Alcohol, vitamin A, and beta-carotene: adverse interactions, including hepatotoxicity and carcinogenicity

Perioperative nutritional therapy in liver transplantation

Protein-energy malnutrition is frequently seen in patients with end-stage liver disease who undergo liver transplantation. This causes a deterioration of the patients' clinical condition and affects their post-transplantation survival. Accurate assessment of the nutritional status and adequate intervention are prerequisites for perioperative nutritional treatment. However, the metabolic abnormalities induced by liver failure make the traditional assessment of the nutritional status difficult. The methods that were recently developed for accurately assessing the nutritional status by body bioelectrical impedance may be implemented in pre-transplant management. Because preoperative malnutrition and the loss of skeletal muscle mass, called sarcopenia, have a significant negative impact on the post-transplantation outcome, it is essential to provide adequate nutritional support during all phases of liver transplantation. Oral nutrition is preferred, but tube enteral nutrition may be required to provide the necessary caloric intake. We herein discuss both bioelectrical impedance and the latest findings in the current perioperative nutritional interventions in liver transplant patients regarding synbiotics, micronutrients, branched-chain amino acid supplementation, the use of immune system modulating formulas, the fluid balance and the offering of nocturnal meals.

Alcoholic beverages and carbonated soft drinks: consumption and gastrointestinal cancer risks

Alcoholic beverages (ABs) and carbonated soft drinks (CSDs) are widely consumed worldwide. Given the high consumption of these beverages, the scientific community has increased its focus on their health impact. There is epidemiological evidence of a causal association between AB intake and digestive cancer, but the role of alcohol in determining cancer is not fully defined. Experimental studies have so far identified multiple mechanisms involved in carcinogenesis; ethanol itself is not carcinogenic but available data suggest that acetaldehyde (AA) and reactive oxygen species-both products of ethanol metabolism-have a genotoxic effect promoting carcinogenesis. Other carcinogenetic mechanisms include nutritional deficits, changes in DNA methylation, and impaired immune surveillance. As CSDs are often suspected to cause certain gastrointestinal disorders, consequently, some researchers have hypothesized their involvement in gastrointestinal cancers. Of all the ingredients, carbon dioxide is prevalently involved in the alteration of gastrointestinal physiology by a direct mucosal effect and indirect effects mediated by the mechanical pressure determined by gas. The role of sugar or artificial sweeteners is also debated as factors involved in the carcinogenic processes. However, several surveys have failed to show any associations between CSDs and esophageal, gastric, or colon cancers. On the other hand, a slight correlation between risk of pancreatic cancer and CSD consumption has been found.

Low-dose ATRA supplementation abolishes PRM formation in rat liver and ameliorates ethanol-induced liver injury

The effects of all-trans-retinoic acid (ATRA) in low doses supplementation on concentrations of polar retinoid metabolites (PRM) and retinoids in the ethanol-fed rat liver, and on hepatocyte injury were investigated. The rat model of alcoholic liver disease (ALD) was induced by intragastric infusion of ethanol, and then the rats were administrated with ATRA in two different doses (150 microg/kg body weight and 1.5 mg/kg body weight) for 4 weeks. Concentrations of retinoids in rat liver and plasma were determined by using HPLC. Liver tissues pathologic changes were observed under the light microscopy and electron microscopy. The serum transaminases concentrations were measured. The results showed that the HPLC analysis of retinoids revealed that retinoids (vitamin A, RA, retinyl palmitate) concentrations in ethanol-fed rat liver and RA concentration in ethanol-fed rat plasma were markedly diminished (P<0.01) after ethanol feeding for 12 weeks. Furthermore, obvious peaks of PRM were formed in livers of ethanol-fed rats. ATRA 150 microg/kg supplementation in ethanol-fed rats for 4 weeks raised RA concentration in both liver and plasma, and also raised vitamin A concentration in liver to control levels, partially restored retinyl palmitate concentration (P<0.05) in liver. ATRA 1.5 mg/kg supplementation raised not only RA concentrations in liver and plasma but also retinyl palmitate concentrations in liver. However, the vitamin A concentration in liver of ATRA-supplemented rats (1.5 mg/kg) was higher than that of controls (P<0.05). The histologic observation of liver tissues indicated that ATRA treatment notably alleviated hepatocellular swelling, steatosis, the swelling of mitochondria and proliferation of smooth endoplasmic reticulum (SER). ATRA treatment greatly decreased levels of serum transaminases as compared with the only ethanol-fed group (P<0.05). It was concluded that low-dose ATRA treatment could restore retinoids concentrations and abolish the PRM formation in liver of ALD rats, and then ameliorate the injury of liver cells.

Effects of ethanol exposure on nervous system development in zebrafish

Alcohol (ethanol) is a teratogen that adversely affects nervous system development in a wide range of animal species. In humans numerous congenital abnormalities arise as a result of fetal alcohol exposure, leading to a spectrum of disorders referred to as fetal alcohol spectrum disorder (FASD). These abnormalities include craniofacial defects as well as neurological defects that affect a variety of behaviors. These human FASD phenotypes are reproduced in the rodent central nervous system (CNS) following prenatal ethanol exposure. While the study of ethanol effects on zebrafish development has been more limited, several studies have shown that different strains of zebrafish exhibit differential susceptibility to ethanol-induced cyclopia, as well as behavioral deficits. Molecular mechanisms underlying the effects of ethanol on CNS development also appear to be shared between rodent and zebrafish. Thus, zebrafish appear to recapitulate the observed effects of ethanol on human and mouse CNS development, indicating that zebrafish can serve as a complimentary developmental model system to study the molecular basis of FASD. Recent studies examining the effect of ethanol exposure on zebrafish nervous system development are reviewed, with an emphasis on attempts to elucidate possible molecular pathways that may be impacted by developmental ethanol exposure. Recent work from our laboratories supports a role for perturbed extracellular matrix function in the pathology of ethanol exposure during zebrafish CNS development. The use of the zebrafish model to assess the effects of ethanol exposure on adult nervous system function as manifested by changes in zebrafish behavior is also discussed.

Role of oxidative stress in the pathogenesis of alcohol-induced liver disease

Chronic alcohol consumption is a well-known risk factor for liver disease, which represents a major cause of morbidity and mortality worldwide. The pathological process of alcohol-induced liver disease is characterized by a broad spectrum of morphological changes ranging from steatosis with minimal injury to more advanced liver damage, including steato-hepatitis and fibrosis/cirrhosis. Experimental and clinical studies increasingly show that the oxidative damage induced by ethanol contribute in many ways to the pathogenesis of alcohol hepatotoxicity. This article describes the contribution of oxidative mechanisms to liver damage by alcohol.

Complex cardiac defects after ethanol exposure during discrete cardiogenic events in zebrafish: prevention with folic acid

BACKGROUND

Fetal alcohol spectrum disorder (FASD) describes a range of birth defects including various congenital heart defects (CHDs). Mechanisms of FASD-associated CHDs are not understood. Whether alcohol interferes with a single critical event or with multiple events in heart formation is not known.

