Hector Orrego

Long-term treatment of alcoholic liver disease with propylthiouracil

Propylthiouracil has been shown experimentally to protect against alcohol-induced hepatocellular necrosis in hypoxic conditions. An earlier, short-term study of patients with alcoholism and liver disease indicated clinical improvement with propylthiouracil, but the effect on mortality could not be assessed. In the present study, we investigated the effect of propylthiouracil on mortality in patients with alcoholic liver disease in a long-term, double-blind, randomized clinical trial involving 310 compliant patients who received propylthiouracil (n = 157) or placebo (n = 153) for a maximum of two years. There were no differences between the two groups in demographic and clinical characteristics and biopsy-confirmed diagnoses at randomization, or in daily urinary alcohol levels during the study. The cumulative dropout rate over two years was not significantly different (propylthiouracil group, 0.68; placebo group, 0.60). The group receiving propylthiouracil (300 mg per day) had a cumulative mortality rate half that in the group receiving placebo (0.13 vs. 0.25 [P less than 0.05] in the total sample, and 0.25 vs. 0.55 [P less than 0.03] in a subgroup of severely ill patients [propylthiouracil group, n = 56; placebo group, n = 41]). Proportional-hazards stepwise regression analyses indicated that only propylthiouracil treatment, prothrombin time, hemoglobin levels, and mean daily urinary alcohol levels significantly affected mortality. The hazards ratio for the complete group indicated that mortality in the propylthiouracil group was 0.38 (95 percent confidence interval, 0.20 to 0.83) that of the placebo group. Protection by propylthiouracil was not observed in patients with high morning urinary alcohol levels. No clinically important side effects of propylthiouracil were observed at the dose used. We conclude that the administration of propylthiouracil can reduce mortality due to alcoholic liver disease.

RELIABILITY OF ASSESSMENT OF ALCOHOL INTAKE BASED ON PERSONAL INTERVIEWS IN A LIVER CLINIC

In 37 patients with alcoholic liver disease urinary alcohol was measured daily for up to 6 months. Every week the patients were asked about their drinking during the past week. Those who convinced the physicians of their abstinence were recorded as not drinking. Patients with alcohol in their urines convincingly denied alcohol intake 52% of the times that they were questioned. 25% of them denied drinking every time. Only 17% of all patients admitted it at all times. Patients who always admitted to drinking had an average urinary alcohol value of 1420 +/- 66 mg/l, compared to 81 +/- 5 mg/l in those who denied drinking every time. Those who admitted drinking intermittently had significantly higher urinary alcohol values (1001 +/- 57 mg/l) when admitting than when denying (538 +/- mg/l). The personal interview should not be used to separate populations of abstainers and non-abstainers in the follow-up of alcoholic patients. On the other hand, deniers appear to consume less alcohol than those who admit their drinking.

Effect of Short-Term Therapy with Propylthiouracil in Patients with Alcoholic Liver Disease

The effect of propylthiouracil (PTU; 300 mg/day) on alcoholic liver disease was evaluated in 133 patients in a short-term randomized double-blind trial. Severity of the disease was assessed by a composite clinical and laboratory index (CCLI). A normalization rate (NR) representing the rate of improvement in CCLI was calculated. Patients with alcoholic hepatitis, with and without cirrhosis, showed a significantly higher NR on PTU (43.6 +/- 4.6) than on placebo (19.8 +/- 3.3; P less than 0.001). A similar effect was observed in patients with abnormal prothrombin (no biopsy): NR was 32.9 +/- 6.9 on PTU and 2.6 +/- 3.7 on placebo (P less than 0.005). The effect of PTU on each clinical and laboratory component of the CCLI was also compared in these two groups. In 38 patients with alcoholic hepatitis and in 25 with abnormal prothrombin, those on PTU showed a greater improvement in 15 of 15 items (P less than 0.001) and 14 of 15 (P less than 0.01), respectively. When patients were divided according to the severity of the disease into those in the lower and upper halves of the CCLI range (81 and 52 patients, respectively), PTU was shown to have a significant effect only in the latter: The NR was 41.4 +/- 3.8 on PTU and 22.5 +/- 4.2 on placebo (P less than 0.005). PTU was ineffective in patients with inactive cirrhosis.

Thyroid hormones in alcoholic liver disease. Effect of treatment with 6-n-propylthiouracil.

