Carbohydrate-deficient transferrin in serum in patients with liver diseases

Enzymes and circulating proteins as markers of alcohol abuse

The identification of alcohol abuse is an important social and clinical objective for which various biochemical procedures have been utilized, serum enzymes and circulating proteins being predominant. Tests are required to detect alcohol abuse as screening procedures in the general population as well as for the specific diagnosis of those presenting as hospital inpatients or outpatients, especially when liver disease is present or suspected. The amino-transferases are of limited value, although the mitochondrial isoenzyme of aspartate amino-transferase has been strongly advocated and is quite useful in detecting alcoholics among patients with liver disease. Gammaglutamyl transferase, by contrast, is raised in all forms of liver disease but can identify 30-50% of those consuming excessive amounts of alcohol before organic damage becomes manifest. Serum carbohydrate-deficient transferrin (CDT) is raised in many alcohol abusers without and most with liver damage, but is rarely elevated in other forms of liver disease. Haemoglobin-associated acetaldehyde, the newest biochemical index to be evaluated in alcoholics, is one of several adducts formed by the reaction of acetaldehyde with various proteins, and antibodies to these adducts may contribute, at least in part, to immunological tissue damage provoked by chronic excessive consumption of alcohol. Its assay is technically complex and it appears to be present in higher concentrations in heavy drinkers than in those who fulfill the criteria of addictive alcohol abuse. Many other markers have been introduced in the last decade but the search for a reliable index continues. CDT comes closest at the present time to matching the desired specificity, although it is of limited value in screening unselected non-hospitalized subjects.

Serum alpha-fetoprotein and alcohol consumption

Fifty-nine persons, 23 chronic alcoholics and 36 normal healthy persons with a well described alcohol consumption, had the serum concentration of alpha-fetoprotein determined by a sensitive monoclonal immunofluorescent assay. A significant elevation in S-AFP was found in alcoholics, median 4.1 kIU/l as compared to 3.0 kIU/l in near-abstainers (< 12 g ethanol per day) (p < 0.02). This difference was not explained by differences in age. S-AFP correlated positively with age (p = 0.01). In non-alcoholics a borderline significant correlation with S-AFP was found with average daily alcohol consumption (self-reported) (p = 0.09) and a significant correlation with the serum concentration of carbohydrate-deficient transferrin (S-CDT) (p = 0.004). In 11 alcoholics 2 months of abstention from alcohol was accompanied by a median reduction of 21% in S-AFP (p < 10(-5)). In alcoholics, but not in social drinkers, S-AFP correlated with S-ASAT (p = 0.004). The increase of S-AFP with alcohol consumption may reflect reversible alcohol-induced liver affection.

Microheterogeneity of serum glycoproteins in alcoholics: is desialo-transferrin the marker of chronic alcohol drinking or alcoholic liver injury?

The appearance of desialo-transferrin (De-TF) in serum has been reported to be a biochemical marker of chronic alcoholism. However, conclusive evidence of whether De-TF is a marker for chronic alcohol drinking or for alcoholic liver disease (ALD) has not yet been obtained. Glycoproteins can be divided into two groups, a transferrin (TF) group and an alpha 1-acid glycoprotein (A1-AG) group, based on the characteristics of microheterogeneity (M-HTG) of each protein. In the present study, the appearance of M-HTG in serum TF and A1-AG in alcohol drinkers was compared. In 96 patients with ALD, M-HTG of TF was found in 66 patients (68.8%), and M-HTG of A1-AG was found in 61 patients (63.5%). In 20 patients with alcoholic pancreatitis, the detection rate of M-HTG of A1-AG was significantly higher than that of TF. In six patients with pancreatitis but not liver disease, M-HTG of TF was not detected. In 14 alcoholics without liver or pancreas disease, M-HTG of TF was not detected, whereas M-HTG of A1-AG was detected in 6 cases--a significant difference. The amount of alcohol consumed was not different in patients with and without liver disease. In non-ALD, M-HTG of both proteins was detected only in patients with decompensated liver cirrhosis. The detection rate of M-HTG in TF was significantly higher than in A1-AG. These results suggest that M-HTG of serum TF is a marker of ALD and that of serum A1-AG is a marker of chronic alcohol drinking.

Carbohydrate-deficient transferrin during 3 weeks' heavy alcohol consumption

To study the effect of controlled heavy drinking of 60 g ethanol/day for 3 weeks on carbohydrate-deficient transferrin (CDT), a commercial double antibody kit (CDTect) was used. By the end of the third drinking week, a statistically significant increase in the mean CDT level was observed. When compared to AST and gamma-glutamyltransferase, CDT was a more informative marker. However, only in 2 of the 10 volunteers did CDT exceed the upper normal level (20 units/liter) recommended by the manufacturer. This indicates that the sensitivity of CDT to detect heavy drinking is lower than that previously reported. The higher accuracy has in general been obtained in studies comparing healthy controls with a low alcohol consumption to alcoholics with an alcohol consumption higher than that used in the present experiment. Our results suggest that it remains to be established whether CDT, although better than AST and gamma-glutamyltransferase, will provide a clinically useful tool in identifying heavy drinkers in populations covering a wide range of alcohol consumption.

