was identified by rVCAM Ab within sites of lymphoid cell aggregations in both liver and pancreas allografts. Further evidence that these cells represent true DC was obtained by identification of VCAM-1 positive morphologically similar cells in both germinal centers and interfollicular areas of reactive lymph nodes; and by similar staining of these cells in allograft organs by a monoclonal antibody to nerve growth factor receptor, previously shown to recognize DC. DCs were generally not seen in normal control organs or portions of allografts uninvolved by lymphoid aggregates. This study provides evidence that 1) endothelial cell expression of VCAM-1 may be important in transplant rejection, 2) different epitopes of VCAM-1 may be preserved in tissue sections and recognized by different antibodies, and 3) there is probably a population of VCAM-1 expressing DC that participates in the cellular rejection progress.

Use of midazolam as a human cytochrome P450 3A probe: I. In vitro-in vivo correlations in liver transplant patients.

The clearance of midazolam (MDZ) in humans is principally due to metabolic biotransformation catalyzed by CYP3A isoforms. A study was conducted in patients who had undergone liver transplants that provides evidence that MDZ can be used as an in vivo probe of interindividual hepatic CYP3A variability. The clearance of MDZ and cyclosporine after i.v. administration were determined in 10 patients approximately 10 days after transplant surgery. Liver biopsy specimens were obtained within 24 hr of the pharmacokinetic study and CYP3A content and MDZ 1'-hydroxylation activity were measured in 13,000 x g tissue supernatants (S-13). The in vitro rate of 1'-hydroxy-MDZ formation was found to correlate significantly with the total CYP3A content in hepatic S-13 fractions (r = .84, P < .01). The total MDZ clearance measured in vivo was highly correlated with the hepatic CYP3A content measured in vitro (r = .93, P < .001) and with in vivo cyclosporine clearance (r = .81, P < .001). For five of the patients, the intrinsic clearance of midazolam to 1'-hydroxy-MDZ (Vmax/Km) in vitro measured in S-13 preparations was scaled for total liver mass and applied to the well stirred model of hepatic clearance to yield a prediction of MDZ clearance in vivo. The mean MDZ clearance predicted from in vitro 1'-hydroxylation data was identical to the mean clearance observed in vivo (0.60 +/- 0.24 versus 0.59 +/- 0.25 liter/min). Together, the results suggest that variability in hepatic CYP3A expression in liver transplant recipients, and possibly in other populations, can be determined by the measurement of MDZ metabolic clearance.