RESULTS

Our zebrafish embryo experiments showed that ethanol interrupts different cardiac regulatory networks and perturbs multiple steps of cardiogenesis (specification, myocardial migration, looping, chamber morphogenesis, and endocardial cushion formation). Ethanol exposure during gastrulation until cardiac specification or during myocardial midline migration did not produce severe or persistent heart development defects. However, exposure comprising gastrulation until myocardial precursor midline fusion or during heart patterning stages produced aberrant heart looping and defective endocardial cushions. Continuous exposure during entire cardiogenesis produced complex cardiac defects leading to severely defective myocardium, endocardium, and endocardial cushions. Supplementation of retinoic acid with ethanol partially rescued early heart developmental defects, but the endocardial cushions did not form correctly. In contrast, supplementation of folic acid rescued normal heart development, including the endocardial cushions.

CONCLUSIONS

Our results indicate that ethanol exposure interrupted divergent cardiac morphogenetic events causing heart defects. Folic acid supplementation was effective in preventing a wide spectrum of ethanol-induced heart developmental defects.

Race-ethnicity is a strong correlate of circulating fat-soluble nutrient concentrations in a representative sample of the U.S. population

Sociodemographic and lifestyle factors exert important influences on nutritional status; however, information on their association with biomarkers of fat-soluble nutrients is limited, particularly in a representative sample of adults. Serum or plasma concentrations of vitamin A, vitamin E, carotenes, xanthophylls, 25-hydroxyvitamin D [25(OH)D], SFAs, MUFAs, PUFAs, and total fatty acids (tFAs) were measured in adults (aged ≥ 20 y) during all or part of NHANES 2003-2006. Simple and multiple linear regression models were used to assess 5 sociodemographic variables (age, sex, race-ethnicity, education, and income) and 5 lifestyle behaviors (smoking, alcohol consumption, BMI, physical activity, and supplement use) and their relation to biomarker concentrations. Adjustment for total serum cholesterol and lipid-altering drug use was added to the full regression model. Adjustment for latitude and season was added to the full model for 25(OH)D. Based on simple linear regression, race-ethnicity, BMI, and supplement use were significantly related to all fat-soluble biomarkers. Sociodemographic variables as a group explained 5-17% of biomarker variability, whereas together, sociodemographic and lifestyle variables explained 22-23% [25(OH)D, vitamin E, xanthophylls], 17% (vitamin A), 15% (MUFAs), 10-11% (SFAs, carotenes, tFAs), and 6% (PUFAs) of biomarker variability. Although lipid adjustment explained additional variability for all biomarkers except for 25(OH)D, it appeared to be largely independent of sociodemographic and lifestyle variables. After adjusting for sociodemographic, lifestyle, and lipid-related variables, major differences in biomarkers were associated with race-ethnicity (from -44 to 57%), smoking (up to -25%), supplement use (up to 21%), and BMI (up to -15%). Latitude and season attenuated some race-ethnicity differences. Of the sociodemographic and lifestyle variables examined, with or without lipid adjustment, most fat-soluble nutrient biomarkers were significantly associated with race-ethnicity.

Hepatic retinoid stores are required for normal liver regeneration

Preliminary studies of liver regeneration induced by partial hepatectomy (PHE) identified a substantial depletion of hepatic retinoid stores, by greater than 70%, in regenerating livers of wild-type C57Bl/6J mice. To understand this, we compared responses of wild-type and lecithin:retinol acyltransferase (Lrat)-deficient mice, which totally lack hepatic retinoid stores, to PHE. The Lrat-deficient livers showed delayed regeneration in the first 24 h after PHE. At 12 h after PHE, we observed significantly less mRNA expression for growth factors and cytokines implicated in regulating the priming phase of liver regeneration, specifically for Hgf and Tgfα, but not Tgfβ. Compared with wild-type mice, the changes in mRNA levels for p21 and cyclins E1, B1, and A2 mRNAs and for hepatocellular BrdU incorporation and mitoses were delayed (i.e., shifted to later times) in regenerating Lrat(-/-) livers. Concentrations of all-trans-retinoic acid were significantly lower in the livers of Lrat(-/-) mice following PHE, and this was accompanied by diminished expression of known retinoid-responsive genes. At later times after PHE, the rate of liver weight restoration for Lrat(-/-) mice was parallel to that of wild-type mice, although additional biochemical differences were observed. Thus, hepatic retinoid stores are required for maintaining expression of signaling molecules that regulate cell proliferation and differentiation immediately after hepatic injury, accounting for the delayed restoration of liver mass in Lrat(-/-) mice.

Retinoids in the treatment of glioma: a new perspective

Primary brain tumors are among the top ten causes of cancer-related deaths in the US. Malignant gliomas account for approximately 70% of the 22,500 new cases of malignant primary brain tumors diagnosed in adults each year and are associated with high morbidity and mortality. Despite optimal treatment, the prognosis for patients with gliomas remains poor. The use of retinoids (vitamin A and its congeners) in the treatment of certain tumors was originally based on the assumption that these conditions were associated with an underlying deficiency of vitamin A and that supplementation with pharmacological doses would correct the deficiency. Yet the results of retinoid treatment have been only modestly beneficial and usually short-lived. Studies also indicate that vitamin A excess and supplementation have pro-oxidant effects and are associated with increased risks of mortality from cancer and other diseases. The therapeutic role of vitamin A in cancer thus remains uncertain and a new perspective on the facts is needed. The modest and temporary benefits of retinoid treatment could result from a process of feedback inhibition, whereby exogenous retinoid temporarily inhibits the endogenous synthesis of these compounds. In fact, repeated and/or excessive exposure of the tissues to endogenous retinoic acid may contribute to carcinogenesis. Gliomas, in particular, may result from an imbalance in retinoid receptor expression initiated by environmental factors that increase the endogenous production of retinoic acid in glia. At the receptor level, it is proposed that this imbalance is characterized by excessive expression of retinoic acid receptor-α (RARα) and reduced expression of retinoic acid receptor-β (RARβ). This suggests a potential new treatment strategy for gliomas, possibly even at a late stage of the disease, ie, to combine the use of a RARα antagonist and a RARβ agonist. According to this hypothesis, the RARα antagonist would be expected to inhibit RARα-induced gliomas, while the RARβ agonist would suppress tumor growth and possibly contribute to the regeneration of normal glia.

Chronic ethanol consumption alters all-trans-retinoic acid concentration and expression of their receptors on the prostate: a possible link between alcoholism and prostate damage

BACKGROUND

Ethanol (EtOH) alters the all-trans-retinoic acid (ATRA) levels in some tissues. Retinol and ATRA are essential for cell proliferation, differentiation, and maintenance of prostate homeostasis. It has been suggested that disturbances in retinol/ATRA concentration as well as in the expression of retinoic acid receptors (RARs) contribute to benign prostate hyperplasia and prostate cancer. This study aimed to evaluate whether EtOH consumption is able to alter retinol and ATRA levels in the plasma and prostate tissue as well as the expression of RARs, cell proliferation, and apoptosis index.

METHODS

All animals were divided into 4 groups (n = 10/group). UChA: rats fed 10% (v/v) EtOH ad libitum; UChACo: EtOH-naïve rats without access to EtOH; UChB: rats fed 10% (v/v) EtOH ad libitum; UChBCo: EtOH-naïve rats without access to EtOH. Animals were euthanized by decapitation after 60 days of EtOH consumption for high-performance liquid chromatography and light microscopy analysis.

