Alcohol consumption and plasma homocysteine

Comparison of homocysteine, vitamin B12 and folic acid between rural and urban ageing Indians and its association with mild cognitive impairment and cardiovascular risk factors: a cross-sectional analysis

The relationship between blood levels of homocysteine (HCY), vitamin B12, folic acid and cognitive impairment is inconclusive. Since HCY is an independent risk factor for cardiovascular diseases, understanding its association with Framingham risk score (FRS) may provide insight into the shared underlying mechanism between cardiovascular disease and cognitive impairment. Cross-sectional analyses utilized baseline data from two ongoing longitudinal studies: the Tata Longitudinal Study of Ageing (n = 923), an urban cohort, and Srinivaspura Ageing, NeuroSenescence and COGnition (n = 4239), a rural cohort. The study compared the HCY, vitamin B12 and folic acid levels across cohorts and normal versus mild cognitive impairment (MCI) participants. The association between HCY and cognitive status was established using regression models. Three models were analysed: model 1-unadjusted; model 2-adjusted for age, gender, smoking, alcohol consumption, diet, hypertension, cardiac illness, diabetes; and model 3-adjusted for variables in model 2 plus vitamin B12 and folic acid. Correlation was calculated between HCY and FRS. The urban cohort exhibited a significantly higher level of HCY [median (IQR) (17.70 (10.2) versus 14.70 (9.7); P < 0.001)], vitamin B12 (251 (231) versus 219 (138); P < 0.001) and folic acid (8.21 (8) versus 5.48 (4); P < 0.001) levels compared to rural cohort. HCY, vitamin B12 and folic acid levels did not differ significantly between normal and MCI participants in the urban cohort. In the rural cohort, among the age-gender matched MCI-normal, participants with normal cognition had higher levels of vitamin B12 (≥60 years) [227 (152) versus 217 (175); P = 0.03] and folic acid (<60 years) [5.91 (4) versus 5.40 (4); P = 0.04] compared to MCI. There was no association between HCY and cognitive status in both the cohorts, but there was a significant positive relationship between vitamin B12 deficiency and Clinical Dementia Rating-Sum of the Boxes (CDR-SOB), as well as folic acid deficiency and CDR-SOB in rural and urban cohorts, respectively, within a specific age group. A significant correlation was observed between FRS and HCY in the rural cohort (r = 0.17, P < 0.001), but not in the urban cohort. This study revealed significant differences in HCY, vitamin B12 and folic acid levels between the cohorts. In the rural cohort, participants with MCI had lower vitamin B12 and folic acid levels in a certain age group. Association between HCY and cognitive status was insignificant in both the cohorts. A small significant correlation between FRS and HCY was seen in the rural cohort.

Hyperhomocysteinemia and its effect on ageing and language functions - HEAL study

Hyperhomocysteinemia or high levels (> 15 µmol/L) of homocysteine (Hcy)in the blood has been suggested to affect the brain through vascular and neurodegenerative pathways and potentially impact cognition. The current study aims to explore the association of high homocysteine with cognition and brain volume changes in a cohort of middle and old agedr adults. The study recruited 1296 participants aged ≥ 45 years from Tata Longitudinal Study of Ageing (TLSA), an ongoing cohort study. The participants underwent detailed cognitive assessments using Addenbrooke's Cognitive Examination-III (ACE-III) and Computerized Assessment of Adult Information Processing (COGNITO) neuropsychological battery and MR imaging using a 3T scanner. The participants were classified based on the median homocysteine level (16.89 µmol/L) into low Hcy (≤ median) and high Hcy (> median) groups. When adjusted for age, gender, years of education, vitamin B12, folate and dyslipidaemia, Generalised Linear Model (GLM) found a significant association of high Hcy with vocabulary task [β (95% CI) - 1.354 (- 2.655, - 0.052); p = 0.041]. Significant associations was also obtained between cerebral white matter volume and high Hcy [β (95% CI) - 5617.182 (- 11062.762, - 173.602); p = 0.043]. The results suggest that people with high Hcy levels performed poorer in cognitive tasks related to language domain and had lesser cerebral white matter volume. This indicates that homocysteine might have a profound impact on brain structure as well as function.

Boric Acid Alleviates Gastric Ulcer by Regulating Oxidative Stress and Inflammation-Related Multiple Signaling Pathways

Oxidative stress and inflammation have pivotal roles in gastric ulcer development caused by alcohol consumption. Trace element boric acid taken into the human and animal body from dietary sources displays strong antioxidant and anti-inflammatory functions. However, the mechanisms underlying these actions of boric acid remain unclear, and its effectiveness in preventing gastric lesions is unknown. Therefore, the present study was undertaken to evaluate the protective effects of boric acid in alcohol-induced gastric ulcer and elucidate its potential mechanisms. Gastric ulcer was induced by 75% oral ethanol administration in rats, and the effectiveness of prophylactic boric acid treatment at 100 mg/kg concentration was assessed by histopathological examination, ELISA assay and qRT-PCR. Gross macroscopic and histopathological evaluations revealed that boric acid alleviated gastric mucosal lesions. Boric acid decreased reactive oxygen species (ROS) and malondialdehyde (MDA) concentration and the overall oxidation state of the body while improving antioxidant status. It reduced the concentration of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). The mRNA expression of JAK2 and STAT3 was decreased while the expression of AMPK was increased with boric acid pretreatment. Moreover, Sema3A and PlexinA1 levels were elevated upon boric acid pretreatment, and homocysteine levels were reduced. Our results demonstrated that boric acid protects gastric mucosa from ethanol-induced damage by regulating oxidative and inflammatory responses. In addition, our findings suggested that the gastroprotective activity of boric acid could be attributed to its regulatory function in the IL-6/JAK2/STAT3 signaling modulated by AMPK and that Sema3A/PlxnA1 axis and homocysteine are potentially involved in this process.

Microfluidic paper-based fluorescence sensor for L-homocysteine using a molecularly imprinted polymer and in situ-formed fluorescent quantum dots

Microfluidic paper-based analytical devices modified with molecularly imprinted polymers (μPADs@MIPs) were developed for fluorescent detection of targeted thiols via in situ UV-induced formation of quantum dots (μPADs@MIPs@QDs). The selectivity enhancement by the MIP layer formed on the filter paper surface was demonstrated for the isolation of L-homocysteine from wine. Followed by the addition of metal precursors solution (Zn/Cd/Cu) and UV irradiation, fluorescent quantum dots were formed thus enabling quantitative detection of the thiol (serving as a QD capping agent). The effect of different semiconductors was investigated to achieve a lower band gap and higher fluorescence intensity. Increasing fluorescence intensity in the presence of thiol groups was obtained for the following precursors mixture composition: ZnCdCu/S > ZnCd/S > ZnCu/S > ZnS. The proposed method has a good relationship between the fluorescence intensity of ZnCdCu/S QDs and L-homocysteine in a linear range from 0.74 to 7.40 μM with a limit of detection (LOD) and quantification (LOQ) of 0.51 and 1.71 μM respectively. This method was applied for the determination of L-homocysteine in white wine with RSD under 6.37%.

