Protoporphyrin-induced cholestasis in the isolated in situ perfused rat liver.

The pathogenesis of liver disease in protoporphyria has been presumed to result from the hepatic deposition of protoporphyrin. To examine the effects of protoporphyrin on hepatic bile flow and histopathology, studies were performed employing an isolated, in situ, rat liver perfusion system. Rat livers in the control group were perfused with 0-80 mumol sodium taurocholate/h. Rat livers in the experimental group were perfused with sodium taurocholate and (a) sufficient quantities of protoporphyrin to produce maximal canalicular secretion and (b) perfusate protoporphyrin concentrations of 0.01, 0.1, and 1 muM. The administration of protoporphyrin sufficient to achieve maximal canalicular secretion was found to significantly reduce bile flow in rats infused with 0, 40, and 80 mumol sodium taurocholate/h. Linear regression analysis defined the relationship between bile flow and biliary bile acid secretion and showed that the bile acid-independent fraction of bile flow was reduced (P < 0.01). Bile acid-dependent flow was unaffected and there was no significant difference in biliary bile acid secretion rates between control and protoporphyrin-perfused livers. Perfusion of rat livers with varying concentrations of protoporphyrin demonstrated the reduction of bile flow was dose-related. Analysis of perfusate enzyme activity did not reveal abnormalities that could account for the cholestasis. Studies to evaluate the effect of protoporphyrin on regional hepatic hemodynamics were inconclusive. Histopathological studies of control and protoporphyrin-perfused rat livers did not show abnormalities on light microscopy. However, canalicular dilatation, distortion, and loss of microvilli were present in the protoporphyrin-perfused livers examined by transmission electron microscopy. Although ultraviolet microscopy showed diffuse fluorescence of the hepatocytes and canaliculi of protoporphyrin-perfused livers, the deposition of protoporphyrin in amorphous or crystalline forms was notably absent in studies with polarizing and transmission electron microscopy. These studies provide evidence that protoporphyrin has hepatotoxic properties that affect the canalicular secretory apparatus. The mechanism(s) responsible for the injury require further clarification.

Asymptomatic bilious ascites following percutaneous liver biopsy.

Asymptomatic bile leakage developed in a woman following percutaneous liver biopsy. The case is remarkable because features of cholestasis were not present at the time of biopsy, the bile leak occurred through the needle tract in the liver, billous ascites occurred without signs of acute peritonitis, and the complication was the initial manifestation of extrahepatic biliary obstruction due to encasement of the common bile duct by histiocytic lymphoma.

Randomized, placebo-controlled comparison of famotidine 20 mg b.d. or 40 mg b.d. in patients with erosive oesophagitis.

METHODS: This US multicentre, randomized, double-blind, placebo-controlled, parallel group study determined the effects of two twice daily oral famotidine regimens on symptom relief and healing of erosive oesophagitis in patients with gastro-oesophageal reflux disease. Three hundred and eighteen patients were enrolled: 66 received placebo, 125 received famotidine 20 mg b.d., and 127 received famotidine 40 mg b.d. Patients maintained diaries of their symptoms. Endoscopy was performed at weeks 0 and 6, and again at week 12 if healing had not occurred. RESULTS: Healing at 6 and 12 weeks was (respectively) 48% (P < or = 0.01 vs. placebo) and 69% (P < or = 0.01 vs. placebo) for famotidine 40 mg b.d.; 32% and 54% (P < or = 0.01 vs. placebo) for famotidine 20 mg b.d., and 18% and 29% for placebo. At both 6 and 12 weeks the healing rates of famotidine 40 mg b.d. were significantly greater than placebo and famotidine 20 mg b.d. Compared to placebo, famotidine produced more frequent global symptom improvement and more rapid heartburn relief. There were no significant differences among treatment groups in the incidence of clinical or laboratory adverse events. CONCLUSIONS: Famotidine 40 mg b.d. was a better regimen than famotidine 20 mg b.d. or placebo. The clinical efficacy paralleled the previously documented effect of the famotidine regimens on decrease of oesophageal acid exposure.

