Screening for Serum Total Homocysteine in Newborn Children

The utility of methylmalonic acid, methylcitrate acid, and homocysteine in dried blood spots for therapeutic monitoring of three inherited metabolic diseases

Backgroud

Routine metabolic assessments for methylmalonic acidemia (MMA), propionic acidemia (PA), and homocysteinemia involve detecting metabolites in dried blood spots (DBS) and analyzing specific biomarkers in serum and urine. This study aimed to establish a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection of three specific biomarkers (methylmalonic acid, methylcitric acid, and homocysteine) in DBS, as well as to appraise the applicability of these three DBS metabolites in monitoring patients with MMA, PA, and homocysteinemia during follow-up.

Methods

A total of 140 healthy controls and 228 participants were enrolled, including 205 patients with MMA, 17 patients with PA, and 6 patients with homocysteinemia. Clinical data and DBS samples were collected during follow-up visits.

Results

The reference ranges (25th-95th percentile) for DBS methylmalonic acid, methylcitric acid, and homocysteine were estimated as 0.04-1.02 μmol/L, 0.02-0.27 μmol/L and 1.05-8.22 μmol/L, respectively. Following treatment, some patients achieved normal metabolite concentrations, but the majority still exhibited characteristic biochemical patterns. The concentrations of methylmalonic acid, methylcitric acid, and homocysteine in DBS showed positive correlations with urine methylmalonic acid (r = 0.849, p < 0.001), urine methylcitric acid (r = 0.693, p < 0.001), and serum homocysteine (r = 0.721, p < 0.001) concentrations, respectively. Additionally, higher levels of DBS methylmalonic acid and methylcitric acid may be associated with increased cumulative complication scores.

Conclusion

The LC-MS/MS method established in this study reliably detects methylmalonic acid, methylcitric acid, and homocysteine in DBS. These three DBS metabolites can be valuable for monitoring patients with MMA, PA, and homocysteinemia during follow-up. Further investigation is required to determine the significance of these DBS biomarkers in assessing disease burden over time.

Determination of underivatized amino acids in human plasma using ion pair liquid chromatography/tandem mass spectrometry

Accurate quantification of amino acids (AA) is essential for several applications, including clinical research, food analysis, and pharmaceutical studies. In this study, we developed an analytical method based on liquid chromatography with electrospray ionization coupled to tandem mass spectrometry detection (LC-ESI-MS/MS). This method was devised to accurately quantify a spectrum of amino acids, notably taurine, creatinine, glutathione (GSH), and sulfur-containing amino acids (SAAs) such as methionine, cysteine, and homocysteine, using only 10 μL of human plasma. A stable isotope derivative of each AA is used as an internal standard (IS) for accurate quantification. For retention and separation on a C18 column, heptafluorobutyric acid (HFBA) was employed as an ion pair agent. Multiple reaction monitoring (MRM) in positive mode with the precursor-to-product ion transitions at m/z is used for quantification. The method showed excellent linearity for all AA with a high correlation coefficient (r > 0.9927). The linear fit indicates that the detector response is linear over the tested range of standard concentrations. The accuracy and precision of the method were within the acceptable range of 92-110% and < 15%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were in the range of 0.001-1.80 µM and 0.004-6.0 µM, respectively. No significant ion suppression or carry over was observed. In conclusion, the assay was validated and found to have adequate accuracy, precision, linearity, sensitivity and selectivity. The assay has been successfully applied to the analysis of human plasma.

Serum 5-Methyltetrahydrofolate Status Is Associated with One-Carbon Metabolism-Related Metabolite Concentrations and Enzyme Activity Indicators in Young Women

Maintaining optimal one-carbon metabolism (OCM) is essential for health and pregnancy. In this cross-sectional study, folate status was assessed based on 5-methyltetrahydrofolate (5-MTHF) levels, and the association between 5-MTHF and OCM-related metabolites was investigated in 227 female Japanese university students aged 18-25 years. The participants were divided into high and low 5-MTHF groups based on their folate status. Serum samples of the participants were collected while they were fasting, and 18 OCM-related metabolites were measured using stable-isotope dilution liquid chromatography-electrospray tandem mass spectrometry. The association between serum 5-MTHF and OCM-related metabolite concentrations was assessed using Spearman's rank correlation coefficient. Serum 5-MTHF concentrations were negatively correlated with total homocysteine (tHcy) concentrations and positively correlated with S-adenosylmethionine (SAM) and total cysteine (tCys) concentrations. Serum 5-MTHF concentrations demonstrated a stronger negative correlation with tHcy/tCys than with tHcy alone. The negative correlation between betaine and tHcy concentrations was stronger in the low 5-MTHF group than in the high 5-MTHF group. The 5-MTHF status could be linked to Hcy flux into the transsulfuration pathway via SAM. Therefore, the tHcy/tCys ratio may be a more sensitive indicator of the 5-MTHF status than tHcy alone. Furthermore, a low 5-MTHF status can enhance Hcy metabolism via betaine.

Biomarkers of cardiovascular disease risk in the neonatal population

The consistently high prevalence of cardiovascular disease (CVD) has urged the need for punctual and effective prevention. Extended research on this specific area has demonstrated the influence of fetal and neonatal periods on the risk of developing CVD in adulthood. Thus, the role of traditional and novel biological markers to the effective screening of CVD among the neonatal population is widely investigated. The objective of the present narrative review is to examine those neonatal biomarkers that may play a role in the development of CVD, to exhibit scientific data that appertain to their association with various perinatal conditions leading to CVD predisposition, and their potential role on prediction and prevention strategies. Multiple biomarkers, traditional and novel, have been mined across the studied literature. Adiposity, insulin resistance, altered lipid profile, inflammation, and endothelial dysfunction seem among the headliners of CVD. Even though various novel molecules have been studied, their clinical utility remains controversial. Therefore, it is quite important for the scientific community to find elements with strong predictive value and practical clinical use.

Vitamin B12 Deficiency (Un-)Detected Using Newborn Screening in Norway

Untreated vitamin B12 (B12) deficiency may cause delayed development in infants. Several newborn screening (NBS) programs have reported an increased detection rate of B12 deficiency when second-tier dried blood spot (DBS) analyses of total homocysteine (tHcy) and methylmalonic acid (MMA) are included. This is a retrospective study of newborns reported from NBS during 2012−2021 with confirmed B12 deficiency. DBSs were retrieved from the NBS biobank for second-tier MMA and tHcy analysis. Thirty-one newborns were diagnosed with B12 deficiency out of 552970 screened. Twenty-five were ascertained from sixty-one false positive (FP) cases of methylmalonic acidemia and propionic acidemia (PA), and six infants screened positive for other NBS metabolic diseases with propionylcarnitine (C3) in the normal range. In the original DBS, 7/23 (30%) and 12/23 (52%) of B12-deficient newborns with FP methylmalonic acidemia/PA had MMA and tHcy > 99th percentile. B12 deficiency was a common differential diagnosis of screening positive for methylmalonic and PA. C3 failed to identify a subset of newborns with B12 deficiency. Second-tier MMA and tHcy analyses in the DBS showed suboptimal sensitivity for identifying infants with B12 deficiency. The shortcomings of NBS should be acknowledged when considering B12 deficiency as a primary target of NBS panels.

