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.

Age dependence of rat liver function measurements

Changes in the galactose elimination capacity, the capacity of urea-N synthesis and antipyrine clearance were studied in male Wistar rats at the age of 8, 20 and 44 weeks. Further, liver tissue concentrations of microsomal cytochrome P-450, microsomal protein and glutathione were measured. All liver function measurements increased from the age of 8 to 44 weeks when expressed in absolute values. In relation to body weight, these function measurements were unchanged or reduced from week 8 to week 20. At week 44, galactose elimination capacity and capacity of urea-N synthesis related to body weight were increased by 10% and 36%, respectively, and antipyrine plasma clearance was reduced to 50%. Liver tissue concentrations of microsomal cytochrome P-450 and microsomal protein increased with age when expressed in absolute values, but were unchanged per g liver, i.e., closely related to liver weight in the age range studied. Glutathione showed an increase of 35% from 8 to 44 weeks of age expressed per g liver. Careful age matching of control animals is important for experimental rat studies.

Transfer of information. A note on the role of professional societies

Professional societies in general are designed to support and raise the prestige of the professions they represent, and the most overt way in which they do this is by attempting to keep the level of information concerning their profession as high as possible.

Traditionally, the predominant type of transfer of information has been scientific papers presented at meetings for the memebership, and this it still so in many cases. The large amount of information communication in this way, and its significance, is beyoned doubt.

The Lugano statements on controlled clinical trials

During a consensus conference in Lugano, Switzerland, 175 statements on controlled clinical trials were drafted by 47 representatives from academia, governmental registration agencies and industry in nine countries. Their opinion on these statements was similar to that of 47 'matched pairs' who did not attend the conference. Thus, the opinion of participants and non-participants appears to reflect the general opinion of those currently involved in designing, conducting and analysing controlled clinical trials. The Lugano statements give answers to the following questions: Is the controlled clinical trial in a crisis? What is the motivation to perform controlled clinical trials? Is it possible for a physician participating in a controlled clinical trial to act in the patient's best interest? Is it possible to obtain truly informed consent in a controlled clinical trial? When is it ethical to withhold active treatment in a controlled clinical trial? What are the controversial issues in the design of a good controlled clinical trial? Is there a double standard with respect to efficacy and adverse drug reactions in controlled clinical trials? What are the alternatives to controlled clinical trials and when should they be performed? How can sponsor bias be minimized? How should an ethics committee decide whether a controlled clinical trial is ethical? Should registration agencies become directly involved in the planning and conduct of controlled clinical trials? Do the declarations of Tokyo and Helsinki facilitate the conduct of ethically valid controlled clinical trials? Is it possible to create an international standard for the conduct and regulation of controlled clinical trials? Why do messages from controlled clinical trials filter into medicine so slowly? Is it possible to bridge the gap between controlled clinical trials and clinical reality? What are the costs of doing and not doing controlled clinical trials? When should drug companies decide to start a trial programme with a specific compound? Is there public hostility against controlled clinical trials? If so, how can it be reduced? The respondents almost unanimously felt that controlled clinical trials are a must: the public must be told that progress in medicine depends on controlled clinical trials, that patients often benefit from participating in them and that the alternative, practising in the face of constant uncertainty, is worse than the possible disadvantages related to the conduct of the trial.

Differing attitudes of industry and academia towards controlled clinical trials

A consensus conference was held in 1984 on controversial issues concerning controlled clinical trials. Thirty-six individuals working in academic institutions, forty-six in industry and twelve in regulatory authorities participated. Academics accepted and industrial representatives rejected the following: existing regulations cannot cope with the rate at which new treatments develop; drug companies may be reluctant to undertake surveillance programmes because sales will fall if adverse reactions are detected; novel remedies should not be promoted before extensive post-marketing surveillance; third parties should finance trials promising to reduce the costs of illness and trialists should be separated from sponsors in data analysis and interpretation, the investigator owning the data unless stated otherwise. Industrial representatives supported and academics rejected the following: government price control inhibits drug development and a multicentre trial can be justified simply by the wish to speed drug registration.

The effect of physiological temperature changes on the galactose elimination capacity of the isolated perfused pig liver

The effect of temperature changes (36-40 degrees C) on the liver function was studied in the isolated perfused pig liver. When compared with control studies no effect was observed on lactate, glucose, bile flow, ATP and energy charge, and the recovery after the changes in temperature was complete. The only significant changes observed regarded the hepatic oxygen uptake and galactose elimination capacity. The increase of 1 degree C resulted in an increase in galactose elimination of 6%, corresponding to a Q10 of 1.98 (SEM 0.12) with an energy of activation of 48 kJ/mol (SEM 4.7). Oxygen uptake was linearly related to galactose elimination (1.75 mol for 1 mole change in galactose elimination). These results indicate that circulatory changes are unimportant within physiological temperature changes. It is concluded that temperature effects on galactose elimination are too small to warrant a correction when used as a clinical test of quantitative liver function.