DNA Hypomethylation as a Potential Link between Excessive Alcohol Intake and Cardiometabolic Dysfunction in Morbidly Obese Adults

A large percentage of obese patients in the United States suffer a comorbid substance use disorder, mainly alcohol use. Alcohol consumption interferes with the absorption of dietary methyl donors such as folate required for the one-carbon metabolism pathway and subsequently for DNA methylation. In this study, we assessed the association between alcohol consumption and DNA methylation in obese subjects. We obtained visceral adipose tissue (VAT) biopsies from bariatric patients. DNA methylation of 94 genes implicated in inflammation and immunity were analyzed in VAT in relation to alcohol consumption data obtained via questionnaires. Vasoreactivity was measured in the brachial artery and the VAT-isolated arterioles. Pro-inflammatory genes were significantly hypomethylated in the heavy drinking category correlating with higher levels of circulating inflammatory cytokines. Alcohol consumption correlated positively with body mass index (BMI), fat percentage, insulin resistance, impaired lipid profile, and systemic inflammation and negatively with plasma folate and vitamin B12, inflammatory gene DNA methylation, and vasoreactivity. In conclusion, these data suggest that alcohol intake is associated with lower DNA methylation and higher inflammation and cardiometabolic risk in obese individuals.

Occupational exposure to particles and biomarkers of cardiovascular disease-during work and after vacation

Objective

Ambient particle matter is a risk factor for cardiovascular disease (CVD). However, little is known about associations between particles in occupational settings and risk of CVD. We investigated associations between occupational dust exposure and biomarkers of CVD, and potential recovery effects after vacation.

Methods

Personal dust exposure measurements (respirable silica, respirable dust < 4 µm, and particles of 0.1–10 µm (PM 0.1–10) were conducted once, and biological sampling were performed twice on non-smoking, male construction workers in Stockholm county, Sweden; during work and immediately after summer vacation. Linear regressions with adjustments for confounders and covariates were performed evaluating associations between occupational dust exposure and biomarkers. Paired t tests were performed evaluating changes before and after vacation.

Results

Sixty-five workers participated. Homocysteine concentrations were significantly higher with increasing concentrations (mg/m³) of respirable silica, respirable dust, and PM 0.1–10, and pulse rate with higher levels of respirable dust and dust of PM 0.1–10. Homocysteine levels were also positively correlated to number of years of dust exposure, as were low-density lipoprotein (LDL) levels. A clear recovery effect was present for LDL after vacation, but not for homocysteine.

Conclusions

Occupational dust exposure was associated with some CVD risk markers, even at mean exposure concentrations below the Swedish occupational exposure limits for respirable silica and respirable dust, respectively. Vacation resulted in recovery for some risk markers. However, the change of the homocysteine and LDL levels suggest a long-term effect. Reduction of occupational exposure to dust may decrease the risk of CVD among exposed workers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-022-01900-5.

Melatonin as a Reducer of Neuro- and Vasculotoxic Oxidative Stress Induced by Homocysteine

The antioxidant properties of melatonin can be successfully used to reduce the effects of oxidative stress caused by homocysteine. The beneficial actions of melatonin are mainly due to its ability to inhibit the generation of the hydroxyl radical during the oxidation of homocysteine. Melatonin protects endothelial cells, neurons, and glia against the action of oxygen radicals generated by homocysteine and prevents the structural changes in cells that lead to impaired contractility of blood vessels and neuronal degeneration. It can be, therefore, assumed that the results obtained in experiments performed mainly in the in vitro models and occasionally in animal models may clear the way to clinical applications of melatonin in patients with hyperhomocysteinemia, who exhibit a higher risk of developing neurodegenerative diseases (e.g., Parkinson’s disease or Alzheimer’s disease) and cardiovascular diseases of atherothrombotic etiology. However, the results that have been obtained so far are scarce and have seldom been performed on advanced in vivo models. All findings predominately originate from the use of in vitro models and the scarcity of clinical evidence is huge. Thus, this mini-review should be considered as a summary of the outcomes of the initial research in the field concerning the use of melatonin as a possibly efficient attenuator of oxidative stress induced by homocysteine.

Homocysteine and psoriasis

Psoriasis is caused by a complex interplay among the immune system, genetic background, autoantigens, and environmental factors. Recent studies have demonstrated that patients with psoriasis have a significantly higher serum homocysteine (Hcy) level and a higher prevalence of hyperhomocysteinaemia (HHcy). Insufficiency of folic acid and vitamin B₁₂ can be a cause of HHcy in psoriasis. Hcy may promote the immuno-inflammatory process in the pathogenesis of psoriasis by activating Th1 and Th17 cells and neutrophils, while suppressing regulatory T cells. Moreover, Hcy can drive the immuno-inflammatory process by enhancing the production of the pro-inflammatory cytokines in related to psoriasis. Hcy can induce nuclear factor kappa B activation, which is critical in the immunopathogenesis of psoriasis. There may be a link between the oxidative stress state in psoriasis and the effect of HHcy. Hydrogen sulfide (H₂S) may play a protective role in the pathogenesis of psoriasis and the deficiency of H₂S in psoriasis may be caused by HHcy. As the role of Hcy in the pathogenesis of psoriasis is most likely established, Hcy can be a potential therapeutic target for the treatment of psoriasis. Systemic folinate calcium, a folic acid derivative, and topical vitamin B12 have found to be effective in treating psoriasis.

Genetic polymorphisms of key enzymes in folate metabolism affect the efficacy of folate therapy in patients with hyperhomocysteinaemia

The aim of this study is to analyse the efficacy rate of folate for the treatment of hyperhomocysteinaemia (HHcy) and to explore how folate metabolism-related gene polymorphisms change its efficacy. This study also explored the effects of gene-gene and gene-environment interactions on the efficacy of folate. A prospective cohort study enrolling HHcy patients was performed. The subjects were treated with oral folate (5 mg/d) for 90 d. We analysed the efficacy rate of folate for the treatment of HHcy by measuring homocysteine (Hcy) levels after treatment. Unconditioned logistic regression was conducted to analyse the association between SNP and the efficacy of folic acid therapy for HHcy. The efficacy rate of folate therapy for HHcy was 56·41 %. The MTHFR rs1801133 CT genotype, TT genotype and T allele; the MTHFR rs1801131 AC genotype, CC genotype and C allele; the MTRR rs1801394 GA genotype, GG genotype and G allele; and the MTRR rs162036 AG genotype and AG+GG genotypes were associated with the efficacy of folic acid therapy for HHcy (P<0·05). No association was seen between other SNP and the efficacy of folic acid. The optimal model of gene-gene interactions was a two-factor interaction model including rs1801133 and rs1801394. The optimal model of gene-environment interaction was a three-factor interaction model including history of hypertension, history of CHD and rs1801133. Folate supplementation can effectively decrease Hcy level. However, almost half of HHcy patients failed to reach the normal range. The efficacy of folate therapy may be genetically regulated.