Value of serum inorganic phosphate in the diagnosis of ischemic bowel disease.

To clarify the value of the serum inorganic phosphate concentration in the diagnosis of ischemic bowel disease, a retrospective study of 24 patients with various causes of intestinal ischemia was carried out. Only 25 percent of the patients had elevations of their serum phosphate concentrations. These patients had the combination of extensive bowel injury, acute renal insufficiency, and acidosis. Mortality was significantly increased in these patients. Thus, the serum phosphate concentration was not a sensitive indicator of ischemic bowel disease, but elevations did predict extensive injury and poor prognosis.

Accuracy and consistency of pancreatography.

Pancreatography is a valuable diagnostic technic to identify structural changes in the pancreatic ductal system. Although specific diagnoses based on ductal changes are not always possible, patients with surgically normal glands and those showing changes of chronic pancreatitis were reliably identified in this series. Patients evaluated for postcholecystectomy pain usually had normal pancreatograms and grossly normal pancreatic glands at the time of surgical exploration. The overall consistency in interpretation of pancreatograms by experienced radiologists was approximately 80 per cent. Pancreatic cancer was poorly predicted due to either minimal changes in the ductal system or inability to distinguish gross changes from those seen with chronic pancreatitis.

Structure-function relationships of protoporphyrin-induced liver injury.

To further define the pathogenesis of protoporphyric liver disease, perfused rat livers received varying doses of protoporphyrin, and aberrations of hepatic ultrastructure and function were correlated. Results indicated that the relative canalicular volume was equally increased in all protoporphyrin-perfused livers; however, bile flow was only minimally diminished at the smallest protoporphyrin dose employed. Protoporphyrin injured microvilli at the sinusoidal pole and reduced the surface density of the endoplasmic reticulum in a dose-related fashion. No crystalline or amorphous material was detectable, and only slight mitochondrial distortions occurred. Thus, cholestasis did not correlate with canalicular dilatation, the presence of crystalline material, or mitochondrial changes. Liver plasma membrane abnormalities appeared to correlate with functional defects and support a direct hepatotoxicity. Long-term protoporphyrin overload studies are needed to assess differences between hepatic and erythroid (parenteral) sources of protoporphyrin overproduction.

Acceleration of cholesterol phase transitions in analog bile by chlorpromazine, pentobarbital and ethinyl estradiol.

The effects of incorporation of chlorpromazine, pentobarbital and ethinyl estradiol on the maintenance of cholesterol supersaturation was studied in bile analogs. Bile solutions were initially supersaturated and microscopically clear. Chlorpromazine and pentobarbital were almost totally solubilized; ethinyl estradiol was poorly solubilized. Chlorpromazine and pentobarbital in concentrations of 5 and 10 mg/ml rapidly (less than 3-5 h) diminished cholesterol in bile filtrates compared to controls; ethinyl estradiol did so at a concentration of 1 mg/ml but less rapidly (24 h). Bile acid and lecithin concentrations, over time, did not differ significantly between groups. The results indicate that drug interactions with bile constituents, without causing their precipitation, can alter the maintenance of cholesterol supersaturation and phase transitions in bile.

Supplemental nutrition and digestive disease.

Nutrition is an antegral part of medical management and patient care. The goal of nutritional therapy is to provide nutrients in form and amount appropriate to patients' needs. Dietary modification and application of available nutritional supplements in digestive disorders should be based upon an appreciation of the fundamental pathophysiological derangements and tailored to restore optimal gastrointestinal function.

Alcohol inhibition of rectosigmoid motility in humans.

The effects of acute intravenous alcohol infusion or sham treatment with normal saline on rectosigmoid motility was determined in healthy adult volunteer subjects. A significant reduction of rectosigmoid wave frequency, amplitude, percent activity and motility index occurred in subjects infused with alcohol when compared to their basal period or corresponding periods in the sham-treated group. Chemical intoxication was achieved in all subjects given alcohol and the percent of the basal motility index varied inversely with the blood alcohol level.

