PET imaging of patients with non-small cell lung cancer employing an EGF receptor targeting drug as tracer

Background:

We have previously developed ¹¹C-erlotinib as a new positron emission tomography (PET) tracer and shown that it accumulates in epidermal growth factor receptor (EGFR)-positive lung cancer xenografts in mice. Here, we present a study in patients with non-small cell lung cancer (NSCLC) investigating the feasibility of ¹¹C-erlotinib PET as a potential method for the identification of lung tumours accumulating erlotinib.

Methods:

Thirteen patients with NSCLC destined for erlotinib treatment were examined by contrast-enhanced computed tomography (CT), ¹¹C-erlotinib PET/low-dose CT and ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) PET/low-dose CT before start of the erlotinib treatment. After 12 weeks treatment, they were examined by ¹⁸F-FDG PET/contrast-enhanced CT for the assessment of clinical response.

Results:

Of the 13 patients included, 4 accumulated ¹¹C-erlotinib in one or more of their lung tumours or lymph-node metastases. Moreover, ¹¹C-erlotinib PET/CT identified lesions that were not visible on ¹⁸F-FDG PET/CT. Of the four patients with accumulation of ¹¹C-erlotinib, one died before follow-up, whereas the other three showed a positive response to erlotinib treatment. Three of the nine patients with no accumulation died before follow-up, four showed progressive disease while two had stable disease after 12 weeks of treatment.

Conclusion:

Our data show a potential for ¹¹C-erlotinib PET/CT for visualizing NSCLC lung tumours, including lymph nodes not identified by ¹⁸F-FDG PET/CT. Large clinical studies are now needed to explore to which extent pre-treatment ¹¹C-erlotinib PET/CT can predict erlotinib treatment response.

Forearm and leg amino acid metabolism in the basal state and during combined insulin and amino acid stimulation after a 3-day fast

AIM

Fasting is characterized by a progressive loss of protein, but data on protein kinetics are unclear and few have studied the effects of re-feeding. The present study was designed to test the hypothesis that a combined infusion of insulin and amino acids after fasting would induce compensatory increases in protein synthesis and reductions in protein breakdown at the whole body level and in muscle.

METHODS

We included 10 healthy male volunteers and studied them twice: (1) in the post-absorptive state and (2) after 72 h of fasting. Amino acid kinetics was measured using labelled phenylalanine and tyrosine, whole body energy expenditure was assessed and urea nitrogen synthesis rates were calculated.

RESULTS

After fasting we observed an increase in arterial blood concentration of branched chain amino acids and a decrease in gluconeogenic amino acids (P < 0.05). Isotopically determined whole body, forearm and leg phenylalanine fluxes were unaltered apart from a 30% decrease in phenylalanine-to-tyrosine conversion (2.0 vs. 1.4 mumol kg(-1) h(-1), P < 0.01). During infusion of insulin and amino acids, amino acid concentrations increased.

CONCLUSION

Our data indicate that after a 72-h fast basal and insulin/amino acid-stimulated regional phenylalanine fluxes in leg and forearm muscle are unaltered. During fasting concentrations of gluconeogenic amino acids decrease and hepatic and/or renal phenylalanine-to-tyrosine conversion decreases. Thus, as opposed to glucose and lipid metabolism, fasting does not induce insulin resistance as regards amino acid metabolism.

FDG-PET improves management of patients with colorectal liver metastases allocated for local treatment: a consecutive prospective study

BACKGROUND AND AIM

Colorectal cancer is a common cancer in the Nordic countries and 50% of the patients develop liver metastases. Liver resection may result in long term survival. Proper staging is therefore essential and CT is the standard imaging modality. We examined whether additional FDG-PET improves therapeutic management of patients with colorectal liver metastases.

PATIENTS AND METHODS

Fifty-four consecutive patients were enrolled. Each patient had a treatment plan made based on our standard evaluation. The patients then had a PET scan and the treatment plan was re-evaluated, taking these results into account.

RESULTS

In 76% of the cases, PET did not change the treatment plan due to complete concordance with CT. In another 19% of the cases, the plan was altered due to finding of more liver lesions by PET than by CT (four patients), fewer or no liver lesions (three patients), and extrahepatic lesions not visible on CT (three patients). In 5% of the cases, non-concordance between PET and CT did not change the therapeutic plan.

CONCLUSION

Pre-treatment FDG-PET, used supplementary to CT, improved the treatment plan in one fifth of the patients with colorectal liver metastases.

Effects of a 3-day fast on regional lipid and glucose metabolism in human skeletal muscle and adipose tissue

AIM

Fasting is characterized by increased whole body lipolysis and lipid oxidation, decreased glucose oxidation and insulin resistance. To identify the regional sources and underlying mechanisms, we studied 10 healthy male volunteers post-absorptively and after 72 h of fasting.

METHODS

Each study comprised a 3-h basal period and a 3-h hyperinsulinaemic euglycaemic clamp and we used a combination of leg and forearm arteriovenous techniques, upper and lower body microdialysis and glucose and palmitate tracers.

RESULTS

In the basal state, plasma levels, fluxes and oxidation rates of free fatty acids all roughly doubled after fasting. Palmitate fluxes across the forearm and leg also increased by two to threefold and interstitial leg muscle glycerol concentrations doubled. Subcutaneous femoral glycerol concentrations and blood flows were unaltered, but abdominal subcutaneous blood flow increased by 50% in the presence of unchanged glycerol concentrations, indicating stimulated abdominal lipolysis. During the clamp, we observed whole body insulin resistance and glucose uptake across the leg and forearm decreased by 60%.

CONCLUSION

Our data show that fasting induces insulin resistance in upper and lower body muscles and suggest that increased lipolysis, is primarily due to the activation of lipolysis in muscle-associated fat (in the leg) and in upper body subcutaneous fat, whereas peripheral subcutaneous fat is spared.

Budd-Chiari and inferior caval vein syndromes due to membranous obstruction of the liver veins: successful treatment with angioplasty and transcaval transjugular intrahepatic porto-systemic shunt

The case is presented of a 25-year-old Caucasian patient with Budd-Chiari syndrome due to membranous obstruction of the liver veins and inferior caval vein syndrome as a result of secondary hyperplasia of the caudate lobe of the liver, obstructing the caval vein. Diagnosis was established by intravascular pressure measurements, ultrasound examinations and caval and liver vein angiograms. Treatment consisting of stent placement in the outlet of a hepatic vein and subsequent transjugular intrahepatic porto-systemic shunt (TIPS) insertion via the caval vein was successful. After 34 months of follow-up the stents remain open and the patient is symptom free. This successful combination of stent placement and TIPS has not been described before. The case report is followed by a review of the literature on the use of angioplasty in short hepatic vein stenosis and TIPS in Budd-Chiari syndrome. It is concluded that angioplasty and TIPS are safe and efficient procedures to reduce liver engorgement and complications of portal hypertension in selected patients with Budd-Chiari syndrome.