Simultaneous estimation of total homocysteine and methylmalonic-acid using LC-MS/MS: Clinical application in adult and pediatric

Quantitative determination of biomarkers homocysteine (Hcy) and methylmalonic acid (MMA), the regulators of cobalamin (Cbl) and folate levels, together used as a biomarkers to diagnose chemical insufficiency/deficiency of Cbl and folate. We report simultaneous clinical estimation of total Hcy and MMA with efficient clean-up, sensitive and selective LC-MS/MS method. Efficient sample clean-up was achieved by a two-step extraction protocol with 100 μL serum. The validated method was applied to 893 clinical samples from 2 cohorts including pediatrics and mothers, respectively, for identifying their Cbl and folate status. The method shows excellent order of linearity for Hcy (22.2nM-3.7 μM) and MMA (42.34 nM - 5.92 μM), respectively. Complete method validation was performed where intraday-interday accuracy-precision and mean stability recovery data were found within ±15%. The validated method was extended for the quantification of serum total Hcy-MMA levels in clinical samples. The efficient extraction with negligible matrix-effect (ME) has reduced LC-MS/MS chocking and clean-up downtime. The rapid, sensitive and robust LC-MS/MS method has been successfully validated for simultaneous estimation of total Hcy and MMA using only 100 μL serum. The method was applicable to large number of clinical samples and was found to be good throughput with low contamination of mass detector, high sensitivity and selectivity.

Breastfed Infants With Spells, Tremor, or Irritability: Rule Out Vitamin B12 Deficiency

BACKGROUND

In Norway, 5-10% of neonates and infants have biomarkers suggesting vitamin B12 deficiency from newborn screening tests and unselected clinical screening, respectively.

AIMS

The aims were to identify risk factors and describe presenting symptoms and biochemical profiles in infants diagnosed with vitamin B12 deficiency.

METHODS

In this case-control study, we searched hospital medical records for infants younger than one year born in 2011-2018, diagnosed with vitamin B12 deficiency. We compared 85 cases with a control group of 252 infants aged 3-7 months. Parents completed questionnaires.

RESULTS

Of the 85 cases with vitamin B12 deficiency, 80% presented with spells (37%) of apneas, motor seizures, or absences within the first two months of life. Tremor (29%) and irritability (18%) were the most common findings at the first examination. Serum total homocysteine ≥10 μmol/L was found in 77% of cases compared to 28% of controls (P < 0.001). None of the mothers were vegetarians, but 25% reported a previous history of vitamin B12 deficiency and 7% had celiac disease. The dose of nitrous oxide given during labor was significantly associated with infant serum total homocysteine level at diagnosis (r = 0.37, 95% confidence interval = 0.16-0.55, P < 0.001) for cases, but not for controls.

CONCLUSION

Spells, tremor, and irritability are common findings in early infant vitamin B12 deficiency. Nitrous oxide given during labor is proposed as a contributing risk factor to the development of early infant vitamin B12 deficiency.

Reference Material for Hammersmith Infant Neurologic Examination Scores Based on Healthy, Term Infants Age 3-7 Months

OBJECTIVE

To provide a valid, continuous reference interval, including a 10th percentile cut-off, for Hammersmith Infant Neurological Examination (HINE) scores based on 3- to 7-month-old term infants with weight appropriate for gestational age.

STUDY DESIGN

In a prospective study, we examined 168 Norwegian infants at one timepoint with HINE at 3-7 months of age. In 134 of these infants Ages and Stages Questionnaire was completed by their parents at 2 years of age to ensure typical motor development. We calculated a reference interval for HINE scores with the 10th percentile as cut-off for age-dependent optimal scores.

RESULTS

The best fitting mean model for HINE total score was 78.1358 + 9659.231∗1/age in weeks²-5104.174∗natural logarithm(age in weeks)/age in weeks², which explained 49.8% of the variance. The HINE total score 10th percentile cut-off corresponded to 52.1 points at age 12 weeks, 55.6 points at 16 weeks, 59.0 points at 20 weeks, 61.8 points at 24 weeks, and 63.8 points at 28 weeks. We found an excellent intraclass correlation coefficient of 0.953 (0.931-0.968) between 2 examiners. The infants had a typical motor development at 2 years follow-up.

CONCLUSION

We have presented a valid, continuous reference interval and a 10th percentile cut-off for HINE scores for infants age 3-7 months.

Associations of variants of folate cycle genes with features of the clinical course of severe intraventricular hemorrhages in premature infants

BACKGROUND

Summary data indicate that it has increased attention to the study of the role of the folate cycle and the genes encoding its key components in the complicated course of the neonatal period in premature infants. Therefore, the aim of our study was to investigate the relationship of folate cycle gene variants with the features of the neonatal course in premature infants with severe intraventricular hemorrhages (IVH).

METHODS

The study included 24 preterm infants with with IVHs of 3d and 4th degree that received standard clinical, laboratory and instrumental examination.

RESULTS

Apgar scores at 1 and 5 minutes were significantly lower in patients with AA genotype according to variant A1298C of the MTHFR gene. The concentration of total protein on 6th day after birth was negatively correlated with the A66G variant of the MTRR gene. The mean concentration of ionized calcium in the first day after birth was higher in the subgroup of patients with the AA genotype (according to variant A1298C of the MTHFR gene). In the subgroup of patients requiring mechanical ventilation, the frequency of AA genotype according to variant A2756G of the MTR gene was significantly increased. The presence of respiratory disorders and oxygen dependence was negatively correlated with variant A1298C MTHFR. The day of surfactant administration was positively correlated with variant A1298C of the MTHFR gene.

CONCLUSION

The results of this study indicate that gene variants MTHFR (C677T, A1298C), MTRR (A66G), MTR (A2756G), RFC1 (G80A) may affect the neonatal course in premature infants with severe IVH.

Serum cobalamin concentrations in dogs infected with canine parvoviral enteritis

OBJECTIVE

To compare the serum cobalamin concentrations in canine parvovirus (CPV)-infected dogs with those of healthy control dogs.

Animals

45 dogs with CPV enteritis and 17 healthy age-matched control dogs.

Procedures

Infection was confirmed by visualization of CPV-2 through fecal electron microscopy. All dogs received supportive care. Serum samples taken at admission were used to determine cobalamin, C-reactive protein, and albumin concentrations.

Results

Serum cobalamin concentrations were significantly lower in the CPV-infected group (median [interquartile range], 173 pmol/L [< 111 to 722 pmol/L]) than in healthy control dogs (379 pmol/L [193 to > 738 pmol/L). There was no association between cobalamin concentration and C-reactive protein or albumin concentration.

Clinical Relevance

While hypocobalaminemia was common in CPV-infected dogs, the clinical relevance of this finding remains to be determined. Studies assessing markers of cellular cobalamin deficiency in dogs with CPV infection appear warranted.

Association of Maternal Vitamin B12 Status With Infant Findings and Neurodevelopment in Vitamin B12-Deficient Breast-fed Babies

Few studies have examined the association between maternal vitamin B12 status and their breast-fed infants' findings. The objective of this study was to analyze the association of maternal B12 status with infant findings including neurodevelopmental outcome in breast-fed babies with B12 deficiency. Correlation analyses between the laboratory findings of infants with B12 deficiency (n=120) and their mothers were performed and the association of maternal B12 status with infant findings including the Denver-II developmental screening test (DDST II) results was examined. There was a significant correlation between infant and maternal B12 levels (r=0.222; P=0.030), and between infant and maternal homocysteine (Hcy) levels (r=0.390; P<0.001). Among the babies 4 months of age or older, maternal Hcy levels were significantly correlated with infant mean corpuscular hemoglobin (r=0.404; P=0.001) and infant mean corpuscular volume (r=0.461; P<0.001). Mothers of infants with abnormal DDST II had lower vitamin B12 (196.9±41.2 vs. 247.0±77.0 pg/mL; P=0.018) and higher Hcy levels (17.3±5.0 vs. 10.7±3.1 µmol/L; P<0.001) than mothers of infants with normal DDST II. A lower maternal vitamin B12 status may be related to impaired neurodevelopment in breast-fed infants with vitamin B12 deficiency. Pregnant and lactating women should be offered easy access to healthy nutrition and vitamin B12 supplements.