Impairment of glucagon-induced hepatic system A activity by short-term ethanol administration in the rat

BACKGROUND/AIMS

System A is a membrane-bound, hormonally regulated carrier of amino acids that is induced by liver regeneration and impaired by ethanol. The mechanism of ethanol inhibition of system A is unknown; this study examines the effects of ethanol on the subcellular expression of system A activity following hormonal induction.

METHODS

Following hormonal treatment and short-term ethanol administration to rats, isolated liver Golgi and plasma membrane vesicles were examined for system A transport, and the kinetic parameters were determined.

RESULTS

Four hours after ethanol administration, the initial rate of system A activity was depressed 30% +/- 9% and 19% +/- 7% into Golgi and plasma membrane vesicles, respectively. The affinity constant of 2-(methylamino)-isobutyric acid uptake was unchanged between control and ethanol-treated vesicles, regardless of their subcellular origin. However, the maximal velocity of system A transport decreased from 1030 to 850 pmol.mg-1 protein.10 s-1 in Golgi vesicles and from 740 to 355 pmol.mg-1 protein.10 s-1 in plasma membrane vesicles.

CONCLUSIONS

Ethanol impairs hormonally induced system A activity in Golgi as well as in the plasma membrane vesicles. Ethanol potentially reduces glucagon induction of system A activity through an impairment of carrier biosynthesis or expression.

Diagnosis of alcohol-related neurological diseases by analysis of carbohydrate-deficient transferrin in serum

Analysis of carbohydrate-deficient transferrin (CDT) in serum has been shown to be a good marker of current regular alcohol consumption at levels that are potentially harmful both to the liver and the nervous system. In this study CDT was analyzed by anion exchange chromatography and the results were evaluated in 134 consecutively examined patients with neurological symptoms of possible or probable alcohol-related etiology. A total of 22% of the patients were regarded as current alcohol abusers and 93% of them had elevated CDT values. The majority of these cases suffered from diseases such as epilepsy, neuropathies, cerebral atrophy/dementia and cerebellopathy. Most of them were still in a socially functioning condition. Low alcohol consuming patients and abstaining patients with a previous history of alcohol abuse had CDT levels within the normal range. The results demonstrated that determination of CDT is a valuable tool in the diagnosis of alcohol-related neurological disorders provided that its biological turnover is taken into account.

Semi-automatic method for determination of different isoforms of carbohydrate-deficient transferrin

Carbohydrate deficient transferrin (CDT) has been reported to be one of the best biochemical markers of alcohol abuse. However, a need still exists for a simple and practical method for widespread laboratory use. A semi-automatic (SA) isoelectric focusing (IEF) assay for CDT (SA-IEF-CDT) by a Phast System is introduced here. Different isoforms of transferrin were separated by IEF on polyacrylamide gels (pI 4.0-6.5) and located by immunofixation with an anti-transferrin serum. The precipitation bands were stained with Coomassie Brilliant Blue and quantitated densitometrically. The present method gave a picture of the relative amounts of 10 different transferrin isoforms. The percentage of CDT with pI > or = 5.7 (representing di-, mono- and asialotransferrin) was calculated. For comparisons transferrin bands with pI > or = 5.6 (tri-, di-, mono-, and asialotransferrin), pI > or = 5.8 (mono- and asialotransferrin) and pI > or = 5.9 (asialotransferrin) as well as GGT, ASAT and ALAT were calculated. The method showed good linearity and it identified different isoforms in concentrations of < 10 mg/l of transferrin. The correlation of the present method with a commercially available method employing anion exchange followed by double antibody RIA (AE-RIA-CDT) was good (n = 38, r = 0.924). In 19/20 (95%) of healthy controls, the CDT value was below 4.4% (mean + 2 S.D.) of total transferrin, while higher values were observed in all 20 (100%) alcoholics. In conclusion, the developed semi-automatic method is a practical and reliable alternative for determination of different transferrin isoforms.