Broccoli Sprout Extract Alleviates Alcohol-Induced Oxidative Stress and Endoplasmic Reticulum Stress in C57BL/6 Mice

The potential efficacy of sulforaphane in protecting alcohol-induced hepatic injury in vivo and its underlying mechanism were investigated. Male C57BL/6 mice were orally administrated with broccoli sprout extract (BSE) containing sulforaphane [7.6, 25.2, and 50.4 mg/kg of body weight (bw)] once a day for 14 days. At the 13th day, mice were challenged with alcohol (5 g/kg of bw) every 12 h for 3 times, which increased malondialdehyde (MDA) levels (4.44 ± 1.24 nmol/mg of protein, p < 0.01) in the liver. Our results showed that low-, medium-, and high-dose BSE markedly reversed the decrease of antioxidant capacity through enhancing glutathione (GSH) (2.07 ± 0.31 mg/g of protein, p < 0.05; 2.31 ± 0.32 mg/g of protein, p < 0.01; and 2.46 ± 0.21 mg/g of protein, p < 0.01), superoxide dismutase (SOD) (483.20 ± 62.76 units/mg of protein; 500.81 ± 49.82 units/mg of protein, p < 0.05; and 605.00 ± < 64.32 units/mg of protein, p < 0.01), glutathione peroxidase (GSH-Px) (318 ± 60.74 units/mg of protein; 400.67 ± 72.47 units/mg of protein, p < 0.01; and 394.72 ± 62.97 units/mg of protein, p < 0.01), and glutathione S-transferase (GST) (31.84 ± 6.34 units/mg of protein, p < 0.05; 30.34 ± 6.40 units/mg of protein, p < 0.05; and 38.08 ± 7.05 units/mg of protein, p < 0.01) in the liver. The protective actions are also associated activation of phase 2 enzymes via nuclear erythoriod-2-related factor 2 (Nrf2). The endoplasmic reticulum (ER)-stress-specific proteins, such as glucose-regulated protein 78 (GRP78), activating transcription factor 6, and protein kinase RNA (PKR)-like ER kinase (PERK), were also significantly attenuated by BSE. These results indicate that BSE protects the liver against alcohol challenge via upregulating antioxidant capacity and downregulating ER stress.

Clinical Manifestations of Isolated Elevated Homocysteine-Induced Peripheral Neuropathy in Adults

OBJECTIVE

To characterize the clinical features of isolated elevated plasma homocysteine (eHcy)-induced peripheral neuropathy (IHIN) in adults.

METHODS

Charts of subjects with the diagnosis of IHIN who visited neuromuscular clinic from January 01, 2012 to September 30, 2014 were reviewed. Subjects with identifiable etiologies for neuropathy, such as B12/folate deficiency; metabolic, toxic, endocrinologic, infectious/inflammatory renal or liver diseases; or traumatic nerve injury, were excluded. Their clinical presentations were recorded and analyzed.

RESULTS

Thirty subjects (age: 63.2 ± 14.8 years, 13 males) were included. They all had an isolated increased homocysteine level (15.4 ± 5.3 μmol/L) but normal levels of B12, folate, and methylmalonic acid. Of 30, 14 (46.7%) had numb feet, 11 (36.7%) had numb hands, 7 (23.3%) had pain in lower extremities, and 10 (33.3%) had tingling in feet. Distal sensory deficits were present in 18/30 (60%) patients. Distal limb weakness was seen in 4 and decreased tendon reflexes in 12 patients.

CONCLUSIONS

Sensory deficits are predominant components of IHIN. Characterizing clinical features of IHIN would help better understand eHcy-related neuropathy and improve its management.

Alcoholic liver disease: focus on prodromal gut health

Alcoholic liver disease (ALD) is implicated in gut disturbances, both functionally and structurally. It has been noticed that the gut-liver interaction is an important feature in the prevention of systemic inflammation as well as liver health. The optimal functioning of the gut-liver axis depends on gut health. Therefore, gut problems may be important for estimating liver inflammation, while our knowledge of ALD could also provide an insight into gut health. Gut problems accompanied by ALD include gut motility and absorption problems, mucosal damage and the dysbiosis of gut microbiota and gastrointestinal carcinogenesis. Moreover, there is emerging evidence that besides direct inflammatory injury caused by alcohol, gut problems related to ALD play a crucial role in the pathogenesis of cardiovascular and immunological disorders. In this regard, we should consider ALD in relation to both gut health and chronic systemic low-grade inflammation. Accordingly, integrative therapeutic strategies are warranted for treating and preventing ALD and systemic inflammation as well as alcohol-related gut problems.

Hyperhomocysteinaemia as a potential marker of early renal function decline in middle-aged Asian people without chronic kidney disease

PURPOSE

High levels of serum total homocysteine (tHcy), often observed in chronic kidney disease (CKD) patients, are a risk factor for cardiovascular disease. However, little is known about the relationship between tHcy and renal function in healthy individuals. We examined whether tHcy levels are related to renal function in Asian individuals without CKD.

METHODS

This cross-sectional study examined 2032 subjects, aged 40-64 years. Individuals with kidney diseases or other conditions that could affect tHcy were excluded. Renal function was determined by estimated glomerular filtration rate (eGFR) from levels of serum creatinine (sCr) and cystatin C.

RESULTS

Age, tHcy, sCr, and cystatin C of the subjects were 54.1 ± 6.0 years, 9.5 (8.0-11.4) μmol/L, 0.81 ± 0.1 mg/dL, and 0.82 ± 0.1 mg/L, respectively. In a multiple linear regression analysis, tHcy was a significant independent determinant of sCr and cystatin C in men (β = 0.206 and β = 0.282, respectively) and women (β = 0.247 and β = 0.229, respectively). Highest tHcy levels were independently associated with increased cystatin C (>s1.10 mg/L) with an odds ratio (OR) of 5.00 [95% confidence interval (CI) 2.81-8.09] and decreased eGFR (<90 mL/min/1.73 m(2)) with an OR of 1.69 (95% CI 1.36-2.11) compared to tHcy levels in the 1st-3rd quartiles.

CONCLUSIONS

Higher levels of tHcy are independently associated with sCr and cystatin C elevation. Our study suggests that tHcy levels may be influenced by renal function in Asian populations without CKD. Future studies are needed to define the role of tHcy in renal function.

Homocysteine levels in schizophrenia patients newly admitted to an acute psychiatric ward

OBJECTIVE

After the discovery of 'homocystinuria syndrome', many studies have suggested that high blood levels of homocysteine may be associated with schizophrenia. The aim of this study was to analyse the association between hyperhomocysteinaemia and schizophrenia.

METHODS

In a population of inpatients suffering from exacerbated schizophrenic disorders (N=100), we evaluated homocysteine levels the day after their admission to an acute psychiatric ward and compared it with that of a non-patient control group (N=110), matched for age and gender. We statistically analysed the correlation between homocysteine levels and selected variables: gender, age, years of illness and number of previous psychiatric admissions as well as Brief Psychiatric Rating Scale, Positive Negative Syndrome Scale and Global Assessment Functioning (GAF) Scores.