RESULTS

EtOH reduced plasma retinol concentration in both UChA and UChB groups, while the retinol concentration was not significantly different in prostate tissue. Conversely, plasma and prostate ATRA levels increased in UChB group compared with controls, beyond the up-regulation of RARβ and -γ in dorsal prostate lobe. Additionally, no alteration was found in cell proliferation and apoptosis index involving dorsal and lateral prostate lobe.

CONCLUSIONS

We conclude that EtOH alters the plasma retinol concentrations proportionally to the amount of EtOH consumed. Moreover, high EtOH consumption increases the concentration of ATRA in plasma/prostate tissue and especially induces the RARβ and RARγ in the dorsal prostate lobe. EtOH consumption and increased ATRA levels were not associated with cell proliferation and apoptosis in the prostate.

The adverse effects of alcohol on vitamin A metabolism

The objective of this review is to explore the relationship between alcohol and the metabolism of the essential micronutrient, vitamin A; as well as the impact this interaction has on alcohol-induced disease in adults. Depleted hepatic vitamin A content has been reported in human alcoholics, an observation that has been confirmed in animal models of chronic alcohol consumption. Indeed, alcohol consumption has been associated with declines in hepatic levels of retinol (vitamin A), as well as retinyl ester and retinoic acid; collectively referred to as retinoids. Through the use of animal models, the complex interplay between alcohol metabolism and vitamin A homeostasis has been studied; the reviewed research supports the notion that chronic alcohol consumption precipitates a decline in hepatic retinoid levels through increased breakdown, as well as increased export to extra-hepatic tissues. While the precise biochemical mechanisms governing alcohol's effect remain to be elucidated, its profound effect on hepatic retinoid status is irrefutable. In addition to a review of the literature related to studies on tissue retinoid levels and the metabolic interactions between alcohol and retinoids, the significance of altered hepatic retinoid metabolism in the context of alcoholic liver disease is also considered.

Adverse effects of antioxidative vitamins

High doses of synthetic antioxidative vitamins: A, E, C and β-carotene are often used on long-term basis in numerous preventive and therapeutic medical applications. Instead of expected health effects, the use of those vitamins may however lead to cases of hypervitaminosis and even to intoxication. The article points out main principles of safety which are to be observed during supplementation with antioxidative vitamins. Toxic effects resulting from erroneous administration of high doses of those substances on organs and systems of the organism are also discussed. Attention is drawn to interactions of antioxidative vitamins with concomitantly used drugs, as well as intensification of adverse effects caused by various exogenous chemical factors. Moreover, the article presents the evaluation of supplementation with these vitamins, which was performed in large studies.

Papillary atrophy of the tongue and nutritional status of hospitalized alcoholics

BACKGROUND

Atrophy of the papillae, mucosa, and dorsum of the tongue are considered classical signs of nutritional deficiencies.

OBJECTIVE

To assess the nutritional status of hospitalized alcoholics with or without papillary atrophy of the tongue.

METHODS

This study was performed with 21 hospitalized alcoholics divided into Atrophic Glossitis Group (n=13) and Normal Tongue Group (n=8). Healthy, non-alcoholic volunteers composed the Control Group (n=8). Anthropometry and bioelectric impedance were performed, and serum vitamins A, E, and B12 were determined.

RESULTS

There were no statistical differences in relation to age (46.7 ± 8.7 vs. 46.8 ± 15.8 years) or gender (92.3% vs. 87.5% male), respectively. Control Group volunteers were also paired in relation to age (47.5 ± 3.1 years) and male predominance (62.5%). In relation to hospitalized alcoholics without atrophic lesions of the tongue and Control Group, patients with papillary atrophy showed lower BMI (18.6 ± 2,5 vs 23.8 ± 3.5 vs 26.7 ± 3,6 kg/m(2)) and body fat content 7.6 ± 3.5 vs 13.3 ± 6.5 vs 19.5 ± 4,9 kg). When compared with the Control Group, alcoholic patients with or without papillary atrophy of the tongue showed lower values of red blood cells (10.8 ± 2.2 vs 11.8 ± 2.2 vs 14.5 ± 1,6g/dL) and albumin (3.6 ± 0.9 vs 3.6 ± 0.8 vs 4.4 ± 0.2g/dL). The seric levels of vitamins A, E, and B12 were similar amongst the groups.

CONCLUSION

Hospitalized alcoholics with papillary atrophy of the tongue had lower BMI and fat body stores than controls, without associated hypovitaminosis.

Dietary quality and adequacy among Aboriginal alcohol consumers in the Northwest Territories, Canada

OBJECTIVES

The present study aimed to assess dietary adequacy and quality among Inuvialuit alcohol consumers and non-consumers in the Northwest Territories (NWT), Canada.

STUDY DESIGN

Cross-sectional study.

METHODS

A validated quantitative food frequency questionnaire was administered to individuals (n = 216) of randomly selected households in 3 NWT communities to capture dietary intake and alcohol consumption over a 30-day recall period. The daily energy and nutrient intake, dietary adequacy and the top food sources of energy and selected nutrients were determined by alcohol consumption status.

RESULTS

Energy intake was higher among all alcohol consumers regardless of gender. Male alcohol consumers had lower nutrient intake density (per 4,184 kJ) of protein, cholesterol and several micronutrients (p ≤ 0.05), and female alcohol consumers had lower intake density of saturated fat (p ≤ 0.01), thiamine, folate and sodium (p ≤ 0.05). Among all men and women, 70-100% had inadequate intakes of dietary fibre, vitamin E and potassium. Non-nutrient-dense foods contributed similar amounts and traditional foods (TF) contributed 3% less to energy comparing alcohol consumers to non-consumers.

CONCLUSION

Nutrient inadequacies are prevalent among Aboriginal populations in the Canadian Arctic and may be exacerbated by alcohol consumption due to alcohol's effects on dietary intake, nutrient transport and metabolism. Adult Inuvialuit who consumed alcohol had increased caloric intake and consumed similar amounts of non-nutrient-dense foods and less nutrient-dense TF. Fewer dietary inadequacies were observed among alcohol consumers than non-consumers, which might be due to the increase in overall food intake among alcohol consumers; however, further exploration of volume and pattern of drinking might help explain this result.

The effect of β-carotene on lumbar osteophyte formation

STUDY DESIGN

Cross-sectional cohort study of elderly people.

OBJECTIVE

The relationships of osteophyte formation on plain lumbar radiographs with serum levels of antioxidants (carotenoids, vitamin A, vitamin E) and other factors were investigated to examine whether antioxidants are involved in lumbar spine degeneration.

SUMMARY OF BACKGROUND DATA

Antioxidants have inhibitory effects on the onset of many diseases. However, the association of lumbar osteophyte formation with antioxidant levels in the general population has not been investigated.

METHODS

The subjects were 286 people (103 men and 183 women; mean age = 68 years) who underwent resident health screening. Osteophyte formation on lumbar lateral radiographs (Nathan classification), lumbar lordosis angles, sacral inclination angles, serum levels of antioxidants, triglyceride levels, body mass index, osteoporosis, back muscle strength, history of alcohol intake, and smoking history were studied in these subjects.

RESULTS

Lumbar osteophyte formation was detected in 48 subjects (17%). Osteophyte formation was significantly more common in elderly persons, men, and subjects with a history of alcohol intake; and had a significant correlation with sacral inclination angle. The levels of α-tocopherol, β-tocopherol, zeaxanthin/lutein, cryptoxanthin, lycopene, α-carotene, and β-carotene were significantly lower in subjects with osteophytes. Logistic regression analysis adjusted for all factors showed that a higher age (odds ratio [OR] = 1.1, 95% confidence interval [CI] = 1.02-1.16; P = 0.02) and a low β-carotene level (OR = 6.7, 95% CI = 1.39-32.6; P = 0.02) were risk factors for osteophyte formation.

