Role of serum IgA. Hepatobiliary transport of circulating antigen

The IgA mediated hepatobiliary excretion of antigen from the circulation was studied using a radiolabeled haptenated protein (dinitrophenyl-human serum albumin) injected intravenously in mice together with monoclonal anti-dinitrophenyl antibodies of different immunoglobulin classes. Antibodies were obtained from ascitic fluids of mice bearing the MOPC315 myeloma (IgA), or immune spleen cell hybridomas (IgG and IgM). IgA antibody brought about the transport of large amounts of antigen from the circulation to the bile during 1-3h. Analysis of bile by gel filtration showed that a large part of the transported antigen remained intact and complexed with IgA. Neither IgA of different specificity nor anti-dinitrophenyl IgM medicated biliary transport of antigen. With anti-dinitrophenyl IgG, only small amounts of low molecular weight fragments of labeled antigen were found in he bile. Preformed immune complex of radiolabeled antigen and IgA antibody were rapidly transported from the circulation to the bile, resulting in threefold-higher levels of radioactivity in bile than in serum. It is proposed that an important function of serum IgA is to mediate the hepatobiliary excretion of corresponding circulating antigens.     

Reflux of billiary components into blood in experimental intrahepatic cholestasis induced in rats by treatment with alpha-naphthylisothiocyanate.

The sera of rats treated with alpha-naphthylisothiocyanate, an agent reported to cause intrahepatic cholestasis, and of rats treated with carbon tetrachloride, are examined for evidence of leakage of bile into blood. The levels of the four bile components assayed, namely IgA, free IgA secretory component, the biliary isoenzyme of 5'-nucleotidase and of direct reacting (conjugated) bilirubin, were all elevated in the sera of rats treated with alpha-naphthylisothiocyanate. No change in any of these components was found in rats treated with carbon tetrachloride, indicating that their appearance in serum is not an inevitable consequence of damage to hepatocytes. As the bile components assayed reach bile by three different routes. their rapid appearance in the sera of rats treated with alpha-naphthylisothiocyanate indicates reflux of bile into blood, presumably as a result of mechanical obstruction of intraheptic bile ducts.     

Impaired liver clearance of bacteria in rats with chronic biliary obstruction

125I-labeled E. coli was injected into the biliary tree of normal rats and rats with 3 weeks' obstruction of the common bile duct to investigate the liver clearance capacity for bacteria. Bile was collected during 15 min, immediately, 1 h, 4 h, or 24 h after the injection. Tissue specimens from the liver, lungs, spleen and kidneys, and blood and urine specimens were collected simultaneously. In normal rats, 40% of the bacteria was recovered in the bile immediately after the injection, whereas 30% was already trapped in the liver. Incubation of the bacteria in the bile duct for 1h, 4h, and 24h resulted in liver retentions of 43%, 15%, and 4%, respectively. The recovery in the bile was 13% after 1-h incubation, and further prolongation of the incubation did not result in a significant decrease. In contrast to these findings, 70% of the injected bacteria was retained in the biliary tree in rats with chronic biliary obstruction (P less than 0.05) as compared to normal rats) and only 1% was trapped in the liver (P less than 0.005) 15 min after injection. One-hour incubation of bacteria in the bile duct decreased the retention in the bile to 30%, but the retention in the liver increased only slightly in these animals. Four and 24 h after injection less than 30% of the bacteria was retained in the hepato-biliary system. Most of these animals showed almost no radioactivity exceeding the background count in the blood, urine, spleen, lungs, and kidneys 15 min after injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Selective transport of polymeric immunoglobulin A in bile. Quantitative relationships of monomeric and polymeric immunoglobulin A, immunoglobulin M, and other proteins in serum, bile, and saliva.

