Serum S-adenosylmethionine Research Articles

Longitudinal Analysis of One-Carbon Metabolism-Related Metabolites in Maternal and Cord Blood of Japanese Pregnant Women.

One-carbon metabolism (OCM) is a complex and interconnected network that undergoes drastic changes during pregnancy. In this study, we investigated the longitudinal distribution of OCM-related metabolites in maternal and cord blood and explored their relationships. Additionally, we conducted cross-sectional analyses to examine the interrelationships among these metabolites. This study included 146 healthy pregnant women who participated in the Chiba Study of Mother and Child Health. Maternal blood samples were collected during early pregnancy, late pregnancy, and delivery, along with cord blood samples. We analyzed 18 OCM-related metabolites in serum using stable isotope dilution liquid chromatography/tandem mass spectrometry. We found that serum S-adenosylmethionine (SAM) concentrations in maternal blood remained stable throughout pregnancy. Conversely, S-adenosylhomocysteine (SAH) concentrations increased, and the total homocysteine/total cysteine ratio significantly increased with advancing gestational age. The betaine/dimethylglycine ratio was negatively correlated with total homocysteine in maternal blood for all sampling periods, and this correlation strengthened with advances in gestational age. Most OCM-related metabolites measured in this study showed significant positive correlations between maternal blood at delivery and cord blood. These findings suggest that maternal OCM status may impact fetal development and indicate the need for comprehensive and longitudinal evaluations of OCM during pregnancy.

Desulfovibrio desulfuricans and its derived metabolites confer resistance to FOLFOX through METTL3

Chemoresistance is a critical factor contributing to poor prognosis in clinical patients with cancer undergoing postoperative adjuvant chemotherapy. The role of gut microbiota in mediating resistance to tumour chemotherapy remains to be investigated. Patients with CRC were categorised into clinical benefit responders (CBR) and no clinical benefit responders (NCB) based on chemotherapy efficacy. Differential bacterial analysis using 16S rRNA sequencing revealed Desulfovibrio as a distinct microbe between the two groups. Employing a syngeneic transplantation model, we assessed the effect of Desulfovibrio on chemotherapy by measuring tumour burden, weight, and Ki-67 expression. We further explored the mechanisms underlying the compromised chemotherapeutic efficacy of Desulfovibrio using metabolomics, western blotting, colony formation, and cell apoptosis assays. In comparison, Desulfovibrio was more abundant in the NCB group. Invivo experiments revealed that Desulfovibrio colonisation in the gut weakened the efficacy of FOLFOX. Treatment with Desulfovibrio desulfuricans elevates serum S-adenosylmethionine (SAM) levels. Interestingly, SAM reduced the sensitivity of CRC cells to FOLFOX, thereby promoting the growth of CRC tumours. These experiments suggest that SAM promotes the growth and metastasis of CRC by driving the expression of methyltransferase-like 3 (METTL3). A high abundance of Desulfovibrio in the intestines indicates poor therapeutic outcomes for postoperative neoadjuvant FOLFOX chemotherapy in CRC. Desulfovibrio drives the manifestation of METTL3 in CRC, promoting resistance to FOLFOX chemotherapy by increasing the concentration of SAM. This study is supported by Wuxi City Social Development Science and Technology Demonstration Project (N20201005).

Identification of potential serum biomarkers for congenital heart disease children with pulmonary arterial hypertension by metabonomics

BackgroundPulmonary arterial hypertension is a common complication in patients with congenital heart disease. In the absence of early diagnosis and treatment, pediatric patients with PAH has a poor survival rate. Here, we explore serum biomarkers for distinguishing children with pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) from CHD.MethodsSamples were analyzed by nuclear magnetic resonance spectroscopy-based metabolomics and 22 metabolites were further quantified by ultra-high-performance liquid chromatography–tandem mass spectroscopy.ResultsSerum levels of betaine, choline, S-Adenosyl methionine (SAM), acetylcholine, xanthosine, guanosine, inosine and guanine were significantly altered between CHD and PAH-CHD. Logistic regression analysis showed that combination of serum SAM, guanine and N-terminal pro-brain natriuretic peptide (NT-proBNP), yielded the predictive accuracy of 157 cases was 92.70% with area under the curve of the receiver operating characteristic curve value of 0.9455.ConclusionWe demonstrated that a panel of serum SAM, guanine and NT-proBNP is potential serum biomarkers for screening PAH-CHD from CHD.