RESULTS

We observed elevated homocysteine levels (an increase of 7.84 µM on average per patient) in 32% of the patients, but we did not find any statistically significant difference between the homocysteine levels of our patients and controls. Hyperhomocysteinaemia presented a positive statistically significant correlation with years of illness (p<0.005) and a negative statistically significant correlation with GAF score (p<0.001), but not with other clinical variables.

CONCLUSIONS

Hyperhomocysteinaemia, which occurred in our schizophrenia patients with poor social and relational functioning after many years of illness, could represent an effect of altered lifestyle due to psychosis, but not a specific marker for schizophrenia.

Endoplasmic reticulum oxidoreductin 1α mediates hepatic endoplasmic reticulum stress in homocysteine-induced atherosclerosis

Endoplasmic reticulum (ER) stress is emerging as an important modulator of different pathological process and as a mechanism contributing to homocysteine (Hcy)-induced hepar injury. However, the molecular event that Hcy-induced ER stress in the hepar under the atherosclerosis background is currently unknown. Endoplasmic reticulum oxidoreductin 1α (ERO1α) plays a crucial role in maintaining ER stress function. In this study, we determined the expression of ERO1α in the hepar in hyperhomocysteinemia and the effect of ERO1α in hepacytes ER stress in the presence of Hcy. HHcy model was established by feeding the methionine diet in apolipoprotein-E-deficient (ApoE-/-) mice, and the hepatocytes were incubated with folate and different concentrations of Hcy. Our results showed that Hcy triggered ER stress characterized by an increased contents of glucose-regulated protein 78 (GRP78), protein kinase RNA-like ER kinase (PERK), activating transcription factor (ATF) 6 and X-box binding protein-1 (XBP-1). The ERO1α expressions in HHcy mice and Hcy-treated hepatocytes were decreased compared with those in ApoE-/- group and control hepacytes (P < 0.05), respectively. Knocking-down the expression of ERO1α with small-interfering RNA significantly augmented Hcy-induced ER stress. Meanwhile, the expressions of ER stress-related factor including GRP78, PERK, ATF6 and XBP-1, were significantly decreased when the ERO1α gene was over-expressed in hepacytes. Our results suggested that ERO1α may be involved in Hcy-induced hepar ER stress, and the inhibition of ERO1α expression can accelerate this process.

Remarkable Anticancer Activity of Teucrium polium on Hepatocellular Carcinogenic Rats

The term cancer has been concomitant with despair, agony, and dreadful death. Like many other diseases, herbal therapy has been used to prevent or suppress cancer. The present study investigated the capability of the decoction of Teucrium polium L. from Lamiaceae family to protect liver cells against hepatocellular carcinoma in carcinogenesis-induced animal model. After 28 weeks of treatment with decoction of Teucrium polium L., serum biochemical markers including ALT, AST, AFP, GGT, ALP, HCY, TNF-α, α2MG, and CBG have been regulated auspiciously. Total antioxidant status also has been increased intensely. Liver lesion score in treated group was lessened and glucocorticoid activity has been intensified significantly. In conclusion, Teucrium polium L. decoction might inhibit or suppress liver cancer development.

Chronic liver inflammation: Clinical implications beyond alcoholic liver disease

Chronic alcohol exposure can lead to alcoholic liver disease, including hepatitis, cirrhosis and hepatocellular carcinoma, and chronic inflammation can simultaneously cause systemic medical illness. Recent evidence suggests that alcoholic liver disease is a predictor for liver-related diseases, cardiovascular disease, immunologic disease, and bone disease. Chronic inflammation in alcoholic liver disease is mediated by a direct inflammatory cascade from the alcohol detoxification process and an indirect inflammatory cascade in response to gut microflora-derived lipopolysaccharides (LPS). The pathophysiology of alcoholic liver disease and its related systemic illness is characterized by oxidative stress, activation of the immune cascade, and gut-liver interactions. Integrative therapeutic strategies for alcoholic liver disease include abstaining from alcohol consumption; general anti-inflammatories such as glucocorticoid, pentoxifylline, and tumour necrosis factor-α antagonist; antioxidants such as N- acetylcysteine; gut microflora and LPS modulators such as rifaximin and/or probiotics. This review focuses on the impact of chronic liver inflammation on systemic health problems and several potential therapeutic targets.

Mechanistic insights of intestinal absorption and renal conservation of folate in chronic alcoholism

Folate mediated one-carbon metabolism is of fundamental importance for various cellular processes, including DNA synthesis and methylation of biological molecules. Due to the exogenous requirement of folate in mammals, there exists a well developed epithelial folate transport system for regulation of normal folate homeostasis. The intestinal and renal folate uptake is tightly and diversely regulated and disturbances in folate homeostasis like in alcoholism have pathological consequences. The study was sought to delineate the regulatory mechanism of folate uptake in intestine and reabsorption in renal tubular cells that could evaluate insights of malabsorption during alcoholism. The folate transporters PCFT and RFC were found to be associated with lipid rafts of membrane surfaces in intestine and kidney. Importantly, the observed lower intestinal and renal folate uptake was associated with decreased levels of folate transporter viz. PCFT and RFC in lipid rafts of intestinal and renal membrane surfaces. The decreased association of folate transporters in lipid rafts was associated with decreased protein and mRNA levels. In addition, immunohistochemical studies showed that alcoholic conditions deranged that localization of PCFT and RFC. These findings could explain the possible mechanistic insights that may result in folate malabsorption during alcoholism.

Homocysteine inhibits hepatocyte proliferation via endoplasmic reticulum stress

Homocysteine is an independent risk factor for coronary, cerebral, and peripheral vascular diseases. Recent studies have shown that levels of homocysteine are elevated in patients with impaired hepatic function, but the precise role of homocysteine in the development of hepatic dysfunction is unclear. In this study, we examined the effect of homocysteine on hepatocyte proliferation in vitro. Our results demonstrated that homocysteine inhibited hepatocyte proliferation by up-regulating protein levels of p53 as well as mRNA and protein levels of p21^Cip1 in primary cultured hepatocytes. Homocysteine induced cell growth arrest in p53-positive hepatocarcinoma cell line HepG2, but not in p53-null hepatocarcinoma cell line Hep3B. A p53 inhibitor pifithrin-α inhibited the expression of p21^Cip1 and attenuated homocysteine-induced cell growth arrest. Homocysteine induced TRB3 expression via endoplasmic reticulum stress pathway, resulting in Akt dephosphorylation. Knock-down of endogenous TRB3 significantly suppressed the inhibitory effect of homocysteine on cell proliferation and the phosphorylation of Akt. LiCl reversed homocysteine-mediated cell growth arrest by inhibiting TRB3-mediated Akt dephosphorylation. These results demonstrate that both TRB3 and p21^Cip1 are critical molecules in the homocysteine signaling cascade and provide a mechanistic explanation for impairment of liver regeneration in hyperhomocysteinemia.