In 17 adults, serum, hepatic bile, and saliva samples were analyzed for their sedimentation profile of IgA and secretory component (SC), and for their concentrations of albumin, orosomucoid, transferrin, IgG, IgA, alpha 2-macroglobulin (alpha 2M), IgM, and SC. Polymeric IgA(p-IgA) averaged 13% (50-700 micrograms/ml) of total IgA in serum, 70% (43-88%) in bile, and 93% (74-98%) in saliva. Most of the p-IgA in bile sedimented with SC, which also occurred free (8-44%), and with IgM. In bile, albumin (155-1,485 micrograms/ml) was the predominant protein, followed by IgG (32-480 micrograms/ml), and total IgA (37-209 micrograms/ml). In saliva, p-IgA (72-902 micrograms/ml) predominated, followed by albumin (16-385 micrograms/ml) and IgG (9-178 micrograms/ml). Secretion-to-serum albumin-relative concentration ratios (S/S-ARCR = 1 for albumin) in bile averaged 22 for p-IgA, 1.91 for IgM, 1.28 for monomeric IgA (m-IgA), 0.70 for IgG, and 0.57 for alpha 2M, indicating for p-IgA, IgM, and to a lesser extent for m-IgA, a selective excretion into bile. In saliva, a 16-fold greater selective excretion of p-IgA (mean S/S-ARCR = 354) was found. Labeled m- and p-IgA were injected intravenously into five patients. Specific activities indicated that for p-IgA 50% was serum derived in bile, as compared with 2% in saliva, and to 85% for m-IgA in bile. In the patient with the highest excretion of 125I-p-IgA in bile, only 2.8% of the injected dose was recovered in bile within 24 h after injection. Compared with rats and rabbits, the serum-to-bile transport of p-IgA in humans is much smaller.     

Biliary physiology in rats with bile ductular cell hyperplasia. Evidence for a secretory function of proliferated bile ductules.

To establish the role of the biliary epithelium in bile formation, we studied several aspects of biliary physiology in control rats and in rats with ductular cell hyperplasia induced by a 14-d extrahepatic biliary obstruction. Under steady-state conditions, spontaneous bile flow was far greater in obstructed rats (266.6 +/- 51.9 microliters/min per kg) than in controls (85.6 +/- 10.6 microliters/min per kg), while excretion of 3-hydroxy bile acids was the same in the two groups. Infusion of 10 clinical units (CU)/kg per h secretin produced a minimal choleretic effect in controls (+3.8 +/- 1.9 microliters/min per kg) but a massive increase in bile flow in the obstructed animals (+127.8 +/- 34.9 microliters/min per kg). Secretin choleresis was associated with an increase in bicarbonate biliary concentration and with a decline in [14C]mannitol bile-to-plasma ratio, although solute biliary clearance significantly increased. Conversely, administration of taurocholate (5 mumol/min per kg) produced the same biliary effects in control rats and in rats with proliferated biliary ductules. In the obstructed animals, the biliary tree volume measured during taurocholate choleresis (67.4 +/- 15.8 microliters/g liver) was significantly greater than that determined during the increase in bile flow induced by secretin (39.5 +/- 10.4 microliters/g liver). These studies indicate that, in the rat, the proliferated bile ductules/ducts spontaneously secrete bile and are the site of secretin choleresis. Furthermore, because the proliferated cells expressed phenotypic traits of bile ductular cells, our results suggest that whereas under normal conditions the biliary ductules/ducts in the rat seem to contribute little to bile formation, secretion of water and electrolytes is a property of biliary epithelial cells.     

Drug absorption in patients with T-tube after cholecystectomy.

The influence of bile flow on the absorption of tetracycline, doxycycline, sulphadimidine and cycloserine was studied in 13 volunteer patients with t-tubes in their main bile ducts after biliary surgery. Their hepatic functions and bile flows were estimated by giving I131 radioiodinated rose-bengal intravenously. About 80% radioactive tracer was recovered from the bile when the t-tube was open, so most of the bile was diverted outside the intestinal tract. Up to 4 hours after administration serum tetracycline levels were lower when the t-tube was open than when the t-tube was closed. In one patient the serum levels were so much reduced that therapeutic serum tetracycline levels could not be achieved. The serum doxycycline levels were fairly high and bile flow did not have any effect on absorption. The 24-hour biliary excretion of doxycycline was only about 15% of the urinary excretion. The absorption of sulphadimidine and cycloserine was not affected by the presence or absence of bile. The bile salts are important surfactants in man, and modify the absorption rate of tetracycline, but not of doxycycline, sulphadimidine and cycloserine. Even in the absence of intact bile flow therapeutic serum tetracycline levels can be expected with the doses currently used.     