The prevalence and clinical relevance of hyperhomocysteinemia suggesting vitamin B12 deficiency in presumed healthy infants

BACKGROUND

Previous studies have demonstrated a high prevalence of biochemical vitamin B12 deficiency in infants in Norway. Increased total homocysteine (tHcy) is the most important marker of B12 deficiency in infants. There is a need to evaluate its clinical relevance.

AIMS

To investigate the prevalence of hyperhomocysteinemia (S-tHcy > 8 μmol/L) suggestive of suboptimal B12 status and the prevalence of clinically relevant hyperhomocysteinemia in presumed healthy infants in Norway. Further, to evaluate risk factors, presence of symptoms and psychomotor development in these children.

METHODS

In a prospective study we clinically examined 252 infants aged 3-7 months using standardized neurological and psychomotor tests prior to analyzing biochemical B12 deficiency markers in 250 infants.

RESULTS

Twenty-five of 250 (10%) infants had hyperhomocysteinemia combined with clinically relevant symptoms suggestive of B12 deficiency. Hyperhomocysteinemia was associated with tremor, excessive sleep, and sub-normal scores in the fine motor section of the Ages and Stages Questionnaire. One-hundred and fourteen of 250 (46%) infants had hyperhomocysteinemia. Multiple regression analysis showed months of infant formula use as the strongest negative predictor for hyperhomocysteinemia.

CONCLUSION

We have demonstrated associations between symptoms suggestive of infant B12 deficiency and increased levels of tHcy in presumed healthy infants The combination of hyperhomocysteinemia and associated relevant symptoms suggestive of B12 deficiency was a common finding, albeit most infants with hyperhomocysteinemia did not show symptoms.

Extracellular cystine influences human preadipocyte differentiation and correlates with fat mass in healthy adults

Plasma cysteine is associated with human obesity, but it is unknown whether this is mediated by reduced, disulfide (cystine and mixed-disulfides) or protein-bound (bCys) fractions. We investigated which cysteine fractions are associated with adiposity in vivo and if a relevant fraction influences human adipogenesis in vitro. In the current study, plasma cysteine fractions were correlated with body fat mass in 35 adults. Strong positive correlations with fat mass were observed for cystine and mixed disulfides (r ≥ 0.61, P < 0.001), but not the quantitatively major form, bCys. Primary human preadipocytes were differentiated in media containing cystine concentrations varying from 10-50 μM, a range similar to that in plasma. Increasing extracellular cystine (10-50 μM) enhanced mRNA expression of PPARG2 (to sixfold), PPARG1, PLIN1, SCD1 and CDO1 (P = 0.042- < 0.001). Adipocyte lipid accumulation and lipid-droplet size showed dose-dependent increases from lowest to highest cystine concentrations (P < 0.001), and the malonedialdehyde/total antioxidant capacity increased, suggesting increased oxidative stress. In conclusion, increased cystine concentrations, within the physiological range, are positively associated with both fat mass in healthy adults and human adipogenic differentiation in vitro. The potential role of cystine as a modifiable factor regulating human adipocyte turnover and metabolism deserves further study.

Hematological findings associated with neurodevelopmental delay in infants with vitamin B12 deficiency

In adults with vitamin B12 deficiency, an inverse correlation between the severity of megaloblastic anemia and the degree of neurological dysfunction has been reported. We aimed to evaluate the association between hematological findings and the results of neurodevelopmental assessment in infants. Denver-II developmental screening test (DDST II) was performed in vitamin B12-deficient infants (n = 122), and its relationship with hematological findings was evaluated. DDST II was abnormal in 15 (12.3%), suspect in 20 (16.4%) and normal in 87 (71.3%) cases. Among the infants aged ≥ 4 months (n = 89), cases with an abnormal DDST II had lower levels of hemoglobin (7.49 ± 3.13 vs. 9.87 ± 1.77 g/dL; P = 0.015), whereas they had higher levels of mean corpuscular volume (MCV) (90.05 ± 19.31 vs. 69.90 ± 10.51 fL; P = 0.002), mean corpuscular hemoglobin (MCH) (28.96 ± 7.50 vs. 22.03 ± 4.58 pg; P = 0.001), homocysteine (44.31 ± 11.51 vs. 21.05 ± 9.23 µmol/L; P < 0.001), transferrin saturation index (25.84 ± 17.72 vs. 9.55 ± 6.38%; P = 0.004) and ferritin (87.28 ± 82.21 vs. 26.59 ± 31.67 ng/mL; P = 0.040) than those with a normal DDST II. The receiver operator characteristic analysis could distinguish infants with an abnormal DDST II from those with a normal DDST II by using a hemoglobin level < 8.75 g/dL [sensitivity: 71.4%, specificity: 76.4%; area under curve (AUC): 0.744], an MCV > 88.4 fL (sensitivity: 76.9%, specificity: 98.2%; AUC 0.813), an MCH > 28.5 pg (sensitivity: 76.9%, specificity: 96.4%; AUC: 0.822), and a homocysteine level > 27.35 µmol/L (sensitivity: 92.9%, specificity: 85.5%; AUC: 0.907). Even mild abnormalities of some commonly evaluated laboratory variables (such as MCV and MCH) in an infant should alert the physicians for the possibility of an underlying vitamin B12 deficiency with some degree of neurological impairment.

Vitamin B12 Deficiency Alters the Gut Microbiota in a Murine Model of Colitis

Purpose: Inflammatory bowel disease (IBD) refers to a spectrum of autoimmune diseases, which result in chronic intestinal inflammation. Previous findings suggest a role for diet, nutrition and dysbiosis of the gut microbiota in both the development and progression of the condition. Vitamin B12 is a key cofactor of methionine synthase and is produced solely by microbes. Previous work links increased levels of homocysteine, a substrate of methionine synthase, MetH, to IBD indicating a potential role for vitamin B12 deficiency in intestinal injury and inflammation. This study assessed the role of vitamin B12 in shaping the gut microbiota and determining responses to intestinal injury using a reproducible murine model of colitis. Methods: The effects of vitamin B12 supplementation and deficiency were assessed in vivo; 3-week-old post-weanling C57Bl/6 mice were divided into three dietary treatment groups: (1) sufficient vitamin B12 (50 mg/Kg), (2) deficient vitamin B12 (0 mg/Kg) and (3) supplemented vitamin B12 (200 mg/Kg) for a period of 4 weeks. Intestinal injury was induced with 2% dextran sodium sulphate (DSS) via drinking water for 5 days. The impact of varying levels of dietary vitamin B12 on gut microbiota composition was assessed using 16S rRNA gene sequencing from fecal samples collected at day 0 and day 28 of the dietary intervention, and 7 days following induction of colitis on day 38, when blood and colonic tissues were also collected. Results: No significant alterations were found in the gut microbiota composition of disease-free animals in response to dietary interventions. By contrast, after DSS-induced colitis, >30 genera were significantly altered in vitamin B12 deficient mice. Altered B12 levels produced no significant effect on composite disease-activity scores; however, administration of a B12 deficient diet resulted in reduced DSS-induced epithelial tissue damage. Conclusions: Vitamin B12 supplementation does not alter the gut microbiota composition under healthy conditions, but does contribute to differential microbial responses and intestinal dysbiosis following the induction of experimental colitis.

Novel method for l-methionine determination using l-methionine decarboxylase and application of the enzyme for l-homocysteine determination

Abbreviations

DTT: dithiothreitol; IPTG: isopropyl-β-d-thiogalactopyranoside; KPB: potassium phosphate buffer; MBTH: 3-methyl-2-benzothiazolinonehydrazone; mdc: the gene coding l-methionine decarboxylase; MetDC: l-methionine decarboxylase; mgl: the gene coding l-methionine γ-lyase; MGL: l-methionine γ-lyase; PLP: pyridoxal 5ʹ-phosphate

Vitamin B12, Folate, and Cognition in 6- to 9-Year-Olds: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Vitamin B₁₂ and folate are important for normal brain development. Our objective for this study was to measure the effects of 6-month supplementation of vitamin B₁₂ and/or folic acid in early childhood on cognition when the children were 6 to 9 years old.