Alcohol-associated folate disturbances result in altered methylation of folate-regulating genes

Folate plays a critical role in maintaining normal metabolic, energy, differentiation and growth status of all mammalian cells. The steady-state accumulation of folate seems to depend on the activity of two enzymes: folylpolyglutamate synthetase (FPGS), which adds glutamate residues, and gamma-glutamyl hydrolase (GGH), which removes them, enabling it to be transported across the biological membranes. Overexpression of GGH and downregulation of FPGS would be expected to decrease intracellular folate in its polyglutamylated form, thereby increasing efflux of folate and its related molecules, which might lead to resistance to drugs or folate deficiency. The study was sought to delineate the activity of GGH and expression FPGS in tissues involved in folate homeostasis during alcoholism and the epigenetic regulation of these enzymes and transporters regulating intracellular folate levels. We determined the activity of GGH and expression of FPGS in tissues after 3 months of ethanol feeding to rats at 1 g/kg body weight/day. The results showed that there was not any significant change in the activity of folate hydrolyzing enzyme GGH in ethanol-fed rats while there was significant down regulation in the expression of FPGS. Ethanol feeding decreased the total as well as polyglutamated folate levels. There was tissue-specific hyper/hypo methylation of folate transporter genes viz. PCFT and RFC by chronic ethanol feeding. Moreover, hypermethylation of FPGS gene was observed in intestine and kidney without any change in methylation levels of GGH in the ethanol-fed rats. In conclusion, the initial deconjugation of polyglutamylated folate by GGH was not impaired in ethanol-fed rats while the conversion of monoglutamylated folate to polyglutamylated form might be impaired. There was tissue-specific altered methylation of folate transporter genes by chronic ethanol feeding.

Folate malabsorption is associated with down-regulation of folate transporter expression and function at colon basolateral membrane in rats

Folates, an essential component (important B vitamin) in the human diet, are involved in many metabolic pathways, mainly in carbon transfer reactions such as purine and pyrimidine biosynthesis and amino acid interconversions. Deficiency of this micronutrient leads to the disruption of folate-dependent metabolic pathways that lead to the development of clinical abnormalities ranging from anaemia to growth retardation. Folate deficiency due to alcohol ingestion is quite common, primarily due to malabsorption. The present study dealt with the mechanistic insights of folate malabsorption in colonic basolateral membrane (BLM). Wistar rats (n 12) were fed 1 g/kg body weight per d ethanol (20 %) solution orally for 3 months and folate transport was studied in the isolated colonic BLM. The folate exit across colon BLM shows characteristics of carrier-mediated process with the major involvement of reduced folate carrier (RFC). The chronic ethanol ingestion decreased the uptake by decreasing the affinity by 46 % (P < 0·01) and the number of transport molecules by 43 % (P < 0·001) at the colon BLM. The decreased uptake was associated with down-regulation of proton-coupled folate transporter (PCFT) and RFC expression at mRNA and protein levels. The extent of decrease was 44 % (P < 0·01) and 24 % (P < 0·05) for PCFT and 23 % (P < 0·01) and 57 % (P < 0·01) for RFC at mRNA and protein levels, respectively. Moreover, folate transporters were associated with lipid rafts (LR) of colon BLM, and chronic alcoholism decreased the association of these transporters with LR.

Hepatocyte proliferation during liver regeneration is impaired in mice with methionine diet-induced hyperhomocysteinemia

Elevated homocysteine levels are defined as hyperhomocysteinemia (HHcy), a disorder that is associated with cardiovascular and neurodegenerative diseases as well as with hepatic fibrosis. Recent studies have shown that HHcy promotes hepatic injury by increasing oxidative stress. Although homocysteine induces cell cycle arrest in a variety of different cell types, it is not known whether HHcy has a definitive role in hepatocyte proliferation during liver regeneration. In this report, we investigated the effect of homocysteine on liver regeneration. Our results demonstrated that mice with HHcy exhibited an impairment in liver regeneration after partial hepatectomy, as measured by immunohistochemical staining of proliferation cell nuclear antigen and bromodeoxyuridine incorporation. Impaired proliferation was also correlated with reduced cyclin D1 induction and elevated expression levels of both p53 and p21Cip1. In addition, the phosphorylation of Akt, which plays an essential role in normal regeneration responses, was attenuated during the early phases of liver regeneration in HHcy mice. Our results also indicated that the cAMP/protein kinase A pathway mediated the inhibitory effect of homocysteine on liver regeneration. These findings provide evidence that impairment of liver regeneration by HHcy may result in delayed recovery from liver injury induced by homocysteine itself.

Reduced de novo synthesis of 5-methyltetrahydrofolate and reduced taurine levels in ethanol-treated chick brains

In previous studies, exogenous ethanol (3 mmol EtOH/kg egg) caused a 1.6-fold increase in chick brain homocysteine (HoCys) levels at 11 days of development and the mixture of 3 mmol EtOH/kg egg and 34 micromol folic acid/kg egg attenuated EtOH-induced increases in chick brain HoCys levels. Because HoCys is converted to methionine utilizing the methyl donor, 5-methyltetrahydrofolate (5-methyl THF), we studied whether exogenous ethanol (3 mmol EtOH/kg egg) or the mixture of 3 mmol EtOH/kg egg and 34 micromol 5-methyl THF/kg egg inhibited chick brain 10-formyltetrahydrofolate dehydrogenase (10-FTHF DH; EC 1.5.1.6) activities and brain N5, N10-methylenetetrahydrofolate reductase (MTHFR; EC 1.5.1.20) activities at 11 days of development. Three daily dosages of 3 mmol EtOH/kg egg (E0-2) caused approximately a 7-fold reduction in brain 10-FTHF DH activities and approximately a 1.9-fold reduction in brain MTHFR activities as compared to controls at 11 days of development (p<or=0.05). Because HoCys is also removed by the transsulfuration pathway, which synthesizes taurine, we studied whether exogenous ethanol (3 mmol EtOH/kg egg) or the mixture of 3 mmol EtOH/kg egg and 34 micromol 5-methyl THF/kg egg influenced chick brain taurine levels. In EtOH-treated and EtOH and 5-methyl THF-treated embryos, brain taurine levels decreased by approximately 5.5-fold and 6.2-fold as compared to controls, respectively (p<or=0.05). Exogenous 5-methyl THF failed to attenuate EtOH-induced decreased brain taurine levels at 11 days of development.

Contribution of endoplasmic reticulum stress to hepatocyte apoptosis in alcoholic liver disease

Endoplasmic reticulum stress represents a subcellular pathological state caused by a disorder of physiological function of the endoplasmic reticulum. Endoplasmic reticulum stress is not only a self-protective mechanism of the body, but also an important factor to promote cell apoptosis. In alcoholic liver disease, endoplasmic reticulum stress induced by several factors such as hyperhomocysteinemia can lead to hepatocyte apoptosis. In this article, we will review the contribution of endoplasmic reticulum stress to hepatocyte apoptosis in alcoholic liver disease.