Cholestasis induced by sulphated glycolithocholic acid in the rat: protection by endogenous bile acids

Sulphated glycolithocholic acid (SGLC) causes cholestasis in experimental animals, despite its sulphated form. In the present study, the cholestatic potency and the pharmacokinetics of SGLC were investigated in rats under two conditions: (a) in the presence of an intact circulating bile acid pool and (b) after exhaustion of the bile acid pool by 24 h of bile diversion. Intravenous administration of SGLC (8 mumol/100 g body weight) to rats with an intact bile acid pool did not cause cholestasis. However, biliary phospholipid and cholesterol concentrations were reduced by 40% and 29% respectively during the first hour after administration. When the same dose of the bile acid was injected in rats with a 24 h biliary drainage, a complete cessation of bile production was observed within 1 h. Twelve hours after the onset of cholestasis, bile production gradually increased again, showed a marked overshoot, and reached control levels after 3 days. In the recovery phase, biliary phospholipid and cholesterol concentrations were greatly reduced. The absence of endogenous bile acids did not change the hepatic clearance rate of a tracer dose of radiolabelled SGLC, but markedly decreased its biliary excretion rate. It was concluded that the hepatotoxic effect of SGLC is much more pronounced in rats with an exhausted bile acid pool, possibly due to a slower biliary excretion of the toxic compound. This phenomenon may have clinical implications for patients with a contracted bile acid pool.     

Excretion of Cefamandole, Cefazolin, and Cephalothin into T-Tube Bile

The biliary tract excretion of cefamandole, cefazolin, and cephalothin was measured in eight patients with T-tubes inserted into their common ducts after ductal exploration for biliary tract stones. Each patient received 1.0 g intravenously of each cephalosporin on 3 separate days; T-tube bile and serum were collected at selected time intervals thereafter. In seven patients, bile and urine were collected for 6 h after the administration of each drug. Mean peak levels of cefamandole, cefazolin, and cephalothin in bile were 352, 46, and 12 μg/ml, respectively. The respective mean peak serum levels were 55.0, 92.8, and 32.4 μg/ml. Despite the fact that peak serum levels of cefazolin were 1.5 times those of cefamandole, levels in bile of cefamandole were about 8 times those of cefazolin. Over a 6-h period, almost three times as much cefamandole was excreted into bile as was cefazolin. Therefore, in those patients with biliary tract sepsis, in whom a cephalosporin is indicated for therapy, cefamandole appears to be the drug of choice.     

Copper metabolism after biliary fistula, obstruction, or sham operation in rats.

Intravenously administered carrier-free 67Cu appeared rapidly in the bile of rats with a recently created biliary fistula; maximal excretion occurred within the first 2 hours. However, if the biliary fistula had been created 3 or 4 days before injection of the 67Cu, only one-fourth to one-half as much of the isotope appeared in the bile. There also was a small decrease in stable biliary copper. When rats with biliary fistula were compared with rats with permanent biliary obstruction, over a period of 6 weeks, both exhibited a marked increase in plasma copper and an equally pronounced increase in the rho-phenylenediamine oxidase activity of plasma but no increase in hepatic copper. Peaks in blood were reached within 2 weeks and then slowly diminished. Sham-operated rats had parallel, but much lower, copper and enzyme changes. Correlations between these rat studies and the copper retention of Wilson's disease and of primary biliary cirrhosis are suggested.     

Hepatic excretion of circulating bilirubin photoproducts in the Gunn rat.

To investigate the origin and metabolism of the intermediates that occur in blood during phototherapy of neonatal jaundice, serum from irradiated homozygous Gunn rats was injected intravenously into other homozygous Gunn rats fitted with bile fistulas, and the excretion of pigment in the bile of the recipient rats was studied. In some experiments the donor rats were labeled with [14C]bilirubin; in others the recipient rats were labeled. Injection of donor serum from irradiated rats caused a transient burst of pigment excretion in the bile of the recipient rats. However, simultaneous bursts of pigment and 14C excretion were observed only when the donor rat was labeled and the recipient rat was not, and not when the donor rat was unlabeled and the recipient rat was labeled. In addition, there was simultaneous transient enhanced excretion of pigment and label when labeled recipient rats were exposed briefly to blue light. We conclude that (a) the phototherapy intermediates previously detected spectroscopically in serum are formed from bilirubin and are excreted in bile independently of bilirubin; (b) the enhanced excretion of pigment in bile during phototherapy is not caused by complex formation between bilirubin and photoproducts, or by liver damage produced by photoproducts or light.     

