Observations of the formation of ethanol in the intestinal tract in man

Can endogenous ethylene glycol production occur in humans? A detailed investigation of adult monozygotic twin sisters

INTRODUCTION

To the best of our knowledge, clinically significant endogenous ethylene glycol production has never been reported in humans, very seldom reported in other animals or microorganisms, and then only under rare and specific conditions. We describe the detailed investigations we undertook in two adult monozygotic twin sisters to ascertain whether they were producing endogenous ethylene glycol.

METHODS

Two previously healthy monozygotic adult twin sisters presented with recurrent episodes of apparent ethylene glycol poisoning beginning at age 35, requiring chronic hemodialysis to remove ethylene glycol and its metabolites as well as to restore metabolic homeostasis. The sisters denied ingestion or exposure to ethylene glycol. At their request, they were admitted to hospital under strict supervision to exclude surreptitious ingestion of ethylene glycol and to evaluate the need for treatment. Hemodialysis was withheld during this prospective study. Twin A was admitted for 14 days and twin B for 11 days. Serial biochemical analyses were performed in blood and urine. Clinical exome sequencing and mitochondrial deoxyribonucleic acid sequencing were also completed.

RESULTS

In both twins, ethylene glycol was detected in urine, along with intermittent increases in concentrations of lactate, glycolate, and glycine in blood and/or urine. Blood ethylene glycol concentrations, however, remained <62 mg/L (<1 mmol/L) but became positive soon after discharge. The oxalate concentration remained normal in blood and urine. Plasma and urine amino acid profiles showed intermittent small increases in glycine, serine, taurine, proline, and/or alanine concentrations. Exome sequencing and mitochondrial deoxyribonucleic acid sequencing were non-diagnostic. Neither twin has been admitted with metabolic acidosis nor ethylene glycol poisoning since chronic hemodialysis was started. Twin A developed a calcium oxalate dihydrate lithiasis.

DISCUSSION

Mitochondrial disease, methylmalonic/propionic/isovaleric aciduria, primary hyperoxaluria, and analyte error were all excluded in these twins, as were obvious common environmental exposures.

CONCLUSION

Detailed investigations were performed in adult monozygotic twin sisters to ascertain whether they were producing endogenous ethylene glycol. Alternative explanations were excluded to the very best of our efforts and knowledge. Global metabolomics, gut microbiome analyses, and whole genome sequencing are pending.

Metabolic Phenotyping Predicts Gemcitabine and Cisplatin Chemosensitivity in Patients With Cholangiocarcinoma

Gemcitabine and cisplatin serve as appropriate treatments for patients with cholangiocarcinoma (CCA). Our previous study using histoculture drug response assay (HDRA), demonstrated individual response patterns to gemcitabine and cisplatin. The current study aimed to identify predictive biomarkers for gemcitabine and cisplatin sensitivity in tissues and sera from patients with CCA using metabolomics. Metabolic signatures of patients with CCA were correlated with their HDRA response patterns. The tissue metabolic signatures of patients with CCA revealed the inversion of the TCA cycle that is evident with increased levels of citrate and amino acid backbones as TCA cycle intermediates, and glucose which corresponds to cancer stem cell (CSC) properties. The protein expression levels of CSC markers were examined on tissues and showed the significantly inverse association with the responses of patients to cisplatin. Moreover, the elevation of ethanol level was observed in gemcitabine- and cisplatin-sensitive group. In serum, a lower level of glucose but a higher level of methylguanidine was observed in the gemcitabine-responders as non-invasive predictive biomarker for gemcitabine sensitivity. Collectively, our findings indicate that these metabolites may serve as the predictive biomarkers in clinical practice which not only predict the chemotherapy response in patients with CCA but also minimize the adverse effect from chemotherapy.

Gut microbiome and metabolome in a non-human primate model of chronic excessive alcohol drinking

