One-carbon metabolism during the menstrual cycle and pregnancy

Many enzymes in one-carbon metabolism (OCM) are up- or down-regulated by the sex hormones which vary diurnally and throughout the menstrual cycle. During pregnancy, estradiol and progesterone levels increase tremendously to modulate physiological changes in the reproductive system. In this work, we extend and improve an existing mathematical model of hepatic OCM to understand the dynamic metabolic changes that happen during the menstrual cycle and pregnancy due to estradiol variation. In particular, we add the polyamine drain on S-adenosyl methionine and the direct effects of estradiol on the enzymes cystathionine β-synthase (CBS), thymidylate synthase (TS), and dihydrofolate reductase (DHFR). We show that the homocysteine concentration varies inversely with estradiol concentration, discuss the fluctuations in 14 other one-carbon metabolites and velocities throughout the menstrual cycle, and draw comparisons with the literature. We then use the model to study the effects of vitamin B12, vitamin B6, and folate deficiencies and explain why homocysteine is not a good biomarker for vitamin deficiencies. Additionally, we compute homocysteine throughout pregnancy, and compare the results with experimental data. Our mathematical model explains how numerous homeostatic mechanisms in OCM function and provides new insights into how homocysteine and its deleterious effects are influenced by estradiol. The mathematical model can be used by others for further in silico experiments on changes in one-carbon metabolism during the menstrual cycle and pregnancy.

To Assess the Level of Vit B12, Vit C and Homocysteine in Chronic Smokers in Central India

Background: Smoking is related to an increased risk of morbidity and mortality. Cigarette smoking has been related to higher levels of homocysteine in the blood. Both have been associated with a higher risk of cardiovascular disease. Smokers also have lower levels of vitamin B12, which affects homocysteine levels by serving as a cofactor or co substrate (folate) for the enzymes that regulate the metabolism of homocysteine. Materials: This study was a case-control study, conducted in the Department of Biochemistry and medicine at DMMC & SMHRC, Nagpur in collaboration with ABVRH, Sawangi (Meghe). In the present study, the total number of subjects included was 200 having age Group between 30-60. The subjects were divided in two groups. Group 1: 100 subjects chronic smokers and Group 2: 100 subjects non- smokers. Results: The homocysteine concentration significantly increased in group 1 ( chronic smokers) 18.50±8.40 as compared to group 02( non smokers ) 8.30±5.30 and p value p<0.005.vitamin B12 concentration significantly decreased in group 01 ( chronic smokers) 340.80±124.70 as compared to group 02 (non smokers) 485.45±175.68 and p value p<0.005. vitamin c concentration significantly decreased in group 1 (chronic smokers) 0.46±0.07 as compared to group 02 (non smokers) 1.12±0.15 and p value p<0.005. Conclusion: On the basis of findings we concluded that the smoking increases Homocysteine levels and lowers the level of Vit B12 and Vit C leading to increase cardiovascular disease risk among chronic smokers.

The Relationship Between Folate, Vitamin B12 and Gestational Diabetes Mellitus with Proposed Mechanisms and Foetal Implications

The incidence of gestational diabetes mellitus (GDM) is rising, which warrants attention due to the associated complications during pregnancy and in the long term for both mother and offspring. Studies have suggested a relationship between maternal folate (vitamin B9) and vitamin B12 status and GDM risk. Seemingly the most problematic scenario occurs when there is B-vitamin imbalance, with high folate and low vitamin B12. This nutritional state can occur in vitamin B12 deficient women who exceed the recommended folic acid supplementation. However, the pathological mechanisms behind this relationship are currently unclear and are explored in this review article. A high folate/low B12 can lead to a functional folate deficiency through the methyl-trap phenomenon, impairing re-methylation of homocysteine and regeneration of folates for DNA synthesis and repair. Consequently elevated homocysteine concentration leads to endothelial dysfunction and oxidative stress. Vitamin B12 deficiency also leads to an impairment of the conversion of methylmalonyl-CoA to succinyl-CoA, which has been associated with insulin resistance. Insulin resistance is thought to contribute to the etiology of GDM. More studies are needed to confirm the impact of these and other mechanisms on disease development. However, it highlights a potential avenue for GDM risk modification through a vitamin B12 supplement and improvement of maternal metabolic health.