Higher S-adenosylhomocysteine and lower ratio of S-adenosylmethionine to S-adenosylhomocysteine were more closely associated with increased risk of subclinical atherosclerosis than homocysteine.

AimTo examine the relationship of C1 metabolites of the methionine cycle with the risk of subclinical atherosclerosis (SA) in the Chinese population.MethodsA total of 2,991 participants aged 45–75 years old were included for data analyses based on the baseline data of the Guangzhou Nutrition and Health Cohort. Three core serum methionine metabolites including serum S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and homocysteine (Hcy) were measured by UPLC-MS/MS. SA was determined by B-mode ultrasound measured carotid intima-media thickness (CIMT) at the common artery and bifurcation segments. Multivariable logistic and linear regression models were performed to estimate the associations of C1 metabolites of the methionine cycle with SA risk or CIMT.ResultsAfter controlling for potential cofounders and other C1 metabolites, in comparison with the lowest quartile, participants in the highest quartile had lower risk of SA by 27.6% (OR = 0.724; 95% CI:0.563–0.93, Ptrend = 0.007) for SAM and 32.2% (OR = 0.678; 95% CI:0.538–0.855, Ptrend < 0.001) for SAM/SAH, while increased SA risk by 27.9% (OR = 1.279; 95% CI: 1.065–1.535, Ptrend < 0.001) for SAH. No significant association was observed for Hcy with SA after further adjustment of SAH and SAM. The results of multivariable linear regression showed similar findings. The highest two standardized coefficients were observed for SAH (β = 0.104 for CCA and 0.121 for BIF, P< 0.001) and SAM/SAH (β = −0.071 for CCA and −0.084 for BIF, P< 0.001). Subgroup analyses suggested more evident associations of SAH with SA were observed in participants of higher cardiovascular risk profiles.ConclusionOur cross-sectional data showed higher serum SAH, but lower SAM/SAH were independently associated with increased risk of SA among the Chinese middle-aged and elderly population.

Association of serum s-adenosylmethionine, s-adenosylhomocysteine, and their ratio with the risk of dementia and death in a community

We examined the association of serum s-adenosylmethionine (SAM), s-adenosylhomocysteine (SAH) (methionine metabolites), and their ratio on the risk of dementia and death in a community-dwelling population of older Japanese individuals. 1371 residents of Hisayama, Japan, aged 65 years or older and without dementia, were followed for a median of 10.2 years (2007–2017). We divided serum SAM, SAH, and SAM/SAH ratio into quartiles. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and their 95% confidence intervals (CIs) of serum SAM, SAH, and SAM/SAH ratio levels on the risk of a composite outcome of all-cause dementia or death, and each outcome. During the follow-up, 635 participants developed all-cause dementia and/or died, of which 379 participants developed dementia and 394 deaths occurred. The multivariable-adjusted HRs of the composite outcome decreased significantly with increasing serum SAM levels (P for trend = 0.01), while they increased significantly with higher serum SAH levels (P for trend = 0.03). Higher serum SAM/SAH ratio levels were significantly associated with a lower risk of the composite outcome (P for trend = 0.002), as well as with lower risk of each outcome. Our findings suggest that the balance of methionine metabolites may closely associate with the risk of dementia and death.