Combined liver vein and spleen pulp pressure measurements in patients with portal or splenic vein thrombosis

BACKGROUND

Patients with thrombosis of the portal or splenic vein may develop portal hypertension with bleeding from oesophageal or gastric varices. The relevant portal pressure cannot be measured by liver vein catheterization or transhepatic puncture of the portal vein because the obstruction is peripheral to the accessible part of the portal system.

METHODS

Liver vein catheterization was combined with percutaneous splenic pressure measurement in 10 patients with portal or splenic vein thrombosis and no cirrhosis, and 10 cirrhotic patients without thrombosis. The splenic pressure was measured by percutaneous puncture below the curvature of the ribs with an angle of the needle to skin of 30 degrees in order to minimize the risk of cutting the spleen if the patient took a deep breath.

RESULTS

None of the patients in whom the described procedure was followed had complications. Pressure measurements in the spleen pulp and splenic vein were concordant. The pressure gradient across the portal venous system (splenic-to-wedged hepatic vein pressure) was -1.3 to 8.5 mmHg (median, 2.8 mmHg) in cirrhosis patients and 0-44 mmHg (median, 18 mmHg) in thrombosis patients, the variation reflecting various degrees of obstruction to flow in the portal venous system. Peripheral portal pressure (splenic-to-free liver vein pressure gradient) was 1.1-28 mmHg (median, 17 mmHg) in cirrhotic patients and 11-52 mmHg (median, 23 mmHg) in thrombosis patients.

CONCLUSIONS

Liver vein catheterization combined with percutaneous splenic pressure measurement is feasible in quantifying pressure gradient across a thrombosis of the portal/splenic vein and in quantifying portal pressure peripheral to this kind of thrombosis.

Intrahepatic heterogeneity of hepatic venous pressure gradient in human cirrhosis

BACKGROUND

The hepatic venous pressure gradient (HVPG) is used to evaluate portal hypertension.

METHODS

We measured HVPG in two separate liver veins in 169 liver vein catheterizations in 102 cirrhosis patients and in 27 patients with no liver disease (controls).

RESULTS

In the controls, the two measurements differed by 0.0 +/- 1.8 mmHg (mean +/- s, n = 27), upper 95% confidence limit 3.6 mmHg (mean + 2 s). HVPG ranged from -0.1 to 8.3 mmHg, upper 95% confidence limit 6.7 mmHg. In cirrhosis, the two measurements agreed within +/- 3.6 mmHg in 39%. In 61%, the measurements differed by 4-34 mmHg. In 35%, fluoroscopy demonstrated hepatic vein-to-hepatic-vein shunting in veins with low HVPG values. In some patients with HVPG measurements above 30 mmHg, Doppler ultrasound examination showed arterialization of the hepatic vasculature.

DISCUSSION

Our results demonstrate a hitherto unrecognized notable heterogeneity of the intrahepatic vasculature and HVPG measurements in cirrhosis. The presumption of interposition of non-flowing blood between the catheter tip and the portal system for the measurement of HVPG may thus be violated in about one-third of the cirrhosis cases because of abnormal outlet into hepatic venous shunts and in a minor fraction because of abnormal arterial inlet. In 26%, one measurement was below 12 mmHg, the other measurement above. If the HVPG had been measured in only one liver vein, 13% of the cases would have been classified in a lower risk group than appropriate according to the 12 mmHg concept of risk of bleeding from oesophageal varices.

Positron emission tomography of hepatic first-pass metabolism of ammonia in pig

Hepatic first-pass metabolism plays a key role in metabolic regulation and drug metabolism. Metabolic processes can be quantified in vivo by positron emission tomography scanning (PET). We wished to develop a PET technique to measure hepatic first-pass metabolism of ammonia. Seven anaesthetised pigs were given positron-labelled ammonia, (13)NH(3), into the portal vein and into the vena cava as successive 2-min infusions followed by 22-min dynamic liver scanning. Vena cava infusion data were used to account for recirculation of tracer and metabolites following the portal vein infusion. The scan data were analysed by a model of sinusoidal zonation of ammonia metabolism with periportal urea formation and perivenous formation of glutamine. The hepatic extraction fraction of (13)NH(3) was 0.73+/-0.16 (mean+/-SD, n=7 pigs). Values of clearance of ammonia to urea and to glutamine were obtained, as were rate constants for washout of these two metabolites. Overall, the modelling showed half of the ammonia uptake to be converted to urea and half to glutamine. The washout rate constant for glutamine was about one-tenth of that for urea. We conclude that hepatic first-pass metabolism of ammonia was successfully assessed by PET.

Metabolites of (18)F-FDG and 3-O-(11)C-methylglucose in pig liver

PET uses (18)F-FDG widely to estimate glucose metabolism in vivo. Dynamic PET data are evaluated by kinetic models of the metabolic pathways. Knowledge of the metabolites of FDG is of critical importance for the interpretation of kinetic PET studies. The purpose of this study was to determine the metabolic pathways of FDG and 3-O-(11)C-methylglucose (MG) in liver tissue in vivo. It is usually assumed that MG is not metabolized and FDG is converted to (18)F-FDG-6-phosphate (FDG-6-P).

METHODS

The study was performed on 6 anesthetized 40-kg pigs that were given the 2 tracers intravenously. The content of metabolites was determined in successive liver tissue biopsies. Freeze-clamped liver tissue samples were subjected to extraction by acetonitrile at -5 degrees C to -10 degrees C, and extracts were analyzed by radio-high-performance liquid chromatography (radio-HPLC). The findings were identified by means of radio-HLPC measurements of the products of in vitro enzymatic reactions.

RESULTS

The applied extraction technique provided almost quantitative recovery of the radioactivity from tissue. After MG injection, only MG was detectable in the liver tissue; no labeled metabolites were found. After FDG injection, 2 metabolites were identified, FDG-6-P and 2-(18)F-fluoro-2-deoxy-6-phosphogluconate (FD-6-PG1). The tissue content of FDG increased rapidly, and, after 5 min, only FDG was identified; hereafter, the fraction of FDG decreased to approximately 40% of the tissue radioactivity after 180 min. After 20 min, FDG-6-P was found in each of the pigs and it increased throughout the measurement period of 180 min, with a somewhat slower rise at late time points. FD-6-PG1 began to appear in the liver tissue after 45 min and increased throughout the 180-min experiment, with the increase somewhat slower than that of FDG-6-P. After 180 min, approximately 40% of the metabolites was attributed to FD-6-PG1. The content of other metabolites was <2%, even after 180 min.

CONCLUSION

After the FDG injection, not only FDG-6-P but also FD-6-PG1 were formed in the liver. Any possible incorporation of FDG into glycogen was of minor importance.