Detection of relapses in alcohol-dependent patients: comparison of carbohydrate-deficient transferrin in serum, 5-hydroxytryptophol in urine, and self-reports

In this study, detection of relapses in male alcohol-dependent patients by biochemical markers and self-reports of alcohol consumption were examined. The patients were trying to stay abstinent from alcohol for 6 months. Four of 15 patients dropped out from treatment after 50-110 days. Ratios of urinary 5-hydroxytryptophol (5-HTOL)/5-hydroxyindole-3-acetic acid and 5-HTOL/creatinine were measured daily and serum carbohydrate-deficient transferrin (CDT) once a week. Clinical ratings and self-reports about alcohol consumption were performed three times a week. According to the self-reports, 3 of the patients drank alcohol frequently, 5 of them sporadically, and 7 of the patients reported no alcohol intake at all. According to the 5-HTOL marker, 4 of the patients drank alcohol frequently, and 11 of them sporadically. No one had all urinary levels of 5-HTOL marker below the reference level. According to the CDT, 3 of the patients drank alcohol frequently, 3 sporadically, and in 9 of the patients no elevated levels of CDT were found. Elevated levels of CDT were preceded by increased values of 5-HTOL marker. The combined results suggested that no one of the patients was totally abstinent from alcohol during the treatment period. The 5-HTOL marker seemed to be useful to reveal recent alcohol drinking, and CDT proved to be useful to validate the patients' self-reports. Together the two biochemical markers showed complementary properties in early detection of relapse and treatment monitoring.

Serum carbohydrate-deficient transferrin as a marker of alcohol consumption in patients with chronic liver diseases

We measured serum levels of carbohydrate deficient transferrin (CDT) in 420 subjects: 100 healthy blood donors, 82 healthy employees, 70 abstaining patients with different chronic nonalcoholic liver disease, 16 abstaining patients with alcoholic fatty liver, 50 abstaining patients with alcoholic liver cirrhosis, 25 abusing patients with alcoholic fatty liver, 41 abusing patients with alcoholic liver cirrhosis, and 36 patients with alcohol dependence syndrome with a daily ethanol consumption of 173 +/- 120 g the last 4 weeks before blood was drawn. In controls the serum level of CDT was significantly higher in females compared with males (17.7 +/- 5.1 and 13.7 +/- 3.8 units/liter, respectively), and the upper normal limit was defined as 27 and 20 units/liter. Sixty-two of 102 (60.8%) abusing patients with alcoholic liver disease had increased levels of CDT compared with 1 of 66 abstaining (1.5%) patients with alcoholic liver disease, and 10 of 70 (14.3%) abstaining patients with nonalcoholic liver disease among them 3 with primary biliary cirrhosis and 2 with chronic autoimmune hepatitis. No correlation was found between serum CDT and gamma-glutamyltranspeptidase (GGT), AST, ALT, and mean red cell volume (MCV). The sensitivity and specificity for serum CDT was 61 and 92%, respectively, compared with 85 and 18% for GGT and 70 and 66% for MCV. No advantage was gained by using the CDT/transferrin ratio. Our study confirms that CDT is a specific marker for chronic alcohol abuse, except in few patients with other chronic liver diseases. Serum CDT seems to be a better indicator of abstention than GGT; AST and MCV in patients with alcoholic liver disease. However, in our hands CDT is not so sensitive for alcohol abuse in patients with liver disease as reported earlier in unselected alcoholics.

Urinary level of L-fucose as a marker of alcoholic liver disease

The urinary levels of L-fucose were measured in 93 alcoholics; 20 of these were without liver disease, 57 with noncirrhotic alcoholic liver disease, and 16 with alcoholic liver cirrhosis. In addition, patients with cirrhosis due to viral infection, and healthy subjects were evaluated. The mean urinary L-fucose concentration showed significantly higher values in patients with alcoholic liver disease and alcoholic liver cirrhosis when compared with the healthy subjects or the chronic alcoholics without liver disease (p < 0.001). The urinary L-fucose level was also significantly higher (p < 0.001) in cases of alcoholic liver cirrhosis than in noncirrhotic alcoholic liver disease (384 +/- 97 vs. 240 +/- 95 mumol/g of creatinine). No difference was observed between the healthy subjects and chronic alcoholics without liver disease (143 +/- 29 vs. 155 +/- 60 mumol/g of creatinine). The urinary level of L-fucose was significantly higher with alcoholic cirrhosis (384 +/- 97 mumol/g of creatinine) than with viral cirrhosis (265 +/- 42 mumol/g of creatinine) (p < 0.001). The measurement of urinary L-fucose may be a useful marker of alcoholic liver disease.

CDT by anion-exchange chromatography followed by RIA as a marker of heavy drinking among men

Carbohydrate-deficient transferrin, CDT, had previously been reported to be an excellent marker for alcoholism. The present population-based study examined the diagnostic value of CDT among consecutive middle-aged males including 122 social drinkers (mean alcohol consumption 88 +/- 79 g per week) and 77 non-alcoholic heavy drinkers (301 +/- 195 g/wk). Ninety-six men with a well-documented history of chronic alcoholism (> or = 1000 g/wk) were used as a reference group. The CDT (containing mainly isotransferrin with pI = 5.8 and 5.9) was separated by anion exchange chromatography and assayed by RIA. The CDT values of social drinkers (mean +/- SD = 14 +/- 5 U/I) were significantly lower than those of heavy drinkers (19 +/- 13 U/I, p < 0.01) and alcoholics (34 +/- 18 U/I, p < 0.001). In the whole material CDT correlated positively with alcohol consumption (r = 0.53, p < 0.001). At a specificity of 91.8%, CDT found 28.6% of the heavy drinkers and 79.2% of the alcoholics; the best traditional marker, GGT, with a specificity of 86.9%, found 35.1% and 64.6%, respectively. In conclusion, CDT is a specific marker, which is superior to traditional markers for identifying alcoholics. Unfortunately, it does not seem to provide additional power for identifying the important group, non-alcoholic heavy drinkers.