METHODS

The study is a follow-up of a factorial randomized, double-blind, placebo-controlled trial in 1000 North Indian children. Children 6 to 30 months of age were randomly assigned to receive a placebo or 1.8 µg of vitamin B₁₂, 150 mg of folic acid, or both daily for 6 months. After 6 years, we re-enrolled 791 of these children for cognitive assessments. We compared the scores of the main outcomes (the Wechsler Intelligence Scale for Children, Fourth Edition [India], the Crichton Verbal Scale, and subtests of the NEPSY-II) between the study groups. We also measured the associations between markers of the B vitamins (plasma cobalamin, folate, and total homocysteine concentrations) in early childhood and the cognitive outcomes.

RESULTS

There were no differences between the intervention groups and the placebo group on the cognitive outcomes. Plasma cobalamin, folate, and total homocysteine concentrations in early childhood were associated with the cognitive outcomes at follow-up in the unadjusted models. These associations disappeared in models adjusted for relevant confounders.

CONCLUSIONS

Our findings, from both an observational and a randomized design suggest that vitamin B₁₂ and folate in children 6 to 36 months have limited public health relevance for long-term cognition.

Vitamin B12 deficiency associated with hyperbilirubinemia and cholestasis in infants

Objective:

To study the correlation between vitamin B12 deficiency and hyperbilirubinemia and cholestasis in infants.

Methods:

The study group consisted of 215 infants who were tested for serum B12 and bilirubin levels out of 335 cases referred to the Centre from June 2011 to 2016 as a part of the screening program established by the Ministry of Health. The following information was obtained from the case files: demographic data; background; family history; serum vitamin B12, folate, plasma homocysteine, and urine methylmalonic acid (MMA) levels; and direct, indirect, and total bilirubin levels.

Results:

About 48.8 percent of cases had vitamin B12 deficiency. No significant differences were found when those cases with vitamin B12 deficiency and those without vitamin B12 deficiency were compared in terms of total, direct, or indirect bilirubin levels. Only two cases (0.9 percent) had cholestasis.

Conclusion:

The study suggests vitamin B12 deficiency is a common phenomenon (48.4 percent), similar to what has been suggested by other studies conducted in Turkey. Therefore, the presence of vitamin B12 deficiency in cases with cholestasis or hyperbilirubinemia may show an association. To prove the correlation between them, more studies are required.

Association between Maternal and Infantile Markers of Cobalamin Status During the First Month Post-Delivery

OBJECTIVE

Exclusively breast-fed infants born to vitamin B12 (cobalamin, cbl)-deficient mothers can develop symptoms within a few months following delivery. The authors aimed to assess the relationship between maternal and infantile markers of cbl status.

METHODS

In 240 full-term infants (age, 2-30 d) admitted to Samsun Maternity and Child Health Hospital and their mothers, complete blood count testing and serum cbl, folate and plasma total homocysteine (tHcy) measurements were performed. In the mothers, serum ferritin and holotranscobalamin (holoTC) levels were measured additionally.

RESULTS

Among the infants, 146 (60.8%) had cbl deficiency (serum cbl <259 pg/mL), whereas 184 (76.7%) mothers had a low cbl level (serum cbl <300 pg/mL). When cbl deficiency was defined as a serum holoTC level < 40 pmol/L, 152 (63.3%) mothers were found as deficient. In addition, 147 (61.3%) infants had an elevated tHcy level (>10 μmol/L), in 35 (23.8%) of these 147 infants tHcy level being markedly elevated (>20 μmol/L). None of the infants had folate deficiency. In the correlational analysis between maternal and infantile markers associated with cbl status, the strongest correlation was observed between maternal holoTC and infantile tHcy (r = -0.49, p < 0.001), followed by the correlation between maternal tHcy and infantile tHcy (r = 0.47, p < 0.001). The weakest correlations were found between maternal cbl and infantile cbl (r = 0.28, p < 0.001), and between maternal cbl and infantile tHcy (r = -0.25, p < 0.001).

CONCLUSIONS

Maternal cbl status is an important determinant of infantile cbl status. Both maternal holoTC and tHcy may assist in predicting infantile cbl status. The finding of high prevalence of maternal and infantile cbl deficiency in this study points towards the need for effective strategies to prevent cbl deficiency in women prior to getting pregnant.

High incidence of low vitamin B12 levels in Estonian newborns

Vitamin B12 deficiency seems to be more common worldwide than previously thought. However, only a few reports based on data from newborn screening (NBS) programs have drawn attention to that subject. In Estonia, over the past three years, we have diagnosed 14 newborns with congenital acquired vitamin B12 deficiency. Therefore, the incidence of that condition is 33.8/100,000 live births, which is considerably more than previously believed. None of the newborns had any clinical symptoms associated with vitamin B12 deficiency before the treatment, and all biochemical markers normalized after treatment, which strongly supports the presence of treatable congenital deficiency of vitamin B12. During the screening period, we began using actively ratios of some metabolites like propionylcarnitine (C3) to acetylcarnitine (C2) and C3 to palmitoylcarnitine (C16) to improve the identification of newborns with acquired vitamin B12 deficiency. In the light of the results obtained, we will continue to screen the congenital acquired vitamin B12 deficiency among our NBS program. Every child with aberrant C3, C3/C2 and C3/C16 will be thoroughly examined to exclude acquired vitamin B12 deficiency, which can easily be corrected in most cases.

Paediatric reference values for total homocysteine, tryptophan, tyrosine and phenylalanine in blood spots

Determining blood concentrations of the amino acids homocysteine, tryptophan, tyrosine and phenylalanine in children is of value in the clinical practice. Over the past decades, the use of blood spot samples to examine amino acid concentrations is increasing rapidly. In children, the use of blood spot samples is especially of relevance, as this method is much less invasive than venous blood sampling. Currently, no paediatric reference values for amino acids in blood spots are available. The aim of the current study was to establish reference values for blood spot concentrations of total homocysteine, tryptophan, tyrosine and phenylalanine in school-age children. Dried blood spots were obtained in a community sample of 104 healthy children, aged 6-12 years old (52% males). Blood spot concentrations of total homocysteine, tryptophan, tyrosine and phenylalanine were determined by positive electrospray liquid chromatography-tandem mass spectrometry. Parents of participants completed questions regarding demographic characteristics. Our sample consisted of healthy children from various ethnic backgrounds, with varying levels of socioeconomic status, in line with the composition of the Dutch society. Blood spot concentrations of total homocysteine, tryptophan, tyrosine and phenylalanine were similar in males and females, and independent of age. In conclusion, paediatric reference values for blood spot concentrations of total homocysteine, tryptophan, tyrosine and phenylalanine were established, which could be of use in the clinical practice.

Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency

BACKGROUND

Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions.

OBJECTIVE

To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management.

DATA SOURCES

Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach.

KEY RECOMMENDATIONS

We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early.

Exploring the Lean Phenotype of Glutathione-Depleted Mice: Thiol, Amino Acid and Fatty Acid Profiles

BACKGROUND

Although reduced glutathione (rGSH) is decreased in obese mice and humans, block of GSH synthesis by buthionine sulfoximine (BSO) results in a lean, insulin-sensitive phenotype. Data is lacking about the effect of BSO on GSH precursors, cysteine and glutamate. Plasma total cysteine (tCys) is positively associated with stearoyl-coenzyme A desaturase (SCD) activity and adiposity in humans and animal models.

OBJECTIVE

To explore the phenotype, amino acid and fatty acid profiles in BSO-treated mice.