Cost-effectiveness of introducing a third-generation test for HBsAg in Danish blood donors

Owing to the low incidence of hepatitis B in Denmark, screening of blood donors for HBsAg has mostly been done by immunoelectroosmophoresis (IEOP). The purpose of the present study was to carry out a cost-effectiveness analysis prior to the introduction of a third-generation test for HBsAg in Danish blood donors. The analysis was performed on data from a subsequent screening of 48 750 blood units by radioimmunoassay (RIA) 3 weeks after donation. The RIA-pos., IEOP-neg. blood donors identified in the study were evaluated by a follow-up examination, and the recipients of RIA-pos., IEOP-neg. blood units were monitored for up to 9 months as to the development of acute hepatitis B. The study shows that the estimated cost for each prevented case of transfusion-associated hepatitis B in Denmark is US$ 1100 when screening donors not previously tested by a third-generation technique, and US$ 240 000 when screening donors tested before by this technique.

Use of a prognostic index in evaluation of liver transplantation for primary biliary cirrhosis

In the Cambridge/King's College Hospital program, one of the main criteria for recommendation of a liver transplant for a patient with primary biliary cirrhosis (PBC), as in other types of end-stage liver disease, has been the overall assessment that survival was likely to be less than one year. In the present study, a recently developed prognostic model, based on six variables, was used retrospectively to estimate the likely survival without transplantation of the first 29 patients receiving a transplant for PBC. Median estimated survival time for the complete group of patients was five months and in only four patients was survival in the absence of transplantation estimated to be more than one year. Comparison of actual survival curves after transplantation with the estimated survival in the absence of such a procedure shows that, despite an initial higher mortality related to surgery and the immediate postoperative period, grafting was associated with a statistically significant improvement in overall survival. No correlation between the outcome after transplantation and the severity of preexisting liver disease, (as assessed by the expected survival) could be determined, but further assessment of preoperative variables is warranted.

Glucoregulation in acute liver failure

Five patients with fatal acute liver failure, given 5 g h-1 of glucose for the previous 12 h, were investigated by the hyper- and euglycaemic glucose 'clamp' technique, and the results compared with reported control values. Initial average blood glucose concentration was normal (6.0 mmol l-1, range 5.0-8.8). Plasma insulin and C-peptide concentrations were increased about tenfold (1450 pmol l-1, range 330-4021, and 3000 pmol l-1, range 670-7650, respectively). The whole body glucose metabolic rate was decreased to about half control values (21 mumol min-1 kg-1, range 6-28) and the insulin sensitivity of the glucose metabolism was decreased to about 15% (9.4 m3 min-1 kg-1, range 3.6-14.4). The calculated metabolic clearance of insulin was normal (520 ml min-1 (m2)-1, range 305-1027) and the calculated systemic delivery rate of insulin was about sixfold increased (1135 pmol min-1 (m2)-1, range 474-2010). The initial glucagon concentrations were fifty-fold increased (550 pmol 1, range 72-1309) and not suppressible by glucose and insulin. The patients thus exhibited pronounced insulin insensitivity and hyperinsulinaemia, attributable primarily to pancreatic hypersecretion. The reason for the relation between, and the pathogenetic importance of, these findings is not known.

Effect of short lasting hypoxia on the metabolic function of the perfused pig liver. Comparison of ischaemic and hypoxaemic hypoxia

The effects of hypoxaemia and ischaemia were compared in the perfused pig liver. Decreased hepatic oxygen uptake, galactose elimination, ATP phosphorylation and increased lactate output occurred when the oxygen supply was diminished below 55% of the mean of controls. Below the control limits for oxygen uptake and oxidative phosphorylation, the change in the above variables were correlated to the degree of hypoxia, with no quantitative differences regarding ischaemic or hypoxaemic hypoxia. Galactose elimination was correlated to the ATP concentration (r = 0.81). After 80 min of hypoxia almost complete recovery was seen. It can be inferred from the data that other factors than oxygen diffusion into the liver cells may limit oxidative metabolism. Long and severe hypoxia may be required before irreversible cellular damage occurs in the liver.