Liver transplantation in patients over 60 years of age

Liver transplantation was previously only offered to patients under 60 years of age. We have analyzed the outcome after acceptance on the waiting list and after liver transplantation of patients over 60 years old. A total of 150 patients over 60 years old were listed for a first liver transplantation during 1990-1998. The annual number increased throughout the period. Primary biliary cirrhosis, primary sclerosing cholangitis, and acute hepatic failure were the most frequent diagnoses. A total of 119 patients received a first liver allograft. The patient 1-year survival was 75% and 3-year survival 62%, which was not significantly lower (P = 0.21) than that of the younger patients. When correcting for year of transplantation, the survival was, however, moderately but significantly lower than among the younger patients. Survival among those > 65 years (n = 38) did not differ from that of patients 60-65 years of age (n = 81). We conclude that an increasing number of patients over 60 years old can be listed for liver transplantation and receive a liver allograft with highly satisfying results.

Liver kinetics of glucose analogs measured in pigs by PET: importance of dual-input blood sampling

Metabolic processes studied by PET are quantified traditionally using compartmental models, which relate the time course of the tracer concentration in tissue to that in arterial blood. For liver studies, the use of arterial input may, however, cause systematic errors to the estimated kinetic parameters, because of ignorance of the dual blood supply from the hepatic artery and the portal vein to the liver.

METHODS

Six pigs underwent PET after [15O]carbon monoxide inhalation, 3-O-[11C]methylglucose (MG) injection, and [18F]FDG injection. For the glucose scans, PET data were acquired for 90 min. Hepatic arterial and portal venous blood samples and flows were measured during the scan. The dual-input function was calculated as the flow-weighted input.

RESULTS

For both MG and FDG, the compartmental analysis using arterial input led to systematic underestimation of the rate constants for rapid blood-tissue exchange. Furthermore, the arterial input led to absurdly low estimates for the extracellular volume compared with the independently measured hepatic blood volume of 0.25 +/- 0.01 mL/mL (milliliter blood per milliliter liver tissue). In contrast, the use of a dual-input function provided parameter estimates that were in agreement with liver physiology. Using the dual-input function, the clearances into the liver cells (K1 = 1.11 +/- 0.11 mL/min/mL for MG; K1 = 1.07 +/- 0.19 mL/min/mL for FDG) were comparable with the liver blood flow (F = 1.02 +/- 0.05 mL/min/mL). As required physiologically, the extracellular volumes estimated using the dual-input function were larger than the hepatic blood volume. The linear Gjedde-Patlak analysis produced parameter estimates that were unaffected by the choice of input function, because this analysis was confined to time scales for which the arterial-input and dual-input functions were very similar.

CONCLUSION

Compartmental analysis of MG and FDG kinetics using dynamic PET data requires measurements of dual-input activity concentrations. Using the dual-input function, physiologically reasonable parameter estimates of K1, k2, and Vp were obtained, whereas the use of conventional arterial sampling underestimated these parameters compared with independent measurements of hepatic flow and hepatic blood volume. In contrast, the linear Gjedde-Patlak analysis, being less informative but more robust, gave similar parameter estimates (K, V) with both input functions.

Feasibility of detecting hypoxia in experimental mouse tumours with 18F-fluorinated tracers and positron emission tomography--a study evaluating [18F]Fluoro-2-deoxy-D-glucose

The study was designed to investigate the binding of [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluoro-2-deoxy-D-glucose ([18F]FDG) in a C3H mouse mammary carcinoma. Non-anaesthetized tumour-bearing animals breathing either normal air or carbogen (to reduce tumour hypoxia) were examined by PET after tracer injection. Tumours were identified by radioactive labelling and methods of defining regions of interest (ROI) in the tumours were investigated. Reference tissue was selected elsewhere in the mice and the ratio between mean radioactivity in tumour and reference tissue was compared. The results showed a correlation between the methods of identifying ROIs and a significantly lower tumour to reference tissue ratio for carbogen-treated mice compared with controls when using [18F]FMISO. Only one of the methods showed a significant difference in the tumour labelling between treatment groups using [18F]FDG. The study supports the contention that [18F]FMISO may be able to identify hypoxia in tumours, whereas a similar role for [18F]FDG is more doubtful.

Dynamic 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography of liver tumours without blood sampling

Positron emission tomography (PET) using 2-[18F]fluoro-2-deoxy-D-glucose (FDG) is a useful diagnostic tool for the detection of tumours. Using dynamic FDG PET, net metabolic clearance of FDG, K, can be calculated by Gjedde-Patlak analysis of the time course of the radioactivity concentrations in tissue and arterial blood. We examined whether time-activity curves (TACs) based on arterial blood sampling could be replaced by TACs obtained from the descending aorta in dynamic PET scans of patients with liver tumours. The study was performed in two parts, using data from dynamic liver scans with arterial blood sampling in human subjects: First, data from four patients with no liver tumours and five patients with liver tumours were used as a training group. Volumes of interest were defined in the descending aorta (aorta VOIs) by four different methods. K values were calculated based on the corresponding TACs and compared with those based on TACs of the arterial blood sample radioactivity concentrations. The aorta VOI which gave K values that were in best agreement with the K values based on the arterial blood sample measurements was called the AORTA-VOI. Use of the AORTA-VOI was subsequently tested in a test group of 19 tumour patients by comparing the K values from the AORTA-VOI with the K values based on the arterial blood sample measurements. The AORTA-VOI consisted of the sum of small regions of interest (ROIs) drawn in the centre of the aorta (approximately six pixels of 2.4x2.4 mm per transaxial slice of 3.1 mm thickness) in as many transaxial slices as possible (30-40 slices). There were no statistically significant differences between the two sets of K values. The ratio of K values in tumour tissue to K values in reference tissue was 2.1-9.7:1 (mean, 5.4:1) based on the AORTA TACs, and 2.1-8.4:1 (mean, 4.6:1) based on blood sample TACs (P>0.3). We conclude that arterial blood sampling can be replaced by the present AORTA-VOI in the calculation of the net metabolic clearance of FDG in dynamic PET studies of liver tumours in human subjects.

[Detection of cholangiocarcinoma in primary sclerosing cholangitis by positron emission tomography]

Primary sclerosing cholangitis (PSC) predisposes to cholangiocarcinoma (CC). PET scanning can assess metabolism in vivo. The glucose analogue [18 F]fluoro-2-deoxy-D-glucose (FDG) accumulates in malignant tumours because of high glucose metabolism. PET scanning of the liver was performed after intravenous FDG in nine patients with PSC, six with PSC + CC, and five controls. "Hot spots" with radioactivity accumulation were seen in each PSC + CC patient, but not in the two other groups. Values of net metabolic clearance of FDG, K (ml min-1 100 ml-1 tissue), was in CC hot spots 1.59 to 4.17 (median, 2.34; n = 6); in reference liver tissues of these patients 0.40 to 0.69 (0.49); in PSC 0.23 to 0.53 (0.36); in controls 0.20 to 0.34 (0.31). The difference between K in CC hot spots and the other groups was statistically significant (P < 0.001). FDG-PET may detect small CC tumours and be useful in therapeutic management of PSC.