Association of serum methionine metabolites with non-alcoholic fatty liver disease: a cross-sectional study

Background and projectNon-alcoholic fatty liver disease (NAFLD) is viewed as the hepatic manifestation of metabolic syndrome. Methionine metabolites have been linked to metabolic syndrome and its related diseases. Whether serum methionine metabolites levels are associated with NAFLD remains unclear. The study aimed to assess the association between methionine metabolites and NAFLD.MethodsThis cross-sectional study included a total of 2814 individuals aged 40–75 years old. All participants underwent anthropometric measurements, laboratory tests, dietary assessment and abdominal ultrasonography. Multivariable logistic regression analysis was performed to estimate the association of methionine metabolites with NAFLD.ResultsOverall, 1446 with and 1368 without NAFLD were enrolled in this study. Participants with NAFLD had significantly higher serum S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and homocysteine (Hcy) levels, and a lower S-adenosylmethionine/S-adenosylhomocysteine (SAM/SAH) ratio than those without NAFLD (all P < 0.001). After adjusting multiple confounders, odds ratios (95% confidence interval) for quartile 4 versus quartile 1 of SAH, Hcy and SAM/SAH ratio were 1.65 (1.27–2.14), 1.63 (1.26–2.12) and 0.63 (0.49–0.83), respectively (all P for trend < 0.01). In addition, serum SAH, Hcy levels and SAM/SAH ratio were significantly correlated with the degree of hepatic steatosis (all P for trend < 0.001).ConclusionElevated serum SAH, Hcy levels and lower SAM/SAH ratio may be independently associated with the presence of NAFLD in middle-aged and elder Chinese.

Generation of Monoclonal Antibodies against S-Adenosylmethionine and Their Application in Diagnosing Liver Diseases

S-AdenosylMethionine (SAM) hapten-carrier conjugates were used to immunize BALB/c mice. Two strains of hybridoma cell lines that stably produced high-titer monoclonal antibodies against SAM were obtained. The biological properties of these two antibodies were characterized. A competitive ELISA (cELISA) was established using these antibodies. The sensitivity and specificity were analyzed, and human serum samples were measured using the SAM cELISA kit.Very little cross-reactivity (&lt; 1%) was observed between the monoclonal antibodies and SAM analogues. These two antibodies are IgG2b-type antibodies. The affinity measured using the cELISA is 5.75 x 109 L/mol for the 118-6 antibody and 7.29 x 1010L/mol for the 84-3 antibody. According to the Immunohistochemistry (IHC) and flow cytometry results, normal liver cells contain much higher levels of SAM than liver cancer cells (p &lt; 0.01). The results from 81 healthy subjects and 99 patients with liver disease showed the following sensitivity using the 240 nM cutoff: 95.65% (44/46) for hepatitis; 95% (19/20) for cirrhosis; 92.86% (13/14) for carcinoma; 100% (19/19) for liver failure; 30.86% (25/81) for healthy subjects; the detection specificity is 69.14% (56/81). Using the 120 nM cutoff, the sensitivitywas 80.43% for hepatitis; 85% for cirrhosis; 71.43% for carcinoma, 100% for liver failure; 3.70% for healthy subjects; the specificity is 96.30% (78/81). SAM, alanine transaminase and aspartate aminotransferase were compared in identifying liver diseases. Serum SAM allowed early detection of abnormal liver function and providing clinicians an important basis for a more accurate diagnosis of liver diseases than alanine transaminase and aspartate aminotransferase. Keywords: S-Adenosylmethionine (SAM); Monoclonal Antibody; Competitive ELISA; Liver Disease Diagnosis Abbreviations: Alanine Transaminase (ALT); Aspartate Aminotransferase (AST); Chronic Hepatitis B (CHB), Competitive ELISA (CELISA); Hematoxylin and Eosin (HE); Hepatocellular Carcinoma (HCC); Homocysteine (HCY); Immunohistochemistry (IHC); Keyhole Limpet Hemocyanin (KLH); L-Methionine(L-Met); Methionine Adenosine Transferase (MAT); Methylthioadenosine (MTA); Optical Density (OD); S-Adenosylhomocysteine(SAH); S-Adenosylmethionine(SAM).