CONCLUSION

The serum levels of carotenoids and vitamin E were significantly lower in subjects with lumbar osteophyte formation, and a low β-carotene level was the strongest risk factor for lumbar osteophytes. This is the first evidence of an association between carotenoids and lumbar osteophyte formation. This finding suggests that appropriate dietary intake of antioxidants is important for inhibition of lumbar spine degeneration in a rapidly aging society.

Effects of ethanol on physiological retinoic acid levels

All-trans-retinoic acid (atRA) serves essential functions during embryogenesis and throughout postnatal vertebrate life. Insufficient or excess atRA causes teratogenic and/or toxic effects in the developing embryo: interference with atRA biosynthesis or signaling likely underlies some forms of cancer. Many symptoms of vitamin A (atRA precursor) deficiency and/or toxicity overlap with those of another pleiotropic agent--ethanol. These overlapping symptoms have prompted research to understand whether interference with atRA biosynthesis and/or action may explain (in part) pathology associated with excess ethanol consumption. Ethanol affects many aspects of retinoid metabolism and mechanisms of action site specifically, but no robust data support inhibition of vitamin A metabolism, resulting in decreased atRA in vivo during normal vitamin A nutriture. Actually, ethanol either has no effect on or increases atRA at select sites. Despite this realization, insight into whether interactions between ethanol and retinoids represent cause versus effect requires additional research.

Fibrosis in alcoholic and nonalcoholic steatohepatitis

Both alcoholic and nonalcoholic steatohepatitis are relevant causes of cirrhosis and liver-related mortality. Alcohol abuse represents a major health problem in many countries, and liver disease is considered one of the most relevant causes of death related to this factor. Nonalcoholic fatty liver disease is the most common hepatic abnormality in the Western world, and progresses to cirrhosis and hepatocellular carcinoma in a significant portion of cases. Moreover, presence of NAFLD is associated with an increased risk of cardiovascular events. In this review, we discuss the characteristics of fibrosis in alcoholic and nonalcoholic steatohepatitis, focussing on the diagnostic issues and predictive factors. In addition, the pathogenetic mechanisms responsible for appearance and progression of fibrosis in the two conditions are briefly discussed.

The eye as an organizer of craniofacial development

The formation and invagination of the optic stalk coincides with the migration of cranial neural crest (CNC) cells, and a growing body of data reveals that the optic stalk and CNC cells communicate to lay the foundations for periocular and craniofacial development. Following migration, the interaction between the developing eye and surrounding periocular mesenchyme (POM) continues, leading to induction of transcriptional regulatory cascades that regulate craniofacial morphogenesis. Studies in chick, mice, and zebrafish have revealed a remarkable level of genetic and mechanistic conservation, affirming the power of each animal model to shed light on the broader morphogenic process. This review will focus on the role of the developing eye in orchestrating craniofacial morphogenesis, utilizing morphogenic gradients, paracrine signaling, and transcriptional regulatory cascades to establish an evolutionarily-conserved facial architecture. We propose that in addition to the forebrain, the eye functions during early craniofacial morphogenesis as a key organizer of facial development, independent of its role in vision.

Solid-phase extraction and GC-MS analysis of potentially genotoxic cleavage products of β-carotene in primary cell cultures

A validated method for the simultaneous determination of prominent volatile cleavage products (CPs) of β-carotene in cell culture media has been developed. Target CPs comprised β-ionone (β-IO), cyclocitral (CC), dihydroactinidiolide (DHA), and 1,1,6-trimethyltetraline (TMT). CPs were extracted by solid-phase extraction applying a phenyl adsorbent, eluted with 10% (v/v) tetrahydrofuran in n-hexane, and identified and quantified by gas chromatography-mass spectrometry with electron impact ionization. Method validation addressed linearity confirmation over two application ranges and homoscedasticity testing. Recoveries from culture media were between 71.7% and 95.7% at 1.0 μg/ml. Precision of recoveries determined in intra-day (N = 5) and inter-day (N = 15) assays were <2.0% and <4.8%, respectively. Limit of detection and limit of quantification of the analysis method were <18.0 and <53.0 ng/ml for β-IO, CC, and TMT, whereas 156 and 474 ng/ml were determined for DHA, respectively. Although extractions of blank matrix proved the absence of interfering peaks, statistical comparison between slopes determined for instrumental and total method linearity revealed significant differences. The method was successfully applied in selecting an appropriate solvent for the fortification of culture media with volatile CPs, including the determination of their availability over the incubation period. For the first time, quantification of volatile CPs in treatment solutions and culture media for primary cells becomes accessible by this validated method.

Figure

Update in pediatrics: focus on fat-soluble vitamins

This article provides an update on fat-soluble vitamins (A, D, E, and K) in the healthy pediatric population and in children with chronic disease states that commonly cause deficiencies, specifically cystic fibrosis and cholestatic liver disease. For each fat-soluble vitamin, the biological function, nutrition availability, absorption, deficiency, toxic states, and monitoring parameters are defined.

Tissue-specific increases in endogenous all-trans retinoic acid: possible contributing factor in ethanol toxicity

All-trans retinoic acid (atRA) is required for neurogenesis and dendritic growth in the hippocampus. The toxic effects of ethanol include developmental defects, cognitive dysfunction, and increased risk of cancer and have some similarities to the detrimental effects of excess atRA, the active form of vitamin A. It is therefore possible that disruption of atRA homeostasis would contribute to the deleterious effects of ethanol. However, previous work, using very high exogenous doses of retinol, found that ethanol toxicity led to decreased formation of atRA, apparently due to competitive inhibition of alcohol dehydrogenase, which is purportedly involved in the conversion of retinol to retinal. A new study, using assays that are highly sensitive for endogenous atRA, has reported that ethanol toxicity in mice actually increased atRA concentration in certain tissues, including brain hippocampus, apparently due to a mobilization of hepatic retinyl esters that led to increased retinol and atRA in specific tissues.

Zebrafish fetal alcohol syndrome model: effects of ethanol are rescued by retinoic acid supplement

This study was designed to develop a zebrafish experimental model to examine defects in retinoic acid (RA) signaling caused by embryonic ethanol exposure. RA deficiency may be a causative factor leading to a spectrum of birth defects classified as fetal alcohol spectrum disorder (FASD). Experimental support for this hypothesis using Xenopus showed that effects of treatment with ethanol could be partially rescued by adding retinoids during ethanol treatment. Previous studies show that treating zebrafish embryos during gastrulation and somitogenesis stages with a pathophysiological concentration of ethanol (100mM) produces effects that are characteristic features of FASD. We found that treating zebrafish embryos with RA at a low concentration (10(-9)M) and 100mM ethanol during gastrulation and somitogenesis stages significantly rescued a spectrum of defects produced by treating embryos with 100mM ethanol alone. The rescued phenotype that we observed was quantitatively more similar to embryos treated with 10(-9)M RA alone (RA toxicity) than to untreated or 100mM ethanol-treated embryos. RA rescued defects caused by 100mM ethanol treatment during gastrulation and somitogenesis stages that include early gastrulation cell movements (anterior-posterior axis), craniofacial cartilage formation, and ear development. Morphological evidence also suggests that other characteristic features of FASD (e.g., neural axis patterning) are rescued by RA supplement.