Interpretation of simultaneous measurements of hepatic extraction fractions of indocyanine green and sorbitol: evidence of hepatic shunts and capillarization?

Sorbitol and indocyanine green (ICG) have high hepatic extraction fractions (E(sorb) and E(ICG)) in normal subjects. A curved relationship has been observed between E(sorb) and E(ICG) in liver disease. According to one interpretation, the decrease of E(sorb) is a result of intrahepatic shunting and 1 - E(sorb) is the fraction of shunted flow (the shunt hypothesis). Under the further assumption that capillarization of functioning sinusoids prevents hepatic uptake of plasma protein-bound ICG and allows uptake of water-soluble sorbitol, the difference E(sorb) - E(ICG) has been suggested as a measure of capillarization. We propose an alternative hypothesis: that the sinusoidal permeability-surface area products for sorbitol and ICG are reduced in proportion by liver disease (proportional reduction hypothesis). Based on the sinusoidal perfusion model, predictions were produced from both hypotheses for the relation between E(sorb) and E(ICG) and the additional effects of capillarization were described. By use of liver vein catheterization, E(sorb) and E(ICG) were simultaneously measured during continuous infusions in 53 human subjects with varying degrees of liver disease. The data were in better agreement with the predictions of the proportional reduction hypothesis than with the shunt hypothesis. Even though both intrahepatic portosystemic shunts and sinusoidal capillarization are known to occur in cirrhosis and also may have influenced our data, they appeared to be of minor importance from a kinetic point of view. These findings favor the proportional reduction hypothesis and do not support the use of systemic nonrenal clearance of sorbitol as a measure of "functional liver blood flow."

Interpretation of simultaneous measurements of hepatic extraction fractions of indocyanine green and sorbitol: evidence of hepatic shunts and capillarization?

Sorbitol and indocyanine green (ICG) have high hepatic extraction fractions (E(sorb) and E(ICG)) in normal subjects. A curved relationship has been observed between E(sorb) and E(ICG) in liver disease. According to one interpretation, the decrease of E(sorb) is a result of intrahepatic shunting and 1 - E(sorb) is the fraction of shunted flow (the shunt hypothesis). Under the further assumption that capillarization of functioning sinusoids prevents hepatic uptake of plasma protein-bound ICG and allows uptake of water-soluble sorbitol, the difference E(sorb) - E(ICG) has been suggested as a measure of capillarization. We propose an alternative hypothesis: that the sinusoidal permeability-surface area products for sorbitol and ICG are reduced in proportion by liver disease (proportional reduction hypothesis). Based on the sinusoidal perfusion model, predictions were produced from both hypotheses for the relation between E(sorb) and E(ICG) and the additional effects of capillarization were described. By use of liver vein catheterization, E(sorb) and E(ICG) were simultaneously measured during continuous infusions in 53 human subjects with varying degrees of liver disease. The data were in better agreement with the predictions of the proportional reduction hypothesis than with the shunt hypothesis. Even though both intrahepatic portosystemic shunts and sinusoidal capillarization are known to occur in cirrhosis and also may have influenced our data, they appeared to be of minor importance from a kinetic point of view. These findings favor the proportional reduction hypothesis and do not support the use of systemic nonrenal clearance of sorbitol as a measure of "functional liver blood flow."

Liver transplantation in the Nordic countries, 1982-1998: changes of indications and improving results

BACKGROUND

Liver transplantation has become an established therapeutic option for patients with life-threatening liver disease. The aim of the present study was to analyse the results of and developments in liver transplantation in the Nordic countries during a 15-year period.

METHODS

Data on all patients receiving a liver allograft in the Nordic countries during 1982-98 and waiting list data for all patients listed for a liver transplantation after 1989 were obtained from the Nordic Liver Transplantation Registry.

RESULTS

A total of 1485 first liver transplantations were performed during 1982-98. The annual number of first liver transplantations increased steadily up to 1993, thereafter remaining around 150-170 per year. There are major differences between countries both in the number of transplants adjusted to populations performed per year, with more than twice as many performed in Sweden as in Norway, and in the relative distribution of patients in accordance with diagnosis. The number of patients more than 60 years old increased and comprised 13%-14% of the total patient population during 1996-98. Primary biliary cirrhosis, primary sclerosing cholangitis, acute hepatic failure, malignant liver disease, and alcoholic cirrhosis are the five most frequent diagnoses. The over-all 1-year patient survival probability has increased from 66% among patients receiving a transplant in 1982-89 to 83% in 1995-1998. The waiting time remains stable, with a median waiting time of 35 days during 1990-98. The mortality of patients while on the waiting list is 7.4% and is not increasing.

CONCLUSION

Results of liver transplantation in the Nordic countries are very similar to those obtained in other countries. Waiting time and mortality remain low. There are, however, major differences between the countries both as to the number of transplantations performed and as to distribution of diagnoses.

Detection of cholangiocarcinoma in primary sclerosing cholangitis by positron emission tomography

Primary sclerosing cholangitis (PSC) predisposes to cholangiocarcinoma (CC), which usually is widespread in the liver at the time of the diagnosis and which has a median survival of approximately 6 months. Positron emission tomography (PET) is a noninvasive scanning method that allows the assessment of metabolism in vivo by means of positron-emitting radiolabeled tracers. [18F]Fluoro-2-deoxy-D-glucose (FDG) is a glucose analogue that accumulates in various malignant tumors because of their high glucose metabolic rates. The purpose of the study was to develop a PET method to detect small CC tumors in patients with PSC. PET scanning of the liver was performed after intravenous injection of 200 MBq FDG in 9 patients with PSC, 6 patients with PSC + CC, and 5 controls. The scanning was performed at successive time intervals for a total of 90 minutes with simultaneous successive arterial blood sampling for radioactivity concentration determination. In each of the PSC + CC patients, 2 to 7 "hot spots" were seen, with volumes of 1.0 to 45 mL (median, 4.4 mL). There were no hot spots in the two other patient groups. The localization of hot spots was confirmed by single-blind evaluation. Data were analyzed by the Gjedde-Patlak plot, yielding values of the net metabolic clearance of FDG, K [mL min(-1) 100 mL(-1) tissue]. In the CC hot spots, maximum K values were 1.59 to 4.17 (median, 2.34; n = 6); in the reference liver tissues of these patients, K values were 0.40 to 0.69 (median, 0.49); in PSC patients, they were 0.23 to 0.53 (median, 0.36); and in controls, they were 0.20 to 0.34 (median, 0.31). The difference between K in CC hot spots and the other groups was statistically significant (P < .001). We conclude that FDG-PET seems to be able to detect small CC tumors and may be useful in the therapeutic management of PSC.