DESIGN

Male C3H/HeH mice aged 11 weeks were fed a high-fat diet with or without BSO in drinking water (30 mmol/L) for 8 weeks. Amino acid and fatty acid changes were assessed, as well as food consumption, energy expenditure, locomotor activity, body composition and liver vacuolation (steatosis).

RESULTS

Despite higher food intake, BSO decreased particularly fat mass but also lean mass (both P<0.001), and prevented fatty liver vacuolation. Physical activity increased during the dark phase. BSO decreased plasma free fatty acids and enhanced insulin sensitivity. BSO did not alter liver rGSH, but decreased plasma total GSH (tGSH) and rGSH (by ~70%), and liver tGSH (by 82%). Glutamate accumulated in plasma and liver. Urine excretion of cysteine and its precursors was increased by BSO. tCys, rCys and cystine decreased in plasma (by 23-45%, P<0.001 for all), but were maintained in liver, at the expense of decreased taurine. Free and total plasma concentrations of the SCD products, oleic and palmitoleic acids were decreased (by 27-38%, P <0.001 for all).

CONCLUSION

Counterintuitively, block of GSH synthesis decreases circulating tCys, raising the question of whether the BSO-induced obesity-resistance is linked to cysteine depletion. Cysteine-supplementation of BSO-treated mice is warranted to dissect the effects of cysteine and GSH depletion on energy metabolism.

Interactions between lifestyle and MTHFR polymorphisms on homocysteine concentrations in young adults belonging to the 1982 Pelotas Birth Cohort

BACKGROUND/OBJECTIVES

Homocysteine (Hcy) is a key intermediate in methionine metabolism. A high plasma concentration of Hcy is an independent risk factor for cardiovascular diseases among other determinants. In this study, we aimed to investigate the interactions between methylenetetrahydrofolate reductase enzyme gene (MTHFR) polymorphisms and lifestyle variables (smoking, alcohol intake and physical activity) on Hcy concentrations in a young Brazilian population.

SUBJECTS/METHODS

The study population comprised 3803 individuals from the Pelotas Birth Cohort, aged 22-23 years. Allelic discrimination assays and chemiluminescence immunoassays were performed for genotyping and serum Hcy measurements, respectively. Linear regression models were used to explore the effect of gene-lifestyle interactions on Hcy concentrations.

RESULTS

Men carrying the MTHFR 677TT genotype, who were also smokers and drinkers (⩾15 g of alcohol per day), had the highest concentration of Hcy (P-value for the interaction <0.001 for smoking and 0.002 for alcohol intake). In contrast, high folate concentrations attenuated the effects of the MTHFR C677T genotype on serum Hcy concentrations (P-value for interaction <0.001). Also, among males, blood folate concentration was the only lifestyle variable able to modify the influence of MTHFR A1298C genotypes on Hcy concentrations (P-value for the interaction <0.001). There was no strong evidence of an interaction between the MTHFR genotypes and the lifestyle variables in women.

CONCLUSIONS

In summary, our study demonstrates a sex difference in Hcy concentrations among Brazilian young adults regarding MTHFR C677T-lifestyle interactions that are worsened under conditions of low blood folate. Identification of potentially modifiable factors related to an increase in homocysteine in young adults, especially in those who are genetically susceptible, is important to prevent negative health consequences in the future.

Vitamin B12, Folate, Homocysteine and Urinary Methylmalonic Acid Levels in Infants

Serum vitamin B12 and folate, and their functional markers, plasma homocysteine and urinary methylmalonate (uMMA) were measured in 204 healthy, term infants at birth, and at 2 and 6 months. Compared with infants receiving formula food, those fed mother's milk had lower vitamin B12 and folate at 2 and 6 months. In infants receiving mother's milk, vitamin B12 levels were similar at birth (238 pg/ml) and 2 months (243 pg/ml), whereas with formula milk the level was significantly higher at 2 months (558 pg/ml) than at birth (257 pg/ml). Vitamin B12 was negatively correlated with homocysteine at birth and 6 months. The level of uMMA (mmol/mol creatinine) was higher at 2 (mother's milk, 25.5; formula, 23.97) and 6 months (19.77; 15) than at birth (11.97; 10.88), and was not correlated with vitamin B12 levels. Homocysteine may be a reliable marker of vitamin B12 status in neonates and infants; however, uMMA is not suitable as a marker of vitamin B12 status.

Amino acid changes during transition to a vegan diet supplemented with fish in healthy humans

Purpose

To explore whether changes in dietary protein sources can lower plasma branched-chain amino acids (BCAAs), aromatic amino acids and sulfur amino acids (SAAs) that are often elevated in the obese, insulin-resistant state and in type 2 diabetes.

Methods

Thirty-six subjects (mean age 31 ± 2 years) underwent a voluntary abstinence from meat, poultry, eggs, and dairy products for 6 weeks, while enriching the diet with fish, in fulfillment of a religious fast. Subjects were assessed 1 week before the fast (V1), 1 week after initiation of the fast (V2) and in the last week of the fast (V3). Thirty-four subjects completed all three visits.

Results

Fasting plasma BCAAs decreased at V2 and remained low at V3 (P < 0.001 for all). Valine showed the greatest decline, by 20 and 19 % at V2 and V3, respectively. Phenylalanine and tryptophan, but not tyrosine, also decreased at V2 and V3. The two proteinogenic SAAs, methionine and cysteine, remained stable, but the cysteine product, taurine, decreased from 92 ± 7 μmol/L to 66 ± 6 (V2; P = 0.003) and 65 ± 6 μmol/L (V3; P = 0.003). A progressive decline in plasma glutamic acid, coupled with an increase in glutamine, was observed. Plasma total and LDL cholesterol decreased at V2 and V3 (P < 0.001 for all).

Conclusion

Changing dietary protein sources to plant- and fish-based sources in an ad libitum setting lowers the plasma BCAAs that have been linked to diabetes risk. These findings point to habitual diet as a potentially modifiable determinant of fasting plasma BCAA concentrations.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-016-1237-6) contains supplementary material, which is available to authorized users.

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.

Vitamin B12 and Folic Acid Improve Gross Motor and Problem-Solving Skills in Young North Indian Children: A Randomized Placebo-Controlled Trial

Objectives

Deficiencies of vitamin B12 and folate are associated with delayed development and neurological manifestations. The objective of this study was to measure the effect of daily supplementation of vitamin B12 and/or folic acid on development in young North Indian children.

Methods

In a randomized, double blind trial, children aged six to 30 months, received supplement with placebo or vitamin B12 and/or folic acid for six months. Children were allocated in a 1:1:1:1 ratio in a factorial design and in blocks of 16. We measured development in 422 children by the Ages and Stages Questionnaire 3rd ed. at the end of the intervention.

Results

Compared to placebo, children who received both vitamin B12 and folic acid had 0.45 (95% CI 0.19, 0.73) and 0.28 (95% CI 0.02, 0.54) higher SD-units in the domains of gross motor and problem solving functioning, respectively. The effect was highest in susceptible subgroups consisting of stunted children, those with high plasma homocysteine (> 10 μmol/L) or in those who were younger than 24 at end study. With the exception of a significant improvement on gross motor scores by vitamin B12 alone, supplementation of either vitamin alone had no effect on any of the outcomes.

Conclusion

Our findings suggest that supplementation of vitamin B12 and folic acid benefit development in North Indian Children.

Trial Registration

ClinicalTrials.gov NCT00717730

Maternal vitamin B12 deficiency detected in expanded newborn screening

OBJECTIVES

Besides the inherited form, vitamin B(12) deficiency may be due to diet restrictions or abnormal absorption. The spread of newborn screening programs worldwide has pointed out that non-inherited conditions are mainly secondary to a maternal deficiency. The aim of our work was to study seven cases of acquired vitamin B12 deficiency detected during our newborn screening project. Moreover, we aimed to evaluate vitamin B(12) and related biochemical parameters status on delivering female to verify the consequences on newborns of eventually altered parameters.