The relationship between alcoholic liver disease and circulating thyroid hormones was investigated in 124 hospitalized patients treated with placebo or propylthiouracil (PTU) for a maximum of 46 days in a double-blind study. Serum triiodothyronine (T3) levels on admission were significantly (P less than 10(-6) and inversely correlated with the severity of alcoholic liver disease. After hospitalization, changes in T3-levels in patients with low admission T3 significantly correlated (P less than 0.001) with the degree of spontaneous improvement of liver function (placebo group). Treatment with 300 mg of PTU daily (Orrego et al. Gastroenterology 76:105--115, 1979) markedly increased the rate of improvement in severely ill patients with low T3 on admission. In this group, serum T3-levels were also increased after PTU, but this increase did not correlate with the change in the patients condition. It is suggested that the known inhibitory effect of PTU on peripheral deiodination of T4 to T3 is marked by a more marked improvement in liver function in this group. PTU treatment in this group reduced the free T4-index and increased TSH levels markedly (16%; P less than 0.02) toward levels found in hypothyroidism. PTU did not improve the condition of mildly ill patients with normal admission T3-levels, nor did it alter free T4-index or serum TSH levels in these patients. Serum T3-levels provide a sensitive indicator of the severity of alcoholic liver disease and of its response to conventional treatment. Serum T3-levels also distinguish between a group of patients, in whom low-dose PTU administration results in a beneficial effect, and another group, in whom no therapeutic effect of PTU is observed.

Studies on metabolic tolerance to alcohol, hepatomegaly and alcoholic liver disease

Abstract We previously reported that chronic ethanol administration to Wistar rats results in an increased rate of ethanol metabolism (EMR) and an increased rate of liver oxygen consumption. These increases, expressed per gram of liver, are obtained in conditions in which little or no hepatomegaly occurs. We have confirmed data showing that when hepatomegaly occurs, it is produced by an increased cell volume rather than by an increase in the number of cells. Intracellular water accounts for 60% of the increase in liver weight while a marked reduction in DNA g of tissue is seen. When the EMR and oxygen consumption following chronic ethanol treatment are expressed per total liver, marked increases are obtained in both parameters, independent of the production of hepatomegaly. In Wistar-derived male SH rats chronic ethanol treatment produces increases in EMR of the order of 100%. In young naive males of this strain, EMR and liver alcohol dehydrogenase (ADH) are high, but both are markedly reduced at the time of sexual maturity (6–10 weeks of age). In male SH rats chronic ethanol administration results in higher EMR and ADH which increase in a parallel fashion. Castration prevents the drop in EMR and ADH in naive animals fed chow or sucrose diet and abolishes the increase in EMR and ADH produced by chronic alcohol administration. It is suggested that, in mature male SH rats, ADH under control of testosterone constitutes the primary rate-limiting step in ethanol metabolism, and that chronic ethanol administration acts as a chemical castration. These studies indicate that, at least in laboratory animals, the mechanisms of metabolic tolerance can vary, and are genetically determined. This may explain some discrepancies found in the literature. We have previously shown that propylthiouracil (PTU) administration reduces liver oxygen consumption and protects animals fed alcohol chronically against hypoxic liver damage. A recently concluded double-blind clinical study in three Toronto hospitals indicates that (PTU) administration (300 mg/day) doubles (p

Low-molecular-weight polyethylene glycol as a probe of gastrointestinal permeability after alcohol ingestion