Hepatic clearance and biliary secretion of protoporphyrin in the isolated, in situ-perfused rat liver.

Models to explain the pathophysiology of protoporphyria have been based on fluxes of protoporphyrin between plasma and liver for which no quantitative data exist. The present studies employed isolated, in situ, recirculating and nonrecirculating rat liver perfusions to define the kinetics of hepatic uptake and biliary secretion of protoporphyrin. Livers from Sprague-Dawley rats were perfused with Krebs-Henseleit-3% albumin solution (bile acid-free) to which protoporphyrin was added. In nonrecirculation studies, hepatic protoporphyrin extraction was determined from 5 sec to 3 min. In recirculation studies, protoporphyrin perfusate disappearance and biliary secretion were determined at 5 and 10 min intervals, respectively. Rate constants derived from compartmental analysis of recirculation studies correlated with early measured values obtained during nonrecirculation; however, a dose-related decrease in the influx rate constant was evident. The overall disappearance of protoporphyrin from perfusate followed first-order kinetics but was neither monoexponential nor saturable. Sinusoidal cells contained less than 8% of the protoporphyrin extracted by the liver. Only 0.1% to 4% of the extracted protoporphyrin was secreted into bile. Therefore, canalicular secretion appeared to be the rate-limiting step in hepatic protoporphyrin disposal. Extrapolations based on these data provide a theoretical framework to appreciate the generation of plasma protoporphyrin concentrations. Within this framework, it may be inferred that if plasma protoporphyrin concentration is in excess of that predicted from total protoporphyrin excretion, a defect in hepatic protoporphyrin clearance exits.

Effect of choleretics on canalicular transport of protoporphyrin in the rat liver.

The major route of protoporphyrin elimination is biliary secretion. To clarify the nature of the secretory process, maximal canalicular secretion of protoporphyrin was determined under basal conditions and after treatment with various choleretics. The maximal secretion of protoporphyrin under basal conditions was 0.07 +/- 0.01 micrograms.min-1.100 g body wt-1. Infusion of physiological amounts of sodium taurocholate increased protoporphyrin secretion 13-fold (0.90 +/- 0.02), primarily by increasing the biliary protoporphyrin concentration. Biliary protoporphyrin secretion tended to plateau in spite of a continued rise in both biliary bile acid secretion and concentration. Infusion of sodium dehydrocholate increased protoporphyrin secretion, but to only 35% of that achieved by sodium taurocholate. Ethacrynic acid and phenobarbital increased bile flow over controls but failed to enhance protoporphyrin transport. Thus, canalicular secretion of protoporphyrin was maximally enhanced by micelle-forming bile acids and unaffected by nonbile acid choleretics. The observed limitation of protoporphyrin secretion may be related to achievement of a canalicular transport maximum or to a toxic effect of protoporphyrin on the transport process.

Lactic acidosis associated with cirrhosis, hepatoma, hemoperitoneum, and hyperphosphatemia.

A patient with cirrhosis developed hemoperitoneum, lactic acidosis, and hyperphosphatemia in the absence of shock. At post-mortem examination occult multicentric hepatocellular carcinoma eroding the liver capsule was present. The case emphasizes the central role of the liver in lactic acidosis, indicates that hemoperitoneum may precipitate this complication, and documents the association of lactic acidosis and hyperphosphatemia.

Methamphetamine-induced ischemic colitis.

A 50-year-old woman with acute onset of right lower quadrant pain and hematochezia proved to have segmental ischemic colitis associated with methamphetamine abuse. The diagnosis was established by colonoscopy with biopsy, and abdominal angiography revealed no thrombosis, vasculitis, or vasospasm. The condition resolved within 10 days. Since methamphetamine abuse is increasing, physicians should be aware of its potential to produce intestinal ischemia.

