581
receptor molecules, is an equilibrium based on the spatial arrangement of receptors and ligands, such that the closer theyare, the tighter or more effective the binding (eg, the polyvalent IgM or the binding of Fc receptors). The differences we describe on tissue sections may be an artifact based on spatial arrangement of GaINAc; there is some evidence for this in the complex bands seen by PAGE/lectin blotting of both Helix-positive and Helix-negative tumours, which can be completely inhibited by 10 mmol/1 GaINAc. Second, if two lectins with the same nominal simple monosaccharide specificity are incubated on the same tissue, however, then quite different histological structures may be stained, although both lectins may be totally inhibited by the same simple sugar. Most lectins have more than one binding site and some are known to be bifunctional (eg, discoidin 1); GaINAc binding lectins such as DBA and SBA can also bind to non-carbohydrate ligands, such as adenine. Third, what lectin binding detects is how many sugars are exposed and how close they are. But binding is determined not only by the sugars but also by their 0 or N linkages to peptides, topology, adjacent structures, charge, hydrophobicity, and van de Waals forces. If the binding site is altered (as by conjugation) simple sugars may continue to inhibit binding to a section but the specificity to complex sugars is altered. If the hydrogen bond energy is donated by peroxidase, for example, then the binding tightness with the glycoconjugate at that point is weakened. Such derivation of lectins can alter the binding characteristics of lectins-for example, succinylation of WGA reduces the affinity for sialic acid although it does not affect binding to G1cNAc, and this property has been applied to tissue sections. Peroxidase is highly glycosylated and avidly reacts with the binding sites of concanavalin A which at the same time can react with tissue glycoconjugates. We do not know how peroxidase reacts with HPA. Concanavalin A conjugated to ’Sepharose’ shows a different spectrum of glycoprotein binding to the native lectin. But this is an unexplored field. With HPA-HRP the staining pattern is very clear and presumably reflects some specific structures, which can be blocked by Ga1NAc, but not the same structure as those detected by native HPA. The use of direct peroxidase-lectin seems to give different results from the indirect methods. Until the HPA binding glycoconjugates are characterised and the methodology is better understood, we suggest that the direct peroxidase-HPA method may be less useful in this system than an indirect method. Department of Histopathology, University College and Middlesex School of Medicine, Middlesex Hospital, London W1P 7PN, UK
SUSAN BROOKS ANTHONY LEATHEM
1 Leathem A, Brooks S. Predictive value of lectin binding on breast-cancer recurrence and survival. Lancet 1987; i 1054-56. 2. Fenlon S, Ellis IO, Bell J, Todd JH, Elston CW, Blamey RW. Helix pomatia and Ulex europeus lectin binding in human breast carcinoma. J Pathol 1987; 152: 169-76. 3. Alam SM, Whitford P, Cushley W, George WD, Campbell AM. Flow cytometric analysis of cell surface carbohydrates in metastatic human breast cancer. Br J Cancer 1990; 62: 238-42. 4. Fukutomi T, Itabashi M, Tsuane S, Yamamoto H, Nanasawa T, Hiroto T. Prognostic contributions of Helix pomatia and carcinoembryonic antigen using histochemical techniques in breast carcinomas. Jpn J Clin Oncol 1989; 19: 127-34. 5. Leathem A, Atkins N. Lectin binding to formalin-fixed paraffin sections. J Clin Pathol 1983; 36: 747-50. 6. Leathem A. Lectin histochemistry. In: Polak J, Van Noorden S, eds. 2nd ed. Bristol: Wnght, 1986: 167-87.
Beclobrate and fatal acute
hepatitis
SIR,-We report the death of a 64-year-old man from acute hepatic failure attributable to beclobrate, a lipid-lowering agent. The patient’s hypercholesterolaemia, first diagnosed at the age of 56, was treated by diet and then with a succession of hypolipidaemic agents. In addition, he received chondroitin sulphate 500 mg thrice daily for osteoarthrosis of the hip. There was no history of self-medication or alcohol abuse. 6½ months after he had started treatment with beclobrate 100 mg daily he became anorexic and jaundiced. His total bilirubin was 304 umol/1 (normal < 17), and transaminases were very much raised. He was admitted to hospital 3 weeks later with a diagnosis of acute hepatitis. He died 7 days later. Investigations revealed no evidence for an infectious (viral or toxoplasmosis) or obstructive cause.