CEBPD reverses RB/E2F1-mediated gene repression and participates in HMDB-induced apoptosis of cancer cells

PURPOSE

Recent evidence indicates that a tumor suppressor gene CEBPD (CCAAT/enhancer-binding protein delta) is downregulated in many cancers including cervical cancer, which provides a therapeutic potential associated with its reactivation. However, little is known for CEBPD activators and the effect of reactivation of CEBPD transcription upon anticancer drug treatment. In this study, we identified a novel CEBPD activator, 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione (HMDB). The purpose of this study is to characterize the mechanism of HMDB-induced CEBPD activation and its potential effect in cancer therapy.

EXPERIMENTAL DESIGN

Methylation-specific PCR assay, reporter assay, and chromatin immunoprecipitation (ChIP) assay were performed to dissect the signaling pathway of HMDB-induced CEBPD transcription. Furthermore, a consequence of HMDB-induced CEBPD expression was linked with E2F1 and retinoblastoma (RB), which discloses the scenario of CEBPD, E2F1, and RB bindings and transcriptional regulation on the promoters of proapoptotic genes, PPARG2 and GADD153. Finally, the anticancer effect of HMDB was examined in xenograft mice.

RESULTS

We demonstrate that CEBPD plays an essential role in HMDB-mediated apoptosis of cancer cells. HMDB up-regulates CEBPD transcription through the p38/CREB pathway, thus leading to transcriptional activation of PPARG2 and GADD153. Furthermore, increased level of CEBPD attenuates E2F1-induced cancer cell proliferation and partially rescues RB/E2F1-mediated repression of PPARG2 and GADD153 transcription. Moreover, HMDB treatment attenuates the growth of A431 xenografts in severe combined immunodeficient mice mice.

CONCLUSIONS

These results clearly demonstrate that HMDB kills cancer cells through activation of CEBPD pathways and suggest that HMDB can serve as a superior chemotherapeutic agent with limited potential for adverse side effects.

Chronic alcohol intake upregulates hepatic expression of carotenoid cleavage enzymes and PPAR in rats

Excessive and chronic alcohol intake leads to a lower hepatic vitamin A status by interfering with vitamin A metabolism. Dietary provitamin A carotenoids can be converted into vitamin A mainly by carotenoid 15,15'-monooxygenase 1 (CMO1) and, to a lesser degree, carotenoid 9'10'-monooxygenase 2 (CMO2). CMO1 has been shown to be regulated by several transcription factors, such as the PPAR, retinoid X receptor, and thyroid receptor (TR). The regulation of CMO2 has yet to be identified. The impact of chronic alcohol intake on hepatic expressions of CMO1 and CMO2 and their related transcription factors are unknown. In this study, Fischer 344 rats were pair-fed either a liquid ethanol Lieber-DeCarli diet (n = 10) or a control diet (n = 10) for 11 wk. Hepatic retinoid concentration and expressions of CMO1, CMO2, PPARγ, PPARα, and TRβ as well as plasma thyroid hormones levels were analyzed. We observed that administering alcohol decreased hepatic retinoid levels but increased mRNA concentrations of CMO1, CMO2, PPARγ, PPARα, and TRβ and upregulated protein levels of CMO2, PPARγ, and PPARα. There was a positive correlation of PPARγ with CMO1 (r = 0.89; P < 0.0001) and both PPARγ and PPARα with CMO2 (r = 0.72, P < 0.001 and r = 0.62, P < 0.01, respectively). Plasma thyroid hormone concentrations did not differ between the control rats and alcohol-fed rats. This study suggests that chronic alcohol intake significantly upregulates hepatic expression of CMO1 and, to a much lesser extent, CMO2. This process may be due to alcohol-induced PPARγ expression and lower vitamin A status in the liver.

Complementary and alternative medicine use in chronic liver disease patients

GOALS

To examine a wide range of sociodemographic and clinical characteristics as potential predictors of complementary and alternative medicine (CAM) use among chronic liver disease (CLD) patients, with a focus on CAM therapies with the greatest potential for hepatotoxicity and interactions with conventional treatments.

BACKGROUND

There is some evidence that patients with CLD commonly use CAM to address general and CLD-specific health concerns.

STUDY

Patients enrolled in a population-based surveillance study of persons newly diagnosed with CLD between 1999 and 2001 were asked about current use of CAM specifically for CLD. Sociodemographic and clinical information was obtained from interviews and medical records. Predictors of CAM use were examined using univariate and multivariate logistic regression analysis.

RESULTS

Of the 1040 participants, 284 (27.3%) reported current use of at least 1 of 3 CAM therapies of interest. Vitamins or other dietary supplements were the most commonly used therapy, reported by 188 (18.1%) patients. This was followed by herbal medicine (175 patients, 16.8%) and homeopathy (16 patients, 1.5%). Several characteristics were found to be independent correlates of CAM use: higher education and family income, certain CLD etiologies (alcohol, hepatitis C, hepatitis C and alcohol, and hepatitis B), and prior hospitalization for CLD.

CONCLUSIONS

Use of CAM therapies that have the potential to interact with conventional treatments for CLD was quite common among this population-based sample of patients with CLD. There is a need for patient and practitioner education and communication regarding CAM use in the context of CLD.

Ethanol elevates physiological all-trans-retinoic acid levels in select loci through altering retinoid metabolism in multiple loci: a potential mechanism of ethanol toxicity

All-trans-retinoic acid (atRA) supports embryonic development, central nervous system function, and the immune response. atRA initiates neurogenesis and dendritic growth in the hippocampus and is required for spatial memory; superphysiological atRA inhibits neurogenesis, causes teratology and/or embryo toxicity, and alters cognitive function and behavior. Because abnormal atRA shares pathological conditions with alcoholism, inhibition of retinol (vitamin A) activation into atRA has been credited widely as a mechanism of ethanol toxicity. Here, we analyze the effects of ethanol on retinoid concentrations in vivo during normal vitamin A nutriture, using sensitive and analytically robust assays. Ethanol either increased or had no effect on atRA, regardless of changes in retinol and retinyl esters. Acute ethanol (3.5 g/kg) increased atRA in adult hippocampus (1.6-fold), liver (2.4-fold), and testis (1.5-fold). Feeding dams a liquid diet with 6.5% ethanol from embryonic day 13 (e13) to e19 increased atRA in fetal hippocampus (up to 20-fold) and cortex (up to 50-fold), depending on blood alcohol content. One-month feeding of the 6.5% ethanol diet increased atRA in adult hippocampus (20-fold), cortex (2-fold), testis (2-fold), and serum (10-fold). Tissue-specific increases in retinoid dehydrogenase mRNAs and activities, extrahepatic retinol concentrations, and atRA catabolism combined to produce site-specific effects. Because a sustained increase in atRA has deleterious effects on the central nervous system and embryo development, these data suggest that superphysiological atRA contributes to ethanol pathological conditions, including cognitive dysfunction and fetal alcohol syndrome.-Kane, M. A., Folias, A. E., Wang, C., Napoli, J. L. Ethanol elevates physiological all-trans-retinoic acid levels in select loci through altering retinoid metabolism in multiple loci: a potential mechanism of ethanol toxicity.