Serum S-adenosylmethionine, but not methionine, increases in response to overfeeding in humans.

Background:Plasma concentration of the methyl donor S-adenosylmethionine (SAM) is linearly associated with body mass index (BMI) and fat mass. As SAM is a high-energy compound and a sensor of cellular nutrient status, we hypothesized that SAM would increase with overfeeding.Methods:Forty normal to overweight men and women were overfed by 1250 kcal per day for 28 days.Results:Serum SAM increased from 106 to 130 nmol/l (P=0.006). In stratified analysis, only those with weight gain above the median (high-weight gainers; average weight gain 3.9±0.3 kg) had increased SAM (+42%, P=0.001), whereas low-weight gainers (weight gain 1.5±0.2 kg) did not (Pinteraction=0.018). Overfeeding did not alter serum concentrations of the SAM precursor, methionine or the products, S-adenosyl-homocysteine and homocysteine. The SAM/SAH (S-adenosylhomocysteine) ratio was unchanged in the total population, but increased in high-weight gainers (+52%, P=0.006, Pinteraction =0.005). Change in SAM correlated positively with change in weight (r=0.33, P=0.041) and fat mass (r=0.44, P=0.009), but not with change in protein intake or plasma methionine, glucose, insulin or low-density lipoprotein (LDL)-cholesterol.Conclusion:Overfeeding raised serum SAM in proportion to the fat mass gained. The increase in SAM may help stabilize methionine levels, and denotes a responsiveness of SAM to nutrient state in humans. The role of SAM in human energy metabolism deserves further attention.

Abstract 3247: SAMe versus placebo for the reduction of serum AFP in patients with hepatitis C cirrhosis and moderately elevated AFP: A randomized, placebo-controlled, double-blind phase II trial

Abstract Background: Hepatocellular carcinoma (HCC) is a common complication of hepatitis C virus related cirrhosis (HCV-C). Alpha-fetoprotein (AFP) has been proposed as a biomarker of HCC risk. S-adenosylmethionine (SAMe) is a food supplement that has an excellent safety profile. The use of SAMe as a chemopreventive is based on abnormalities in methionine cycle (with decreased SAMe levels) in patients with cirrhosis, increased risk of HCC in experimental animals deprived of SAMe, and the prevention of liver cancer by SAMe administration in animal models of chemically-induced HCC. Methods: This was a prospective, randomized, placebo-controlled, double-blind phase IIb trial to determine if SAMe (up to 2.4 grams/day) for 24 weeks reduced serum AFP levels in patients with HCV-C. Inclusion criteria: lab evidence of HCV-C (platelet count &amp;lt;150,000/mm3), AFP 15-100 ng/mL (normal less than 9 ng/mL). Exclusion criteria: non-HCV liver diseases, decompensated HCV-C (MELD&amp;gt;15), or history of, or mass suspicious for HCC. Primary outcome was decline in AFP between week 0 and 24. Secondary outcomes: change in other HCC-related markers (des-gamma carboxyprothrombin, AFP-L3), blood tests for HCV RNA, SAMe metabolites, serum markers of oxidative stress, and quality of life. Results: A total of 110 patients were enrolled and 87 completed study. After the 24-week treatment, AFP declined among patients receiving SAMe (-1.9 ng/mL) and increased among patients receiving placebo (+5.9 ng/mL; p=0.16). Neither des-gamma carboxyprothrombin (DCP) nor AFP-L3 changed significantly with SAMe treatment. There were no significant differences in serum HCV RNA between groups. Blood levels of SAMe and S-adenosylhomocysteine (SAH) increased 3-5 fold among patients receiving SAMe and were unchanged in placebo group (p&amp;lt;0.01). Serum glutathione and methionine did not change significantly. Several components of quality of life improved among patients receiving SAMe. There were 5 serious adverse events in the placebo group and 7 in the SAMe group; none were attributable to SAMe. Conclusions: SAMe administration for 24 weeks in patients with HCV-C and elevated AFP did not decrease AFP significantly nor alter liver function. SAMe significantly increased serum SAMe and SAH levels, but did not alter serum glutathione level or serum markers of oxidative stress. Citation Format: Timothy Morgan, Frank L. Meyskens, John Hoefs, Ke-Qin Hu, Tarek Hassanein, Thomas D. Boyer, Neville R. Pimstone, Kathy Osann, Rachel Gonzalez, L M. Rodriguez. SAMe versus placebo for the reduction of serum AFP in patients with hepatitis C cirrhosis and moderately elevated AFP: A randomized, placebo-controlled, double-blind phase II trial. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3247. doi:10.1158/1538-7445.AM2014-3247