At necropsy there was liver panlobular hepatic necrosis with bridging, consistent with an adverse drug reaction. The histological appearances were identical to those found by the same histopathologist (L. B.) in a previously reported fatal case of acute hepatitis attributed to beclobrate in a 63-year-old woman.’
Beclobrate has been licensed in Switzerland since 1988 for the of hyperlipidaemia. Increased serum levels of liver enzymes and, less frequently, hepatitis have been reported with other lipid-lowering agents of the fibrate type2-5 but the two patients discussed here are the first with fatal acute liver failure during 35 000 patient-years of treatment with beclobrate. Since there are no unequivocal histological features of drug-related hepatic damageit is not possible to prove that the hepatitis was due to beclobrate. However, the histological features, the unpredictable and rare nature of the reaction in the absence of any evidence of a dose-relationship, hypersensitivity, or similar response in animal models suggests that this is an idiosyncratic drug reaction.7 Despite the wide use of hypolipidaemic drugs, little is known about their treatment
hepatotoxicity. Beclobrate has now been withdrawn from the market since the risk of hepatic damage is believed to outweigh the potential benefits of the drug. CHU Vaudois, 1011 Lausanne, Switzerland
D. VOUILLAMOZ M.-D. SCHALLER
Institute of
Pathology, Hôpital Universitaire, Basle
L. BIANCHI
University Institute of Pathology, Lausanne
P. CHAUBERT
Department of Internal Medicine, Inselspital, Berne
W. REINHART
CHU Vaudois, Lausanne
J. THORENS
D. ARMSTRONG A. L. BLUM
1. Aebi U, Reinhart WH. Beclobrate and liver disease. Ann Intern Med 1990; 114: 483. 2. Illingworth DR. Lipid-lowering drugs: an overview of indications and optimum therapeutic use. Drugs 1987; 33: 259-79. 3. Gendreau-Tranquart C, Barbieux JP, Gillion JM, et al. Un cas d’hépatitie à l’exifone et au bézafibrate. Gastroenterol Clin Biol 1989; 13: 427. 4. Valmalle R, Bacq Y, Furet Y, Dorval E, Barbieux JP, Metman EH. Hépatite aigue mortelle lors d’un traitement par maleate de perhexiline et bézafibrate. Gastroenterol Clin Biol 1989; 13: 530. 5. Uglesic A, Ljachnicky N, Langzzeittherapie der typ-II-und der typ-IVhyperlipoproteinämie mit beclobrat. Schweiz Rundsch Med Prax 1988; 77: 755-61. 6. Bianchi L, De Groote J, Desmet V, et al. Guidelines for diagnosis of therapeutic drug-induced liver injury in liver biopsies. Lancet 1974; i: 854-57. 7. Kaplowitz N, Yee Aw T, Simon FR, Stolz A. UCLA conference: drug-induced hepatotoxicity. Ann Intern Med 1986; 104: 826-39.
Oral naloxone in
opioid-associated constipation
SIR,-In Dr Sykes’ letter (June 15, p 1475) it is not clear how the naloxone dose was calculated-was x% of the total 24 h opioid dose given every 4 h or was the 24 h naloxone dose x% of the 24 h opioid dose? We undertook a similar study to ascertain whether oral naloxone would reverse morphine-associated constipation in patients with cancer. The study was approved by the Canterbury Area Health Board ethics committee and patients gave written informed consent. Twelve patients completed the study. The daily dose of morphine ranged between 10 and 380 mg (median 120). The dose of naloxone was escalated from 0-4 mg up to 4 mg, with 4 patients treated at two dose levels and 4 at three or four dose levels. The maximum single dose of naloxone used was 0-5% of daily morphine dose in 3 patients, 0.5-1.0% in 2,1-2% in 5,4% in 1, and 10% in 1. None had a laxative effect at any of these dose levels; none experienced colic although one noticed increased bowel activity and none recorded any increase in pain either on linear analogue scale or as increased analgesia requirement. Doses in excess of 12 mg were not used because of a previous report of painful abdominal cramps and antagonism of analgesia.’ Sykes makes no mention of cost. In New Zealand, naloxone costs$13.15 for 0-4 mg or £11.48/mg. In view of the lack of efficacy at doses up to 4 mg, we have suspended further investigation since naloxone is currently not a cost-effective laxative