Calcium accelerates cholesterol phase transitions in analog bile.

Analog bile supersaturated with cholesterol was constituted, filtered and divided into equal portions containing no calcium or calcium, 2.5-15 mM. Aliquots were removed over the next 48 h and filtrates analyzed for cholesterol, bile acid and lecithin. Calcium accelerated cholesterol loss from solution in a dose-related fashion.

Effect of bile acid hydroxylation on biliary protoporphyrin excretion in rat liver.

The relationships between bile acid structure, protoporphyrin load, and biliary protoporphyrin excretion were studied in rat livers perfused with 0 or 0.7 mumol/min taurocholate and protoporphyrin loads between 350 and 35,525 nmol. Bile acid treatment increased the excretion of extracted protoporphyrin from 0.4 to 28%, the maximal biliary protoporphyrin concentration 32-fold, the protoporphyrin excretion rate approximately 150-fold, and the coupling of excreted protoporphyrin to bile acid. Infusions (0.7 mumol/min) of bile acids differing in structure with 1,500 nmol protoporphyrin all significantly increased protoporphyrin excretion but ursodeoxycholate and tauroursodeoxycholate did so less than others. Infusions (0.175-1.4 mumol/min) of taurocholate, deoxycholate, ursodeoxycholate, and chenodeoxycholate confirmed that protoporphyrin excretion increased significantly more with taurocholate or deoxycholate than chenodeoxycholate and chenodeoxycholate more than ursodeoxycholate. The relative ineffectiveness of dihydroxylated bile acids with a hydroxy group at the seven position (alpha- or beta-configuration) was not correlated with physicochemical parameters of the bile acids and remains unexplained. The findings suggest that ursodeoxycholate is the least acceptable bile acid to consider as a potential treatment for protoporphyria.

Protoporphyrin overload in unrestrained rats: biochemical and histopathologic characterization of a new model of protoporphyric hepatopathy.

We determined the feasibility of producing protoporphyric hepatopathy in unrestrained rats by infusing protoporphyrin into their portal circulation via chronic indwelling catheters. Sprague-Dawley rats, 200-300 g, received single (8.5-27.8 mumol) or multiple (64.1-208.7 mumol) infusions of protoporphyrin over 3-240 h. Single protoporphyrin infusions increased the hepatic protoporphyrin concentration from < 1 nmol/g up to 1368 nmol/g; multiple infusions up to 3908 nmol/g. The maximal non-hepatic tissue concentrations averaged 243 nmol/g in the spleen. Hepatocanalicular and ductular birefringent pigmented deposits were found in all livers, generally proportional to the protoporphyrin load. Aggregates of crystalline protoporphyrin were detected in biliary ductules, canaliculi, hepatocytes, Kupffer cells and fat-storage cells by electron microscopy. Laboratory abnormalities included elevations of the transaminases, LDH, GGTP and bilirubin and a modest fall in the haematocrit suggesting a mixture of red blood cell and hepatic injury. Thus, protoporphyric hepatopathy was produced by infusions of protoporphyrin into the portal circulation. This model may aid in understanding the pathogenesis and pathophysiology of liver disease in protoporphyria.

Transampullary septectomy for post-cholecystectomy pain.

Twenty-eight patients with chronic, incapacitating upper abdominal pain after cholecystectomy had excision of the common wall between the terminal bile duct and duct of Wirsung (ampullary septum). Twenty-two also had a sphincteroplasty: six had had this procedure previously. Pancreatic function studies, scintiscans, ultrasound and pancreatograms were non-diagnositic. Hyperamylasemia was an uncommon finding. Eight patients were found to have evidence of mild pancreatitis at exploration. There was gross scarring of the ampullary septum in 22 cases. Histologic examination revealed inflammation in 12 septa; the degree of fibrosis could not be assessed since 14 control septa from autopsy material free from biliary tract disease revealed a comparable degree of collagen and smooth muscle. There were no deaths, and minimal morbidity. In follow-up from seven to 59 months (mean = 26), 16 patients are relatively free of pain, five have occasional episodes which require non-narcotic analgesics, and seven have gained no relief from the operative procedure. A randomized controlled trial is recommended.