A relationship between the gut microbiome and alcohol use disorder has been suggested. Excessive alcohol use produces changes in the fecal microbiome and metabolome in both rodents and humans. Yet, these changes can be observed only in a subgroup of the studied populations, and reversal does not always occur after abstinence. We aimed to analyze fecal microbial composition and function in a translationally relevant baboon model of chronic heavy drinking that also meets binge criteria (drinking too much, too fast, and too often), i.e., alcohol ~1 g/kg and blood alcohol levels (BALs) ≥ 0.08 g/dL in a 2-hour period, daily, for years. We compared three groups of male baboons (Papio anubis): L = Long-term alcohol drinking group (12.1 years); S = Short-term alcohol drinking group (2.7 years); and C = Control group, drinking a non-alcoholic reinforcer (Tang®) (8.2 years). Fecal collection took place during 3 days of Drinking (D), followed by a short period (3 days) of Abstinence (A). Fecal microbial alpha- and beta-diversity were significantly lower in L vs. S and C (p's < 0.05). Members of the commensal families Lachnospiraceae and Prevotellaceae showed a relative decrease, whereas the opportunistic pathogen Streptococcus genus showed a relative increase in L vs. S and C (p's < 0.05). Microbiota-related metabolites of aromatic amino acids, tricarboxylic acid cycle, and pentose increased in L vs. S and C (FDR-corrected p < 0.01), with the latter two suggesting high energy metabolism and enhanced glycolysis in the gut lumen in response to alcohol. Consistent with the long-term alcohol exposure, mucosal damage and oxidative stress markers (N-acetylated amino acids, 2-hydroxybutyrate, and metabolites of the methionine cycle) increased in L vs. S and C (FDR-corrected p < 0.01). Overall, S showed few differences vs. C, possibly due to the long-term, chronic alcohol exposure needed to alter the normal gut microbiota. In the three groups, the fecal microbiome barely differed between conditions D and A, whereas the metabolome shifted in the transition from condition D to A. In conclusion, changes in the fecal microbiome and metabolome occur after significant long-term excessive drinking and are only partially affected by acute forced abstinence from alcohol. These results provide novel information on the relationship between the fecal microbiome and metabolome in a controlled experimental setting and using a unique non-human primate model of chronic excessive alcohol drinking.

Selection pressure at altitude for genes related to alcohol metabolism: A role for endogenous enteric ethanol synthesis?

NEW FINDINGS

What is the topic of this review? Highland natives have undergone natural selection for genetic variants advantageous in adaptation to the hypobaric hypoxia experienced at high altitude. Why genes related to alcohol metabolism appear consistently selected for has not been greatly considered. We hypothesize that altitude-related changes in the gut microbiome offer one possible explanation. What advances does it highlight? Low intestinal oxygen tension might favour the production of ethanol through anaerobic fermentation by the gut microbiome. Subsequent increases in endogenous ethanol absorption could therefore provide a selection pressure for gene variants favouring its increased degradation, or perhaps reduced degradation if endogenously synthesized ethanol acts as a metabolic signalling molecule.

ABSTRACT

Reduced tissue availability of oxygen results from ascent to high altitude, where atmospheric pressure, and thus the partial pressure of inspired oxygen, fall (hypobaric hypoxia). In humans, adaptation to such hypoxia is necessary for survival. These functional changes remain incompletely characterized, although metabolic adaptation (rather than simple increases in convective oxygen delivery) appears to play a fundamental role. Those populations that have remained native to high altitude have undergone natural selection for genetic variants associated with advantageous phenotypic traits. Interestingly, a consistent genetic signal has implicated alcohol metabolism in the human adaptive response to hypobaric hypoxia. The reasons for this remain unclear. One possibility is that increased alcohol synthesis occurs through fermentation by gut bacteria in response to enteric hypoxia. There is growing evidence that anaerobes capable of producing ethanol become increasingly prevalent with high-altitude exposure. We hypothesize that: (1) ascent to high altitude renders the gut luminal environment increasingly hypoxic, favouring (2) an increase in the population of enteric fermenting anaerobes, hence (3) the synthesis of alcohol which, through systemic absorption, leads to (4) selection pressure on genes relating to alcohol metabolism. In theory, alcohol could be viewed as a toxic product, leading to selection of gene variants favouring its metabolism. On the contrary, alcohol is a metabolic substrate that might be beneficial. This mechanism could also account for some of the interindividual differences of lowlanders in acclimatization to altitude. Future research should be aimed at determining any shifts to favour ethanol-producing anaerobes after ascent to altitude.

The Role of Leaky Gut in Nonalcoholic Fatty Liver Disease: A Novel Therapeutic Target

The liver directly accepts blood from the gut and is, therefore, exposed to intestinal bacteria. Recent studies have demonstrated a relationship between gut bacteria and nonalcoholic fatty liver disease (NAFLD). Approximately 10–20% of NAFLD patients develop nonalcoholic steatohepatitis (NASH), and endotoxins produced by Gram-negative bacilli may be involved in NAFLD pathogenesis. NAFLD hyperendotoxicemia has intestinal and hepatic factors. The intestinal factors include impaired intestinal barrier function (leaky gut syndrome) and dysbiosis due to increased abundance of ethanol-producing bacteria, which can change endogenous alcohol concentrations. The hepatic factors include hyperleptinemia, which is associated with an excessive response to endotoxins, leading to intrahepatic inflammation and fibrosis. Clinically, the relationship between gut bacteria and NAFLD has been targeted in some randomized controlled trials of probiotics and other agents, but the results have been inconsistent. A recent randomized, placebo-controlled study explored the utility of lubiprostone, a treatment for constipation, in restoring intestinal barrier function and improving the outcomes of NAFLD patients, marking a new phase in the development of novel therapies targeting the intestinal barrier. This review summarizes recent data from studies in animal models and randomized clinical trials on the role of the gut–liver axis in NAFLD pathogenesis and progression.