Association analyses suggest multiple interaction effects of the methylenetetrahydrofolate reductase polymorphisms on timing of menarche and natural menopause in white women

OBJECTIVE

This study aimed to investigate whether polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene are associated with age at menarche and age at natural menopause in white women.

METHODS

In a cross-sectional study, a total of 305 randomly selected unrelated white women were genotyped for six single nucleotide polymorphisms (SNPs) of the MTHFR gene (including one common replacement, rs1801133). This sample was comprehensively analyzed for the association of the SNPs with age at menarche. Then a subsample of 210 women who experienced natural menopause was analyzed for the association of the MTHFR gene with age at natural menopause.

RESULTS

Duration of breast-feeding was a significant predictor of earlier natural menopause (P < 0.05). No individual SNPs were associated with either age at menarche or age at natural menopause. However, three significant (P < 0.05) SNP-SNP interaction effects (rs2066470/rs1476413, rs2066470/rs4846049, and rs17037390/rs4846049) on the onset of menarche were determined. Three haplotypes were significantly associated with age at menopause (P < 0.05). Four SNPs (rs2066470, rs17037390, rs1801133, and rs4846048) indicated significant interaction effects with various lifestyle factors on age at natural menopause.

CONCLUSIONS

The results of our study suggest that the MTHFR gene may influence the onset of menarche and natural menopause. This effect is probably due to the multiple SNP-SNP and SNP-environment interactions. More independent studies are needed to further clarify the possible contribution of this gene to the timing of menarche and menopause.

Exogenous folate ameliorates ethanol-induced brain hyperhomocysteinemia and exogenous ethanol reduces taurine levels in chick embryos

The effects of exogenous ethanol and/or folic acid on endogenous homocysteine (HoCys) and SAM (S-adenosylmethionine)/SAH (S-adenosylhomocysteine) levels in chick brains were studied at 11 days of development. Embryonic EtOH (3.0 mmol/kg egg) exposure caused a 1.6-fold increase in brain HoCys levels and a 9-fold decrease in brain SAM/SAH levels as compared to controls (p<or=0.05). Brain HoCys and SAM/SAH levels returned to control values when injected with a mixture of EtOH and folic acid (3.0 mmol EtOH/kg egg and 34 mumol folic acid/kg egg). The effects of exogenous EtOH on the remethylation pathway, as measured by 10-formyltetrahydrofolate dehydrogenase (10-FTHF DH) activities, and the transsulfuration pathway, as measured by taurine levels, were studied at 18 days of development. A single dosage of EtOH (3.0 mmol/kg egg; E(0)) and two daily dosages of EtOH (E(0-1)) failed to influence brain and hepatic 10-FTHF DH activities when compared to controls. However, three daily dosages of EtOH (E(0-2)) caused approximately a two-fold increase in brain 10-FTHF DH activities and a three-fold increase in hepatic 10-FTHF DH activities as compared to controls (p<or=0.05). Three daily EtOH dosages (E(0-2)) caused reduced taurine levels in both brain and hepatic tissues (p<or=0.05). Meanwhile, a single EtOH dosage (E(0)), two daily EtOH dosages (E(0-1)), and three daily EtOH dosages (E(0-2)), caused reduced hepatic taurine levels as compared to controls (p<or=0.05).

Role of signaling pathways in the regulation of folate transport in ethanol-fed rats

Folate is an essential cofactor for normal cellular proliferation and tissue regeneration. Alcohol-associated folate deficiency is common, primarily due to intestinal malabsorption, the mechanism of which needs attention. The aim of the present study was to evaluate the regulatory events of folate transport in experimental alcohol ingestion. For this, male Wistar rats were fed 1 g/kg body weight/day ethanol (20% solution) orally for 3 months and folate transport was studied in isolated intestinal epithelial cells across the crypt-villus axis. The role of different signaling pathways in folate transport regulation was evaluated independently to that of reduced folate carrier (RFC) expression. The results showed that differentiated cells of villus possess high folate uptake activity as compared to mid villus and crypt base cells. During chronic ethanol ingestion, decrease in transport was observed all along the crypt-villus axis but was more pronounced at proliferating crypt base stem cells. Studying the effect of modulators of signaling pathways revealed the folate transport system to be under the regulation of cAMP-dependent protein kinase A (PKA), the activity of which was observed to decrease upon alcohol ingestion. In addition, protein kinase C might have a role in folate transport regulation during alcoholic conditions. The deregulation in the folate transport system was associated with a decrease in RFC expression, which may result in lower transport efficiency observed at absorptive surface in alcohol-fed rats. The study highlights the role that perturbed regulatory pathways and RFC expression play in the decreased folate transport at brush border surface during alcohol ingestion.

Alcohol increases homocysteine and reduces B vitamin concentration in healthy male volunteers--a randomized, crossover intervention study

BACKGROUND

Few studies have examined the effect of alcohol consumption on total homocysteine (tHcy) concentrations.

AIM

To assess the effect of an 8-week intervention with vodka or red wine on plasma tHcy and B vitamin concentrations in healthy male volunteers. To assess the effect on tHcy according to methylenetetrahydrofolate reductase (MTHFR) 677C>T genotype.

DESIGN AND METHODS

A randomized controlled crossover intervention study measuring tHcy and serum folate and vitamin B(12) concentrations was conducted in 78 male subjects (21-70 years). Following a 2-week washout period during which no alcohol was consumed, all subjects consumed 24 g alcohol (either 240 ml red wine or 80 ml vodka)/day for a 2-week period. Following a further 2-week washout, participants consumed the alternate intervention for 2 weeks.

RESULTS

A significant increase in plasma tHcy was observed after the 2-week red wine intervention (5%, P = 0.03), and a non-significant increase in tHcy with vodka intervention (3%, P = 0.09). When the two interventions were compared, the change in tHcy did not differ between the vodka and red wine interventions (P = 0.57). There were significant decreases in serum vitamin B(12) and folate concentrations, and this decrease did not differ between interventions. The increase in tHcy observed in both interventions did not vary by MTHFR 677C>T genotype.

CONCLUSION

A 2-week alcohol intervention resulted in a decrease in folate and vitamin B(12) status and an increase in plasma tHcy. The effect of alcohol intervention on tHcy, folate and vitamin B(12) concentrations did not differ between the red wine and vodka intervention groups.

Homocysteine enhances cell proliferation in hepatic myofibroblastic stellate cells

Homocysteine is an intermediate in sulfur amino acid metabolism, which takes place mainly in the liver. Recent studies have shown that hyperhomocysteinemia in patients and murine models develop hepatic fibrosis. To define mechanisms underlying homocysteine-induced hepatic fibrosis, the effect of homocysteine on hepatic stellate cell (HSC) proliferation was examined. In the present study, homocysteine promoted proliferation in myofibroblastic HSCs. Homocysteine elicited a transient formation of reactive oxygen species (ROS). The initial ROS activated extracellular signal-regulated kinase and p38 mitogen-activated protein kinase, which were involved in the activation of NAD(P)H oxidases and the generation of more ROS. The activation of NAD(P)H oxidases resulted from upregulation of the expression of p22(phox) and the phosphorylation of p47(phox). The ROS derived from NAD(P)H oxidases activated the PI3K/Akt pathway, thus promoting cellular proliferation in HSCs. These findings provide a mechanistic explanation for the development and progression of hepatic fibrosis in hyperhomocysteinemia.