Methylenetetrahydrofolate reductase gene rs1801133 polymorphism and essential hypertension risk from a comprehensive analysis

Background Essential hypertension (EH) is common and multifactorial disorders likely to be influenced by multiple genes. The methylenetetrahydrofolate reductase (MTHFR) gene rs1801133 polymorphism is related to MTHFR enzyme activity and to plasma homocysteine concentration. In addition, variations in MTHFR functions likely play roles in the etiology of EH. So far, larger number of studies between MTHFR rs1801133 polymorphism and EH have provided controversial or inconclusive results. To better assess the purported relationship, we performed a comprehensive analysis of 50 publications. Methods Eligible studies were identified by searching the PubMed, Wanfang and CNKI databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess this association. Results Overall, increased significant associations were detected between MTHFR rs1801133 polymorphism and EH risk (such as T vs. C: OR = 1.37, 95%CI = 1.24–1.52, P = 0.000), the same as in race subgroup (Asian: T vs. C: OR = 1.46, 95%CI = 1.29–1.67, P = 0.000; China: T vs. C: OR = 1.51, 95%CI = 1.30–1.74, P = 0.000). Similar associations were also found in source of control and genotype methods subgroups. Conclusions Our study showed evidence that MTHFR rs1801133 null genotype may increase EH risk. Future studies with larger sample size are warranted to further evaluate this association in more detail.

The features of metabolic transformations of homocysteine and cysteine in rats’ hepatocytes under the nutritional imbalance

The work is devoted to the study of the homocysteine concentration in blood plasma and the activity of the enzymes of cysteine catabolic transformations γ-glutamate-cysteine ligase and cysteine dioxygenase in rats’ hepatocytes under the conditions of consumption of excessive sucrose content on the background of alimentary protein deprivation. It was found, that the consumption of a high-sucrose diet in animals is accompanied by the increase of homocysteine concentration in plasma by 57% compared to control, whereas the excess of sucrose under the conditions of protein deficiency leads to hypohomocysteinemia (the content of homocysteine decreased by 43% compared to control). The increased plasma homocysteine levels in excess-consuming sucrose can be considered as a prognostic marker of functional disorders of the transsulfuration pathway in the liver and used in the diagnosis of hepatopathologies. Since, the cysteine content in liver cells increased under the conditions of high-sucrose diet consumption, the increasing γ-GCS, a key enzyme of glutathione synthesis, is probably associated with the maintenance of intercellular glutathione stores. Our data of the occurrence hypohomocysteinemia under the conditions of the consumption of excessive amounts of sucrose on the background of dietary protein deficiency highlight gaps in the understanding of the correlation between the metabolic processes of methionine, homocysteine and cysteine in the liver. Under the excessive consumption of sucrose on the background of protein deficiency, the exogenous protein deficiency can be considered as a key factor in reducing the γ-GCS activity (36%) and the cysteine content, because not only the amount of this amino acid is reduced but also its synthesis is disrupted. At the same time, the maximum increase in cysteine dioxygenase activity in rats’ hepatocytes under the conditions of high-sucrose/low-protein diet consumption on the background of decreased γ-GCS activity indicates the utilization of excess cysteine with the formation of taurine and sulfates.

Polymorphism of folate cycle genes as a risk factor of hyperhomocysteinemia

Hyperhomocysteinemia (HHc) is a new factor being considered at the moment that can cause damage to vessel walls. Its occurrence depends on genetic peculiarities of a body. Our research goal was to estimate frequency of genetic polymorphisms (SNP) in folate cycle genes among people living in Perm region and its influence on homocysteine (Hc) concentration in blood serum. We examined 189 women (32.2±5.25). Hc concentration in blood serum was determined with immune chemiluminescent procedure. We examined frequency of SNP in folate cycle genes with pyrosequencing. Homozygote state as per minor alleles in methylene tetrahydrofolate reductase (MTHFR) gene (rs 1801133 и rs 1801131) and MTR gene (rs 1805087) was registered 7.5, 5.4, and 13.75 times less frequently than homozygote state as per neutral alleles. Heterozygote state prevailed for genes of methionine synthase reductase and folate transport protein among examined SNP. Homozygotes as per minor allele SNP in MTHFR gene (Ala222Val; rs 1801133) had higher Hc concentration in blood serum that amounted to 8.476 ± 3.193 mmol/L and was 1.276 times higher than the same parameter in homozygotes as per neutral allele (р=0.0036). We didn’t establish any influence on Hc contents in blood serum for the remaining 4 SNP in folate cycle genes (р> 0.1). Examined SNP in MTHFR and MTR genes tended to have neutral alleles more frequently than minor ones. SNP in genes of other examined proteins belonging to folate cycle didn’t have any differences in frequency of examined alleles. We didn’t detect a combination of homozygote state as per two SNP in MTHFR gene or homozygote state as per one SNP and heterozygote state as per another one in a genome. Only SNP in MTHFR gene (Ala222Val, rs 1801133) authentically causes increase in homocysteine concentration out of all the examined SNP in genes of folate cycle enzymes and proteins.