DESIGN AND METHODS

35,000 newborns were screened; those showing altered propionyl carnitine (C3) underwent second-tier test for methylmalonic acid (MMA) on dried blood spot (DBS). Subsequently, newborns positive to the presence of MMA on DBS and their respective mothers underwent further tests: serum vitamin B(12), holo-transcobalamin (Holo-TC), folate and homocysteine; newborns were also tested for urinary MMA content. A control study was conducted on 203 females that were tested for the same parameters when admitted to hospital for delivery.

RESULTS

Approximately 10% of the examined newborns showed altered C3. Among these, seven cases of acquired vitamin B(12) deficiency were identified (70% of the MMA-positive cases). Moreover, our data show a high frequency of vitamin B(12) deficiency in delivering female (approximately 48% of examined pregnants).

CONCLUSIONS

We suggest to monitor vitamin B(12) and Holo-TC until delivery and to reconsider the reference interval of vitamin B(12) for a better identification of cases at risk. Finally, newborns from mothers with low or borderline levels of vitamin B(12) should undergo second-tier test for MMA; in the presence of MMA they should be supplemented with vitamin B(12) to prevent adverse effects related to vitamin B(12) deficiency.

Simultaneous determination of cystathionine, total homocysteine, and methionine in dried blood spots by liquid chromatography/tandem mass spectrometry and its utility for the management of patients with homocystinuria

BACKGROUND

Disorders of homocysteine and B-vitamin metabolism represent a significant problem in clinical practice. Establishing the diagnosis requires specialized tests with demanding preanalytical requirements. To advance the detection of patients with these disorders, we developed a method for the simultaneous determination of cystathionine (Cysta), methionine (Met) and total homocysteine (tHcy) in dried blood spots (DBSs).

METHODS

A punch from a DBS sample was mixed with a solution of isotopically labeled internal standards, and analytes were extracted using methanol/0.1% formic acid/0.5mol/L dithiothreitol. The extract was injected into an LC-MS/MS system operating in MRM mode.

RESULTS

The analytical performance of the method employing DBS is adequate for its purpose and the type of sample. Compared with Cysta, tHcy and Met plasma levels, our method exhibited a negative bias between -3.8% and -42.2% due to the lower concentrations of these analytes in erythrocytes. The tHcy level and the Met/Cysta ratio in DBS enabled the clear detection of 12 patients with disorders of transsulfuration and with genetic and nutritional remethylation defects.

CONCLUSIONS

The ease of collecting and transporting DBS samples may advance diagnostic procedures in patients with neuropsychiatric disorders and thromboembolism. Consequently, this approach may facilitate detection and simplify the monitoring of patients with homocystinuria.

Gene-environment interactions in severe intraventricular hemorrhage of preterm neonates

Intraventricular hemorrhage (IVH) of the preterm neonate is a complex developmental disorder, with contributions from both the environment and the genome. IVH, or hemorrhage into the germinal matrix of the developing brain with secondary periventricular infarction, occurs in that critical period of time before the 32nd to 33rd wk postconception and has been attributed to changes in cerebral blood flow to the immature germinal matrix microvasculature. Emerging data suggest that genes subserving coagulation, inflammatory, and vascular pathways and their interactions with environmental triggers may influence both the incidence and severity of cerebral injury and are the subject of this review. Polymorphisms in the Factor V Leiden gene are associated with the atypical timing of IVH, suggesting an as yet unknown environmental trigger. The methylenetetrahydrofolate reductase (MTHFR) variants render neonates more vulnerable to cerebral injury in the presence of perinatal hypoxia. The present study demonstrates that the MTHFR 677C>T polymorphism and low 5-min Apgar score additively increase the risk of IVH. Finally, review of published preclinical data suggests the stressors of delivery result in hemorrhage in the presence of mutations in collagen 4A1, a major structural protein of the developing cerebral vasculature. Maternal genetics and fetal environment may also play a role.

Dietary practices in pyridoxine non-responsive homocystinuria: a European survey

BACKGROUND

Within Europe, the management of pyridoxine (B6) non-responsive homocystinuria (HCU) may vary but there is limited knowledge about treatment practice.

AIM

A comparison of dietetic management practices of patients with B6 non-responsive HCU in European centres.

METHODS

A cross-sectional audit by questionnaire was completed by 29 inherited metabolic disorder (IMD) centres: (14 UK, 5 Germany, 3 Netherlands, 2 Switzerland, 2 Portugal, 1 France, 1 Norway, 1 Belgium).

RESULTS

181 patients (73% >16 years of age) with HCU were identified. The majority (66%; n=119) were on dietary treatment (1-10 years, 90%; 11-16 years, 82%; and >16 years, 58%) with or without betaine and 34% (n=62) were on betaine alone. The median natural protein intake (g/day) on diet only was, by age: 1-10 years, 12 g; 11-16 years, 11 g; and >16 years, 45 g. With diet and betaine, median natural protein intake (g/day) by age was: 1-10 years, 13 g; 11-16 years, 20 g; and >16 years, 38 g. Fifty-two percent (n=15) of centres allocated natural protein by calculating methionine rather than a protein exchange system. A methionine-free l-amino acid supplement was prescribed for 86% of diet treated patients. Fifty-two percent of centres recommended cystine supplements for low plasma concentrations. Target treatment concentrations for homocystine/homocysteine (free/total) and frequency of biochemical monitoring varied.

CONCLUSION

In B6 non-responsive HCU the prescription of dietary restriction by IMD centres declined with age, potentially associated with poor adherence in older patients. Inconsistencies in biochemical monitoring and treatment indicate the need for international consensus guidelines.

Plasma sulfur amino acids and stearoyl-CoA desaturase activity in two Caucasian populations

In rats, dietary restriction of the cysteine precursor methionine suppresses hepatic stearoyl-CoA desaturase (SCD)-1 expression and activity, whereas cysteine supplementation reverses these effects. In 2 independent cohorts: Hordaland Health Study (HUSK; N=2021, aged 71-74y), Norway, and Hoorn study (N=686, aged 50-87y), Netherlands, we examined the cross-sectional associations of plasma sulfur-containing compounds (SCC; methionine, S-adenosylmethionine, S-adenosylhomocysteine, homocysteine, cystathionine, total cysteine (tCys), glutathione and cysteinylglycine) with SCD-16 index (16:1n-7/16:0), estimated from fatty acid profiles of total plasma or serum lipids. Only tCys was consistently associated with SCD-16 index after adjustments for sex and age (HUSK: partial r=0.14; Hoorn: partial r=0.11, P<0.001 for both), and after further adjustments for other SCC, body fat, diet, exercise and plasma lipids (HUSK: partial r=0.07, P=0.004; Hoorn: partial r=0.12, P=0.013). Together with animal data showing an effect of dietary cysteine on SCD1, our results suggest a role for cysteine in SCD1 regulation in humans.

The impact of genetic and environmental factors on homocysteine levels in preterm neonates

BACKGROUND

Hyperhomocysteinemia may be associated with vascular complications in adults. Whereas pediatric thrombosis risk peaks in neonates, data on homocysteine (Hcy) levels assessed in term and preterm infants during the perinatal period are scarce. In the present study, we aimed to establish Hcy reference values for preterm infants and study their potential associations with the early post-natal health status. Plasma Hcy and hematocrit levels and MTHFR polymorphisms (C677T and A1298C substitution) were studied in a large cohort of preterm infants in a tertiary referral medical center during an 18-month period. Data were collected on maternal history and delivery as well as on post-natal complications.

