Mutations in the CEL VNTR cause a syndrome of diabetes and pancreatic exocrine dysfunction.

Dysfunction of the exocrine pancreas is observed in diabetes, but links between concurrent exocrine and endocrine pancreatic disease and contributing genetic factors are poorly characterized. We studied two families with diabetes and exocrine pancreatic dysfunction by genetic, physiological and in vitro functional studies. A genome-wide screen in Family 1 linked diabetes to chromosome 9q34 (maximal lod score 5.07). Using fecal elastase deficiency as a marker of exocrine pancreatic dysfunction refined the critical chromosomal region to 1.16 Mb (maximal lod score 11.6). Here, we identified a single-base deletion in the variable number of tandem repeats (VNTR)-containing exon 11 of the carboxyl ester lipase (CEL) gene, a major component of pancreatic juice and responsible for the duodenal hydrolysis of cholesterol esters. Screening subjects with maturity-onset diabetes of the young identified Family 2, with another single-base deletion in CEL and a similar phenotype with beta-cell failure and pancreatic exocrine disease. The in vitro catalytic activities of wild-type and mutant CEL protein were comparable. The mutant enzyme was, however, less stable and secreted at a lower rate. Furthermore, we found some evidence for an association between common insertions in the CEL VNTR and exocrine dysfunction in a group of 182 unrelated subjects with diabetes (odds ratio 4.2 (1.6, 11.5)). Our findings link diabetes to the disrupted function of a lipase in the pancreatic acinar cells.

Modulation of the homocysteine-betaine relationship by methylenetetrahydrofolate reductase 677 C->t genotypes and B-vitamin status in a large-scale epidemiological study.

CONTEXT: Betaine is formed from the essential nutrient choline or is supplied from the diet. It serves as a substrate in the betaine-homocysteine methyltransferase reaction and thereby provides methyl groups for the homocysteine-methionine cycle, which is regulated by enzymes dependent on folate, vitamin B12, riboflavin (vitamin B2), or vitamin B6. OBJECTIVE: We investigated how betaine affected total homocysteine (tHcy) concentration within the frame of variable B-vitamin status and according to the methylenetetrahydrofolate reductase (MTHFR) 677C->T genotype. DESIGN/SETTING/PATIENTS: This is a population-based study with a cross-sectional design. It includes 10,601 healthy men and women aged 50-64 yr. OUTCOME MEASURES: Plasma samples were analyzed for tHcy, betaine, choline, dimethylglycine, riboflavin, and vitamin B6, whereas folate and vitamin B12 were analyzed in serum. RESULTS: Betaine was a strong determinant of plasma tHcy in subjects with low serum folate and the MTHFR TT genotype. The association was further strengthened at low levels in the circulation of the other B-vitamins (B2, B6, and B12). Thus, in subjects with the combination of serum folate in the lowest quartile, low vitamin B2, B6, and B12 status, and the MTHFR TT genotype, the difference in tHcy (mean, 95% confidence interval) across extreme plasma betaine quartiles was 8.8 (1.3-16.2) micromol/liter. CONCLUSION: Betaine may thus be an important one-carbon source, particularly in MTHFR 677 TT subjects with inadequate B-vitamin status.

Betaine and folate status as cooperative determinants of plasma homocysteine in humans.

OBJECTIVE: Two published studies have demonstrated that betaine in the circulation is a determinant of plasma total homocysteine, but none had sufficient power to investigate the possible effect modification by folate status. METHODS AND RESULTS: We measured homocysteine, betaine, folate, vitamin B(6), and related compounds in serum/plasma from 500 healthy men and women aged 34 to 69 years before (fasting levels) and 6 hours after a standard methionine loading test. Choline, dimethylglycine, and folate were determinants of plasma betaine in a multiple regression model adjusting for age and sex. The increase in homocysteine after loading showed a strong inverse association with plasma betaine and a weaker inverse association with folate and vitamin B(6). Fasting homocysteine showed a strong inverse relation to folate, a weak relation to plasma betaine, and no relation to vitamin B(6). Notably, adjusted (for age and sex) dose-response curves for the postmethionine increase in homocysteine or fasting homocysteine versus betaine showed that the inverse associations were most pronounced at low serum folate, an observation that was confirmed by analyses of interaction. CONCLUSIONS: Collectively, these results show that plasma betaine is a strong determinant of increase in homocysteine after methionine loading, particularly in subjects with low folate status. In 500 healthy subjects, postmethionine load increase in tHcy showed a stronger inverse relation to betaine than to folate and vitamin B6, whereas for fasting tHcy, betaine was a weaker determinant than folate. For both tHcy modalities, the association with betaine was most pronounced in subjects with low folate status.