S24 * S-ADENOSYLMETHIONINE IN THE PATHOGENESIS AND TREATMENT OF ALCOHOLIC LIVER DISEASE * S24.1 * THE ROLE OF ALTERED SAME METABOLISM IN ALCOHOL-INDUCED ER STRESS AND LIVER INJURY

S24 * S-ADENOSYLMETHIONINE IN THE PATHOGENESIS AND TREATMENT OF ALCOHOLIC LIVER DISEASE * S24.1 * THE ROLE OF ALTERED SAME METABOLISM IN ALCOHOL-INDUCED ER STRESS AND LIVER INJURY

α-Lipoic acid induces elevated S-adenosylhomocysteine and depletes S-adenosylmethionine

Lipoic acid is a disulfhydryl-containing compound used in clinical medicine and in experimental models as an antioxidant. We developed a stable isotope dilution capillary gas chromatography/mass spectrometry assay for lipoic acid. We assayed a panel of the metabolites of transmethylation and transsulfuration 30 min after injecting 100 mg/kg lipoic acid in a rat model. Lipoic acid values rose 1000-fold in serum and 10-fold in liver. A methylated metabolite of lipoic acid was also detected but not quantitated. Lipoic acid injection caused a massive increase in serum S-adenosylhomocysteine and marked depletion of liver S-adenosylmethionine. Serum total cysteine was depleted but liver cysteine and glutathione were maintained. Serum total homocysteine doubled, with increases also in cystathionine, N,N-dimethylglycine, and α-aminobutyric acid. In contrast, after injection of 2-mercaptoethane sulfonic acid, serum total cysteine and homocysteine were markedly depleted and there were no effects on serum S-adenosylmethionine or S-adenosylhomocysteine. We conclude that large doses of lipoic acid displace sulfhydryls from binding sites, resulting in depletion of serum cysteine, but also pose a methylation burden with severe depletion of liver S-adenosylmethionine and massive release of S-adenosylhomocysteine. These changes may have previously unrecognized deleterious effects that should be investigated in both human disease and experimental models.

Improvement of aggressive behavior and quality of life impairment following S-Adenosyl-Methionine (SAM-e) augmentation in schizophrenia

S-Adenosyl-Methionine (SAM-e), functions as a primary methyl group donor for several metabolic compounds. Since SAM-e is involved in several metabolic processes, its administration may have a role in the amelioration of several disorders. In addition, SAM-e increases catechol- O-methyltransferase (COMT) enzyme activity, which may ameliorate aggressive symptoms in certain patients. We have therefore investigated the efficacy of SAM-e in managing schizophrenia symptomatology in patients with the low activity COMT polymorphism. Eighteen patients with chronic schizophrenia were randomly assigned to receive either SAM-e (800 mg) or placebo for 8 weeks in double-blind fashion. Results indicated some reduction in aggressive behavior and improved quality of life following SAM-e administration. Female patients showed improvement of depressive symptoms. Clinical improvement did not correlate with serum SAM-e levels. Two patients receiving SAM-e exhibited some exacerbation of irritability. This preliminary pilot short-term study cautiously supports SAM-e as an adjunct in management of aggressive behavior and quality of life impairment in schizophrenia.