Sorbitol as a test substance for measurement of liver plasma flow in humans

The objective of this study was to evaluate whole-body removal kinetics of sorbitol, the use of extrarenal sorbitol clearance to estimate hepatic plasma flow in humans, and to compare measurements of liver flow by Fick's principle using either indocyanine green (ICG) or sorbitol. A sorbitol bolus (5 mmol/kg) was given intravenously to 6 controls for determination of sorbitol elimination capacity (SEC) and distribution volume, V(sorb)d. Sorbitol infusion (287 micromol/ min) was given to 17 liver patients and 11 controls. Extrarenal sorbitol clearance (V(sorb)x was calculated as infusion rate (corrected for renal excretion and accumulation in V(sorb)d) divided by arterial concentration. Liver flow (Q(ICG)) was calculated from the ICG infusion and arterial and hepatic venous ICG concentrations by Fick's principle. Average SEC was 73 micromol/min/kg, V(sorb)d was 0.16 L plasma per kilogram, and in vivo V(sorb)d was 3 mmol/L. Renal sorbitol excretion rate was 0.03 to 0.31 of infusion rate. Extrahepatic extrarenal removal was not significantly different from zero but varied considerably. Hepatic extraction fraction of sorbitol, (E(sorb)), measured by liver vein catheterization, was 0.35 to 1.04 (median, 0.86) in cirrhotic patients and 0.90 to 0.98 (0.86) in controls. The requirements for using Cl(sorb)x as an estimate of Q(ICG) was not violated by the data in controls, Cl(sorb)x/Q(ICG) 0.70 to 1.55 [median, 1.08]), whereas there was a systematic underestimation in cirrhotic patients (0.72-1.08 [0.85]). Liver flow calculated by Fick's principle using either sorbitol or ICG agreed well. E(sorb) > E(ICG) in each individual except one. Curvilinear relationship between E(sorb) and E(ICG) was in agreement with different kinetic parameters for sorbitol and ICG, and did not require additional assumption of intrahepatic shunts.

Hepatic ICG removal in the pig depends on plasma protein and hematocrit: evidence of sinusoidal binding disequilibrium and unstirred water layer effects

The influence of binding protein concentration and hematocrit on hepatic uptake of indocyanine green (ICG) was studied in anesthetized pigs during constant infusion of ICG. By exchange transfusions, we either substituted plasma protein with dextran 70 (n = 8) or changed hematocrit (n = 8). Intrinsic hepatic clearance of ICG, K, was calculated from plasma flow rate and concentrations in peripheral artery and liver vein after correction for extrahepatic distribution. By analyzing the relative change of K versus either the protein dilution factor or the change in plasma volume fraction (1-hct), we evaluated four current models for hepatic uptake of protein-bound substances even though a number of model parameters were unknown (parameter-free testing). Protein dilution factors (unitless) of 0.506 +/- 0.027, 0.673 +/- 0.011, and 0.749 +/- 0.028 were associated with inverse K ratios of 0.621 +/- 0.025, 0.758 +/- 0.021, and 0.817 +/- 0.013. These data rejected the traditional hypothesis that ICG uptake is proportional to the unbound concentration. They were compatible with development of binding disequilibrium along the sinusoidal lumen, an unstirred water layer close to the hepatocyte surface, or facilitated uptake from the bound pool. A plasma volume ratio [(1-hct2)/(1-hct1)] of 1.14 +/- 0.02 was associated with a K ratio of 1.07 +/- 0.02 (P = .01). Only sinusoidal binding disequilibrium predicted this finding, whereas an additional unstirred water layer effect could not be excluded. The observations could be simulated by a model that included both of these effects. Thus, neither the relative changes of K nor the absolute K values required the assumption of facilitated uptake from the bound pool. The parameter-free design presented may be useful with other ligands in intact animals.

The Nordic multicenter double-blind randomized controlled trial of prophylactic ursodeoxycholic acid in liver transplant patients

BACKGROUND

Prophylactic treatment with ursodeoxycholic acid (UDCA) has been reported to reduce the incidence of acute rejection after liver transplantation compared with historical controls. We investigated this in a prospective, randomized, placebo-controlled multicenter study.

METHODS

Fifty-four liver transplant patients were allocated to the UDCA treatment group (15 mg/kg/day), and 48 patients were allocated to the placebo group. Trial medicine was started on the first postoperative day and was given for 3 months. Follow-up was for 12 months. Treatment was stratified for adults with chronic liver disease (n=77), adults with acute liver failure (n=10), and children (n=15).

RESULTS

The frequency of patients with acute rejection was 65% in the UDCA treatment group and 68% in the placebo group. The frequency of steroid-resistant rejection was similar in both groups. The probability of acute rejection, analyzed according to the intention-to-treat policy with Kaplan-Meier analysis, was similar in both treatment groups. No significant differences were found in patient survival and graft survival probabilities. For the biochemical markers of cholestasis, only gamma-glutamyltransferase was significantly improved after 2 months of UDCA treatment.

CONCLUSIONS

The initial optimistic report of a beneficial effect of prophylactic treatment with UDCA on acute rejection after liver transplantation was not confirmed in this controlled study.

Effects of brain death and glucose infusion on hepatic glycogen and blood hormones in the pig

We wished to study the effects of intravenous glucose/ insulin infusion to brain-dead pigs on the hepatic glycogen content. Four groups of 40-kg pigs were studied: brain-dead and control pigs given isotonic saline or glucose/insulin (7.5 mg glucose/kg/min, 1.25 mU insulin/kg/ min) (n = 5 to 10 in each group). Brain death was induced by inflating a balloon placed in the epidural space. In brain-dead pigs given saline, liver glycogen decreased from 45 +/- 11 mmol/g DNA (mean +/- SEM) to 7 +/- 3 mmol/ g DNA after 6 hours. Thereafter, it increased to 28 +/- 9 mmol/g DNA after 9 hours (P = .05 compared with the 6-hour measurement). These changes were accompanied by transient increases in plasma adrenaline, glucose, free fatty acids (FFA), and glucagon. Following glucose/ insulin infusion, hepatic glycogen increased steadily and was approximately double after 12 hours (P < .01) in both brain-dead and in non-brain-dead pigs. In brain-dead pigs, the increases in the aforementioned blood measurements were smaller following glucose/insulin infusion than following saline infusion. However, studies of longer duration will be needed to examine these effects on a time scale that is relevant to human organ donors. In conclusion, the decrease in hepatic glycogen content after brain death could be prevented by intravenous glucose/insulin infusion probably because of a reduction of the adrenaline response to the induction of brain death.