Effects of S-adenosylmethionine on liver methionine metabolism and steatosis with ethanol-induced liver injury in rats

Background

Hyperhomocysteinemia is implicated in the pathogenesis of various liver diseases. In this study, the effects of S-adenosylmethionine (SAM) on hyperhomocysteinemia and steatosis with ethanol-induced liver injury in rats were examined and their mechanisms were explored.

Methods

Forty-eight female Sprague–Dawley rats were randomly divided into four groups as control, model, low-dose, and high-dose SAM groups. Except the control group, all rats were fed high-fat-containing diet plus ethanol and fish oil gavaged for 8 weeks. SAM was administered by intraperitoneal injection after the 4 weeks’ exposure of ethanol. Serum homocysteine (Hcy), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglyceride (TG), tumor necrosis factor α (TNF-α), and transforming growth factor β1 (TGF-β1) levels were determined. The contents of liver malondialdehyde (MDA) and glutathione (GSH) were assayed. Liver histology was also examined. The expressions of TNF-α and TGF-β1 mRNAs in the liver were detected by the reverse transcriptase-polymerase chain reaction assay.

Results

Compared with the control group, the model group rats developed marked liver damage, accompanied by an increase in Hcy, ALT, AST, TC, TG, TNF-α, TGF-β1, and MDA levels. However, the levels of GSH were decreased. These responses were associated with the increased expression of TNF-α and TGF-β1 mRNAs in the livers, as well as the existence of hepatocellular necrosis and neutrophil infiltration in the livers. In treatment groups, SAM provided significant protection from the liver injury induced by alcohol, resulting in a decrease in serum TNF-α, TGF-β1 levels, lipid peroxidation, and the expressions of TNF-α and TGF-β1 mRNAs in the livers, as well as an increase in GSH levels. However, no statistical difference was observed in these parameters between the two different dose treatment groups. In the study, SAM did not affect plasma total homocysteine (tHcy) levels significantly.

Conclusion

SAM prevents alcohol-induced liver injury in rats by reducing liver lipid peroxidation, anti-inflammation, and antihyperplasia. In addition, it does not affect the plasma tHcy levels.

Prevalence and effects of gene-gene and gene-nutrient interactions on serum folate and serum total homocysteine concentrations in the United States: findings from the third National Health and Nutrition Examination Survey DNA Bank

BACKGROUND

Abnormalities of folate and homocysteine metabolism are associated with a number of pediatric and adult disorders. Folate intake and genetic polymorphisms encoding folate-metabolizing enzymes influence blood folate and homocysteine concentrations, but the effects and interactions of these factors have not been studied on a population-wide basis.

OBJECTIVE

The objective was to assess the prevalence of these genetic polymorphisms and their relation to serum folate and homocysteine concentrations.

DESIGN

DNA samples from 6793 participants in the third National Health and Nutrition Examination Survey (NHANES III) during 1991-1994 were genotyped for polymorphisms of genes coding for folate pathway enzymes 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T and 1298A-->C, methionine synthase reductase (MTRR) 66A-->G, and cystathionine-beta-synthase 844ins68. The influence of these genetic variants on serum folate and homocysteine concentrations was analyzed by age, sex, and folate intake in 3 race-ethnicity groups.

RESULTS

For all race-ethnicity groups, serum folate and homocysteine concentrations were significantly related to the MTHFR 677C-->T genotype but not to the other polymorphisms. Persons with the MTHFR 677 TT genotype had a 22.1% (95% CI: 14.6%, 28.9%) lower serum folate and a 25.7% (95% CI: 18.6%, 33.2%) higher homocysteine concentration than did persons with the CC genotype. Moderate daily folic acid intake (mean: 150 microg/d; 95% CI: 138, 162) significantly reduced the difference in mean homocysteine concentrations between those with the MTHFR 677 CC and TT genotypes. We found a significant interaction between MTHFR 677C-->T and MTRR 66A-->G on serum homocysteine concentrations among non-Hispanic whites.

CONCLUSIONS

The MTHFR 677C-->T polymorphism was associated with significant differences in serum folate and homocysteine concentrations in the US population before folic acid fortification. The effect of MTHFR 677C-->T on homocysteine concentrations was reduced by moderate daily folic acid intake.

Dissection of endoplasmic reticulum stress signaling in alcoholic and non-alcoholic liver injury

Accumulation of unfolded or malfolded proteins induces endoplasmic reticulum (ER) stress which elicits a complex network of interacting and parallel responses that dampen the stress. The ER stress response in the liver is controlled by intrinsic feedback effectors and is initially protective. However, delayed or insufficient responses or interplay with mitochondrial dysfunction may turn physiological mechanisms into pathological consequences including apoptosis, fat accumulation and inflammation all of which have an important role in the pathogenesis of liver disorders such as genetic mutations, viral hepatitis, insulin resistance, ischemia/reperfusion injury, and alcoholic and non-alcoholic steatosis. In both alcohol and non-alcohol-induced ER stress, a common candidate is hyperhomocysteinemia. Betaine supplementation and/or expression of betaine-homocysteine methyltransferase (BHMT) promote removal of homocysteine and alleviate ER stress, fatty accumulation and apoptosis in cultured hepatocytes and mouse models. The rapidity and magnitude of homocysteine-induced activation of each of the main ER resident transmembrane sensors including inositol requiring enzyme 1 (IRE-l alpha), activating transcription factor 6 (ATF-6) and RNA-activated protein kinase (PKR)-like ER kinase (PERK) appear different in different experimental models. Dissection and differentiation of ER stress signaling may reveal clues on the specific importance of the ER stress response in contributing to liver injury and thus provide better strategies on prevention and treatment of liver disease.

Preditores sócio-demográficos, de estilo de vida e gineco-obstétricos das concentrações séricas ou plasmáticas de homocisteína, ácido fólico e vitaminas B12 e B6 em mulheres de baixa renda de São Paulo, Brasil

O presente estudo investigou fatores sócio-demográficos, de estilo de vida e gineco-obstétricos associados às concentrações séricas ou plasmáticas de homocisteína, ácido fólico, vitaminas B12 e B6 em mulheres de baixa renda de São Paulo, Brasil. Concentrações séricas de ácido fólico e vitamina B12 foram analisadas por fluoroimunoensaio; concentrações plasmáticas de homocisteína e vitamina B6, por cromatografia líquida de alta performance em fase reversa. Variáveis independentes foram inicialmente selecionadas segundo pressupostos teóricos, correlação de Pearson ou teste Kruskal-Wallis (p < 0,20). Concentrações alteradas segundo pontos de corte para homocisteína, ácido fólico, vitaminas B12 e B6 foram observadas em 20%, 6%, 11% e 67% das participantes, respectivamente. Idade foi positivamente correlacionada à vitamina B6 e homocisteína plasmáticas (p < 0,001). Índice de massa corporal foi positivamente correlacionado à vitamina B6 plasmática (p < 0,001). Modelos de regressão linear múltiplos explicaram 10,2%, 5,8%, 14,4% e 9,4% das concentrações de ácido fólico, vitamina B12, vitamina B6 e homocisteína, respectivamente. No presente estudo, variáveis sócio-demográficas, de estilo de vida e gineco-obstétricas apresentaram contribuição importante na variação das concentrações dos indicadores bioquímicos avaliados.