罗格列酮对原位肝移植胆道缺血-再灌注损伤的作用

目的 探讨过氧化物酶体增殖物活化受体-γ(PPAR-γ)配体罗格列酮在原位肝移植胆道缺血-再灌注损伤中作用的分子机制.方法 40只SD大鼠随机(随机数字法)分成假手术组(SO组)、缺血-再灌注组(I/R组)、罗格列酮组(ROS组)和GW9662组,每组10只.通过改良"双袖套法"建立大鼠自体原位肝移植胆道缺血-再灌注模型,通过肝脏及胆管组织病理学变化、血生化指标检测评价模型建立是否成功.SO组行自体原位肝移植术,I/R行建模缺血-再灌注,ROS在缺血-再灌注后以罗格列酮0.3mg/kg经门静脉注射,GW9662在ROS基础上10 min后经门静脉以0.3mg/kg注射GW9662,各组均于实验后4h取部分肝脏和胆管组织用于免疫组化检测;右心室穿刺抽血采用ELISA法测定细胞因子含量.采用方差分析进行统计学处理.结果 组织中细胞因子IL-1β,TNF-α,IL-6活性主要表达在肝细胞及胆管细胞胞浆中,转录因子NF-κB则在胞浆及胞核中均有表达;I/R组及GW9662组上述蛋白表达升高,和SO组以及ROS组比较明显增高(P＜0.05).血清中I/R组大鼠IL-1β,TNF-α及IL-6同步升高,较SO组明显增高(P＜0.05);罗格列酮干预后血清中IL-1β,TNF-α及IL-6和SO组比较无明显变化(P＞0.05);给予罗格列酮阻滞剂GW9662后,IL-1β,TNF-α及IL-6的含量和SO组比较则明显增高(P＜0.05).结论 PPAR-γ的配体罗格列酮对原位肝移植胆道缺血-再灌注损伤有保护作用,这种保护作用的机制与拮抗核因子-κB和抑制其表达,减少下游IL-6,IL-1β以及TNF-α等细胞因子的释放有关.

Abstract：

Objective To explore the effective molecular mechanism of PPAR-γligands rosiglitazone to biliary ischemia-reperfusion injury in autologous liver transplantation. Method A total of 40 SD rats were randomly (random number) divided into sham operation group (SO), ischemia - reperfusion group (Ⅰ/R), rosiglitazone (ROS) and GW9662 group, with 10 ones in each. The models, rat biliary ischemiareperfusion injury of autologous liver transplantation, were made by modified two-cuff technique. Tissues of the liver and bile ducts and blood of those models were evaluated by pathological and biochemical methods to make sure the models were made successfully or not. SO group suffered autologous orthotopic liver transplantation, and L/R group suffered both that and ischemia-reperfusion. ROS group were injected rosiglitazone (0.3mg/kg) via portal vein after having been done all as I/R. GW9662 group suffered all as ROS, and 10min later ,they were injected GW9662(0.3mg/kg) via portal vein. 4h after the experiment, tissues of livers and bilary ducts were taken to be tested by immunohistochemistry method, and the blood punctured from the right ventricular were taken to be determined by ELISA. ANOVA was used for statistical analysis.Results IL-1β, TNF-α and IL-6 were mainly expressed in the cytoplasm of hepatocytes and bile duct cells,while NF-κB was expressed both in the cytoplasm and nuclei. Expression of those proteins in L/R and GW9662 group was increased, significantly higher when compared to the SO and ROS (P ＜ 0.05). IL-1β,TNF-α and IL-6 in rat serum were simultaneously increased, and significantly higher than SO(P ＜0.05).Compared with the SO, expressions of the IL-1 β,TNF-α and IL-6 were not significantly changed in ROS (P＞ 0.05 )but significantly increased in GW9662. Conclusions PPAR-γ ligand rosiglitazone took protective role in biliary ischemia-reperfusion injury in autologous liver transplantation. The mechanism correlates with the release of the IL-lα, IL-1β and TNF-α and other inflammatory mediators, which decreased as the expression of NF-κB inhibited by its antagonist.     

Biliary excretion of moxalactam.