Ethanol enhances desialylation of transferrin by liver endothelial cells in the rat

Desialylated transferrin is emerging as a reliable index of alcoholism, and liver endothelial cells are known to partially desialylate transferrin. The effect of a single intraperitoneal injection of ethanol on the desialylation of transferrin in the rat was studied. In pulse-chase experiments, fully sialylated diferric transferrin labeled with 125I (protein moiety) or 3H (sialyl residues) was incubated with isolated, fractionated liver endothelial cells from rats that were given ethanol. The supernatants then were subjected to column chromatography using RCA120-agarose to separate and quantify the desialylated fraction of transferrin. Saline-treated animals served as controls. Incubation of the endothelial cells derived from the liver of ethanol-treated rats resulted in a 263% increase in desialylation level of transferrin. Our data indicate that administering ethanol in rats enhances the desialylation of transferrin by rat liver endothelial cells.

Orosomucoid system: 17 additional orosomucoid variants and proposal for a new nomenclature

There are two forms of orosomucoid (ORM) in the sera of most individuals. They are encoded by two separate but closely linked loci, ORM1 and ORM2. A number of variants have been identified in various populations. Duplication and nonexpression are also observed in some populations. Thus, the ORM system is very complicated and its nomenclature is very confusing. In order to propose a new nomenclature, ORM variants detected by several laboratories have been compared and characterized by isoelectric focusing (IEF) followed by immunoprinting. A total of 57 different alleles including 17 new ones were identified. The 27 alleles were assigned to the ORM1 locus, and the others to the ORM2 locus. The designations ORM*F1, ORM1*F2, ORM1*S and ORM2*M were adopted for the four common alleles instead of ORM1*1, ORM1*3, ORM1*2 and ORM2*1 (ORM2*A), respectively. The variants were designated alpha numerically according to their relative mobilities after IEF in a pH gradient of 4.5-5.4 with Triton X-100 and glycerol. For the duplicated genes a prefix is added to a combined name of two alleles, e.g. ORM1*dB9S. Silent alleles were named ORM1*Q0 and ORM2*Q0 conventionally. In addition, the effects of diseases to ORM band patterns after IEF are also discussed.

N-glycosylation of serum proteins in disease and its investigation using lectins

The majority of serum proteins are glycosylated. When disease is present, subtle changes occur in this glycosylation. These changes could provide the basis for more sensitive and more discriminative clinical tests. In order to address this possibility, a review is given of serum protein glycosylation in liver disease, inflammation and cancer. It is concluded that liver disease is accompanied by reduced sialylation and increased glycan branching; whereas cancer is accompanied by increased sialylation and increased fucosylation. In inflammation, the type of glycosylation change observed seems to depend upon the disease studied. Glycoprotein analysis can already be used for diagnosis in a few clinical situations; however, further studies are required in most diseases to provide a more detailed picture of the glycosylation changes that are occurring. This situation will change with the increasing availability of simpler techniques for glycoprotein analysis. One such group of techniques are lectin-based methods. The usefulness of these methods for glycoprotein analysis and the suitability for analysing clinical specimens are discussed in detail.

Laboratory markers of ethanol intake and abuse: a critical appraisal

Laboratory markers for ethanol intake and abuse and chronic alcoholism currently in use have been critically reviewed. The merits and pitfalls of each test have been evaluated. The clinical use of the new test of carbohydrate-deficient transferrin has been particularly emphasized. Carbohydrate-deficient transferrin currently provides the highest specificity and sensitivity of all commonly used markers of alcoholism.

Carbohydrate-deficient transferrin (CDT) in serum as a possible indicator of heavy drinking in young university students

Carbohydrate-deficient transferrin (CDT) in serum was studied as a possible marker of heavy drinking in a sample of 187 female and 102 male 1st year university students from Finland. CDT was measured by a new radioimmunoassay (Pharmacia CDT RIA). Alcohol consumption was measured on a quantity-frequency scale. For female students CDT was 18.2 +/- 0.45 units/liter (mean +/- SEM) and for male students 13.3 +/- 0.48 units/liter. 9.6% of female students and 7.8% of male students had elevated CDT with a cut-off level of 26 units/liter for females and 20 units/liter for males. The correlation between CDT and reported alcohol consumption was 0.30 (p less than 0.001) for females and 0.25 (p = 0.014) for males. Those reporting a consumption of at least 10 kg of pure ethanol per year were considered as heavy drinkers (3.7% of females and 22.5% of males). In female students the average CDT of heavy drinkers did not differ significantly from that of social drinkers but in teetotalers CDT was significantly (p less than 0.03) lower than in female alcohol users. In male students the average CDT of heavy drinkers was higher than the average of social drinkers (p less than 0.1) and significantly higher than the average of teetotalers (p less than 0.001). In the detection of heavy drinking among male students elevated CDT had a specificity of 96.2% and a sensitivity of 21.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Utility and evaluation of biochemical markers of alcohol consumption