Down-regulation of reduced folate carrier may result in folate malabsorption across intestinal brush border membrane during experimental alcoholism

Folate plays a critical role in maintaining normal metabolic, energy, differentiation and growth status of all mammalian cells. The intestinal folate uptake is tightly and diversely regulated, and disturbances in folate homeostasis are observed in alcoholism, attributable, in part, to intestinal malabsorption of folate. The aim of this study was to delineate the regulatory mechanisms of folate transport in intestinal absorptive epithelia in order to obtain insights into folate malabsorption in a rat model of alcoholism. The rats were fed 1 g.kg(-1) body weight of ethanol daily for 3 months. A reduced uptake of [(3)H]folic acid in intestinal brush border membrane was observed over the course of ethanol administration for 3 months. Folate transport exhibited saturable kinetics and the decreased intestinal brush border membrane folate transport in chronic alcoholism was associated with an increased K(m) value and a low V(max) value. Importantly, the lower intestinal [(3)H]folic acid uptake in ethanol-fed rats was observed in all cell fractions corresponding to villus tip, mid-villus and crypt base. RT-PCR analysis for reduced folate carrier, the major folate transporter, revealed that reduced folate carrier mRNA levels were decreased in jejunal tissue derived from ethanol-fed rats. Parallel changes were observed in reduced folate carrier protein levels in brush border membrane along the entire crypt-villus axis. In addition, immunohistochemical staining for reduced folate carrier protein showed that, in alcoholic conditions, deranged reduced folate carrier localization was observed along the entire crypt-villus axis, with a more prominent effect in differentiating crypt base stem cells. These changes in functional activity of the membrane transport system were not caused by a general loss of intestinal architecture, and hence can be attributed to the specific effect of ethanol ingestion on the folate transport system. The low folate uptake activity observed in ethanol-fed rats was found to be associated with decreased serum and red blood cell folate levels, which might explain the observed jejunal genomic hypomethylation. These findings offer possible mechanistic insights into folate malabsorption during alcoholism.

Evaluation of the kinetic properties of the folate transport system in intestinal absorptive epithelium during experimental ethanol ingestion

Folate plays a critical role in maintaining normal metabolic, energy, differentiation and growth status of all mammalian cells. The disturbances in body folate homeostasis such as intestinal malabsorption in alcoholism are well-known contributor to folate deficiency associated disorders. The study was sought to delineate the kinetic features of folate transport in intestinal absorptive epithelium that could highlight insights of malabsorption during alcoholism. We studied [(3)H]-folic acid transport in intestinal brush border membrane (BBM) after 3 months of ethanol administration at 1 g/kg body weight/day to rats. The results showed that the folate transport exhibited saturable kinetics and was pH, Na(+), temperature, divalent cation sensitive, besides -SH group(s) was/were found important in the folate transport system to be efficiently operative. Importantly, the decreased intestinal BBM folate transport in chronic alcoholism was associated with increased K (m) and decreased V (max) during alcoholism. In addition, S-S group status of the transporter and presence of Na(+ )at the absorptive site seems to be perturbed during ethanol ingestion. However, H(+)/folate(-) coupled transport provided the driving force for transport as pH optimum in acidic range was not altered during alcoholism. The inhibition constants of methotrexate and unlabelled folic acid revealed that the two analogues are handled differently by the folate transport system. In addition, the low activity of folate transport system during chronic ethanol exposure was associated with low RBC folate levels. Overall, these findings suggest that the deregulated folate transport kinetics might contribute to intestinal folate malabsorption in alcoholism.

Plasma homocysteine, folate and B12 in chronic schizophrenia

Elevated plasma levels of the amino acid homocysteine have been associated with schizophrenia, particularly in young male patients. Among other factors, low folate and vitamin B12 levels have been implicated in the increase in homocysteine. In order to investigate this association, we determined plasma homocysteine, folate and B12 levels in 97 (67 males and 30 females) inpatients with chronic schizophrenia and 103 (46 males and 57 females) controls. Patients and controls did not differ in folate or B12 levels, after adjusting for age. Patients with schizophrenia had higher plasma homocysteine than controls (mean=15.42 micromol/l in cases versus 11.54 micromol/l in controls: F(1,195)=17.978; p<0.001). This difference persisted after controlling for folate and B12 concentrations. Both male and female patients had increased plasma homocysteine compared to controls [(males: mean=16.61 micromol/l in cases versus mean=13.72 in controls: F(1,110)=5.54; p=0.020) (females: mean=12.78 micromol/l in cases versus mean=9.79 micromol/l in controls: F(1,84)=13.54; p<0.001)]. When dividing our sample into two age groups (age < and > or =50 years), both young and older females and younger males with schizophrenia had increased plasma homocysteine compared to controls. We therefore suggest that homocysteinemia is a general risk factor for schizophrenia. We further suggest that it is not limited to young male patients and is not necessarily associated with low folate or B12 levels.

Association of thyroid dysfunction with vitamin B12, folate and plasma homocysteine levels in the elderly: a population-based study in Sicily

Association of thyroid dysfunction with plasma homocysteine levels and vitamin B

Subjects (n=279) aged 60–85 years (119 males and 160 females) were examined using self-reported signs, clinical examination and laboratory tests.

Hypothyroidism and/or goiter were two characteristics that were not associated with a significant change in homocysteine when compared with euthyroidism and the absence of goiter. Vitamin B

Our results suggest that the influence of thyroid hormones on homocysteine is much weaker in elderly subjects than in selected patients with hypothyroidism.

Clin Chem Lab Med 2007;45:143–7.

ER stress: can the liver cope?

Hepatocytes contain abundant endoplasmic reticulum (ER) which is essential for protein metabolism and stress signaling. Hepatic viral infections, metabolic disorders, mutations of genes encoding ER-resident proteins, and abuse of alcohol or drugs can induce ER stress. Liver cells cope with ER stress by an adaptive protective response termed unfolded protein response (UPR), which includes enhancing protein folding and degradation in the ER and down-regulating overall protein synthesis. When the UPR adaptation to ER stress is insufficient, the ER stress response unleashes pathological consequences including hepatic fat accumulation, inflammation and cell death which can lead to liver disease or worsen underlying causes of liver injury, such as viral or diabetes-obesity-related liver disease.