A hydrophilic-interaction chromatography tandem mass spectrometry method for quantitation of serum s-adenosylmethionine in patients infected with human immunodeficiency virus

Background s-Adenosylmethionine (SAM) 1 has been suggested as a diagnostic test and surrogate marker for Pneumocystis jirovecii pneumonia (PCP) in HIV-positive patients. In this study, we report a robust hydrophilic-interaction liquid chromatography tandem mass spectrometry (LC-MS/MS) assay that can be used to quantitate serum SAM in clinical laboratories. Methods Proteins in serum samples were precipitated using trichloroacetic acid. The supernatant was separated after centrifugation. D 3d 3-SAM was added as the internal standard. SAM and d 3-SAM were extracted using a mixed-mode cation exchange column. Extracts were dried under nitrogen and reconstituted in H 2O and acetonitrile (1:9, vol:vol). HPLC-tandem mass spectrometry analysis was performed with a silica column and multiple reaction monitoring for SAM and d 3-SAM. Results The limit of quantitation (LOQ) for SAM was 10ng/mL. The assay was linear between 10 and 500ng/mL. Intra-assay coefficient of variation (CV) was 8% and inter-assay CV was 17% at the LOQ. Turnaround time for each specimen was approximately 1h. Using this method, we found that serum SAM concentration was correlated with fasting status, especially methionine intake. We also measured acute and convalescent serum SAM levels of 8 HIV-positive patients with PCP and non-PCP pneumonia. SAM concentrations in convalescent samples were significantly increased compared to acute levels only in patients with PCP. Conclusions The LC-MS/MS method had sufficient analytical sensitivity for detecting low levels of SAM found in HIV-infected patients and can be used for quantitative measurements in a clinical laboratory. This method facilitates research and possible clinical application of SAM as a marker for PCP.

Elevated serum S-adenosylhomocysteine in cobalamin-deficient megaloblastic anemia

Impaired methylation due to accumulation of S-adenosylhomocysteine (SAH) may contribute to the pathophysiology of cobalamin-deficient anemia. We assayed serum S-adenosylmethionine (SAM), SAH, total homocysteine (tHcy), and methylmalonic acid (MMA) in 15 subjects with cobalamin-deficient megaloblastic anemia and compared results with those of 19 subjects with anemia/pancytopenia due to other causes. Cobalamin-deficient subjects had a median hematocrit level of 20% and mean cell volume of 111.7 fL. The median serum cobalamin level was 37 pg/mL, MMA 3030 nmol/L, and tHcy 62.0 μmol/L. SAH was elevated in 13 of 15 subjects (median, 42 nmol/L) and the median SAM value was normal (103 nmol/L), but SAM/SAH ratio was low (2.5). The SAH was higher and SAM/SAH ratio was lower in cobalamin-deficient subjects compared with those with other anemias after excluding 4 patients with renal insufficiency. SAM concentrations were not low in cobalamin deficiency. Cobalamin injections corrected anemia, MMA, tHcy, SAM/SAH ratio, and SAH. Some hematologic variables were inversely correlated with SAH and cobalamin but not tHcy or MMA. In conclusion, serum SAH is elevated in cobalamin-deficient subjects with megaloblastic anemia and corrects with parenteral cobalamin therapy.

Elevated serum S-adenosylhomocysteine in cobalamin-deficient elderly and response to treatment