The kinetics of continuously infused indocyanine green in the pig

Indocyanine green (ICG) is used in cardiology and hepatology for the estimation of cardiac output, liver function, and splanchnic blood flow. ICG is bound to plasma proteins and ultimately excreted by the liver. We studied the whole body kinetics of ICG during constant infusion in pigs weighing 30-40 kg. The conventional kinetic model (backflux model) assumes that deviations from one-compartmental linear kinetics is caused by backflux from a liver storage to plasma, and that no extravascular, extrahepatic distribution takes place. This model was tested against an alternative (redistribution) model postulating that temporary redistribution of ICG into an extrahepatic extravascular storage was responsible for the deviations while the hepatic uptake was a one-way first-order process. A mathematical analysis of the two models showed that they predicted different time courses of the hepatic extraction fraction of ICG. Thus, with blood sampling from both a peripheral artery and a hepatic vein, a discriminative model-testing experiment was possible. This test required a first-order steady-state hepatic removal of ICG which was confirmed in 7 experiments with infusion rates varied in a stepwise fashion (0.133 +/- 0.003, 0.269 +/- 0.010, 0.547 +/- 0.020 and 0.130 +/- 0.003 mumol.min-1). In the model-testing experiments (n = 10) ICG was infused at a constant rate of 0.135 +/- 0.07 mumol.min-1. The mean concentration in peripheral artery (microM) was well fitted by the biexponential function C(t) = 0.476.(1-0.632.e-0.216.1-0.368.e-0.0172.1). The time course of the observed hepatic extraction fraction was significantly different (p = 0.004) from that predicted from the backflux model but in agreement (p = 0.98) with the new model assuming hepatic removal to be a one-way process and implying temporary ICG redistribution into an extrahepatic, extravascular storage with an apparent volume of 0.144 +/- 0.023 L.Kg-1. Accordingly, extravascular ICG was demonstrated in a number of different tissues after 4-hr infusion (n = 3). If ICG is used to estimate hepatic blood flow according to Fick's principle, the use of a backflux model to correct for non-steady-state conditions will lead to an overestimation of hepatic blood flow of 28% after 25-min infusion, 16% after 50 min, and 6% after 100 min. The study indicated that distribution of ICG between plasma and tissues is not instantaneous, and that the time course of the redistribution itself significantly influences whole body kinetics. Comparison with a previously published study by Ott, Keiding, and Bass of ICG kinetics after bolus injection suggested that a two-compartment model was insufficient and that the kinetics for the exchange of ICG between plasma and the redistribution space may be nonlinear. The study demonstrates how blood sampling on both sides of the eliminating organ can expose the influence of redistribution. The discriminative model test for constant infusion experiments is novel and may be useful with other ligands.

Glucose homeostasis during exercise in humans with a liver or kidney transplant

To investigate the role of liver nerve activity on hepatic glucose production during exercise, liver-transplant subjects (LTX, n = 7, 25-62 yr, 4-18 mo postoperative) cycled for 40 min, 20 min at 52 +/- 3% (SE) maximal O2 consumption (VO2max) and 20 min at 83 +/- 1% VO2max, respectively. Kidney-transplant (KTX) and healthy control subjects (C) matched for sex and age exercised at the same %VO2max as LTX. VO2max was lower in both LTX (1.59 +/- 0.12 l/min) and KTX (1.59 +/- 0.07) than in C (2.60 +/- 0.26). At rest plasma renin and insulin were higher and plasma adrenocorticotropic hormone and cortisol lower in transplant corticosteroid-treated subjects compared with C. In LTX, hepatic glucose production (Ra) increased from 11.9 +/- 0.9 (rest) to 17.6 +/- 1.8 and 25.5 +/- 1.8 mumol.min-1.kg-1 at 52 and 82% VO2max, respectively. Peripheral glucose uptake was similar to Ra, and glucose remained at basal postabsorptive levels. During exercise the Ra increase as well as norepinephrine, insulin, and growth hormone responses were similar in LTX compared with both KTX and C. The increase in epinephrine was smaller in LTX than in C, the only group showing an increase in cortisol. The increase in plasma renin activity during exercise was attenuated in KTX compared with LTX and C. During exercise blood lactate rose more and plasma glycerol and free fatty acid levels were lower in LTX and KTX compared with C.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic removal of two fractions of indocyanine green after bolus injection in anesthetized pigs

In the anesthetized pig, we studied the kinetics after intravenous bolus injection of two fractions of indocyanine green (ICG): the genuine ICGg (95-99% of total) and a degradation product, ICGdp (1-5%). Plasma concentrations were followed in the carotid artery and a hepatic vein. ICGg disappearance curves (n = 7) were biexponential with rate constants alpha = 0.189 +/- 0.021 min-1 and beta = 0.0356 +/- 0.0061 min-1. The hepatic extraction fraction was constant with time. A detailed mathematical analysis showed this to be in disagreement with the conventional assumption that the biexponential plasma disappearance curve is a result of backflux from the liver storage to plasma. In contrast, our observations were predicted by an alternative model assuming temporary extrahepatic, extravasal redistribution during first-order, one-way hepatic uptake. Nevertheless, when a large bolus of sulfobromophthalein (BSP) was injected 20 min after ICG, a net backflux of ICG could be demonstrated, presumably due to countertransport. Thus a sufficient description of ICGg kinetics must include the complex kinetic behavior of the hepatic membrane carrier involved. Mass spectrometry suggested that ICGdp is formed by two ICGg molecules. Plasma elimination of ICGdp was slower (alpha = 0.0094 +/- 0.0007 min-1). Analysis of the bile after bolus injection (n = 2) of ICGdp revealed two possible metabolites of ICGdp that were not found in urine. Since BSP injection did not alter the ICGdp disappearance curve, ICGdp is probably not taken up by the same hepatic membrane carrier as ICGg.

[Attitude of the population to organ transplantation]

The attitude of the Danish population towards organ transplantation was examined by means of an interview study, executed by the Gallup Institute. From a sample population of 1391 persons above 18 years of age, 798 persons (70%) were interviewed, in the period April 24th to May 3rd 1992. When asked what they thought the general attitude toward transplantation was amongst the population, 65% answered "positive" or "very positive". The attitudes to three situations, namely to organ donation after the death of a parent, spouse or child was examined subsequently. Amongst those who had an opinion, 75% (72-76%) were positive and 25% (24-27%) were negative. The younger the interviewed person, the more positive the attitude. According to the Danish law the relatives can decide for or against organ donation if the deceased has not expressed her view on organ donation. In view of the general positive attitude of the population it is proposed that we introduce a system where every adult person is asked concerning his/her attitude, e.g. in connection with the yearly income tax form or renewal of the health insurance certificate.