Comparative Hepatoprotective Effect of Vitamins A and E Against Gasoline Vapor Toxicity in Male and Female Rats

Background

Plasma alanine transferase(ALT), aspartate transferase(AST), α-glutamyl transferase(GGT), and alkaline phosphatase(ALP) activities are known biomarkers in assessing hepatic functional integrity. A remarkable rise in the activities of these enzymes normally signifies hepatotoxicity of chemical agent(s) in the biological system. Exposure to 17.8 cm³h^-1m^-3 of PMS blend unleaded gasoline vapors (UGV) for 6 hr/day, 5 days/week for 20 weeks have been reported to cause hepatotoxicity in rats.

Methods

In this study, the comparative hepatoprotective effect of vitamins A (retinol) and E (α-tocopherol) against UGV-induced toxicity was assessed in male and female rats. Retinol and α-tocopherol at prophylactic dosage (400 and 200 IU/kg/day, respectively) were separately administered orally to the test rats concomitant with exposure to UGV in the last two weeks of the experiment.

Results

The results of this study indicated that exposure to UGV caused significant increase (P < 0.05) in the activities of serum ALT, AST, ALP, GGT and bilirubin in male and female rats. Oral administration of prophylactic doses of retinol and α-tocopherol produced a significant decrease (P < 0.05) in the activities of these parameters in male and female test rats, compared with the non-treated test rats; but insignificant increase(P ≥ 0.05), compared with the control. However, the hepatoprotective effect of α-tocopherol was observed to be more potent than that of retinol.

Conclusions

The result of this study demonstrated that the hepatoprotective potency of α-tocopherol against gasoline vapors toxicity was higher than that of retinol in male and female rats, although the female gender of the animal model responded to treatment with both vitamins better than the males. Hence, the work suggested the beneficial effects of both vitamins against hepatotoxicity in individuals frequently exposed to gasoline vapors.

Vitamin A deficiency injures liver parenchyma and alters the expression of hepatic extracellular matrix

Vitamin A is an essential lipid-soluble nutrient that is crucial for morphogenesis and adult tissue maintenance. The retinoid homeostasis in the liver depends on a regular supply of vitamin A from an adequate dietary intake to preserve the normal organ structure and functions. This study focuses on the effect of vitamin A deficiency on the morphology and extracellular proteins expression of the liver in adult Wistar rats. Animals were fed with a normal (control group) or deficient vitamin A diet for 3 months. At the end of the experimental period, histological examination of the livers under light and electron microscopy revealed that vitamin A deficiency produced a loss of hepatocyte cord disposition with an irregular parenchymal organization. Abundant fat droplets were present in the cytoplasm of the hepatocytes. Elongated myofibroblastic-like cells with an irregular cytoplasmic process and without lipid droplets could be seen at the perisinusoidal space, where an elevated intensity of alpha smooth muscle actin (alpha-SMA) was observed. These results suggest that an activation of hepatic stellate cells (HSCs) occurred. Moreover, immunochemical methods revealed that vitamin A deficiency led to an increased expression of hepatic fibronectin, laminin and collagen type IV. We propose that vitamin A deprivation caused liver injury and that HSCs underwent a process of activation in which they produced alpha-SMA and synthesized extracellular components. These changes may be a factor predisposing to liver fibrosis. In consequence, vitamin A deprivation could affect human and animal health.

Contribution of NADH increases to ethanol's inhibition of retinol oxidation by human ADH isoforms

BACKGROUND

A decrease in retinoic acid levels due to alcohol consumption has been proposed as a contributor to such conditions as fetal alcohol spectrum diseases and ethanol-induced cancers. One molecular mechanism, competitive inhibition by ethanol of the catalytic activity of human alcohol dehydrogenase (EC 1.1.1.1) (ADH) on all-trans-retinol oxidation has been shown for the ADH7 isoform. Ethanol metabolism also causes an increase in the free reduced nicotinamide adenine dinucleotide (NADH) in cells, which might reasonably be expected to decrease the retinol oxidation rate by product inhibition of ADH isoforms.

METHODS

To understand the relative importance of these two mechanisms by which ethanol decreases the retinol oxidation in vivo we need to assess them quantitatively. We have built a model system of 4 reactions: (1) ADH oxidation of ethanol and NAD(+), (2) ADH oxidation of retinol and NAD(+), (3) oxidation of ethanol by a generalized Ethanol(oxidase) that uses NAD(+), (4) NADH(oxidase) which carries out NADH turnover.

RESULTS

Using the metabolic modeling package ScrumPy, we have shown that the ethanol-induced increase in NADH contributes from 0% to 90% of the inhibition by ethanol, depending on (ethanol) and ADH isoform. Furthermore, while the majority of flux control of retinaldehyde production is exerted by ADH, Ethanol(oxidase) and the NADH(oxidase) contribute as well.

CONCLUSIONS

Our results show that the ethanol-induced increase in NADH makes a contribution of comparable importance to the ethanol competitive inhibition throughout the range of conditions likely to occur in vivo, and must be considered in the assessment of the in vivo mechanism of ethanol interference with fetal development and other diseases.

High dose lycopene supplementation increases hepatic cytochrome P4502E1 protein and inflammation in alcohol-fed rats

Recent in vitro evidence suggests that the antioxidant lycopene can prevent alcohol-induced oxidative stress and inflammation. However, knowledge of possible interactions in vivo between escalating doses of lycopene and chronic alcohol ingestion are lacking. In this study, we investigated potential interactions between alcohol ingestion and lycopene supplementation and their effect on hepatic lycopene concentration, cytochrome P4502E1 (CYP2E1) induction, and inflammation. Fischer 344 rats (6 groups, n = 10 per group) were fed either a liquid ethanol Lieber-DeCarli diet or a control diet (isocaloric maltodextrin substituted for ethanol) with or without lycopene supplementation at 2 doses (1.1 or 3.3 mg x kg body weight(-1) x d(-1)) for 11 wk. Plasma and hepatic concentrations of lycopene isomers were assessed by HPLC analysis. We examined expressions of hepatic CYP2E1 and tumor necrosis factor-alpha (TNFalpha) and the incidence of hepatic inflammatory foci. Both plasma and hepatic lycopene concentrations were greater in alcohol-fed rats than in control rats supplemented with identical doses of lycopene. In contrast, alcohol-fed rats had a lower percentage of lycopene cis isomers in the plasma and the liver compared with control rats fed the same dose of lycopene. Notably, lycopene supplementation at the higher dose significantly induced hepatic CYP2E1 protein, TNFalpha mRNA, and the incidence of inflammatory foci in the alcohol-fed rats but not in the control rats. These data indicate an interaction between chronic alcohol ingestion and lycopene supplementation and suggest a need for caution among individuals consuming high amounts of both alcohol and lycopene.

Role of nutrition in liver transplantation for end-stage chronic liver disease

Patients with end-stage liver disease often reveal significant protein-energy malnutrition, which may deteriorate after listing for transplantation. Since malnutrition affects post-transplant survival, precise assessment must be an integral part of pre- and post-surgical management. While there is wide agreement that aggressive treatment of nutritional deficiencies is required, strong scientific evidence supporting nutritional therapy is sparse. In practice, oral nutritional supplements are preferred over parenteral nutrition, but enteral tube feeding may be necessary to maintain adequate calorie intake. Protein restriction should be avoided and administration of branched-chain amino acids may help yield a sufficient protein supply. Specific problems such as micronutrient deficiency, fluid balance, cholestasis, encephalopathy, and comorbid conditions need attention in order to optimize patient outcome.