Inhibition of liver surface membrane Na+, K+-adenosine triphosphatase, Mg+2-adenosine triphosphatase and 5'-nucleotidase activities by protoporphyrin. Observations in vitro and in the perfused rat liver.

To clarify the pathogenesis of protoporphyrin-induced cholestasis, liver surface membrane enzyme activities were determined after (a) isolated rat liver perfusion with protoporphyrin administered by bolus (1.0 mumol) or bolus plus constant infusion (1.0 mumol + 0.05 mumol/min) and (b) combination of liver surface membrane with protoporphyrin (0.9-53.4 nmol/ml) in vitro. The perfusion studies showed that protoporphyrin significantly inhibited Na+, K+- and Mg+2-adenosine triphosphatase activities. In vitro, these adenosine triphosphatase activities and the 5'-nucleotidase activity were inhibited linearly by protoporphyrin up to a concentration of approximately 18 mumol/ml; thereafter, enzyme activity was maintained. Greater inhibition of the adenosine triphosphatase activities occurred with protoporphyrin than was reported for chlorpromazine at similar molar concentrations. This effect was independent of the quantity of membrane protein analyzed and was not reversible with a 50:1 dilution. The inhibitory effect of protoporphyrin on surface membrane enzyme activities was also nonselective. Although the hepatotoxic effects of protoporphyrin may be more generalized, the present data underscore protoporphyrin's toxic interaction with liver surface membranes.

Importance of bile acid structure in amelioration of griseofulvin-induced murine protoporphyric hepatopathy.

This study investigated the effects of bile acid structure on griseofulvin-induced murine hepatopathy and explored the mechanism(s) of cholestasis in this model of protoporphyria. Mice were fed pulverized chow with cholate, chenodeoxycholate, or ursodeoxycholate, with or without griseofulvin. After 1 to 4 weeks, bile flow, bile acid excretion and composition, biliary protoporphyrin excretion, hepatic protoporphyrin contents, liver histology, and griseofulvin plasma concentrations were determined. Additionally, bile acid absorption was measured. Griseofulvin induced a progressive increase in liver weight, hepatic protoporphyrin content, and histopathologic evidence of cholestasis. Biliary protoporphyrin excretion increased and pigmented gallbladder microliths developed. Bile flow and bile acid excretion fell in relation to liver weight but not in relation to body weight. Cholic acid augmented biliary protoporphyrin excretion, markedly reduced hepatic protoporphyrin content, and obviated the development of intrahepatic biliary thrombi. Ursodeoxycholate and chenodeoxycholate both reduced biliary protoporphyrin excretion. This was associated with bile acid compositional changes, particularly a fall in cholic acid. Although histopathologic abnormalities were not altered, these bile acids reduced hepatic protoporphyrin contents. Bile acid treatments with griseofulvin all increased bile flow and bile acid excretion relative to controls, but differences in the relationship of bile flow to bile acid structure on protoporphyrin disposition. They document biliary excretion as the principal mode of cholic acid amelioration of griseofulvin-induced hepatopathy. They also suggest distinctive roles for griseofulvin and protoporphyrin in the generation of the cholestasis.

Esophageal columnar epithelial beta-galactosidase and beta-glucuronidase.

We have compared the activity of the lysosomal enzymes, beta-galactosidase and beta-glucuronidase, in esophageal columnar, gastric fundic, and small intestinal epithelia. Beta-Galactosidase activity in esophageal columnar epithelium was less than that in intestinal tissue. Beta-Glucuronidase activity in the esophageal columnar epithelium was greater than that in gastric fundic tissue. Thus, this unique epithelium has enzyme characteristics which are dissimilar to both intestinal and gastric fundic tissue. This tends to support previous findings that suggested a metaplastic derivation.