The prognosis of patients with alcoholic liver disease. An international randomized, placebo-controlled trial on the effect of malotilate on survival

The aim of this study was to examine the effect of malotilate on survival in patients with alcoholic liver disease and to determine prognostic variables for survival. Four hundred and seven patients with alcoholic liver diseases, from seven European liver units, entered a randomized placebo-controlled, double-blind trial: 140 patients received malotilate 1500 mg/day, 133 patients received 750 mg/day, and 134 patients received placebo. The patients were included in the study over a period of 3 1/2 years, and the study was closed 1 year after the entry of the last patient. Eighty-four patients died (35, 19, 30 patients in groups 1500 mg/day, 750 mg/day, and placebo, respectively). Survival was slightly better in the 750 mg/day group than in the two other treatment groups, when tested by conventional log-rank tests (p = 0.06). However, a treatment effect was supported by a highly significant (p = 0.006) non-proportionality of the death intensity in patients receiving 750 mg/day against those receiving either 1500 mg/day or placebo. Prognostic variables for survival were evaluated using the multiple Cox regression analysis of clinical and laboratory variables and with or without liver histology variables, as determined at entry into the study. The analysis was stratified for the three treatment regimens. In the analysis including liver histology variables, independent significant prognostic variables were: years of high alcohol intake, prothrombin index, alkaline phosphatases, creatinine, immunoglobulin M, white blood cell count, and liver cell steatosis. In the analysis without liver histology variables, prognostic variables were: years of high alcohol intake, prothrombin index, alkaline phosphatases, creatinine, and immunoglobulin M.

No reinnervation of hepatic sympathetic nerves after liver transplantation in human subjects

Transplantation of the liver results in surgical denervation of the organ. However, it is not known whether and to what extent sympathetic reinnervation occurs postoperatively in the transplanted human liver. Thirty-two liver biopsies (right lobe) were obtained from 13 liver-transplanted patients 1, 3, 6, 12 or 30 months after transplantation and 11 biopsies were obtained from 11 non-transplanted subjects with normal liver tests. The concentrations of the sympathetic neurotransmitter norepinephrine and of epinephrine were determined in liver tissue homogenates. The concentration of norepinephrine was 0.019 +/- 0.05 nmol. g wet liver tissue-1 (mean and SE, n = 32) in the transplanted patients, which was only 1% of the concentration in biopsies from control subjects (2.180 +/- 0.420 nmol.g wet liver tissue-1). The hepatic norepinephrine concentration did not increase significantly over time in liver-transplanted patients during the observation period (0.015 +/- 0.008 nmol.g wet wt-1 (1 month post) (n = 8) vs. 0.024 +/- 0.018 nmol.g wet wt-1 (12 months post) (n = 6) and 0.012 +/- 0.006 nmol.g wet wt-1 (30 months post) (n = 5)) (p < 0.05). The liver tissue concentration of epinephrine was markedly lower in liver-transplanted subjects (0.01 +/- 0.003 nmol.g wet tissue-1) than in control subjects (0.04 +/- 0.007 nmol.g-1) (p < 0.01). This study indicates that within the first years after transplantation, there is no evidence of sympathetic liver nerve reinnervation in liver-transplanted patients.

Plasma elimination of indocyanine green in the intact pig after bolus injection and during constant infusion: comparison of spectrophotometry and high-pressure liquid chromatography for concentration analysis

Indocyanine green is used to estimate liver blood flow rate and hepatic intrinsic clearance. However, its use as a test substance for studies of liver function has been limited by two puzzling kinetic observations: a biexponential plasma decay after bolus injection with an extremely slow late phase and an apparently steadily decreasing clearance value during constant infusion. These observations have been made with spectrophotometric concentration analysis. In anesthetized 30- to 40-kg pigs, we examined plasma concentration curves of indocyanine green after intravenous bolus injection and during long-term infusion. We compared spectrophotometry with high-pressure liquid chromatography for measurement of plasma indocyanine green concentration. In freshly prepared commercially available indocyanine green, high-pressure liquid chromatography could separately measure two fractions, the genuine indocyanine green (97% to 99% of total) and an in vitro degradation product (1% to 3%). Because their spectra were nearly identical, these fractions could not be distinguished by spectrophotometry. After intravenous administration both fractions were identified in the plasma by high-pressure liquid chromatography. In the first series (n = 6) 25 mg of indocyanine green was injected intravenously for 5 min. When analyzed by high-pressure liquid chromatography, the genuine indocyanine green plasma concentration decay was biexponential with rate constants 0.196 +/- 0.021 (mean +/- S.E.M., n = 6) and 0.0372 +/- 0.0064 min-1. The degradation product of indocyanine green decayed almost monoexponentially, with a rate constant of 0.0093 +/- 0.0002 min-1. With spectrophotometry a biexponential decay was observed with rate constants 0.130 +/- 0.012 and 0.0095 +/- 0.0001 min-1. The biexponential decay of indocyanine green after spectrophotometry was the result of codetermination of the two fractions: genuine indocyanine green was responsible for initial phase, and the degradation product of indocyanine green was responsible for the late phase. In the second series (n = 9), indocyanine green was administered as a constant intravenous infusion. From 90 to 240 min the intrinsic hepatic clearance of genuine indocyanine green did not change detectably with time. In contrast, the degradation product of indocyanine green never reached steady-state concentrations. Because of code-termination of these two indocyanine green fractions, the apparent intrinsic hepatic clearance of indocyanine green estimated from spectrophotometry was steadily decreasing by 8.9% +/- 1% per hour of its initial value. At the same time estimation of liver plasma flow rate based on Fick's principle was not affected by the choice of analytical methodology. These observations indicate that high-pressure liquid chromatography is superior to spectrophotometry for kinetic analysis of indocyanine green elimination.

Enhancement of unbound clearance of ICG by plasma proteins, demonstrated in human subjects and interpreted without assumption of facilitating structures

The kinetics of hepatic removal of protein-bound substances were studied in nine human subjects with various liver diseases by the use of indocyanine green as a model substance. Intrinsic hepatic clearance of indocyanine green was measured by means of a constant infusion of indocyanine green and concentration measurements of indocyanine green in arterial and hepatic venous plasma samples. During the indocyanine green infusion, 1-1.51 of dextran-70 was given whereby a stable dilution of the plasma protein concentration by a factor of 0.6-0.8 was obtained. In each of the subjects, the intrinsic clearance of indocyanine green increased after the protein dilution (range 11-64%). Elimination of ethanol (not protein bound), similarly assessed, was not significantly changed. The traditional hypothesis that unbound clearance (intrinsic clearance divided by the free fraction of the ligand) is independent of protein concentration was refuted since in each of the subjects the protein dilution was followed by a reduction of the unbound clearance of ICG (P < 0.005, n = 9). We examined whether these observations imply some special mechanism (e.g. a hepatocyte protein receptor) by which the unbound clearance is enhanced by the binding protein(s). The previously developed pseudofacilitation model--describing the effects of ligand-protein diffusion and dissociation in an unstirred plasma layer near the hepatocyte--was extended to the case of a mixture of binding proteins, and parameter-free bounds were derived to predict the response of intrinsic clearance to protein dilution. The observed changes of the intrinsic clearance values did not violate these bounds (P < 0.002, n = 9). Thus no facilitating mechanisms are necessary to account for the observed deviations from the traditional hypothesis.