The biliary excretion of moxalactam was studied in 11 postsurgery patients who had indwelling T-tubes inserted in their common bile ducts. Peak levels of moxalactam in the bile reached mean levels of 33.7 +/- 11.1 and 173.7 +/- 67.0 micrograms/ml 2 h after intravenous administration of a single 500- or 2,000-mg dose, respectively. In 5 of the 10 patients given the 2,000-mg dose, peak moxalactam concentrations in the bile were 2 to 12 times higher than simultaneous serum levels, but considerable variation in the biliary excretion of moxalactam was observed among the individual patients.     

Changes in size, subclass, and metabolic properties of serum immunoglobulin A in liver diseases and in other diseases with high serum immunoglobulin A

We have studied the relative contributions of monomeric (m-) and polymeric IgA (p-IgA) and of IgA1 and IgA2 to total serum IgA in healthy adults and patients with liver disease (LD) or with other diseases and high serum IgA. Serum concentration of total secretory component (SC) was also determined. In addition, fractional catabolic rates (FCR) and synthetic rates for both m- and p-IgA were measured in nine controls and nine cirrhotics. Our results support four main conclusions: (a) In healthy adults, intravascular p-IgA contributes to only 4-22% (mean 12%) of serum IgA, because its FCR and synthetic rate are approximately two times higher and four times smaller, respectively, than those of intravascular m-IgA. (b) in LD, biliary obstruction does not result in a significant increase in serum p-IgA unlike in rats and rabbits, indicating that in humans the SC-dependent biliary transport of p-IgA plays a much less significant role in selective removal of p-IgA from plasma than in rats and rabbits. (c) In contrast to biliary obstruction, parenchymal LD results in a significant and preferential increase in serum p-IgA, which in cirrhotics correlates with a selective reduction of the p-IgA-FCR. This supports a role for the human liver in selective removal of p-IgA from plasma, but another mechanism than the SC-dependent biliary transport should be considered. (d) Total SC, p-IgA, and IgA2 in serum are unlinked parameters, not necessarily reflecting mucosal events. A marked increase in serum SC occurs almost selectively in LD. Although a shift to IgA2 is suggested in Crohn's disease and alcoholic cirrhosis, a shift to IgA1 frequently associated to a shift to p-IgA occurs in chronic active LD, primary Sicca, and connective tissue diseases.     

Regulation of biliary cholesterol secretion in the rat. Role of hepatic cholesterol esterification

Although the significance of the enterohepatic circulation of bile salts in the solubilization and biliary excretion of cholesterol is well established, little is known about the intrahepatic determinants of biliary cholesterol output. Studies were undertaken to elucidate some of these determinants in the rat. Feeding 1% diosgenin for 1 wk increased biliary cholesterol output and saturation by 400%. Bile flow, biliary bile salt, phospholipid and protein outputs remained in the normal range. When ethynyl estradiol (EE) was injected into these animals, biliary cholesterol output decreased to almost normal levels under circumstances of minor changes in the rates of biliary bile salt and phospholipid outputs. Similarly, when chylomicron cholesterol was intravenously injected into diosgenin-fed animals, biliary cholesterol output significantly decreased as a function of the dose of chylomicron cholesterol administered. Relative rates of hepatic cholesterol synthesis and esterification were measured in isolated hepatocytes. Although hepatic cholesterogenesis increased 300% in diosgenin-fed animals, the contribution of newly synthesized cholesterol to total biliary cholesterol output was only 19 +/- 9%, compared with 12 +/- 6% in control and 15 +/- 5% in diosgenin-fed and EE-injected rats. The rate of oleate incorporation into hepatocytic cholesterol esters was 30% inhibited in diosgenin-fed rats. When EE was injected into these animals, the rate of cholesterol esterification increased to almost 300%. To investigate further the interrelationship between hepatic cholesterol esterification and biliary cholesterol output, we studied 21 diosgenin-fed rats. Six of them received in addition EE and 10 received chylomicron cholesterol. The relationships between biliary cholesterol output as a function of both microsomal acyl-CoA:cholesterol acyltransferase (ACAT) activity and hepatic cholesterol ester concentration were significantly correlated in a reciprocal manner. From these results it is concluded that the size of the biliary cholesterol precursor pool can be rapidly modified through changes in the activity of the hepatic ACAT.     