Biochemical markers of alcohol consumption have a variety of clinical and research applications. Currently available markers such as the serum gamma-glutamyl transpeptidase (GGT), serum transaminases, and the mean corpuscular volume (MCV) lack sufficient sensitivity and specificity to be used for screening of alcoholism in ambulatory patients. However, these tests can be helpful in corroborating a clinical suspicion of alcoholism. A number of special laboratory markers of alcoholism recently have been developed which may have increased diagnostic accuracy. Promising potential markers include serum carbohydrate-deficient transferrin (CDT), red blood cell acetaldehyde, and acetaldehyde adducts. The application of reliable and practical markers of alcohol consumption could lead to significant improvements in the treatment of alcoholism and in the assessment of clinical trials.

Isoelectric focusing/western blotting: a novel and practical method for quantitation of carbohydrate-deficient transferrin in alcoholics

Carbohydrate-deficient transferrin (CDT) has been described as the single, most accurate marker of chronic alcohol consumption. Rapid, sensitive, and specific measurement of serum CDT levels can thus provide important clinical information concerning patient diagnosis and treatment. To date, however, methods used for assessing CDT concentrations [e.g., analytical isoelectric focusing combined with immunofixation and micro anion-exchange chromatography followed by radioimmunoassay (RIA)] have not been practical enough for widespread laboratory application. In the present study, we examined the use of a different technique, namely isoelectric focusing (IEF) combined with Western blotting (IEF/WB). Serum proteins (20-40 micrograms) were first focused according to isoelectric points (pI) on high-resolution agarose IEF gels (ampholyte pH range of 5-8) containing nonionic detergent. The focused proteins were transferred electrophoretically to nitrocellulose filters, and then stained immunochemically with antihuman transferrin IgG. IEF/WB completely resolved CDT (focusing at pI 5.7 and 5.9) from other serum transferring isoforms, as assessed with neuraminidase-generated CDT standards. Computerized densitometric scanning of the immunoblots allowed CDT levels to be quantitated directly rather than as a quotient. Serum CDT content determined by IEF/WB was highly correlated (r2 = 0.962; n = 17) with values determined previously by RIA. In a larger subject group, CDT levels (mg/liter) measured by IEF/WB were 139 +/- 54 in recently-drinking alcoholics (n = 58), 81 +/- 8 in abstaining alcoholics (n = 7), and 68 +/- 16 in healthy control subjects (n = 16).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ethanol on the uptake, binding, and desialylation of transferrin by rat liver endothelium: implications in the pathogenesis of alcohol-associated hepatic siderosis

Chronic alcoholism has been reported to be associated with a reduced carbohydrate content of transferrin (TF), particularly, its reduced sialylation state. Low sialylation state of TF now serves as an objective marker of chronic alcohol abuse. To investigate the pathophysiological significance of this finding in relation to hepatic siderosis, also commonly associated with chronic alcoholism, the authors have investigated the effect of ethanol on the uptake, binding, and desialylation of transferrin by isolated rat liver endothelium in vitro. In pulse-chase experiments, transferrin labeled with either 125I (protein-labeled) or 3H (sialic acid-labeled) was incubated with isolated, fractionated liver endothelium with and without ethanol, and the supernates were subjected to column chromatography using RCA120- agarose. Incubation of the endothelium with increasing concentrations of ethanol resulted in a progressive increase in the desialylation rate of transferrin which was maximal when 160 mM concentration of ethanol was used. These data indicate that ethanol significantly promotes the desialylation of transferrin by rat liver endothelium. The implications of these findings in the pathogenesis of hepatic siderosis of the alcoholic are discussed.

Serum beta-hexosaminidase and alpha-mannosidase activities as markers of alcohol abuse

In 25-alcohol-dependent patients in whom detoxication treatment has been introduced serum total beta-hexosaminidase, thermostable beta-hexosaminidase, alpha-mannosidase and gamma glutamylotransferase (GGT) and serum high density lipoprotein (HDL) cholesterol were determined during alcohol withdrawal. The assays were also performed in a group of dependent individuals after a 1 month or longer period of abstinence. Marked increase in beta-hexosaminidase activity was observed in intoxicated patients. The activity decreased rapidly after the cessation of drinking, resembling the decrease in HDL cholesterol level in its dynamics. The alpha-mannosidase activity rise was less pronounced and its normalization was slow, similar to the GGT activity normalization rate. The rise of beta-hexosaminidase activity was mostly due to the thermostable component of the enzyme. Total beta-hexosaminidase or thermostable beta-hexosaminidase activity determinations appear to be simple and reliable markers of alcohol abuse.