Gut microbiome in HCC - Mechanisms, diagnosis and therapy

The microbiome exerts essential functions in health and disease, modulating key processes in metabolism, inflammation and immunity. Recent evidence has revealed a key role of the microbiome in carcinogenesis as well as anti-cancer immune responses in mouse models and patients. Herein, we will review functions of the gut microbiome in hepatocellular carcinoma (HCC), the third leading cause of worldwide cancer mortality. The majority of HCC develops in patients with chronic liver disease, caused by viral hepatitis, non-alcoholic fatty liver disease (NAFLD) and alcohol-related fatty liver disease. In this review, we will discuss mechanisms by which the gut-liver axis promotes the development of HCC in mouse models and patients, including dysbiosis, the leaky gut and bacterial metabolites, with a particular focus on NAFLD as the fastest growing cause of HCC development. Moreover, we will review recent progress in harnessing the gut microbiome as a potential diagnostic tool and novel therapeutic target in patients with HCC, in particular in the setting of immunotherapy.

Microbiota and Alcohol Use Disorder: Are Psychobiotics a Novel Therapeutic Strategy?

In recent years, there has been an exciting focus of research attempting to understand neuropsychiatric disorders from a holistic perspective in order to determine the role of gut microbiota in the aetiology and pathogenesis of such disorders. Thus, the possible therapeutic benefits of targeting gut microbiota are being explored for conditions such as stress, depression or schizophrenia. Growing evidence indicates that there is bidirectional communication between gut microbiota and the brain that has an effect on normal CNS functioning and behavioural responses. Alcohol abuse damages the gastrointestinal tract, alters gut microbiota and induces neuroinflammation and cognitive decline. The relationship between alcohol abuse and hypothalamic-pituitary-adrenal axis activation, inflammation and immune regulation has been well documented. In this review, we explore the connection between microbiota, brain function and behaviour, as well as the mechanisms through which alcohol induces microbiota dysbiosis and intestinal barrier dysfunction. Finally, we propose the study of psychobiotics as a novel pharmaceutical strategy to treat alcohol use disorders.

The Role of Probiotics in Nonalcoholic Fatty Liver Disease: A New Insight into Therapeutic Strategies

Nonalcoholic fatty liver disease (NAFLD) encompasses a broad spectrum of pathological hepatic conditions ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), which may predispose to liver cirrhosis and hepatocellular carcinoma (HCC). Due to the epidemic obesity, NAFLD is representing a global health issue and the leading cause of liver damage worldwide. The pathogenesis of NAFLD is closely related to insulin resistance (IR), adiposity and physical inactivity as well as genetic and epigenetic factors corroborate to the development and progression of hepatic steatosis and liver injury. Emerging evidence has outlined the implication of gut microbiota and gut-derived endotoxins as actively contributors to NAFLD pathophysiology probably due to the tight anatomo-functional crosstalk between the gut and the liver. Obesity, nutrition and environmental factors might alter intestinal permeability producing a favorable micro-environment for bacterial overgrowth, mucosal inflammation and translocation of both invasive pathogens and harmful byproducts, which, in turn, influence hepatic fat composition and exacerbated pro-inflammatory and fibrotic processes. To date, no therapeutic interventions are available for NAFLD prevention and management, except for modifications in lifestyle, diet and physical exercise even though they show discouraging results due to the poor compliance of patients. The premise of this review is to discuss the role of gut–liver axis in NAFLD and emphasize the beneficial effects of probiotics on gut microbiota composition as a novel attractive therapeutic strategy to introduce in clinical practice.

Biomarkers of Alcohol Consumption in Body Fluids - Possibilities and Limitations of Application in Toxicological Analysis

BACKGROUND

Ethyl alcohol is the most popular legal drug, but its excessive consumption causes social problems. Despite many public campaigns against alcohol use, car accidents, instances of aggressive behaviour, sexual assaults and deterioration in labor productivity caused by inebriated people is still commonplace. Fast and easy diagnosis of alcohol consumption is required in order to introduce proper and effective therapy, and is crucial in forensic toxicology analysis. The easiest method to prove alcohol intake is determination of ethanol in body fluids or in breath. However, since ethanol is rapidly metabolized in the human organism, only recent consumption can be detected using this method. Because of that, the determination of alcohol biomarkers was introduced for monitoring alcohol consumption over a wider range of time.