Polymorphism of folate cycle genes as a risk factor of hyperhomocysteinemia

Hyperhomocysteinemia (HHc) is a new factor being considered at the moment that can cause damage to vessel walls. Its occurrence depends on genetic peculiarities of a body. Our research goal was to estimate frequency of genetic polymorphisms (SNP) in folate cycle genes among people living in Perm region and its influence on homocysteine (Hc) concentration in blood serum. We examined 189 women (32.2±5.25). Hc concentration in blood serum was determined with immune chemiluminescent procedure. We examined frequency of SNP in folate cycle genes with pyrosequencing. Homozygote state as per minor alleles in methylene tetrahydrofolate reductase (MTHFR) gene (rs 1801133 и rs 1801131) and MTR gene (rs 1805087) was registered 7.5, 5.4, and 13.75 times less frequently than homozygote state as per neutral alleles. Heterozygote state prevailed for genes of methionine synthase reductase and folate transport protein among examined SNP. Homozygotes as per minor allele SNP in MTHFR gene (Ala222Val; rs 1801133) had higher Hc concentration in blood serum that amounted to 8.476 ± 3.193 mmol/L and was 1.276 times higher than the same parameter in homozygotes as per neutral allele (р=0.0036). We didn’t establish any influence on Hc contents in blood serum for the remaining 4 SNP in folate cycle genes (р> 0.1). Examined SNP in MTHFR and MTR genes tended to have neutral alleles more frequently than minor ones. SNP in genes of other examined proteins belonging to folate cycle didn’t have any differences in frequency of examined alleles. We didn’t detect a combination of homozygote state as per two SNP in MTHFR gene or homozygote state as per one SNP and heterozygote state as per another one in a genome. Only SNP in MTHFR gene (Ala222Val, rs 1801133) authentically causes increase in homocysteine concentration out of all the examined SNP in genes of folate cycle enzymes and proteins

Cut-off value of serum homocysteine in relation to increase of coronary artery calcification

A recent study reported that coronary artery calcification (CAC) and serum homocysteine were well associated; however, no report is available for the cut-off value of serum homocysteine according to increase of coronary-artery calcification volume score (CVS). The data of 469 out of 777 subjects in 1 health promotion center located in Seoul were selected after exclusion of the missing data of serum homocysteine and CVS. CVS was categorized into 2 groups: CVS=0 and CVS>0. Serum homocysteine according to the CVS groups was compared, and the cut-off value of serum homocysteine according to the increase of CVS (>0) was calculated using the receiver operating characteristic curve. Mean age was 54.5 years and the proportion of females was 22.2%. Mean serum homocysteine concentration and CVS were 11.2 μmol/L and 50.4, respectively. After adjustments for age and sex, serum homocysteine was associated with CVS (r=0.167, p=0.001), and Log(Homocysteine) also showed a significant difference according to the CVS groups. The cut-off value of serum homocysteine according to the increase of CVS (>0) was 9.45 μmol/L (area under the curve=0.569 (95% CI 0.512 to 0.625), p=0.015). The cut-off value of serum homocysteine was 9.45 μmol/L according to the increase of coronary-artery CVS.

Gender- and age-related differences in homocysteine concentration: a cross-sectional study of the general population of China

The primary goals of this study were to evaluate the gender- and age-related differences in homocysteine concentration in the general population of China and possible influencing factors. A total of 7872 subjects, divided into male and female groups, participated in this retrospective study. The average homocysteine level, prevalence of hyperhomocysteinemia, and independent factors affecting homocysteine concentration were analyzed. The homocysteine level was significantly higher in males than in females in each age range (aged 20–30, aged 30–40, aged 40–50, aged 50–60, aged 60–80, aged over 80) (P < 0.0001), and the trend did not abate with age. The homocysteine concentration first decreased and then increased, being lowest at 30–50 years of age and significantly increased after 50 years of age. Factors associated with homocysteine concentration in males were smoking status (current smokers versus ex-smokers: β: 0.112), estimated glomerular filtration rate (β = − 0.192), blood urea nitrogen (β = − 0.14), diastolic blood pressure (β = − 0.113), free triiodothyronine (β = − 0.091), serum potassium (β = − 0.107) and cystatin C (β = 0.173). In females, independent factors associated with homocysteine concentration were cystatin C (β = 0.319), albumin (β = 0.227), free thyroxine (β = 0.179), age (β = 0.148), free triiodothyronine (β = − 0.217) and serum potassium (β = − 0.153). The homocysteine level was significantly higher in males than in females and increased markedly after 50 years of age in both groups. The independent factors associated with increased homocysteine concentration differed between males and females.