Phenotypic expression of the HLA linked iron-loading gene in males over the age of 40 years: a population study using serial serum ferritin estimations

The frequency of the HLA linked iron-loading gene was assessed in 1783 Afrikaner men over the age of 40 years living in the South Western Cape. Measurements, made on three occasions over a 4.5 year period, included the serum ferritin concentration, a screening test for reduced unsaturated iron-binding capacity and the percentage transferrin saturation. The serum gamma-glutamyl transferase concentration was used as a marker of alcohol abuse. The diagnosis of homozygosity was based on a serum ferritin concentration that was persistently greater than 400 micrograms l-1 and a percentage transferrin saturation greater than 55%. Using these criteria, 17 subjects were diagnosed as homozygous, corresponding to a disease frequency of 0.0095, a gene frequency of 0.0976 and a heterozygote frequency of 0.176 (95% confidence limits: 0.135-0.213). None of the subjects had overt clinical haemochromatosis. Typing for the HLA-A, -B, -C and -DR loci showed that the HLA-A3 allele (frequency 0.6471 and relative risk 4.4) was the only independent marker for the iron-loading gene in this asymptomatic population. Using the present approach it was not possible to distinguish between heterozygotes, alcohol abusers and normal subjects with serum ferritin concentrations at the upper end of the normal range.

Morphologic changes in the small intestine after chronic alcohol consumption

The morphology of the small-intestinal mucosa was studied in 11 alcoholic patients admitted to hospital for detoxification. A first biopsy specimen from the small intestine was taken as soon as possible after admission and a second specimen after about 6 weeks of abstinence. The specimens were studied in the light microscope, in the scanning electron microscope, and by immunohistochemistry. Morphometrically, a slight reduction in villus height in relation to crypt depth was observed. One patient had a subtotal villus atrophy. After abstinence the villus height was increased in five of the six patients who accepted a second biopsy. No obvious changes were seen in the frequency and appearance of peptidergic nerves or endocrine cells. Ultrastructurally, pronounced alterations were seen in the surface ultrastructure of the enterocytes. In two specimens bacterial adhesion to the mucosal surface was also found. The ultrastructural changes were unaltered after abstinence. In serum the concentrations of zinc were reduced, and the levels of copper were elevated compared with a group of teetotallers. A recently developed marker of high alcohol consumption, carbohydrate-deficient transferrin, was as good an indicator as the other conventional biochemical markers.

Concanavalin A crossed affinity immunoelectrophoresis and image analysis for semiquantitative evaluation of microheterogeneity profiles of human serum transferrin from alcoholics and normal individuals

The microheterogeneity profile of human serum transferrin from normal and alcoholic subjects was investigated qualitatively and quantitatively by means of Concanavalin A crossed affinity immunoelectrophoresis and an image analysis program. Differences in amounts of nonreacting transferrin molecules were found, suggesting an increase in triantennary glycosylation of transferrin from alcoholics compared with normal individuals. The increased amount of a highly retarded fraction in crude sera from alcoholics was demonstrated to be artefactual, probably due to entrapment or coprecipitation as the fraction disappeared after repeating the analysis with immunosorbent-purified transferrin. In conclusion, affinity electrophoresis represents a simple approach for demonstration of variations in the neutral monosaccharides of glycans and can discriminate between transferrin from alcoholics and normal individuals.

Effect of acute and chronic ethanol administration on rat liver alpha 2,6-sialyltransferase activity responsible for sialylation of serum transferrin

The effect of a single administration and a 6-week treatment with ethanol on rat liver sialyltransferase activity towards asialoglycoproteins and N-acetyllactosamine (Gal beta 1,4GlcNAc) was studied. Since only the alpha 2,6-sialyltransferase is involved in the in vivo sialylation of transferrin, Gal beta 1,4GlcNAc was chosen as an acceptor and alpha 2,6-sialyl-N-acetyllactosamine was separated from the corresponding alpha 2,3-sialyl isomer present in the sialyltransferase reaction mixture by high-performance liquid chromatography. After a single ethanol administration there was a low (about 20%) but significant (p less than 0.005) reduction of sialyltransferase activity towards asialotransferrin as well as a reduced alpha 2,6-sialyltransferase activity towards N-acetyllactosamine. An opposite result was found in the chronically ethanol-treated rats: in these animals either the total or alpha 2,6-sialyltransferase activity was slightly higher than in control animals. Blood ethanol concentration was significantly high (3.3 +/- 1.2 mg/ml) only in the acute-treated animals, suggesting that the accumulation in the body of ethanol and/or its metabolites induces a reduction of liver alpha 2,6-sialyltransferase activity responsible for the transferrin sialylation. Current results are consistent with the finding (Stibler H, Hultcrantz R: Alcohol Clin Exp Res 11:468-473, 1987) that an enhanced level of hyposialylated transferrin isoforms is a marker of present but not previous alcohol abuse.