OBJECTIVE

The objective of this study was to review published studies focusing on the sample preparation methods and chromatographic or biochemical techniques for the determination of alcohol biomarkers in whole blood, plasma, serum and urine.

METHODS

An electronic literature search was performed to discuss possibilities and limitations of application of alcohol biomarkers in toxicological analysis.

RESULTS

Authors described the markers of alcohol consumption such as: ethanol, its nonoxidative metabolites (ethyl glucuronide, ethyl sulfate, phosphatidylethanol, ethyl phosphate, fatty acid ethyl esters) and oxidative metabolites (acetaldehyde and acetaldehyde adducts). We also discussed issues concerning the detection window of these biomarkers, and possibilities and limitations of their use in routine analytical toxicology for monitoring alcohol consumption or sobriety during alcohol therapy.

Gut-Liver Axis Derangement in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most frequent type of chronic liver disease in the pediatric age group, paralleling an obesity pandemic. A “multiple-hit” hypothesis has been invoked to explain its pathogenesis. The “first hit” is liver lipid accumulation in obese children with insulin resistance. In the absence of significant lifestyle modifications leading to weight loss and increased physical activity, other factors may act as “second hits” implicated in liver damage progression leading to more severe forms of inflammation and hepatic fibrosis. In this regard, the gut–liver axis (GLA) seems to play a central role. Principal players are the gut microbiota, its bacterial products, and the intestinal barrier. A derangement of GLA (namely, dysbiosis and altered intestinal permeability) may promote bacteria/bacterial product translocation into portal circulation, activation of inflammation via toll-like receptors signaling in hepatocytes, and progression from simple steatosis to non-alcoholic steato-hepatitis (NASH). Among other factors a relevant role has been attributed to the farnesoid X receptor, a nuclear transcriptional factor activated from bile acids chemically modified by gut microbiota (GM) enzymes. The individuation and elucidation of GLA derangement in NAFLD pathomechanisms is of interest at all ages and especially in pediatrics to identify new therapeutic approaches in patients recalcitrant to lifestyle changes. Specific targeting of gut microbiota via pre-/probiotic supplementation, feces transplantation, and farnesoid X receptor modulation appear promising.

Insulin resistance alters hepatic ethanol metabolism: studies in mice and children with non-alcoholic fatty liver disease

OBJECTIVE

Increased fasting blood ethanol levels, suggested to stem from an increased endogenous ethanol synthesis in the GI tract, are discussed to be critical in the development of non-alcoholic fatty liver disease (NAFLD). The aim of the present study was to further delineate the mechanisms involved in the elevated blood ethanol levels found in patients with NAFLD.

DESIGN

In 20 nutritionally and metabolically screened children displaying early signs of NAFLD and 29 controls (aged 5-8 years), ethanol plasma levels were assessed. Ethanol levels along the GI tract, in vena cava and portal vein, intestinal and faecal microbiota, and activity of alcohol dehydrogenase (ADH) and cytochrome P450 2E1 (CYP2E1) were measured in wild-type, ob/ob and anti-TNFα antibody (aT) treated ob/ob mice.

RESULTS

Despite not differing in dietary pattern or prevalence of intestinal overgrowth, fasting ethanol levels being positively associated with measures of insulin resistance were significantly higher in children with NAFLD than in controls. Ethanol levels were similar in portal vein and chyme obtained from different parts of the GI tract between groups while ethanol levels in vena cava plasma were significantly higher in ob/ob mice. ADH activity was significantly lower in liver tissue obtained from ob/ob mice in comparison to wild-type controls and ob/ob mice treated with aT.

CONCLUSIONS

Taken together, our data of animal experiments suggest that increased blood ethanol levels in patients with NAFLD may result from insulin-dependent impairments of ADH activity in liver tissue rather than from an increased endogenous ethanol synthesis.

TRIAL REGISTRATION NUMBER

NCT01306396.

Pathogenesis of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease and a risk factor for cirrhosis and hepatocellular carcinoma. The pathological features of NASH include steatosis, hepatocyte injury, inflammation, and various degrees of fibrosis. Steatosis reflects disordered lipid metabolism. Insulin resistance and excessive fatty acid influx to the liver are two important contributing factors. Steatosis is also likely associated with lipotoxicity and cellular stresses such as oxidative stress and endoplasmic reticulum stress, which result in hepatocyte injury. Inflammation and fibrosis are frequently triggered by various signals such as proinflammatory cytokines and chemokines, released by injuried hepatocytes and activated Kupffer cells. Although much progress has been made, the pathogenesis of NASH is not fully elucidated. The purpose of this review is to discuss the current understanding of NASH pathogenesis, mainly focusing on factors contributing to steatosis, hepatocyte injury, inflammation, and fibrosis.