Altered hepatobiliary disposition of acetaminophen metabolites after phenobarbital pretreatment and renal ligation: evidence for impaired biliary excretion and a diffusional barrier

The effects of phenobarbital (Pb)-pretreatment and bilateral renal ligation on the disposition of acetaminophen, acetaminophen glucuronide (AG) and acetaminophen sulfate (AS) were examined in serum, bile and urine of rats. Pb-pretreatment significantly decreased the percentage of the acetaminophen dose (100 mg/kg) excreted in bile as the glucuronide and sulfate conjugates in rats with intact kidneys [AG (0.94% vs. 6.49%); AS (1.41% vs. 4.19%)] and in renal-ligated rats [AG (2.22% vs. 7.71%); AS (6.12% vs. 9.13%)], compared to vehicle-pretreated controls. Decreased biliary recovery of AG occurred despite a Pb-induced increase in the fraction of the acetaminophen dose converted to AG. Similarly, biliary recovery of AS was reduced further than expected based on Pb-associated decreases in the fraction of the acetaminophen dose converted to AS. These observations suggest that the hepatobiliary disposition of AG and AS was altered at multiple sites due to 1) direct interactions with Pb (or a Pb metabolite) and/or 2) metabolic induction by Pb. Renal ligation shifted the metabolic pathway toward sulfation, with a subsequent increase in biliary recovery of AS. However, renal ligation did not alter the percentage of the dose excreted as AG in bile despite a marked elevation in AG serum concentrations. Furthermore, biliary excretion rate vs. time profiles of AG and AS in renal-ligated rats exhibited a terminal half-life exceeding that of acetaminophen in serum. These data provide evidence that diffusional barriers between blood and hepatocytes influence the hepatic disposition and routes of elimination of polar metabolites such as AG and AS.     

Ultrasonographic identification of dilated intrahepatic bile ducts and their differentiation from portal venous structures.

The appearance of dilated intrahepatic bile ducts was evaluated on ultrasonograms of 50 patients with proven extrahepatic biliary obstruction. Five characteristic changes allowed differentiation between biliary and portal venous systems. These changes included: 1) alteration in the anatomic pattern adjacent to the main right portal venous segment and the main portal vein bifurcation. 2) Irregular walls of dilated bile ducts. 3) Stellate confluence of dilated bile ducts. 4) Acoustic enhancement by dilated bile ducts. 5) Peripheral location of dilated bile ducts. Many patients exhibited more than one of these findings. Parasagittal scans of the main right portal vein were the most sensitive for detection of intrahepatic ductal dilatation. Recognition of the characteristic changes and knowledge of the portal venous anatomy makes it possible to diagnose extrahepatic biliary obstruction with a high degree of confidence.     

Plasma alkaline phosphodiesterase I in intrahepatic cholestasis induced by alpha-naphthylisothiocyanate in rats

1. Administration of alpha-naphthylisothiocyanate (ANIT) to rats produced dose-dependent increases in plasma bile acid and bilirubin concentrations. Similar increases in plasma bile acid and bilirubin concentrations were evident in bile duct ligated rats, indicating that the severity of cholestasis is almost identical in both models. 2. Plasma alkaline phosphodiesterase I was increased by only 50-80% while alkaline phosphatase was increased more than threefold after ANIT administration. This is in contrast to an earlier study [S. R. Simpson, K. Rahman & D. Billington (1984) Clinical Science 67, 647-652] where, after bile duct ligation, serum alkaline phosphodiesterase I was elevated sixfold before any increase in alkaline phosphatase activity became apparent. Thus, plasma alkaline phosphodiesterase I does not offer as sensitive a marker of intrahepatic cholestasis (induced by ANIT) as it does of extrahepatic cholestasis (induced by bile duct ligation). 3. Hepatic alkaline phosphodiesterase I was unaffected by ANIT pretreatment while hepatic alkaline phosphatase was increased up to seven times. It is suggested that raised plasma alkaline phosphodiesterase I is due to regurgitation of the biliary enzyme rather than overspill of the enzyme from liver into blood. 4. Gel filtration showed that 24 h and 96 h after ANIT administration, rat serum contained a high molecular weight form of alkaline phosphodiesterase I, suggesting a different isoenzyme profile.     