Evaluation of carbohydrate-deficient transferrin compared with Tf index and other markers of alcohol abuse

It has been known for some years that a partial deglycosylation of transferrin occurs in the sera of alcohol abusers. Different methods have been proposed in order to evaluate this carbohydrate-deficient fraction of serum transferrin. Chromatofocusing or isoelectric focusing followed by direct immunofixation have been used until now. Recently, a new method called the carbohydrate-deficient transferrin (CDT) test based on ion-exchange chromatography has been developed by Stibler et al. (Alcohol Clin Exp Res 10:535-544, 1986). Here we compare this new method with results obtained using our Tf index determination method. The upper limit of normal values was set to the 90th percentile of the values observed in a reference population. The population under investigation consisted of 50 healthy volunteers and 160 alcohol abusers whose ethanol consumption was evaluated through a questionnaire. Sensitivity and specificity of the CDT test have been found higher than 0.76 and 0.90, respectively. The correlation between both methods was 0.794, a satisfactory result considering that the CDT test and the Tf index do not exactly measure the same part of the carbohydrate-deficient transferrin. In a population of 23 patients with liver diseases not related to alcohol abuse, no abnormal CDT value was observed. We can conclude from these results that the CDT test now seems to be the best test to detect alcohol abusers.

Separation of different forms of transferrin by isoelectric focusing to detect effects on the liver caused by xenobiotics

Several genetic variants and also isoforms of transferrin differing in carbohydrate structure can be separated by polyacrylamide or agarose gel isoelectric focusing. Numerous blood plasma or serum samples can be analyzed in parallel in each gel. Studies of the heterogeneity of transferrin have already revealed many results of importance to different fields of human medicine. Gene typing can give important and useful information for paternity determination and in forensic medicine. The gene type C 2 seems to have increased frequency in certain malfunctions. Futhermore, functional abnormalities of liver cells can be revealed by determination of the concentrations of transferrin isoforms differing mainly in their carbohydrate parts. The isoforms can be quantified with zone immunoelectrophoresis assay. Thus valuable information can be obtained about important modulated regulations of cell and membrane functions, even when these are disturbed by disease and xenobiotics. The information may be useful e.g. in the detection of individuals suffering from toxic effects, to identify toxic agents and exposure conditions. Studies of house painters revealed that exposure to different types of paints had an effect on transferrin. Determination of the concentration of the isotransferrin with pI 5.7 in blood samples from alcoholics can be used as a marker for the detection of liver dysfunction and for the monitoring of therapy treatments. In addition, by analyzing the isotransferrins a rare genetic abnormality can be detected.

Assessment of the transferrin index in screening heavy drinkers from a general practice

The aim of this study was to assess the performance of the transferrin (Tf) index in screening heavy drinkers and to compare its performance to that of gamma glutamyl transpeptidase (GGT). Tf index, GGT, and transaminase activities were determined in a group of 173 subjects (49% males) recruited in a family doctor's practice (age: 54 +/- 1.5 yr; daily alcohol intake: 32 +/- 3.5 g; mean +/- SEM). Tf subfractions were quantified by isoelectric focusing and immunofixation on polyacrylamide gel. The Tf pl 5.7 to 5.4 ratio, or Tf index, was used as a marker of excessive drinking, with a cut-off point at 7%. Alcohol consumption was assessed through a face-to-face interview. Excessive drinkers were defined as those with a daily alcohol intake greater than 80 g over at least 2 years; 20 were classified as excessive drinkers (alcohol consumption: 92-232 g/day). All but four had normal transaminase activities indicating the low prevalence of hepatic impairments in this sample. The Tf index was found to have a sensitivity of 45%, specificity 89%, positive predictive value 35%, negative predictive value 92%. The corresponding results for GGT were 52%, 80%, 27%, and 92%, respectively. Concordance between the Tf index and GGT was assessed by the kappa coefficient (kappa) which was 0.22 indicating poor agreement between the two markers in selecting excessive drinkers (perfect association: kappa = 1, no association: kappa = 0).

Transferrin microheterogeneity in rats treated chronically with ethanol

The microheterogeneity of rat serum transferrin was analyzed by isoelectric focusing and immunofixation from Wistar rats chronically treated with ethanol either by inhalation (4 weeks) or by a liquid diet (6 weeks) and from pair-fed controls. In spite of the length of ethanol exposure, a daily ethanol intake of 13-18 g/kg b.wt. and BAC levels of 1.0-4.1 g/l, no transferrin abnormality similar to that found in human alcoholics was observed. It is apparent that these two common animal models for chronic high ethanol consumption are not suitable for experimental studies of ethanol-associated effects on transferrin.