receptor molecules, is an equilibrium based on the spatial arrangement of receptors and ligands, such that the closer theyare, the tighter or more effective the binding (eg, the polyvalent IgM or the binding of Fc receptors). The differences we describe on tissue sections may be an artifact based on spatial arrangement of GaINAc; there is some evidence for this in the complex bands seen by PAGE/lectin blotting of both Helix-positive and Helix-negative tumours, which can be completely inhibited by 10 mmol/1 GaINAc. Second, if two lectins with the same nominal simple monosaccharide specificity are incubated on the same tissue, however, then quite different histological structures may be stained, although both lectins may be totally inhibited by the same simple sugar. Most lectins have more than one binding site and some are known to be bifunctional (eg, discoidin 1); GaINAc binding lectins such as DBA and SBA can also bind to non-carbohydrate ligands, such as adenine. Third, what lectin binding detects is how many sugars are exposed and how close they are. But binding is determined not only by the sugars but also by their 0 or N linkages to peptides, topology, adjacent structures, charge, hydrophobicity, and van de Waals forces. If the binding site is altered (as by conjugation) simple sugars may continue to inhibit binding to a section but the specificity to complex sugars is altered. If the hydrogen bond energy is donated by peroxidase, for example, then the binding tightness with the glycoconjugate at that point is weakened. Such derivation of lectins can alter the binding characteristics of lectins-for example, succinylation of WGA reduces the affinity for sialic acid although it does not affect binding to G1cNAc, and this property has been applied to tissue sections. Peroxidase is highly glycosylated and avidly reacts with the binding sites of concanavalin A which at the same time can react with tissue glycoconjugates. We do not know how peroxidase reacts with HPA. Concanavalin A conjugated to ’Sepharose’ shows a different spectrum of glycoprotein binding to the native lectin. But this is an unexplored field. With HPA-HRP the staining pattern is very clear and presumably reflects some specific structures, which can be blocked by Ga1NAc, but not the same structure as those detected by native HPA. The use of direct peroxidase-lectin seems to give different results from the indirect methods. Until the HPA binding glycoconjugates are characterised and the methodology is better understood, we suggest that the direct peroxidase-HPA method may be less useful in this system than an indirect method. Department of Histopathology, University College and Middlesex School of Medicine, Middlesex Hospital, London W1P 7PN, UK
SUSAN BROOKS ANTHONY LEATHEM
1 Leathem A, Brooks S. Predictive value of lectin binding on breast-cancer recurrence and survival. Lancet 1987; i 1054-56. 2. Fenlon S, Ellis IO, Bell J, Todd JH, Elston CW, Blamey RW. Helix pomatia and Ulex europeus lectin binding in human breast carcinoma. J Pathol 1987; 152: 169-76. 3. Alam SM, Whitford P, Cushley W, George WD, Campbell AM. Flow cytometric analysis of cell surface carbohydrates in metastatic human breast cancer. Br J Cancer 1990; 62: 238-42. 4. Fukutomi T, Itabashi M, Tsuane S, Yamamoto H, Nanasawa T, Hiroto T. Prognostic contributions of Helix pomatia and carcinoembryonic antigen using histochemical techniques in breast carcinomas. Jpn J Clin Oncol 1989; 19: 127-34. 5. Leathem A, Atkins N. Lectin binding to formalin-fixed paraffin sections. J Clin Pathol 1983; 36: 747-50. 6. Leathem A. Lectin histochemistry. In: Polak J, Van Noorden S, eds. 2nd ed. Bristol: Wnght, 1986: 167-87.
Beclobrate and fatal acute
hepatitis
SIR,-We report the death of a 64-year-old man from acute hepatic failure attributable to beclobrate, a lipid-lowering agent. The patient’s hypercholesterolaemia, first diagnosed at the age of 56, was treated by diet and then with a succession of hypolipidaemic agents. In addition, he received chondroitin sulphate 500 mg thrice daily for osteoarthrosis of the hip. There was no history of self-medication or alcohol abuse. 6½ months after he had started treatment with beclobrate 100 mg daily he became anorexic and jaundiced. His total bilirubin was 304 umol/1 (normal < 17), and transaminases were very much raised. He was admitted to hospital 3 weeks later with a diagnosis of acute hepatitis. He died 7 days later. Investigations revealed no evidence for an infectious (viral or toxoplasmosis) or obstructive cause.
