Binding of acetaldehyde to rat gastric mucosa during ethanol oxidation.

Acetaldehyde, the first product of ethanol metabolism, has previously been shown to form potentially harmful adducts with various proteins. The aim of this study was to investigate whether acetaldehyde--either exogenous or metabolically derived--binds to gastric mucosal proteins. Homogenized rat gastric mucosa was incubated with various concentrations of radiolabeled acetaldehyde or ethanol for different time periods. Acetaldehyde-protein adducts were determined by a liquid scintillation counter. In addition, mucosa was incubated with nonlabeled ethanol, and the acetaldehyde formed was measured by using headspace gas chromatography. Incubation of gastric mucosa with (14C)-acetaldehyde led to a concentration- and time-dependent radiolabeling of mucosal proteins. Formation of acetaldehyde adducts occurred relatively rapidly within 30 minutes and even at low acetaldehyde levels (5 micromol/L). Stable adducts represented 77% +/- 5% (mean +/- SEM) of the total adducts formed. In the presence of ethanol, acetaldehyde production and adduct formation took place in a concentration- and time-dependent manner. 4-Methylpyrazole and sodium azide inhibited acetaldehyde production to 7% +/- 1% of control and decreased the amount of acetaldehyde adducts to 55% +/- 8%. Enhanced acetaldehyde formation (to 420% +/- 50%) was clearly reflected in increased adduct formation (550% +/- 110%). In conclusion, both exogenous and endogenous acetaldehyde binds to gastric mucosal proteins in vitro. Gastric mucosal acetaldehyde production and the consequent adduct formation could be a pathogenetic factor behind ethanol-associated gastric injury.

Separation of hemoglobin acetaldehyde adducts by high-performance liquid chromatography-cation-exchange chromatography.

A HPLC-based method was developed to provide a simple way to study changes to hemoglobin induced by acetaldehyde in vitro. This method distinguished 18 human hemoglobin fractions including a new acetaldehyde-induced fraction HbA1ach3. The method consists of a Poly CAT A cation-exchange column and a stepwise salt and pH gradient, with a total analysis time of 31 min. The formation of acetaldehyde adducts was studied by incubation of hemoglobin with different Ach concentrations (5-1000 microM) and different incubation times (0-48 h). Physiological (5-250 microM) Ach concentrations induced increases mainly in 3 known fractions: HbA1ach1, HbA1prec, and HbA1d3; plus, it caused the formation of a new fraction, HbA1ach3. The specificity of the changes to acetaldehyde was studied by incubation of hemoglobin with glucose and acetylsalicylic acid. HbA1ach3 was the only acetaldehyde-induced hemoglobin fraction which was not also increased by glucose and acetylsalicylic acid treatment. The formation of HbA1ach3 showed a dose and time dependence on acetaldehyde incubations. Dialyzation and reduction experiments showed that HbA1ach3 is a stable adduct of hemoglobin, and incubation with purified HbAO showed that HbA1ach3 is an adduct of HbAO. The within-run and between-run coefficients of variation for HbA1ach3 (0.83% of total hemoglobin) were 10.8 and 15.1%, respectively, and the analytical recovery was 82-97%. These results indicate that in addition to the new, acetaldehyde-specific fraction HbA1ach3, several other types of hemoglobin adducts were formed with acetaldehyde. The current method might be useful in clarifying the relationships between hemoglobin and acetaldehyde in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate-deficient transferrin as an alcohol marker among female heavy drinkers: a population-based study.

Carbohydrate-deficient transferrin (CDT) has previously been reported to be an excellent marker of male alcoholics. Less is known of its efficiency among women and especially of early-phase alcohol abuse in nonselected populations. The present population-based study examined the diagnostic value of CDT among consecutive women, including 13 teetotallers, 135 social drinkers (mean alcohol consumption 45 +/- 34 g/week), and 57 nonalcoholic heavy drinkers (197 +/- 97 g/week). Sixty-two women with a well-documented history of chronic alcoholism (942 +/- 191 g/week) were also studied, as well as 36 pregnant women used as a reference group. Two weeks of abstinence among 11 alcoholics was followed. The CDT (containing part of isotransferrin with pI = 5.7, 5.8, and 5.9) was separated by anion exchange chromatography and assayed by radioimmunoassay. In the whole material, CDT correlated significantly with alcohol consumption (r = 0.43, p < 0.001) but not with conventional markers (gamma-glutamyltransferase, AST, ALT, and mean corpuscular volume). The CDT values of alcoholics (34 +/- 20 units/liter) were significantly (p < 0.001) higher than those of teetotallers (19 +/- 6 units/liter), social drinkers (20 +/- 6 units/liter), or pregnant women (16 +/- 3 units/liter). Heavy drinkers also had higher values (25 +/- 13 units/liter), but the difference did not reach statistic significance. The specificity of CDT was on the level of conventional markers when the cut-off value was increased from 26 to 29 units/liter. At a specificity of 95%, CDT found 19% of the heavy drinkers and 52% of the alcoholics; the best traditional marker, AST, with a specificity of 97%, found 7% and 56%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The separation of hemoglobin-acetaldehyde adducts by cation exchange chromatography: a brief history.

Screening for alcohol abuse in its early phase, and the diagnosis of alcohol-related organ damage by laboratory tests in clinical settings, have often been unreliable. Protein-acetaldehyde adducts may be helpful in trying to solve this problem and hemoglobin, with its acetaldehyde adducts, appears to be a suitable model for studying protein-acetaldehyde adducts as condensation products of acetaldehyde, a harmful metabolite of ethanol. The modification by acetaldehyde alters the chromatographic properties of the hemoglobin molecule, producing a modified form that can be separated from other hemoglobin forms by cation exchange chromatographic techniques. The methods for the separation of hemoglobin acetaldehyde adducts have been improved in recent years, allowing us today to detect in vitro changes in hemoglobin caused by "physiological" concentrations of acetaldehyde and raising the possibility of developing a method suitable for clinical detection of hemoglobin acetaldehyde adducts.