Effect of lipid peroxidation products on the activity of human retinol dehydrogenase 12 (RDH12) and retinoid metabolism

Mutations in human Retinol Dehydrogenase 12 (RDH12) are known to cause photoreceptor cell death but the physiological function of RDH12 in photoreceptors remains poorly understood. In vitro, RDH12 recognizes both retinoids and medium-chain aldehydes as substrates. Our previous study suggested that RDH12 protects cells against toxic levels of retinaldehyde and retinoic acid [S.A. Lee, O.V. Belyaeva, I.K. Popov, N.Y. Kedishvili, Overproduction of bioactive retinoic acid in cells expressing disease-associated mutants of retinol dehydrogenase 12, J. Biol. Chem. 282 (2007) 35621-35628]. Here, we investigated whether RDH12 can also protect cells against highly reactive medium-chain aldehydes. Analysis of cell survival demonstrated that RDH12 was protective against nonanal but not against 4-hydroxynonenal. At high concentrations, nonanal inhibited the activity of RDH12 towards retinaldehyde, suggesting that nonanal was metabolized by RDH12. 4-Hydroxynonenal did not inhibit the RDH12 retinaldehyde reductase activity, but it strongly inhibited the activities of lecithin:retinol acyl transferase and aldehyde dehydrogenase, resulting in decreased levels of retinyl esters and retinoic acid and accumulation of unesterified retinol. Thus, the results of this study showed that RDH12 is more effective in protection against retinaldehyde than against medium-chain aldehydes, and that medium-chain aldehydes, especially 4-hydroxynonenal, severely disrupt cellular retinoid homeostasis. Together, these findings provide a new insight into the effects of lipid peroxidation products and the impact of oxidative stress on retinoid metabolism.

Cancer in the Sami population of Sweden in relation to lifestyle and genetic factors

The reindeer herding Sami of Sweden have low incidences of cancer. The aim of the present study was to investigate the cancer risk in a large cohort of Swedish Sami, containing Sami with different lifestyle and genetic Sami heritage. A cohort of 41,721 Sami identified in official national registers between 1960 and 1997, was divided into two sub-populations -- reindeer herding Sami (RS) and non-reindeer herding Sami (NRS). A demographically matched non-Sami reference population (NS) was used as standard when incidence and mortality ratios were calculated. Incidence and mortality data were obtained from the Swedish Cancer and Cause of Death Registers for the period 1961-2003. For Sami men, lower risks were found for cancers of the colon and prostate, and for malignant melanoma and non-Hodkins lymphoma, but higher for stomach cancer. The Sami women showed higher risks for cancers of the stomach and the ovaries, but lower risk for cancer of the bladder. The RS demonstrated lower relative cancer risks compared with the NRS. The lowest relative risk was found among the RS men, while the highest were observed among the NRS women. The RS men who had adopted a more westernized lifestyle showed a similar relative risk for prostate cancer as that of the NS living in the same region. Most of these differences in cancer risks could probably be ascribed to differences in lifestyle. It is concluded that the traditional Sami lifestyle contains elements, e.g. dietary contents and physical activity that may protect them from developing cancer.

Protective effect of some vitamins against the toxic action of ethanol on liver regeneration induced by partial hepatectomy in rats

AIM

To investigate the effects of vitamins (A, C and E) on liver injury induced by ethanol administration during liver regeneration in rats.

METHODS

Male Wistar rats subjected to 70% partial hepatectomy were divided into five groups (groups 1-5). During the experiment, animals of Group 1 drank only water. The other four groups (2-5) drank 30 mL of ethanol/L of water. Group 3 additionally received vitamin A, those of group 4 vitamin C and those of group 5 received vitamin E. Subsequently serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin and bilirubin were measured colorimetrically. Lipid peroxidation (thiobarbituric-acid reactive substances, TBARS) both in plasma and liver was measured, as well as liver mass gain assessment and total DNA.

RESULTS

Compared with sham group, serum AST and ALT increased significantly under ethanol treatment (43% and 93%, respectively, with P < 0.05). Vitamin C and vitamin E treatment attenuated the ethanol-induced increases in ALT and AST activity. Ethanol treatment also decreased serum albumin concentration compared to sham group (3.1 +/- 0.4 g/dL vs 4.5 +/- 0.2 g/dL; P < 0.05). During liver regeneration vitamins C and E significantly ameliorated liver injury for ethanol administration in hepatic lipid peroxidation (4.92 nmol/mg and 4.25 nmol/mg vs 14.78 nmol/mg, respectively, with P < 0.05). In association with hepatic injury, ethanol administration caused a significant increase in both hepatic and plasma lipid peroxidation. Vitamins (C and E) treatment attenuated hepatic and plasma lipid peroxidation.

CONCLUSION

Vitamins C and E protect against liver injury and dysfunction, attenuate lipid peroxidation, and thus appear to be significantly more effective than vitamin A against ethanol-mediated toxic effects during liver regeneration.

An overview of interactions between micronutrients and of micronutrients with drugs, genes and immune mechanisms

The objective of the present review is to examine critically the consequences of interactions that micronutrients undergo with nutrients and non-nutrients (mainly prescribed medicines) in diets and lifestyle factors (smoking, tea and alcohol consumption). In addition, the review describes recent work on interactions between nutrients and genes, the influence of gene polymorphisms on micronutrients, the impact of immune responses on micronutrients and specific interactions of antioxidant micronutrients in disease processes to minimise potential pro-oxidant damage.

Vitamin A liver store: a case-control study

The present study aims to assess the vitamin A liver store in individuals who died of several causes and to compare them with those who died of violent causes. A case-control study was performed with 60 individuals, where 30 died of violent causes (control) and 30 of other causes (cardiovascular diseases, infections, other chronic degenerative diseases, several causes). According to the cause of death, the mean retinol from liver stores was 281.5 +/- 63.50 mg/g for individuals who died of violent causes--a significantly higher amount (P < 0.05) than those observed in the other group (105.4 +/- 87.54 mg/g by cardiovascular diseases, 88.1 +/-78.03 mg/g by infections, 162.4 +/- 119.19 mg/g by other chronic degenerative diseases and 205.5 + 126.63 mg/g by several causes). The highest prevalence of low vitamin A was observed in individuals who died of infections and cardiovascular diseases, which emphasizes the role of vitamin A in these pathological processes.

Mortality in the Sami population of North Norway, 1970-98

AIMS

The pattern of mortality among many groups of indigenous people has been shown to be disadvantageous in comparison with the general population. Knowledge regarding causes of death among the Sami population in the northern part of Norway is limited. The Sami constitute an ethnic minority whose lifestyle diverges from that of the rest of the population.

METHODS

A cohort of 19,801 persons of Sami origin was followed up to evaluate specific causes of mortality during the period 1970-98. Standardized mortality rates (SMR) were calculated using the rural population of the three Norwegian counties included in the study as a reference population.

