David Sherman

A duodenal mucosal abnormality in the reduction of Fe(III) in patients with genetic haemochromatosis.

BACKGROUND--Previous in vitro studies have shown that the uptake of Fe(III) by freshly isolated duodenal mucosal biopsy specimens is increased in patients with genetic haemochromatosis. Moreover, in the mouse it has recently been found that reduction of Fe(III) to Fe(II) is a prerequisite for iron uptake by the proximal intestine. AIMS/METHODS--This study used the in vitro technique to investigate the rates of reduction and uptake of 59Fe(III) by duodenal mucosal biopsy specimens obtained at endoscopy from treated and untreated patients with genetic haemochromatosis. RESULTS--The rate of reduction of iron in the medium was proportional to the incubation time and was not caused by the release of reducing factors from the tissue fragments. Ferrozine, a specific Fe(II) chelator and ferricyanide, a non-permeable oxidising agent, inhibited uptake of 59Fe showing that reduction of Fe(III) precedes uptake. The rates (all values given as pmol/mg/min) of reduction (152 (49) v 92 (23)) and uptake (8.3 (4.0) v 3.6 (1.3), mean (SD)), were significantly increased in biopsy specimens from the untreated group (n = 6) compared with those from 10 control subjects (p < 0.04). Furthermore, the reduction and uptake rates were still increased in five patients in whom iron stores were normal after venesection treatment. CONCLUSIONS--These results show that there is a persistent abnormality in the reduction and uptake of iron by the intestine in genetic haemochromatosis.

No association between the c2 allele at the cytochrome P450IIE1 gene and alcohol induced liver disease, alcohol Korsakoff's syndrome or alcohol dependence syndrome

Cytochrome P450IIE1 metabolises, and is induced by ethanol. The 5 regulatory sequence of the gene is polymorphic; that identified by the c2 allele has been shown by transfection studies to confer an increased rate of transcription. A recent report indicating an association between this allele and alcohol induced cirrhosis suggests that it may contribute to the genetic vulnerability to this disease. We have examined this polymorphism in patients of western European origin with alcohol induced cirrhosis, alcohol Korsakoffs syndrome and alcohol dependence syndrome. We were unable to detect any association between this allele and any of these diseases.

Alcohol and acetaldehyde dehydrogenase gene polymorphism and alcoholism

Inherited variations in alcohol and aldehyde dehydrogenases, the principal enzymes of ethanol metabolism, have been implicated in determining susceptibility to alcoholism and alcohol-related organ damage. An association between an RFLP for the alcohol dehydrogenase-2 (ADH2) gene and alcohol-induced liver damage was demonstrated in a Caucasian population. Genotyping studies revealed an increase in the ADH3(2) allele in patients with alcohol-induced cirrhosis. PCR studies of the ALDH5 gene have demonstrated diverse polymorphism within a short segment of its coding region, with marked inter-racial variation in allele frequencies. In addition, the Caucasian alcohol-induced flushing reaction has been characterised and its relationship with phenotypic polymorphism of ALDH1 examined.

Differential effects of flumazenil in alcoholic and nonalcoholic cirrhotic patients

Ligands to the benzodiazepine receptor (BZR) accumulate in hepatic encephalopathy; the benzodiazepine antagonist flumazenil can reverse some manifestations of this condition. This study was designed to explore the effects of flumazenil on cognitive function and anxiety levels in cirrhotic patients without hepatic encephalopathy. Twenty such patients — ten alcoholic, ten nonalcoholics — and ten normal volunteers matched for age and sex were randomly allocated to treatment order (flumazenil or placebo first) in a double-blind cross-over trial. Cognitive function was evaluated with a battery of psychological tests shown previously to be sensitive to the impairment induced by liver disease. Cirrhotic patients performed worse than controls on several tests: digit cancellation, digit symbol substitution, key tapping and Reitans trail B test. Flumazenil did not reverse these cognitive impairments but it did induce anxiety in nonalcoholic cirrhotics. On one index of memory — delayed word recall — alcoholics performed worse than nonalcoholic cirrhotics. Flumazenil reversed this memory impairment in the alcoholic cirrhotic group. These results suggest that alcohol consumption induces changes at the BZR that are different from changes induced solely by liver impairment.

Diverse polymorphism within a short coding region of the human aldehyde dehydrogenase-5 (ALDH5) gene

Human aldehyde dehydrogenase-5 gene (originally named as ALDHX) is expressed in liver and testis. The ALDH5 does not contain introns in the coding sequence for 517 amino acid residues. Within a short nucleotide region of the gene, the following three nucleotide changes were found in high frequencies, i.e., a silent C↔T at nucleotide (nt) 183, C↔T at nt 257 associated with a Val↔Ala substitution, and T↔G at nt 320 associated with a Arg↔Leu substitution. The frequency of C at nt 183 is 81% in Caucasians and 65% in Japanese, and the difference is statistically not significant. The frequency of C at nt 257 is 76% in Caucasians and 55% in Japanese, and the difference is statistically significant (P = 0.02). The frequency of T at nt 320 is 71% in Caucasians, while it is only 27% in Japanese. The racial difference at nt 320 is highly significant (P < 0.001). No significant difference was found in the genotypes of the three nucleotide positions between alcoholic and nonalcoholic Caucasians within the limited numbers of subjects examined.

Total pancreatic and salivary serum iso-amylase activities in alcohol misusers in relapse and remission and in alcoholic liver disease

By means of immunoinhibition by specific salivary monoclonal antibodies in combination with a chromogenic substrate, assays of serum amylase were performed in control subjects, in chronic alcohol misusers in relapse or remission and in patients with alcoholic liver disease (ALD). There was a selective increase in the salivary isoenzyme in the ALD group. There were no significant changes in either of the alcohol misusing groups, compared with control subjects. It is suggested that the increase in salivary iso-amylase observed in patients with ALD is related to the previously reported functional and histological abnormalities in the parotid glands of this group of patients. It is also suggested that assay of pancreatic iso-amylase may be more discriminatory than total amylase levels in detecting pancreatic disease in patients with alcoholic cirrhosis.

The Role of Alcohol and Aldehyde Dehydrogenases In Alcohol-Related Diseases: Clinical Studies of Molecular Markers

The rapid advances achieved in the field of molecular genetics over the past few years have had a profound effect on the study of complex conditions as well as single gene disorders. In the field of alcoholism and alcohol - related diseases, the application of these new techniques is now gathering pace. There is general agreement that a significant genetic component exists in alcoholism, as illustrated by the twin and adoption studies performed over the past 20 years, but this clearly does not conform to a simple Mendelian model. The central question that is being addressed concerns the inherited basis for the observed variation in individual responses to ethanol.