[Liver transplantation in Denmark. First-year experiences]

During the first 12 months of the Danish Liver Transplantation program, which began in October 1990, 21 transplantations were performed in 11 women, six men and three children. One patient required a retransplant. Fourteen operations were performed electively and six patients were transplanted for acute and subacute fulminant liver failure and coma, two patients had reduced size livers because of large donor liver. There were no peroperative deaths. One of the elective patients died after three weeks from multiorgan failure and sepsis. Two of the emergency patients died after 20 and 22 days. One from graft dysfunction due to stenosis of the celiac trunk and the other of exudative pericarditis. One patient died from chronic rejection and CMV-infection after seven months. Complications were relatively few and acute rejection occurred in 40% of the patients. Fifteen patients are discharged with normal liver function and 11 of these were back at work, school or previous functions in the home. It is concluded that these results are comparable to the best results from other centres but that 21 transplants in 12 months must be a minimum activity.

Intrinsic hepatic clearance of indocyanine green in the pig: dependence on plasma protein concentration

Intrinsic hepatic clearance (K) of indocyanine green (ICG) is used as a quantitative measure of liver function. ICG is tightly bound to plasma proteins. The purpose of this study was to examine the effect of changes of plasma protein concentration on K in anaesthetized pigs with intact hepatic circulation. In addition, an attempt was made to evaluate the corresponding changes of the unbound intrinsic clearance of ICG. The plasma protein concentration was changed by exchange of plasma with either dextran-70 or donor pig plasma. Plasma albumin concentration was measured in a peripheral artery and changes of the concentrations of other plasma proteins were assumed to parallel those of albumin. ICG was given as a constant infusion and K was calculated from peripheral artery and hepatic vein concentrations of ICG according to the sinusoidal perfusion model. One experimental series comprised 3 measurement periods: From Period 1 to Period 2 (eight animals) albumin concentration was decreased by 36.6 +/- 6.5% (Mean +/- SD). This was associated with an increase of K of 32.8 +/- 28.8% (P = 0.004). From Period 2 to 3 (five animals) albumin was increased by 13.2 +/- 3.2% and K decreased by 18.5 +/- 8.3% (P = 0.03). In the second experimental series (eight animals), albumin concentration was increased by 21.6 +/- 10.3% and K decreased by 20.3 +/- 8.1% (P = 0.001). For both series, changes in albumin concentration were associated with oppositely directed changes of K in 20 out of 21 comparisons (P less than 0.001). Thus K depends not only on hepatocyte function but also on plasma protein concentration. This finding should affect interpretation of K when used as a liver function test. Changes of the unbound intrinsic clearance of ICG were examined indirectly by means of the K.a product (a: albumin concentration). According to the overall evaluation of the data the unbound intrinsic clearance of ICG was not affected by the changes in plasma protein concentration, but the results were internally inconsistent, apparently due to a time-dependency of the K.a product. We suggest this to be due to a slow but steady decrease of the 'background' K. After correction for the average decrease of K of 0.102% per min our data were in accordance with the hypothesis that the unbound clearance of K was enhanced by the binding protein(s) of ICG.

Pharmacokinetics of paroxetine in patients with cirrhosis

In a 14-day multiple-dose study the pharmacokinetics of paroxetine was investigated in 12 patients with alcoholic cirrhosis and in 6 subjects without liver disease. The dose of 20-30 mg paroxetine daily was adjusted to the reduction in liver function, as assessed by the galactose elimination capacity. Accordingly, all but two of the cirrhotic patients received 20 mg, while all six control subjects received 30 mg. Dose-corrected, trough drug concentration at steady state (CSSmin) and dose-corrected AUC24h were significantly higher in the patients with liver diseases than in the control subjects [3.4 vs 1.5 ng.ml-1 per mg paroxetine and 89 vs 43 h (ng).ml-1 per mg paroxetine]. The elimination t1/2 was prolonged [83 vs 36 h], but the difference was not statistically significant, and the cirrhotic patients were still able to clear almost all the paroxetine by metabolism. All but two patients with cirrhosis experienced nausea during the first two or three days after the first dose, while none of the controls had this symptom. The study showed slower elimination of paroxetine and consequently higher plasma levels in patients with cirrhosis, suggesting that in the latter the dose of paroxetine should be in the lower end of the therapeutic range.

CCl4 cirrhosis in rats: irreversible histological changes and differentiated functional impairment

Cirrhosis of the rat liver was induced by a 12 week individualized CCl4/phenobarbital treatment. After treatment, all surviving animals (81%) showed cirrhosis of the liver. The cirrhosis induced was irreversible when evaluated 24 weeks after cessation of treatment. Quantitative liver function measurements were reduced in a differentiated manner. Ranked according to the most pronounced changes they are: capacity of urea-N synthesis (CUNS), galactose elimination capacity (GEC) and antipyrine clearance (APC). Hepatic glutathione concentrations were only slightly decreased after the CCl4 treatment. It is possible to produce a high incidence of irreversible cirrhosis with differentiated functional impairment in the rat.

Galactose removal kinetics during hypoxia in perfused pig liver: reduction of Vmax, but not of intrinsic clearance Vmax/Km

The galactose elimination kinetics was examined in five perfused pig livers of 1.2 kg during hypoxia induced by administration of 2, 4 or 7% oxygen in the oxygenator instead of 20% as used in nine control experiments, previously published. Galactose was given as four to five successive constant infusion rates so that successive steady-state period with galactose concentrations from 0.04 to 5 mmol l-1 were obtained in each experiment. From the relationship between the calculated elimination rate and the perfusate galactose concentration, values of the maximal elimination rate Vmax and the half saturation concentration Km were calculated. Both Vmax and Km were reduced by hypoxia: the lower the oxygen supply, the greater the reduction. Vmax was about 0.08 mmol min-1 kg-1 liver at 2% oxygen and about 0.18 mmol min-1 kg-1 liver at 4-7% oxygen; both being significantly lower than the value of 0.43 mmol min-1 kg-1 liver at 20% oxygen. Km was about 0.07 mmol l-1 at 2% oxygen and 0.13 mmol l-1 at 7% oxygen; both significantly lower than the value of 0.23 mmol l-1 at 20% oxygen. A nearly parallel reduction of liver ATP concentration and galactose Vmax indicates that the galactose Vmax may reflect the phosphorylation capacity of the liver cells. The Vmax/Km ratio (intrinsic hepatic clearance) was unchanged during hypoxia.