Gut microbiome and nonalcoholic fatty liver diseases

We review recent findings and hypotheses on the roles of gut microbiome in the pathogenesis of nonalcoholic fatty liver diseases (NAFLD). Microbial metabolites and cell components contribute to the development of hepatic steatosis and inflammation, key components of nonalcoholic steatohepatitis (NASH), the severe form of NAFLD. Altered gut microbiome can independently cause obesity, the most important risk factor for NAFLD. This capability is attributed to short-chain fatty acids (SCFAs), major gut microbial fermentation products. SCFAs account for a large portion of caloric intake of the host, and they enhance intestinal absorption by activating GLP-2 signaling. However, elevated SCFAs may be an adaptive measure to suppress colitis, which could be a higher priority than imbalanced calorie intake. The microbiome of NASH patients features an elevated capacity for alcohol production. The pathomechanisms for alcoholic steatohepatitis may apply to NASH. NAFLD/NASH is associated with elevated Gram-negative microbiome and endotoxemia. However, many NASH patients exhibited normal serum endotoxin indicating that endotoxemia is not required for the pathogenesis of NASH. These observations suggest that microbial intervention may benefit NAFLD/NASH patients. However, very limited effects were observed using traditional probiotic species. Novel probiotic therapy based on NAFLD/NASH specific microbial composition represents a promising future direction.

Meta-omic platforms to assist in the understanding of NAFLD gut microbiota alterations: tools and applications

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide as a result of the increasing prevalence of obesity, starting from early life stages. It is characterized by a spectrum of liver diseases ranging from simple fatty liver (NAFL) to steatohepatitis (NASH), with a possible progression to fibrosis, thus increasing liver-related morbidity and mortality. NAFLD development is driven by the co-action of several risk factors, including obesity and metabolic syndrome, which may be both genetically induced and diet-related. Recently, particular attention has been paid to the gut-liver axis, which may play a physio-pathological role in the onset and progression of the disease. The gut microbiota is intended to act as a bioreactor that can guarantee autonomous metabolic and immunological functions and that can drive functional strategies within the environment of the body in response to external stimuli. The complexity of the gut microbiota suggests that it behaves as an organ. Therefore, the concept of the gut-liver axis must be complemented with the gut-microbiota-liver network due to the high intricacy of the microbiota components and metabolic activities; these activities form the active diet-driven power plant of the host. Such complexity can only be revealed using systems biology, which can integrate clinical phenomics and gut microbiota data.

Ethanol metabolism and its effects on the intestinal epithelial barrier

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.

Characterization of gut microbiomes in nonalcoholic steatohepatitis (NASH) patients: a connection between endogenous alcohol and NASH

Nonalcoholic steatohepatitis (NASH) is a serious liver disease associated with obesity. Characterized by metabolic syndrome, hepatic steatosis, and liver inflammation, NASH is believed to be under the influence of the gut microflora. Here, the composition of gut bacterial communities of NASH, obese, and healthy children was determined by 16S ribosomal RNA pyrosequencing. In addition, peripheral blood ethanol was analyzed to monitor endogenous ethanol production of patients and healthy controls. UniFrac-based principle coordinates analysis indicated that most of the microbiome samples clustered by disease status. Each group was associated with a unique pattern of enterotypes. Differences were abundant at phylum, family, and genus levels between healthy subjects and obese patients (with or without NASH), and relatively fewer differences were observed between obese and the NASH microbiomes. Among those taxa with greater than 1% representation in any of the disease groups, Proteobacteria, Enterobacteriaceae, and Escherichia were the only phylum, family and genus types exhibiting significant difference between obese and NASH microbiomes. Similar blood-ethanol concentrations were observed between healthy subjects and obese non-NASH patients, but NASH patients exhibited significantly elevated blood ethanol levels.

CONCLUSIONS

The increased abundance of alcohol-producing bacteria in NASH microbiomes, elevated blood-ethanol concentration in NASH patients, and the well-established role of alcohol metabolism in oxidative stress and, consequently, liver inflammation suggest a role for alcohol-producing microbiota in the pathogenesis of NASH. We postulate that the distinct composition of the gut microbiome among NASH, obese, and healthy controls could offer a target for intervention or a marker for disease.