Carbohydrate-deficient transferrin (CDT) in serum in women with early alcohol addiction

Carbohydrate-deficient transferrin (CDT) in serum was determined by micro anion exchange chromatography and a transferrin radioimmune assay in 58 consecutive women treated for early alcohol dependence compared, with 62 healthy females with an alcohol consumption of 0-15 g of ethanol/day. The upper normal CDT level was 74 mg/l. CDT was elevated above this value in 83% of the alcoholic women with an intake of 60 g of ethanol/day or more for at least 7 days within the preceding two weeks. CDT values were significantly positively correlated with daily alcohol consumption but not with GT, ASAT, ALAT or MCV. During abstinence CDT level declined exponentially with a half-life of 14 +/- 3 days. The results indicated that CDT may be as sensitive and specific a marker in women with early alcohol addiction as in previously studied male alcoholics. The amount of alcohol consumed appeared to be more important than sex or liver function. Determination of CDT may thus offer a means for early objective diagnosis and adequate treatment also of women in early stages of alcoholism.

Changes in carbohydrate-deficient transferrin levels after alcohol withdrawal

Sequential serum levels of carbohydrate-deficient transferrin (CDT) were determined in 72 alcoholics at various intervals during detoxification. Before treatment, 57 patients (79%) had increased CDT values (Group A), whereas in 15 individuals (21%) (Group B), CDT levels were within the normal range. In 51 Group A patients, CDT decreased progressively after cessation of alcohol intake (half-life, 16 +/- 5 days), but fluctuated and remained abnormal in the remaining six. Nine Group B patients maintained normal CDT values throughout the follow-up period, but slightly or moderately increased levels were recorded on one occasion in the other six Group B subjects. Patients whose CDT levels had reached normal values after treatment, showed a recurrent increase in CDT after a relapse. gamma-Glutamyl transferase activities, which were elevated in 56% of Group A and in 80% of Group B alcoholics, showed a decrease after cessation of alcohol consumption in most patients with initially elevated values (Group A, 30 of 32; Group B, 10 of 12). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, as well as mean corpuscular volumes (MCV) were normal in the majority of patients. CDT/total transferrin ratios correlated positively with CDT levels. CDT proved to be the most sensitive marker for chronic alcoholism (79%), whereas GGT activity levels were more useful only in patients with normal CDT levels before alcohol withdrawal. In the assessment of treatment outcome, the combination of CDT and GGT as markers yielded a sensitivity of 95%.

Carbohydrate-deficient transferrin, a marker for chronic alcohol consumption in different ethnic populations

Serum levels of carbohydrate-deficient transferrin (CDT) were determined in a racially mixed population of 107 alcoholics, 18 healthy, nonalcoholic control subjects, 62 abstinent alcoholics, and in 64 Caucasian patients with various nonalcoholic liver diseases. The upper limit of normal CDT levels was 80 mg/liter (2 SD above the mean). CDT values exceeding this level were found in more than 80% of Black, Puerto Rican, and Caucasian alcoholics who had consumed greater than or equal to 50 g of alcohol/day for 1 month or longer prior to testing. Puerto Rican alcoholics had higher CDT values than the Black and Caucasian ethnic groups; however, these differences were significant only when compared to the Black population. Of 64 patients with nonalcoholic liver diseases, one individual with chronic active hepatitis (CAH) with an alcohol consumption of 20 g/day, and 10 of 26 subjects with primary biliary cirrhoses (PBC), who claimed to consume either no or only occasional moderate amounts of alcohol, had CDT levels ranging from 81 to 144 mg/liter. Seven of these individuals were in advanced stages of PBC. Total transferrin levels were variable and not significantly different in all subject groups studied. CDT/total transferrin ratios were increased in most patients with abnormal amounts of CDT, and there was a significant correlation between these ratios and CDT levels in all study groups. Serum enzyme parameters as well as red blood cell mean corpuscular volumes did not correlate with CDT values.(ABSTRACT TRUNCATED AT 250 WORDS)

Transferrin phenotype and level of carbohydrate-deficient transferrin in healthy individuals

Elevated concentrations of carbohydrate-deficient components of transferrin (CDT) in serum may be used as a sensitive and specific marker of regular, high alcohol consumption. When determined by a new, simplified assay, CDT values are nearly normally distributed in low- or non-alcohol-consuming control populations. The importance of transferrin phenotype for this normal variation was analyzed in 100 healthy, European men and women with no or negligible alcohol intake. No significant relation was found between phenotype and CDT value in this population. The three rare B-variants found had low CDT levels, and one subject, examined outside the study, with a rare D-variant indicated that D-variants may result in false-positive CDT values. Moreover, women tended to have somewhat higher values than men, in whom CDT levels were weakly correlated with age. Other as yet undefined biological factors are clearly responsible for the major part of the normal variation of CDT values in nonalcoholic individuals.