Updating prognosis and therapeutic effect evaluation in cirrhosis with Cox's multiple regression model for time-dependent variables

A multivariate Cox regression analysis with time-dependent variables has been performed on the data of 415 patients with cirrhosis included in a controlled clinical trial of 10-15 mg prednisone daily versus placebo. The analysis showed that a poor prognosis was associated with a low prothrombin index, marked ascites, GI bleeding, high age, high daily alcohol consumption, high bilirubin and alkaline phosphatase and low albumin values, little liver connective tissue inflammation, and poor nutritional status. Prothrombin index and ascites showed significant interaction with the treatment in such a manner that high prothrombin index and absence of ascites were associated with a beneficial effect of prednisone, whereas low prothrombin index and presence of ascites were associated with a harmful effect of prednisone treatment. The final model was validated in independent patients by comparing their actual survival with that predicted from the model, using a split-sample testing technique. The prognostic factors were combined with an index that can be used to update prognosis whenever changes occur in the clinical status of a patient during the course of the disease. The probability of surviving the next 3 or 6 months can be estimated from the prognostic index at any time during the course. The index may be of value for the correct timing of special therapeutic procedures such as liver transplantation.

Beneficial effect of azathioprine and prediction of prognosis in primary biliary cirrhosis. Final results of an international trial

The effect of azathioprine on survival of patients with primary biliary cirrhosis was studied prospectively in a multinational, double-blind, randomized clinical trial including 248 patients of whom 127 received azathioprine and 121 placebo. There were 57 deaths in the azathioprine group and 62 in the placebo group. The actual survival was slightly longer during azathioprine than during placebo treatment. Using Cox multiple regression analysis and adjusting for slight imbalance between the two treatment groups, the therapeutic effect of azathioprine was statistically significant (p = 0.01), with azathioprine reducing the risk of dying to 59% of that observed during placebo treatment (95% confidence interval 40%-90%) or improving survival time by 20 mo in the average patient. Furthermore, azathioprine slowed down progressing incapacitation. Side effects of azathioprine were relatively few. The analysis revealed that the following five variables independently implied poor prognosis: high serum bilirubin, old age, cirrhosis, low serum albumin, and central cholestasis. These factors were combined to a "prognostic index" for prediction of outcome in new patients. The index was validated on independent patient data. On the basis of these results we recommend azathioprine as a routine treatment of primary biliary cirrhosis.

Screening of Danish blood donors for hepatitis B surface antigen using a third generation technique

The profit to be gained by testing Danish blood donors for hepatitis B surface antigen (HBsAg) with a third generation technique instead of the currently used immunoelectrophoresis was investigated by additional screening of 48 750 blood units by radioimmunoassay three weeks after donation. Twenty nine units were positive for HBsAg on radioimmunoassay (0.059%). Only six of these were found by immunoelectrophoresis (0.012%). Most of the 23 donors positive on radioimmunoassay and negative on immunoelectrophoresis were healthy carriers of HBsAg (20) or had asymptomatic chronic liver disease (two). One donor had acute hepatitis B. Fifteen of the 23 blood units were transfused. The 15 recipients were monitored biochemically and serologically for up to nine months. One recipient developed fulminant hepatitis B, three developed acute hepatitis B, and one became a healthy carrier of HBsAg. All these patients had received blood from healthy carriers of HBsAg. Two recipients were immunised against HBsAg, and in one patient no seroconversion was observed. The remaining recipients died soon after transfusion or were protected by antibodies to HBsAg that had been present before the transfusion. Testing of Danish blood donors using a third generation technique identified a substantial number of donors positive for HBsAg overlooked by immunoelectrophoresis. Most of these donors were healthy carriers of HBsAg. Blood taken from such carriers is highly infectious when transfused, probably because of the large amount of material transmitted.

Changes of laboratory variables with time in cirrhosis: prognostic and therapeutic significance

The time change of laboratory variables in cirrhosis was studied by analysis of data from 488 patients with cirrhosis included in a controlled clinical trial of long-term prednisone vs. placebo. In the placebo group, a marked regression towards normal was seen within 3 months of entry into the trial (increase in serum albumin, acetylcholinesterase, cholesterol, hemoglobin and decrease in erythrocyte sedimentation rate). The subsequent course did not show a clear pattern, except for a slight increase in serum bilirubin and decrease in albumin. When studied in relation to the time of death in patients dying from a "hepatic" cause, marked increase in bilirubin and decrease in prothrombin index, albumin and cholesterol were seen in the year prior to death with little change before that time. In the prednisone group, a more marked decrease in bilirubin, SGOT, alkaline phosphatase, gamma-globulin, sulfobromophthalein retention, erythrocyte sedimentation rate and increase in leukocytes, prothrombin index and cholesterol were seen during the first 3 months. In relation to time of death from a "hepatic" cause, similar changes were seen as in the placebo group except that alkaline phosphatase increased and cholesterol did not decrease. A beneficial effect of prednisone on survival, as expressed by a previously developed therapeutic index, was associated with decrease in SGOT, alkaline phosphatase and gamma-globulin within the first 3 months. An increase in SGOT during prednisone seemed to be associated with harmful effects of therapy.