Low plasma antibodies specific for phosphatidylethanol in alcohol abusers and patients with alcoholic pancreatitis

Phosphatidylethanol (PEth) is a group of alcohol-modified phospholipids present in cell membranes after heavy drinking. Our aim was to demonstrate the presence of human plasma antibodies binding to PEth and to address their specificity and value in detecting subjects engaged in heavy alcohol consumption. Antibodies to PEth were analyzed in plasma from heavy drinkers (n=20), patients with alcoholic pancreatitis (n=58) and control subjects (n=24), using chemiluminescent immunoassay. Heavy drinkers and patients with alcoholic pancreatitis demonstrated significantly lower levels of plasma IgG, IgA and IgM titers to PEth compared with controls (P<0.001). The specificity of the antibodies to PEth was demonstrated with competitive liquid phase immunoassays and flow cytometry. The plasma IgG, but not IgA or IgM, titers to PEth in heavy drinkers correlated with the whole blood PEth concentration determined by liquid chromatography-mass spectrometry (r=0.655, P=0.002). Compared with traditional markers for alcohol abuse (aspartate aminotransferase, gamma-glutamyl transpeptidase and mean corpuscular volume), receiver operating characteristic curve analysis showed that a low plasma IgA to PEth had the highest area under the curve (AUC 0.940, P<0.001). In conclusion, plasma IgG, IgA and IgM antibodies binding specifically to PEth were found in subjects of all study groups. Subjects with heavy alcohol consumption showed markedly lower plasma immunoglobulin levels to PEth, potentially making them useful as a biomarker to distinguish heavy from moderate alcohol use.

Effect of alcohol consumption on the gut

Both acute and chronic alcohol consumption have severe effects on the structure and function of the entire gastrointestinal tract (GIT) which result in a vicious cycle. The healthy person who begins to drink heavily, first experiences the toxic effects of high concentrations of ethanol. Mucosal damage compromises the basic functions of the GIT. Suppression of the gastrointestinal immune system and increased transport of toxins across the mucosa result in increased susceptibility to infections. Inhibition of digestion, absorption and secretion cause diarrhea and reduce the transfer of nutrients to the rest of the body. As the individual becomes more dependent on alcohol, the functional reserve and regenerative capacity of the GIT are overwhelmed and malnutrition increases. The rate of progression of this cycle depends on several factors including nutritional intake. Whilst the clinical effects of alcohol are well recognized, more research is required to fully elucidate the underlying mechanisms.

Autobrewing revisited: endogenous concentrations of blood ethanol in residents of the United Arab Emirates

Endogenous ethanol concentrations in blood were determined by sensitive headspace gas chromatography/mass spectrometry in 1557 residents of the United Arab Emirates. The subjects were from 13 nationalities, of both sexes and of different age groups. There was no significant difference in blood ethanol concentration between nationalities or between sexes within and between nationalities. The data was pooled and the overall median, minimum, maximum, 25% percentile and 75% percentile were 0.04, 0.00, 3.52, 0.01 and 0.09 mg/dl respectively. The values of blood ethanol concentration as reported in this study indicate that they are far too low to have any forensic significance.

Endogenous ethanol 'auto-brewery syndrome' as a drunk-driving defence challenge

The concentration of ethanol in blood, breath or urine constitutes important evidence for prosecuting drunk drivers. For various reasons, the reliability of the results of forensic alcohol analysis are often challenged by the defence. One such argument for acquittal concerns the notion that alcohol could be produced naturally in the body, hence the term 'auto-brewery' syndrome. Although yeasts such as Candida albicans readily produce ethanol in-vitro, whether this happens to any measurable extent in healthy ambulatory subjects is an open question. Over the years, many determinations of endogenous ethanol have been made, and in a few rare instances (Japanese subjects with very serious yeast infections) an abnormally high ethanol concentration (> 80 mg/dl) has been reported. In these atypical individuals, endogenous ethanol appeared to have been produced after they had eaten carbohydrate-rich foods. A particular genetic polymorphism resulting in reduced activity of enzymes involved in hepatic metabolism of ethanol and a negligible first-pass metabolism might explain ethnic differences in rates of endogenous ethanol production and clearance. Other reports of finding abnormally high concentrations of ethanol in body fluids from ostensibly healthy subjects suffer from deficiencies in study design and lack suitable control experiments or used non-specific analytical methods. With reliable gas chromatographic methods of analysis, the concentrations of endogenous ethanol in peripheral venous blood of healthy individuals, as well as those suffering from various metabolic disorders (diabetes, hepatitis, cirrhosis) ranged from 0-0.08 mg/dl. These concentrations are far too low to have any forensic or medical significance. The notion that a motorist's state of intoxication was caused by endogenously produced ethanol lacks merit.