Gastrointestinal permeability has been assessed previously by the excretion of PEG-400, which consists of inert molecules that are neither degraded nor metabolized and are excreted intact in the urine. We report here the effects of alcohol on gastrointestinal permeability using PEG-400. Ten grams of PEG-400 dissolved in 60 ml of water were given to 12 intoxicated alcoholics (mean blood alcohol: 2406 mg/liter). The mean urinary excretion of PEG-400 in the following 6 hr was 3.75±0.3 gsem. When repeated after sobering up (mean elapsed time: 45 hr), all except one subject showed a decrease in PEG-400 excretion (mean: 2.08±0.2 g) (P<0.001). Similar experiments were conducted in two series with 12 normal controls. (1) In 7 subjects the administration on consecutive days of (a) PEG-400 (10 g) alone, (b) 19.2 g (0.42 mol) of ethanol plus PEG-400 (10 g), (c) PEG-400 (10 g) alone, and (d) PEG-400 (10 g) plus a diuretic (40 mg furosemide) resulted in the following values of PEG-400 excretion in urine: (a) 2.12±0.3 g; (b) 3.5±0.3 g,P<0.005; (c) 2.02±0.4, NS; and (d) 2.2±0.2 g, NS. (2) In the second experiment (5 subjects) the administration on subsequent days of (a) PEG-400 (10 g)+0.42 mol of urea; (b) PEG-400 (10 g)+19.2 g ethanol; (c) PEG-400 (10 g)+0.42 mol of urea resulted also, as in the previous experiment, in increased urinary excretion of PEG-400 after the solution (b) containing ethanol (P<0.001). Peak serum levels of PEG-400 were (a) 0.094±0.01 g/liter; (b) 0.152±0.02 g/liter (P<0.05); and (c) 0.095±0.01 (P<0.05). The ratio of urea-creatinine clearance and urinary volumes were the same in the three periods. Therefore, PEG-400 excretion was not related to changes in urinary clearance or in volume, since the furosemide increased the volume but not PEG-400 excretion. It is concluded that ethanol increases the permeability of the gastrointestinal tract as measured by the PEG-400 test, both in chronic alcoholics during intoxication and in nonalcoholics after a small dose of ethanol. The permeability alteration is transient once ethanol ingestion stops.

Cloning and nucleotide sequence of human liver cDNA encoding for cystathionine γ-lyase

Abstract We have cloned and sequenced a full-length cDNA (1083 bp) encoding the human liver cystathionine-γ-lyase enzyme (cystathionase). The human cystathionase sequence presented a substantial deletion of 132 bases (44 amino acids) compared to that reported for rat cystathionase, and of 135 bases (45 amino acids) compared to that reported for yeast cystathionase. After re-alignment for the missing nucleotides, the human cDNA sequence shows significant amino acid homology to that for the rat enzyme (85%) and the yeast enzyme (50%). A search for an undeleted cDNA, by the polymerase chain reaction, yielded a second clone which contained the missing 132 bases. Flanking nucleotides in the latter clone were identical to those in the cDNA clone containing the deletion. The two forms of human cystathionase deduced from the two cDNA clones may be derived from two different genes or may be splice variants.

Protection by Propylthiouracil Against Carbon Tetrachloride-Induced Liver Damage

Rats given a single intragastric dose of carbon tetrachloride (CCl4), 0.25, 0.50, or 1.0 ml per kg) showed a dose-dependent increase in SGOT, serum ornithine carbamyltransferase, and liver necrosis (graded histologically as 0 to 4+) 24 hr after the treatment. Daily intubation with propylthiouracil (PTU) for 10 days in doses of 5 to 50 mg per kg significantly reduced the elevation of SGOT activity, completely suppressed the serum ornithine carbamyltransferase changes, and reduced the degree of necrosis found 24 hr after the intragastric administration of CCl4. Similar protection was found when CCl4 was given intraperitoneally. When PTU was given in liguid diets for 6 days, protection against CCl4 was increased. PTU did not affect the absorption or covalent binding of 14CCl4 to lipids or proteins. Also, control and PTU-treated rats did not differ with respect to glucose-6-phosphatase activity and conjugated diene production after CCl4. Thus, it has been observed that PTU affords partial protection against some end-stage consequences of CCl4 liver injury such as cell necrosis and release of intracellular enzymes. However, PTU afforded no protection against early chemical effects such as covalent binding of CCl4 carbon, lipid peroxidation, or loss of glucose-6-phosphatase. Therefore, it is concluded that the mechanism of the PTU effect comes into play after the initial effects of CCl4 are exerted and in some unknown manner modulates the expression of these early effects.

Haemodynamic and organ blood flow responses to sevoflurane during spontaneous ventilation in the rat: a dose-response study