Complete bile duct sequestration after liver transplantation,caused by ischemic-type biliary lesions

Ischemic-type biliary lesions (ITBLs) are the most frequent cause of nonanastomotic biliary strictures in liver grafts, affecting about 2-19 % of patients after liver transplantation. ITBL is characterized by bile duct destruction, subsequent stricture formation, and sequestration. We report here the case of a patient affected by extremely severe ITBL, with sequestration and disintegration of the entire bile duct system, in which it was possible to extract the complete biliary tree endoscopically in a single piece. Histological examination revealed that all cells of the bile duct wall had been destroyed within 3 months after liver transplantation and replaced by connective tissue. Subsequently, biliary stricture formation occurred at the hepatic hilum, as well as the adjacent large bile ducts. It may be hypothesized that cellular rejection of small bile ducts leads to the vanishing bile duct syndrome, whereas cellular rejection of large bile ducts results in ITBL. The strictures were repeatedly dilated by endoscopic means, allowing successful control of stricture formation, as well as maintenance of liver function. At the time of writing, the grafted organ and the patient had survived for more than 3 years in good health. This is the first detailed report on a sequestration of the entire bile duct system caused by ITBL, successfully treated for several years by endoscopic means.     

The effect of obstruction on the biliary excretion of cefoperazone and ceftazidime

The biliary excretion of cefoperazone and ceftazidime was studied by endoscopic cannulation of the common bile duct, in patients with complete biliary obstruction and in an unobstructed control group. Patients were given each drug prophylactically for 24 h before endoscopy and as a single dose at the time of cannulation. In unobstructed patients biliary excretion of ceftazidime was passive. At the time of cannulation bile contained 10% of the peak serum concentration, rising to 20% 90 min later. Cefoperazone excretion was active. At cannulation biliary concentrations were 200% of the serum peak, 900% at 60 min and 700% at 90 min. In obstructed patients, bile sampled immediately at decompression contained neither antibiotic. Passive excretion of both drugs occurred rapidly after relief of obstruction and biliary concentrations were 20% of maximum serum levels at 60 min. Twenty-four hours later passive excretion had further improved, but the active excretion mechanism of cefoperazone had still not recovered. We conclude that obstruction impairs active as well as passive biliary excretion of antibiotics, that drainage is essential for the control of sepsis in obstructed cholangitis, and that both cefoperazone and ceftazidime achieve similar and therapeutic concentrations in bile during the 24 h after decompression.     

Bilirubin Diglucuronide Formation in Intact Rats and in Isolated Gunn Rat Liver

Bilirubin diglucuronide (BDG) may be formed in vitro by microsomal UDP glucuronosyl transferase (EC 2.4.1.17)-mediated transfer of a second mole of glucuronic acid from UDP-glucuronic acid, or by dismutation of bilirubin monoglucuronide (BMG) to BDG and unconjugated bilirubin, catalyzed by an enzyme (EC 2.4.1.95) that is concentrated in plasma membrane-enriched fractions of rat liver. To evaluate the role of these two enzymatic mechanisms in vivo, [³H]bilirubin mono-[¹⁴C]glucuronide was biosynthesized, purified by thin-layer chromatography, and tracer doses were infused intravenously in homozygous Gunn (UDP glucuronyl transferase-deficient) rats or Wistar rats. Bilirubin conjugates in bile were separated by high-pressure liquid chromatography and ³H and ¹⁴C were quantitated. In Gunn rats, the ¹⁴C:³H ratio in BDG excreted in bile was twice the ratio in injected BMG. In Wistar rats the ¹⁴C:³H ratio in biliary BDG was 1.25 ± 0.06 (mean ± SEM) times the ratio in injected BMG. When double labeled BMG was injected in Wistar rats after injection of excess unlabeled unconjugated bilirubin (1.7 μmol), the ¹⁴C:³H ratio in BDG excreted in bile was identical to the ratio in injected BMG. Analysis of isomeric composition of bilirubin conjugates after alkaline hydrolysis or alkaline methanolysis indicated that the bile pigments retained the IX_α configuration during these experiments. The results indicate that both enzymatic dismutation and UDP glucuronyl transferase function in vivo in BDG formation, and that dismutation is inhibited by a high intrahepatic concentration of unconjugated bilirubin. This hypothesis was supported by infusion of [³H]bilirubin-monoglucuronide in isolated perfused homozygous Gunn rat liver after depletion of intrahepatic bilirubin by perfusion with bovine serum albumin (2.5%), and after bilirubin repletion following perfusion with 0.34 mM bilirubin. From 20 to 25% of injected radioactivity was recovered in BDG in bile in the bilirubin-depleted state; only 8-10% of radioactivity was in BDG in bile after bilirubin repletion.