The effect of cocaine abuse on plasma levels of sulfated dopamine and salsolinol in alcoholics

This study investigated the effect of cocaine abuse on peripheral dopamine and its tetrahydroisoquinoline metabolite salsolinol in chronic alcoholics. Specifically, the concentration of dopamine sulfate and salsolinol sulfate was measured in plasma samples obtained from the blood of a group of alcoholics (n = 40) and alcoholics with cocaine dependence (n = 55). The concentrations of sulfoconjugated dopamine and salsolinol were measured by a radioenzymatic technique. The results of this study showed that chronic alcoholics (627 +/- 195 pg/ml) and alcoholics with cocaine addiction (409 +/- 76 pg/ml) had significantly (p < 0.05) elevated levels of salsolinol sulfate (mean +/- SEM) in their plasma as compared to controls (99.5 +/- 7.5 pg/ml). However, alcoholics with cocaine dependence produced significantly (p < 0.01) higher concentration of dopamine sulfate in their plasma (7520 +/- 1299 pg/ml) as compared to chronic alcoholics (3896 +/- 438 pg/ml) and controls (2124 +/- 104 pg/ml). Differences in plasma dopamine sulfate among alcoholics with cocaine dependence vs. alcoholics without cocaine dependence may be interpreted as a reflection of increased extracellular dopamine metabolism associated with chronic cocaine exposure.

Influence of nutritional substrates on the formation of volatiles by the fecal flora

The influence of metabolic substrates on the formation of volatile compounds by the colonic flora was measured in a fecal incubation system. The presence of carbohydrates (0, 25, and 50 mg/20 mL fecal suspension) led to a dose-related increase in the formation of alcohols and H2 and to a dose-related decrease in the formation of toxic mercaptans. This effect seemed to be independent of pH. The presence of albumin or fat (50 mg/20 mL fecal suspension) as substrates for the colonic flora gave rise to the formation of significantly higher amounts of methanethiol. Small amounts of pentane were found in the headspace after incubation with oil. These data show that the formation of volatile metabolites by the colonic flora is greatly influenced by the available substrates.

Interrelationship between activation of dopaminergic pathways and cerebrospinal fluid concentration of dopamine tetrahydroisoquinoline metabolite salsolinol in humans: preliminary findings

The main objective of this study was to determine whether the activation of dopaminergic pathways, through adrenal-caudate transplantation, stimulated the production of dopamine and salsolinol in cerebrospinal fluid (CSF) of patients with Parkinson's disease. Dopamine sulfate and salsolinol sulfate in CSF specimens were measured by radioenzymatic technique. The results of this study demonstrated that the replacement of degenerative nigrostriatal neurons with new dopamine-producing cells by adrenal brain transplants in patients with Parkinson's disease resulted in significant increase (p less than 0.05) in CSF levels of free dopamine, dopamine sulfate, free salsolinol, and salsolinol sulfate as compared with preoperative levels. Moreover, the oral administration of L-dopa to these transplanted patients caused substantial (p less than 0.001) elevation in CSF levels of free dopamine (before L-dopa, 146 +/- 57 pg/ml; after L-dopa, 575 +/- 207 pg/ml), dopamine sulfate (before L-dopa, 1966 +/- 945 pg/ml; after L-dopa, 41679 +/- 29326 pg/ml), free salsolinol (before L-dopa, 43 +/- 29 pg/ml; after L-dopa, 186 +/- 90 pg/ml), and salsolinol sulfate (before L-dopa, 405 +/- 477 pg/ml; after L-dopa, 2908 +/- 2572 pg/ml), respectively.

Assay of physiological levels of 2,3-butanediol diastereomers in blood and urine by gas chromatography-mass spectrometry

We present an assay for 2,3-butanediol by gas chromatography-mass spectrometry of its trimethylsilyl ethers. 2R,3R- and/or 2S,3S-2,3-butanediol and meso-2,3-butanediol are quantitated with corresponding internal standards of [2,3-2H2]butanediol. Limits of detection are 1 and 0.1 microM for split and splitless injections, respectively. Blood concentrations of 2,3-butanediol in nonalcoholics are 0.5 +/- 0.3 (SD) microM for 2R,3R- and/or 2S,3S-2,3-butanediol and 0.8 +/- 0.4 microM for meso-2,3-butanediol (n = 9). Two hours after alcohol ingestion, blood levels had risen in eight of nine subjects to 1.2 +/- 0.7 microM for 2R,3R-/2S,3S-2,3-butanediol and to 1.2 +/- 0.6 microM for meso-2,3-butanediol. Baseline urinary excretion of 2,3-butanediol is 0.4 +/- 0.2 mumol/mmol creatinine for 2R,3R-/2S,3S-2,3-butanediol and 0.9 +/- 0.5 mumol/mmol creatinine for meso-2,3-butanediol.