S-Adenosylmethionine (SAM)-dependent methylation reactions produce S-adenosylhomocysteine (SAH), the precursor of homocysteine, which has been associated with adverse events when it is elevated. We studied a cohort of elderly with a high prevalence of cobalamin deficiency to determine whether SAH, SAM, or their ratio was abnormal; whether they correlated with other markers of vitamin deficiency; and whether they changed with cobalamin therapy. A convenience sample of elderly attending nutrition centers was enrolled for baseline demographic, biochemical, and nutritional assessments. Methylmalonic acid (MMA), total homocysteine, and other metabolites were measured by using gas chromatography-mass spectrometry. Serum SAM and SAH were measured by using stable-isotope-dilution liquid chromatography-mass spectrometry. Subjects found to have elevated serum MMA were treated with oral cyanocobalamin tablets (1000 microg/d) for 3 mo. Subjects with normal MMA were randomly assigned to 1 of 3 dosage groups: 0, 25, or 100 microg cyanocobalamin/d. The 149 elderly subjects had a mean age of 76.3 y; 81% were female, and 30% were African American. Serum MMA concentrations were elevated in 30% and SAH concentrations were elevated in 64% of the cohort. Those with elevated MMA concentrations had higher SAH and SAM concentrations. High-dose oral cobalamin lowered SAH, MMA, and total homocysteine concentrations significantly, although subjects with creatinine concentrations >109 umol/L had higher posttreatment SAH than did those with lower creatinine. Elevated serum SAH concentrations are common in elderly and are strongly influenced by both renal status and cobalamin deficiency. These elevated concentrations can be lowered with high-dose oral cobalamin therapy.

Low ratio of S-adenosylmethionine to S-adenosylhomocysteine is associated with vitamin deficiency in Brazilian pregnant women and newborns

Pregnant women with low cobalamin concentrations are unable to provide the necessary amount of cobalamin to their fetuses. The effect of low maternal cobalamin concentrations on transmethylation metabolism in pregnant women and their newborns is unknown. We investigated the relation between maternal and neonatal cobalamin concentrations and changes in total homocysteine (tHcy), S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH). Hematologic data and concentrations of cobalamin, red blood cell folate, serum folate, tHcy, methylmalonic acid, SAM, SAH, and other metabolites were measured in 119 serum specimens from pregnant Brazilian women (gestational age: 37-42 wk) and their newborns' placental veins at the time of delivery. The tHcy concentrations were higher in placental vein serum from newborns whose mothers had low cobalamin. Serum SAH concentrations were elevated and serum SAM and methionine concentrations were decreased in pregnant women with lower cobalamin concentrations. SAM:SAH was significantly decreased in both cobalamin-deficient pregnant women and their newborns. Lower maternal cobalamin concentrations are associated with higher tHcy and lower SAM:SAH in newborns. Because SAM:SAH is closely linked with the activity of numerous enzymatic methylation reactions, these results suggest that methylation could be impaired in cobalamin-deficient pregnant women and their newborns.

Quantification of Serum and Urinary S-Adenosylmethionine and S-Adenosylhomocysteine by Stable-Isotope-Dilution Liquid Chromatography-Mass Spectrometry

We have developed an assay that uses stable-isotope-dilution liquid chromatography-mass spectrometry to assess S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in body fluids to investigate the relationship of these metabolites to hyperhomocysteinemia. Commercially obtained SAM (D(3) methyl) and (13)C(5)-SAH uniformly labeled in the adenosyl moiety, which was synthesized using S-adenosylhomocysteine hydrolase, were added to samples followed by perchloric acid protein precipitation, C(18) chromatography, and analysis by liquid chromatography-mass spectrometry with quantification by comparison of the areas of internal standard and endogenous peaks. Estimates of intraassay imprecision (CV) were 5% and 17% for SAM and SAH, respectively (n = 10). SAM decreased and SAH increased in serum and plasma samples at both 4 degrees C and room temperature over 80 h. SAM and SAH were unstable in samples stored longer than 2 years at -20 degrees C. In 48 volunteers, the estimated reference intervals [from mean (2 SD) of log-transformed data] for serum SAM and SAH were 71-168 and 8-26 nmol/L, respectively. Fractional excretion of SAM was higher than that of SAH, and the urinary SAM:SAH ratio was much higher than the serum or erythrocyte SAM:SAH ratios. Stable-isotope-dilution liquid chromatography-mass spectrometry can be used to quantify SAM and SAH in biological fluids and tissues. Sample handling and storage must be stringently controlled for any epidemiologic or clinical use of such assays.