Early features of primary biliary cirrhosis: an analysis of 85 patients

A standardized clinical, laboratory, and histological assessment was carried out on 85 patients with primary biliary cirrhosis within 1 year of developing symptoms. Presenting symptoms included pruritus (n = 30), jaundice (n = 9), variceal bleeding (n = 6), ascites (n = 5), fatigue (n = 4), and abdominal pain (n = 4). Ten patients had symptoms not immediately suggestive of hepatic etiology and a further 17 were asymptomatic, the diagnosis being made fortuitously. Eighty four percent were not incapacitated and 52 were anicteric. Less than half were pigmented, 22% had xanthoma, and only 12% were deeply jaundiced. In contrast, all had significant laboratory abnormalities with alkaline phosphatase activity greater than 400 IU/L in 60% and IgM greater than 2.5 g/L in 75%. Mitochondrial antibody was detectable in 83% with a titer greater than 1:160 in 70%. Cirrhosis was present in 24 patients, nine of whom were anicteric and a further 11 had fibrosis or scarring.

Double blind controlled trial of d-penicillamine in patients with primary biliary cirrhosis

One hundred and eighty nine patients with primary biliary cirrhosis were entered into a double blind, placebo controlled randomised trial starting in January 1978 to assess the therapeutic value of d-penicillamine 1200 mg daily. Eighteen of the 98 patients receiving d-penicillamine and 22 of the 91 placebo treated patients died during the study. Thirty six per cent of those on d-penicillamine and 8% of those on placebo were withdrawn from the study. No difference in overall survival was noted between the two groups of patients whether the results were analysed for the entire period of observation or only during the period in which the patients were receiving therapy. The mortality rate of those receiving d-penicillamine in histological stage I to II, however, was one third of that of the placebo group although this difference did not reach statistical significance. Using the occurrence rate ratio as the statistical method of analysis, no effect of d-penicillamine was noted on any clinical, biochemical or histological features examined, except the serum alanine aminotransferase activity which was greater in those on active treatment. In this trial we have been unable to establish any therapeutic benefit from the drug.

A therapeutic index that predicts the individual effects of prednisone in patients with cirrhosis

Our aim was to construct an index that accurately predicts the degree of benefit or harm that prednisone therapy holds for patients with liver cirrhosis. The admission and survival data of 488 patients with cirrhosis who participated in a controlled clinical trial of prednisone in a dosage of 10-15 mg daily (251 patients) versus placebo (237 patients) and who were observed for up to 12 yr were analyzed using Cox's multiple regression model. Four variables each provided significant therapeutic information: antinuclear factor (p = 0.02) and large piecemeal necroses (p = 0.02) were associated with a beneficial effect, whereas ascites (p = 0.0004) and large regenerative nodules (p = 0.0007) were associated with a harmful effect of prednisone. From these four variables a therapeutic index was constructed. For a given patient the therapeutic index is a measure of how big the effect will be if prednisone is given. The gain in survival time obtained by administering prednisone according to the therapeutic index was estimated to be 349 yr, mainly confined to 217 patients with a significant positive (121) or negative (96) therapeutic index. The therapeutic index may prove useful for the optimal administration of prednisone treatment in new patients with cirrhosis.

Kinetics of glucose metabolism in relation to insulin concentrations in patients with alcoholic cirrhosis and in healthy persons

To characterize the insulin resistance in alcoholic cirrhosis we determined in vivo insulin-glucose disposal dose-response relationships in 6 patients with alcoholic cirrhosis of varying severity and in 6 control subjects, using the glucose-insulin clamp technique. Each subject was infused sequentially with insulin at rates of 0.5, 1.0, 2.0, and 10 mU/min X kg, each rate for 2 h. Euglycemia was maintained by a continuous servo-adjusted glucose infusion. The amount of glucose infused during the last 40 min of each 2-h period, corrected for accumulation in the glucose space, reflects overall net glucose metabolism. The dose-response curves demonstrated saturation kinetics. Lineweaver-Burk plots were consistently convex, rejecting a simple Michaelis-Menten relationship, but were linear when accommodated to allosterism with two active sites. The calculated affinity constant (i.e., the concentration of insulin leading to half-maximum glucose metabolism) of patients with cirrhosis was higher than that of normal controls (104 +/- 30 vs. 32 +/- 3 mU/L, mean +/- SD). In addition the maximum rate of glucose metabolism was significantly lower than that of normals (53 +/- 9 vs. 72 +/- 16 mumol/min X kg). We conclude that, in patients with alcoholic cirrhosis, insulin resistance is caused both by a marked decrease in sensitivity to insulin and a decreased maximum effect of insulin, indicating a combined receptor-postreceptor defect as the underlying cause.