RESULTS

The study cohort included 167 infants whose mean gestational age was 30.98 ± 2.34 weeks (range: 26-36 weeks), mean birth weight 1327.6 ± 327 g, and mean Hcy level 7.99 ± 3.27 (range: 2.2-21.2) µmol/L. Maternal intake of folic acid was inversely associated with the babies' Hcy levels (P = 0.0001). Increased Hcy levels positively correlated with birth weight, gestational age (P < 0.005), total number of pregnancies (P = 0.012), and presence of MTHFR polymorphism. Higher Hcy levels were associated with feeding (P = 0.008), especially total parenteral nutrition (P = 0.0001). There was no correlation between Hcy levels and any vascular post-natal complications.

CONCLUSIONS

During their post-natal hospitalization, preterm infants may have relatively high, that is, within the adult normal range, Hcy levels which are influenced by genetic and environmental factors. Despite the fact that no correlation was found between Hcy levels and post-natal complications, these associations should be further studied.

Role of thrombophilic factors in full-term infants with neonatal encephalopathy

BACKGROUND

Neonatal encephalopathy (NE) is a serious condition, primarily seen following hypoxia-ischemia (HI). Two different patterns of brain injury can be recognized on magnetic resonance imaging (MRI): white matter/watershed (WM/WS) or basal ganglia/thalamus (BGT) injury. Whether these patterns of injury can be attributed to different associated risk factors still needs to be established.

METHODS

In 118 infants with clinical signs of NE following perinatal HI, thrombophilic factors, such as factor V Leiden and prothrombin gene mutation, C677T and A1298C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, and plasma levels of homocysteine and lipoprotein(a), were prospectively investigated. Antenatal and perinatal variables were studied.

RESULTS

WM/WS injury was seen in 45 infants, BGT injury in 40, and normal neuroimaging in 33. Antenatal factors did not differ across these groups. The BGT pattern was associated with lower Apgar scores, whereas the WM/WS pattern was associated with hypoglycemia (<2.0 mmol/l), CT or TT 677 polymorphism in the MTHFR gene, and plasma homocysteine levels in the upper quartile.

CONCLUSION

In infants with NE following perinatal HI, the WM/WS pattern of injury was associated with hypoglycemia, the MTHFR 677CT or TT genotype, and higher levels of plasma homocysteine. BGT injury showed an association with signs suggestive of acute HI.

The association of fasting plasma sulfur-containing compounds with BMI, serum lipids and apolipoproteins

BACKGROUND AND AIM

Sulfur amino acids are recognized as potent modulators of lipid metabolism. Plasma total cysteine (tCys) is associated with fat mass, obesity and serum LDL-cholesterol and apolipoprotein (Apo)-B in large population studies. It is not known how fasting plasma concentrations of cysteine precursors and products relate to these associations in humans, given that sulfur-containing compounds (SCC) influence rodent weight gain and serum lipids.

METHODS AND RESULTS

We investigated the cross-sectional associations of fasting plasma SCC (methionine, total homocysteine, cystathionine, tCys, taurine and total glutathione) with BMI and fasting serum lipids and apolipoproteins in 854 men and women with and without cardiovascular disease (CVD). In multiple linear regression analysis adjusted for age, gender, CVD and other SCC, neither methionine, taurine, nor total glutathione was associated with BMI. Plasma taurine was, however, inversely related to HDL-cholesterol (partial r = -0.12, p = 0.004) and its associated apoA1 (partial r = -0.18, p < 0.001). Plasma cystathionine correlated positively with triglycerides and BMI, while tCys positively correlated with total cholesterol, LDL-cholesterol (partial r = 0.20, p < 0.001) and its associated apoB. The associations of SCC with serum lipids were independent of BMI. tCys was also independently associated with BMI (partial r = 0.20, p < 0.001) after adjustment for other SCC, glucose, lipids and apolipoproteins.

CONCLUSIONS

Fasting tCys is associated with BMI independently of metabolically related SCC. Elevation of plasma SCC is generally associated with an unfavorable lipid profile. The negative relations of plasma taurine with HDL-C and apoA1 deserve further investigation.

The Association between Serum Homocysteine Levels and Retinopathy of Prematurity

Objective:

To evaluate the relationship between serum total homocysteine levels and retinopathy of prematurity (ROP).

Methods:

This prospective case-control study involved premature infants diagnosed with ROP 4 weeks after birth (cases); controls were premature infants not developing ROP during follow-up. Fasting serum total homocysteine concentrations were determined in all participants 4 weeks after birth, using high performance liquid chromatography.

Results:

A total of 45 and 35 infants were included in the case and control groups, respectively. The mean ± SD (range) serum total homocysteine levels were 10.36 ± 1.72 μmol/l (7.45 - 14.84) in infants with ROP and 8.41 ± 2.12 μmol/l (5.56 - 13.90) in controls. This difference was statistically significant. Mean ± SD total homocysteine levels were higher in infants with more severe ROP (11.45 ± 1.76 μmol/l) compared with mild ROP (9.92 ± 1.56 μmol/l).

Conclusions:

Elevated serum total homocysteine levels are associated with the development of ROP in premature infants. Further studies with larger patient populations are required, to improve understanding of the relationship between homocysteine and ROP development.

Cobalamin deficiency

Cobalamin (Cbl, vitamin B12) consists of a corrinoid structure with cobalt in the centre of the molecule. Neither humans nor animals are able to synthesize this vitamin. Foods of animal source are the only natural source of cobalamin in human diet. There are only two enzymatic reactions in mammalian cells that require cobalamin as cofactor. Methylcobolamin is a cofactor for methionine synthase. The enzyme methylmalonyl-CoA-mutase requires adenosylcobalamin as a cofactor. Therefore, serum concentrations of homocysteine (tHcy) and methylmalonic acid (MMA) will increase in cobalamin deficiency. The cobalamin absorption from diet is a complex process that involves different proteins: haptocorrin, intrinsic factor and transcobalamin (TC). Cobalamin that is bound to TC is called holotranscobalamin (holoTC) which is the metabolically active vitamin B12 fraction. HoloTC consists 6 and 20% of total cobalamin whereas 80% of total serum cobalamin is bound to another binding protein, haptocorrin. Cobalamin deficiency is common worldwide. Cobalamin malabsorption is common in elderly subjects which might explain low vitamin status. Subjects who ingest low amount of cobalamin like vegetarians develop vitamin deficiency. No single parameter can be used to diagnose cobalamin deficiency. Total serum cobalamin is neither sensitive nor it is specific for cobalamin deficiency. This might explain why many deficient subjects would be overlooked by utilizing total cobalamin as status marker. Concentration of holotranscobalamin (holoTC) in serum is an earlier marker that becomes decreased before total serum cobalamin. Concentrations of MMA and tHcy increase in blood of cobalamin deficient subjects. Despite limitations of these markers in patients with renal dysfunction, concentrations of MMA and tHcy are useful functional markers of cobalamin status. The combined use of holoTC and MMA assays may better indicate cobalamin status than either of them. Because Cbl deficiency is a risk factor for neurodegenerative diseases an early diagnosis of a low B12 status is required which should be followed by an effective treatment in order to prevent irreversible damages.

Dietary cystine level affects metabolic rate and glycaemic control in adult mice

Plasma total cysteine (tCys) is strongly and independently associated with obesity in large human cohorts, but whether the association is causal is unknown. Dietary cyst(e)ine increases weight gain in some rodent models. We investigated the body composition, metabolic rate and metabolic phenotype of mature C3H/HeH mice assigned to low-cystine (LC) or high-cystine (HC) diets for 12 weeks.