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 15/3. Human acetaldehyde levels: aspects of current interest

The determination of acetaldehyde levels in blood and other tissues is a difficult task, and depends on the method used. Different methods and their pros and cons are discussed in detail. Quantitative results are shown for endogenous acetaldehyde levels and for acetaldehyde levels during alcohol intoxication. One article pertains to acetaldehyde bound to blood and tissue proteins.

Endogenous ethanol--its metabolic, behavioral and biomedical significance

Ethanol is constantly formed endogenously from acetaldehyde, and level of the former can be measured in both human beings and animals. Acetaldehyde can be generated in situ from the metabolism of pyruvate, threonine, deoxyribose-5-phosphate, phosphoethanolamine, alanine and presumably from other substrates. The levels of blood and tissue endogenous ethanol change as a function of various physiologic and experimental conditions such as starvation, aging, stress, cooling, adrenalectomy, etc. and are regulated by many exogenous compounds such as antimetabolites, derivatives of amino acids, lithium salts, disulfiram, cyanamide, etc. Under free choice alcohol selection situations, the levels of endogenous ethanol in rat blood and alcohol preference by the animals are negatively correlated. Similar negative correlations have been found between the levels of blood endogenous ethanol and the frequency of delirium in alcoholic patients undergoing alcohol withdrawal. Endogenous ethanol and acetaldehyde can therefore be regarded as compounds which fulfil substrate, regulatory and modulator functions.

Lack of differences in blood and tissue concentrations of endogenous ethanol in conventional and germfree rats

Headspace gas chromatography was used to determine the concentrations of endogenous ethanol in blood and tissue of conventional and germfree rats. In all biological specimens analysed, the four principal volatile endogenous substances were identified as methanol, acetaldehyde, ethanol and acetone. No statistically significant differences in the concentrations of endogenous ethanol were noted between conventional and germfree animals. In whole blood, liver, kidney, and brain of germfree rats the concentrations of endogenous ethanol were 4.2 +/- 0.19 microM, 5.1 +/- 0.55 microM, 8.2 +/- 0.59 microM and 4.4 +/- 0.17 microM (means +/- SE), respectively. The higher concentration in kidney was also observed in conventional rats. Our results suggest that ethanol is a normal metabolic intermediate in rats and does not exclusively arise from microbial fermentation reactions in the gastrointestinal tract.

Determination of endogenous ethanol in blood and breath by gas chromatography-mass spectrometry

We describe methods for the determination of endogenous ethanol in biological specimens from healthy abstaining subjects. The analytical methods were headspace gas chromatography (GC) for plasma samples and gas chromatography-mass spectometry (GC/MS) with deuterium labelled species 2H3-ethanol and 2H5-ethanol as internal standards for breath analysis. Ethanol in rebreathed air was about 10% higher than in directly analysed end-expired alveolar air. Known volumes of rebreathed air were passed through a liquid-N2 freeze trap and the volatile constituents of breath were concentrated prior to analysis by GC or GC/MS. Besides endogenous ethanol, peaks were seen on the chromatograms for methanol, acetone and acetaldehyde as well as several as yet unidentified substances. The endogenous alcohols ethanol and methanol were confirmed from their mass chromatograms and the GC/MS profile also indicated the presence of endogenous propan-1-ol. The concentration of endogenous ethanol in plasma showed wide inter-subject variations ranging from below detection limits to 1.6 micrograms/ml (34.8 mumol/l) and with mean +/- SD of 0.39 +/- 0.45 micrograms/ml (8.5 +/- 9.8 mumol/l). We aim to characterise further the role of endogenous ethanol with the main focus on dynamic aspects such as the rate of formation and turnover.

A sweat-patch test for alcohol consumption: evaluation in continuous and episodic drinkers

We evaluated the sweat-patch test for its ability to detect alcohol consumption. During an 8-day study, volunteers drank whisky while wearing sweat-patches that collected sweat continuously at a steady rate. We offered 1.0, 2.0, or 5.0 g ethanol/kg/day to 6 continuous drinkers, and 5.0 g ethanol/kg/day for 2 days to 8 episodic drinkers, and removed sweat patches after 2, 4, 6, and 8 days. The concentration of ethanol in the collected sweat (Cs) rose: (1) progressively with the amount of alcohol consumed: and (2) linearly with the mean concentration of ethanol in the blood (Cb) during the sweat collection period (In Cs = 0.80 In Cb - 1.40; r = 0.93, p < 0.001). The test clearly distinguished drinkers from nondrinkers (Cs < 0.0022 G/L when no ethanol consumed; Cs > 0.0067 G/L when 0.5 G ethanol/kg/day consumed and when Cb > 0.013 G/L). The sweat patch test provides an objective index of drinking behavior with potential applications in clinical practice and research.