RESULTS

Among Sami, 5,955 total deaths were observed, as opposed to 5,537 expected (SMR = 1.08). For both Sami women and men a significantly higher SMR for cerebrovascular diseases was found, which was more pronounced for women. For Sami men, an excess SMR for violent death was observed (SMR 1.32, 95% confidence interval (CI) 1.20-1.46); this was highest among Sami men living in a reindeer-breeding family. For both genders, mortality from all malignant neoplasms combined was lower than in the reference population. SMRs were 0.86 (95% CI 0.79-0.94) and 0.89 (95% CI 0.80-0.99) for men and women, respectively. Low SMRs were also observed for chronic liver diseases, 0.18 (95% CI 0.02-0.63) and 0.12 (95% CI 0.00-0.68) for Sami men and women, respectively. To be a member of a reindeer breeding household appeared to offer protection from mortality caused by circulatory system diseases in men, especially mortality from ischaemic heart disease.

CONCLUSIONS

The total mortality in the North Norway Sami population, an ethnic minority in Norway, was slightly higher when compared with a regional reference population. The differences observed when evaluating mortality by diagnosis might be due to lifestyle, diet, psychosocial, and/or genetic factors.

Metabolism of retinol during mammalian placental and embryonic development

Retinol (vitamin A) is a fat-soluble nutrient indispensable for a harmonious mammalian gestation. The absence or excess of retinol and its active derivatives [i.e., the retinoic acids (RAs)] can lead to abnormal development of embryonic and extraembryonic (placental) structures. The embryo is unable to synthesize the retinol and is strongly dependent on the maternal delivery of retinol itself or precursors: retinyl esters or carotenoids. Before reaching the embryonic tissue, the retinol or the precursors have to pass through the placental structures. During this placental step, a simple diffusion of retinol can occur between maternal and fetal compartments; but retinol can also be used in situ after its activation into RA(1) or stored as retinyl esters. Using retinol-binding protein knockout model, an alternative way of embryonic retinol supply was described using retinyl esters incorporated into maternal chylomicrons. In the embryo, the principal metabolic event occurring for retinol is its conversion into RAs, the active molecules implicated on the molecular control of embryonic morphogenesis and organogenesis. All these placental and embryonic events of retinol transport and metabolism are highly regulated. Nevertheless, some genetic and/or environmental abnormalities in the transport and/or metabolism of retinol can be related to developmental pathologies during mammalian development.

Role of ethanol in the regulation of hepatic stellate cell Function

Evidence has accumulated to suggest an important role of ethanol and/or its metabolites in the pathogenesis of alcohol-related liver disease. In this review, the fibrogenic effects of ethanol and its metabolites on hepatic stellate cells (HSCs) are discussed. In brief, ethanol interferes with retinoid metabolism and its signaling, induces the release of fibrogenic cytokines such as transforming growth factor β-1 (TGFβ-1) from HSCs, up-regulates the gene expression of collagen I and enhances type I collagen protein production by HSCs. Ethanol further perpetuates an activated HSC phenotype through extracellular matrix remodeling. The underlying pathophysiologic mechanisms by which ethanol exerts these pro-fibrogenic effects on HSCs are reviewed.

Vitamin A metabolic aspects and alcoholic liver disease

The liver is a strategic organ in the metabolism of macro and micronutrients; when its functioning is compromised, it may cause some change in the nutritional status of vitamin A. The purpose of this article is to review scientific evidence in literature on the liver metabolism of vitamin A, the role of ethanol and retinol interactions on hepatic morphology, besides the alterations in the metabolism of this vitamin in alcoholic liver disease. Data were collected from Medline database. The liver is the main organ responsible for the storage, metabolism and distribution of vitamin A to peripheral tissues. This organ uses retinol for its normal functioning such as cell proliferation and differentiation. This way, vitamin A deficiency seems to alter liver morphology. Patients with alcoholic liver disease have been found to have low hepatic levels of retinol in all stages of their disease. In alcoholic liver disease, vitamin A deficiency may result from decreased ingestion or absorption, reduction in retinoic acid synthesis or increased degradation. Long-term alcohol intake results in reduced levels of retinoic acid, which may promote the development of liver tumor. So, in chronic alcoholic subjects, vitamin A status needs to be closely monitored to avoid its deficiency and clinical effects, however its supplementation must be done with caution since the usual dose may be toxic for those who consume ethanol.

Asymmetric cleavage of beta-carotene yields a transcriptional repressor of retinoid X receptor and peroxisome proliferator-activated receptor responses

beta-Carotene and its metabolites exert a broad range of effects, in part by regulating transcriptional responses through specific nuclear receptor activation. Symmetric cleavage of beta-carotene can yield 9-cis retinoic acid (9-cisRA), the natural ligand for the nuclear receptor RXR, the obligate heterodimeric partner for numerous nuclear receptor family members. A significant portion of beta-carotene can also undergo asymmetric cleavage to yield apocarotenals, a series of poorly understood naturally occurring molecules whose biologic role, including their transcriptional effects, remains essentially unknown. We show here that beta-apo-14'-carotenal (apo14), but not other structurally related apocarotenals, represses peroxisome proliferator-activated receptors (PPAR) and RXR activation and biologic responses induced by their respective agonists both in vitro and in vivo. During adipocyte differentiation, apo14 inhibited PPARgamma target gene expression and adipogenesis, even in the presence of the potent PPARgamma agonist BRL49653. Apo14 also suppressed known PPARalpha responses, including target gene expression and its known antiinflammatory effects, but not if PPARalpha agonist stimulation occurred before apo14 exposure and not in PPARalpha-deficient cells or mice. Other apocarotenals tested had none of these effects. These data extend current views of beta-carotene metabolism to include specific apocarotenals as possible biologically active mediators and identify apo14 as a possible template for designing PPAR and RXR modulators and better understanding modulation of nuclear receptor activation. These results also suggest a novel model of molecular endocrinology in which metabolism of a parent compound, beta-carotene, may alternatively activate (9-cisRA) or inhibit (apo14) specific nuclear receptor responses.

Risk factors and mechanisms of hepatocarcinogenesis with special emphasis on alcohol and oxidative stress

Hepatocellular cancer is the fifth most frequent cancer in men and the eighth in women worldwide. Established risk factors are chronic hepatitis B and C infection, chronic heavy alcohol consumption, obesity and type 2 diabetes, tobacco use, use of oral contraceptives, and aflatoxin-contaminated food. Almost 90% of all hepatocellular carcinomas develop in cirrhotic livers. In Western countries, attributable risks are highest for cirrhosis due to chronic alcohol abuse and viral hepatitis B and C infection. Among those with alcoholic cirrhosis, the annual incidence of hepatocellular cancer is 1-2%. An important mechanism implicated in alcohol-related hepatocarcinogenesis is oxidative stress from alcohol metabolism, inflammation, and increased iron storage. Ethanol-induced cytochrome P-450 2E1 produces various reactive oxygen species, leading to the formation of lipid peroxides such as 4-hydroxy-nonenal. Furthermore, alcohol impairs the antioxidant defense system, resulting in mitochondrial damage and apoptosis. Chronic alcohol exposure elicits hepatocyte hyperregeneration due to the activation of survival factors and interference with retinoid metabolism. Direct DNA damage results from acetaldehyde, which can bind to DNA, inhibit DNA repair systems, and lead to the formation of carcinogenic exocyclic DNA etheno adducts. Finally, chronic alcohol abuse interferes with methyl group transfer and may thereby alter gene expression.