At necropsy there was liver panlobular hepatic necrosis with bridging, consistent with an adverse drug reaction. The histological appearances were identical to those found by the same histopathologist (L. B.) in a previously reported fatal case of acute hepatitis attributed to beclobrate in a 63-year-old woman.’
Beclobrate has been licensed in Switzerland since 1988 for the of hyperlipidaemia. Increased serum levels of liver enzymes and, less frequently, hepatitis have been reported with other lipid-lowering agents of the fibrate type2-5 but the two patients discussed here are the first with fatal acute liver failure during 35 000 patient-years of treatment with beclobrate. Since there are no unequivocal histological features of drug-related hepatic damageit is not possible to prove that the hepatitis was due to beclobrate. However, the histological features, the unpredictable and rare nature of the reaction in the absence of any evidence of a dose-relationship, hypersensitivity, or similar response in animal models suggests that this is an idiosyncratic drug reaction.7 Despite the wide use of hypolipidaemic drugs, little is known about their treatment
hepatotoxicity. Beclobrate has now been withdrawn from the market since the risk of hepatic damage is believed to outweigh the potential benefits of the drug. CHU Vaudois, 1011 Lausanne, Switzerland
D. VOUILLAMOZ M.-D. SCHALLER
Institute of
Pathology, Hôpital Universitaire, Basle
L. BIANCHI
University Institute of Pathology, Lausanne
P. CHAUBERT
Department of Internal Medicine, Inselspital, Berne
W. REINHART
CHU Vaudois, Lausanne
J. THORENS
D. ARMSTRONG A. L. BLUM
1. Aebi U, Reinhart WH. Beclobrate and liver disease. Ann Intern Med 1990; 114: 483. 2. Illingworth DR. Lipid-lowering drugs: an overview of indications and optimum therapeutic use. Drugs 1987; 33: 259-79. 3. Gendreau-Tranquart C, Barbieux JP, Gillion JM, et al. Un cas d’hépatitie à l’exifone et au bézafibrate. Gastroenterol Clin Biol 1989; 13: 427. 4. Valmalle R, Bacq Y, Furet Y, Dorval E, Barbieux JP, Metman EH. Hépatite aigue mortelle lors d’un traitement par maleate de perhexiline et bézafibrate. Gastroenterol Clin Biol 1989; 13: 530. 5. Uglesic A, Ljachnicky N, Langzzeittherapie der typ-II-und der typ-IVhyperlipoproteinämie mit beclobrat. Schweiz Rundsch Med Prax 1988; 77: 755-61. 6. Bianchi L, De Groote J, Desmet V, et al. Guidelines for diagnosis of therapeutic drug-induced liver injury in liver biopsies. Lancet 1974; i: 854-57. 7. Kaplowitz N, Yee Aw T, Simon FR, Stolz A. UCLA conference: drug-induced hepatotoxicity. Ann Intern Med 1986; 104: 826-39.
Oral naloxone in
opioid-associated constipation
SIR,-In Dr Sykes’ letter (June 15, p 1475) it is not clear how the naloxone dose was calculated-was x% of the total 24 h opioid dose given every 4 h or was the 24 h naloxone dose x% of the 24 h opioid dose? We undertook a similar study to ascertain whether oral naloxone would reverse morphine-associated constipation in patients with cancer. The study was approved by the Canterbury Area Health Board ethics committee and patients gave written informed consent. Twelve patients completed the study. The daily dose of morphine ranged between 10 and 380 mg (median 120). The dose of naloxone was escalated from 0-4 mg up to 4 mg, with 4 patients treated at two dose levels and 4 at three or four dose levels. The maximum single dose of naloxone used was 0-5% of daily morphine dose in 3 patients, 0.5-1.0% in 2,1-2% in 5,4% in 1, and 10% in 1. None had a laxative effect at any of these dose levels; none experienced colic although one noticed increased bowel activity and none recorded any increase in pain either on linear analogue scale or as increased analgesia requirement. Doses in excess of 12 mg were not used because of a previous report of painful abdominal cramps and antagonism of analgesia.’ Sykes makes no mention of cost. In New Zealand, naloxone costs$13.15 for 0-4 mg or £11.48/mg. In view of the lack of efficacy at doses up to 4 mg, we have suspended further investigation since naloxone is currently not a cost-effective laxative