To determine the systemic haemodynamic and organ blood flow responses to the administration of sevoflurane during spontaneous ventilation, heart rate, cardiac index, mean arterial pressure, arterial blood gases, and blood flows to the brain, spinal cord, heart, kidneys and splanchnic organs were measured awake (control values) and after 30 min of anaesthesia with 0.5,1.0,1.2 or 1.5 MAC sevoflurane in rats. Cardiac output and organ blood flows were measured using radiolabelled microspheres. The MAC (mean ± SEM) of sevoflurane was found to be 2.30 ± 0.05%. At each concentration, haemodynamic variables were similar to awake values with the exception of a 12% reduction in mean arterial pressure at 1.5 MAC (P < 0.01). Arterial PCO2 increased in a dose-related fashion. Cerebral and spinal cord blood flows increased at 1.2 and 1.5 MAC whereas coronary and renal blood flows did not change significantly. Portal tributary blood flow and preportal vascular resistance were unaffected. Hepatic arterial flow increased by 63% at 1.5 MAC (P < 0.05) but total liver blood flow remained unchanged compared with awake values. In conclusion, the administration of sevoflurane during spontaneous ventilation produces a high degree of cardiovascular stability and maintains blood flow to major organs in the rat.RésuméAfin de déterminer les réponses de l’hémodynamique systémique et du débit sanguin aux organes face à l’administration de sévoflurane sous ventilation spontanée, la fréquence cardiaque, l’index cardiaque, la tension artérielle moyenne, les gaz sanguins artériels, et les débits sanguins au cerveau, à la moëlle épinière, au coeur, aux reins et aux organes splanchniques ont été mesurés chez les rats éveillés (valeur de contrôle) et après 30 minutes d’anesthésie avec 0,5, 1,0, 1,2 et 1,5 MAC de sévoflurane. Le débit cardiaque et les débits sanguins aux organes ont été mesurés en utilisant des microsphères marquées aux radioisotopes. Le MAC (moyenne ± SEM) du sévoflurane a été évalué à 2,30 ± 0,05%. A chaque concentration, les variables hémodynamiques étaient semblables aux variables en état d’éveil, à l’exception d’une réduction de 12% de la tension artérielle moyenne à 1,5 MAC (P < 0,01). La PCO2 artérielle augmentait proportionnellement à la dose. Les débits sanguins cérébraux et de la moëlle épinière augmentaient à 1,2 et 1,5 MAC, tandis que les débits sanguins coronariens et rénaux n ’ont pas changé de façon significative. Le débit sanguin tributaire portal et la résistance vasculaire préportale n’étaient pas affectés. Le débit sanguin hépatique augmentait de 63% à 1,5 MAC (P < 0,05) mais le débit sanguin hépatique total demeurait inchangé comparativement aux valeurs en état d’éveil. En conclusion, l’administration de sévoflurane sous ventilation spontanée produit un haut degré de stabilité cardiovasculaire et maintient le débit sanguin aux organes majeurs chez le rat.

Role of adenosine in the ethanol-induced potentiation of the effects of general anesthetics in rats

Acetate, derived from ethanol metabolism in the liver, is released into the circulation and utilized in many tissues including the brain. The subsequent metabolism of acetate results in the production of adenosine that has a number of effects in the central nervous system. The purpose of the present studies, therefore, was to investigate the contribution of metabolically generated adenosine to the ethanol-induced potentiation of the inhalational agents isoflurane and sevoflurane. Changes in the anesthetic requirement for isoflurane and sevoflurane were determined in rats using the tail-clamp procedure. Both ethanol and sodium acetate reduced anesthetic requirement for isoflurane and sevoflurane in a dose-dependent fashion. The effect of acetate on anesthetic requirement was completely blocked by the administration of the adenosine receptor blocker, 8-phenyltheophylline. The ethanol-induced reduction in anesthetic requirement, however, was only partially blocked by 8-phenyltheophylline. Direct intracerebroventricular (i.c.v.) administration of the water-soluble adenosine receptor blocker, 8-sulfophenyltheophylline, also completely blocked the effect of acetate and partially blocked the effect of ethanol. This i.c.v. administration demonstrates that the actions of ethanol and acetate on anesthetic requirement are a central nervous system effect. The i.c.v. administration of the adenosine A1 receptor subtype agonist, R-phenylisopropyl adenosine, potentiated the anesthetic effects of isoflurane and suggests that the A receptor mediates the observed potentiation of anesthetic effect. This is further supported by the concomitant administration of 5-N-ethylcarboxamido adenosine, a non-selective adenosine agonist, with the selective A1 antagonist, 8-cyclopentyltheophylline, showing A1 receptor potentiation of anesthetic requirements. The studies show that (1) acetate potentiates the anesthetic effects of the inhalational anesthetics, sevoflurane and isoflurane; (2) acetate contributes in part to the effect of ethanol on anesthetic potency through metabolically generated adenosine; (3) these effects are likely mediated via adenosine A1 receptor subtypes.