Compared to LC mice, HC mice gained more weight (P=.004 for 12-week weight gain %), with increased fat mass and lean mass, and lowered O₂ consumption and CO₂ production by calorimetry. The HC mice had 30% increase in intestinal fat/body weight % (P=.003) and ∼twofold elevated hepatic triglycerides (P=.046), with increased expression of hepatic lipogenic factors, peroxisome proliferator-activated receptor-γ and sterol regulatory element binding protein-1. Gene expression of both basal and catecholamine-stimulated lipolytic enzymes, adipose triglyceride lipase and hormone-sensitive lipase was inhibited in HC mice adipose tissue. The HC mice also had elevated fasting glucose (7.0 vs. 4.5 mmol/L, P<.001) and a greater area under the curve (P<.001) in intraperitoneal glucose tolerance tests, with enhanced expression of the negative regulator of insulin signaling, protein tyrosine phosphatase-1B, in liver and adipose tissue.

Overall, high cystine intake promotes adiposity and an adverse metabolic phenotype in mice, indicating that the positive association of plasma tCys with obesity in humans may be causal.

Folate and cobalamin status in relation to diet in healthy 2-y-old children

BACKGROUND

Limited data exist on sources of folate and cobalamin in the toddler diet.

OBJECTIVE

We examined the influence of diet on folate and cobalamin status in healthy toddlers in an unfortified population.

DESIGN

Dietary intake was assessed in 178 children, aged 24 mo, by using 7-d food records and related to serum folate and cobalamin status in 155 children.

RESULTS

Median (25th-75th percentile) daily intakes of folate and cobalamin were 87 μg (74-104 μg) and 3.1 μg (2.4-3.8 μg), respectively. Thirty-five percent of subjects had a folate intake below the Norwegian recommendations (80 μg folate/d), but only 5.8% of subjects had low serum folate concentrations (<10 nmol/L). All children reached the recommended cobalamin intake (0.8 μg cobalamin/d). Median (25th-75th percentile) serum concentrations were as follows: folate, 19 nmol/L (14-24 nmol/L); cobalamin, 410 pmol/L (334-521 pmol/L); holotranscobalamin, 94 pmol/L (67-121 pmol/L); holohaptocorrin, 315 pmol/L (241-409 pmol/L); methylmalonic acid, 0.16 μmol/L (0.13-0.20 μmol/L); and total homocysteine, 5.0 μmol/L (4.2-5.7 μmol/L). Folate intake correlated with serum folate concentrations (ρ = 0.25, P < 0.01), and cobalamin intake correlated with serum holotranscobalamin concentrations (ρ = 0.21, P < 0.05). In multivariate models, serum folate concentrations were significantly positively associated with the consumption of fruit and berries and grain products; however, this was not the case with dairy products, which was the food group that contributed most to folate intake. Cobalamin status was associated with dairy products (cobalamin and holotranscobalamin), cobalamin supplements (cobalamin and holohaptocorrin), and liver pâté (holotranscobalamin).

CONCLUSIONS

In this unfortified toddler population, folate status was associated with intakes of fruit and berries and grain products. Cobalamin status was associated with intakes of dairy, liver pâté, and supplements. In the assessment of vitamin sources, vitamin availability must be considered.

The effect of folinic acid supplementation on homocysteine concentrations in newborns

OBJECTIVE

The incidence of cerebrovascular accidents (CVA) occurring perinatally is relatively high and aspects of the multifactorial pathophysiology remain unclear. Elevated homocysteine concentrations have been shown to be associated with an increased risk for CVA in children and even in newborns. We studied the possible homocysteine lowering effect of folinic acid in newborns.

METHOD

We included 37 newborns in our prospective randomized folinic acid (given as 5-formyltetrahydrofolate) intervention study from patients admitted to our neonatal intensive care unit (18 controls, 19 intervention group). We measured total homocysteine (tHcy) and plasma folate concentrations at three time points (baseline, 1 and 2 weeks after intervention). The intervention group was treated with folinic acid (70 μg/kg/day) for 2 weeks. We calculated median concentrations (25th and 75th percentiles).

RESULTS

Median tHcy concentrations at the three time points did not differ from each other in the control group nor in the intervention group. We also could not observe different tHcy concentrations between both groups. Plasma folate concentrations increased in the intervention group (mean increase 167% (95% confidence interval (CI) -291, 625)) compared with control group (mean increase -12% (95% CI -132, 108)), P for treatment effect: 0.03.

CONCLUSION

We could not demonstrate a homocysteine lowering effect of folinic acid administration in newborns. This indicates that one carbon metabolism in newborns differs form adults. Cobalamin might be a better strategy to lower tHcy concentrations in newborns.

Maternal folate and cobalamin status predicts vitamin status in newborns and 6-month-old infants

Our aim in this longitudinal study was to determine predictors of folate and cobalamin status in infancy. Data were collected from 364 mother-infant pairs with blood measurements from pregnancy ( approximately 18 wk; n = 149), newborns (cord serum; n = 361), and 6-mo-old partially or exclusively breast-fed children (n = 221). Serum/plasma folate, cobalamin, holotranscobalamin (holoTC), holohaptocorrin (holoHC), methylmalonic acid (MMA) and total homocysteine (tHcy) at birth and 6 mo were related to maternal vitamin status, parity, lifestyle variables, and anthropometry. In multivariate analyses, the strongest predictors of folate at birth and 6 mo were maternal folate and cord folate, respectively (P < 0.01). Maternal holoTC best predicted cobalamin status at birth (positively associated with cord cobalamin, holoTC, and holoHC; inversely with MMA and tHcy; P < or = 0.001), whereas maternal and cord holoHC were the strongest predictors of cobalamin status at 6 mo (positively associated with cobalamin, holoTC, holoHC; inversely with tHcy; P < 0.05). The association between cobalamin status and parity was negative at birth but positive at 6 mo. Birth weight, female sex, and smoking were associated with low cobalamin or high tHcy at birth but showed no or opposite associations at 6 mo. In conclusion, maternal folate and cobalamin status exerts a long-term positive effect on infant vitamin status. The effect of smoking, parity and female sex on cobalamin status did not persist beyond the newborn period. Maternal holoTC was the superior predictor of newborn cobalamin status, while holoHC could be a valuable marker for predicting cobalamin status later in infancy.

Low plasma vitamin B12 in pregnancy is associated with gestational 'diabesity' and later diabetes

AIMS/HYPOTHESIS

This study was designed to test the hypothesis that low plasma vitamin B(12) concentrations combined with high folate concentrations in pregnancy are associated with a higher incidence of gestational diabetes (GDM) and later diabetes.

METHODS

Women (N = 785) attending the antenatal clinics of one hospital in Mysore, India, had their anthropometry, insulin resistance (homeostasis model assessment-2) and glucose tolerance assessed at 30 weeks' gestation (100 g oral glucose tolerance test; Carpenter-Coustan criteria) and at 5 years after delivery (75 g OGTT; WHO, 1999). Gestational vitamin B(12) and folate concentrations were measured in stored plasma samples.

RESULTS

Low vitamin B(12) concentrations (<150 pmol/l, B(12) deficiency) were observed in 43% of women and low folate concentrations (<7 nmol/l) in 4%. B(12)-deficient women had higher body mass index (p < 0.001), sum of skinfold thickness (p < 0.001), insulin resistance (p = 0.02) and a higher incidence of GDM (8.7% vs 4.6%; OR 2.1, p = 0.02; p = 0.1 after adjusting for BMI) than non-deficient women. Among B(12)-deficient women, the incidence of GDM increased with folate concentration (5.4%, 10.5%, 10.9% from lowest to highest tertile, p = 0.04; p for interaction = 0.2). Vitamin B(12) deficiency during pregnancy was positively associated with skinfold thickness, insulin resistance (p < 0.05) and diabetes prevalence at 5 year follow-up (p = 0.009; p = 0.008 after adjusting for BMI). The association with diabetes became non-significant after excluding women with previous GDM (p = 0.06).

CONCLUSIONS/INTERPRETATION

Maternal vitamin B(12) deficiency is associated with increased adiposity and, in turn, with insulin resistance and GDM. Vitamin B(12) deficiency may be an important factor underlying the high risk of 'diabesity' in south Asian Indians.