Betaine concentration as a determinant of fasting total homocysteine concentrations and the effect of folic acid supplementation on betaine concentrations.

BACKGROUND: Remethylation of homocysteine to methionine can occur through either the folate-dependent methionine synthase pathway or the betaine-dependent betaine-homocysteine methyltransferase pathway. The relevance of betaine as a determinant of fasting total homocysteine (tHcy) is not known, nor is it known how the 2 remethylation pathways are interrelated. OBJECTIVE: The objectives of the study were to examine the relation between plasma betaine concentration and fasting plasma tHcy concentrations and to assess the effect of folic acid supplementation on betaine concentrations in healthy subjects. DESIGN: A double-blind randomized trial of 6 incremental daily doses of folic acid (50-800 microg/d) or placebo was carried out in 308 Dutch men and postmenopausal women (aged 50-75 y). Fasted blood concentrations of tHcy, betaine, choline, dimethylglycine, and folate were measured at baseline and after 12 wk of vitamin supplementation. RESULTS: Concentrations of tHcy were inversely related to the betaine concentration (r = -0.17, P < 0.01), and the association was independent of age, sex, and serum concentrations of folate, creatinine, and cobalamin. Folic acid supplementation increased betaine concentration in a dose-dependent manner (P for trend = 0.018); the maximum increase (15%) was obtained at daily doses of 400-800 microg/d. CONCLUSIONS: The plasma betaine concentration is a significant determinant of fasting tHcy concentrations in healthy humans. Folic acid supplementation increases the betaine concentration, which indicates that the 2 remethylation pathways are interrelated.

Plasma choline and betaine and their relation to plasma homocysteine in normal pregnancy.

BACKGROUND: Plasma concentrations of total homocysteine (tHcy) decrease during pregnancy. This reduction has been investigated in relation to folate status, but no study has addressed the possible role of betaine and its precursor choline. OBJECTIVE: We investigated the courses of plasma choline and betaine during normal human pregnancy and their relations to plasma tHcy. DESIGN: Blood samples were obtained monthly; the initial samples were taken at gestational week (GW) 9, and the last samples were taken approximately 3 mo postpartum. The study population comprised 50 women of West African descent. Most of the subjects took folic acid irregularly. RESULTS: Plasma choline (geometric x; 95% reference interval) increased continuously during pregnancy, from 6.6 (4.5, 9.7) micromol/L at GW 9 to 10.8 (7.4, 15.6) micromol/L at GW 36. Plasma betaine decreased in the first half of pregnancy, from 16.3 (8.6, 30.8) micromol/L at GW 9 to 10.3 (6.6, 16.2) micromol/L at GW 20 and remained constant thereafter. We confirmed a reduction in plasma tHcy, and the lowest concentration was found in the second trimester. From GW 16 onward, an inverse relation between plasma tHcy and betaine was observed. Multiple regression analysis showed that plasma betaine was a strong predictor of plasma tHcy from GW 20 onward. CONCLUSIONS: The steady increase in choline throughout gestation may ensure choline availability for placental transfer with subsequent use by the growing fetus. Betaine becomes a strong predictor of tHcy during the course of pregnancy. Both of these findings emphasize the importance of choline and betaine status during normal human pregnancy.

Betaine as a determinant of postmethionine load total plasma homocysteine before and after B-vitamin supplementation.

OBJECTIVE: Betaine is a substrate in the betaine-homocysteine methyltransferase reaction, converting homocysteine to methionine. There are only sparse data on plasma betaine as a determinant of the plasma total homocysteine (tHcy) concentration. METHODS AND RESULTS: Ninety patients undergoing coronary angiography were randomized into 4 groups administered oral: (1) folic acid (0.8 mg), vitamin B12 (0.4 mg), and vitamin B6 (40 mg); (2) folic acid and vitamin B12; (3) vitamin B6 alone; or (4) placebo. Nonfasting blood samples were collected at baseline and 3, 14, and 28 days and 3, 6, and 12 months after treatment start. A 4-hour methionine-loading test (0.1 g/kg) was performed at baseline and after 3 months. At baseline, median (interquartile range) plasma betaine was 36.9 micromol/L (range: 30.3 to 46.8) and was increased by 15% after methionine loading. The postmethionine load (PML) increase in tHcy was inversely related to plasma betaine (beta=-0.29, P=0.02) and even more strongly to PML betaine (beta=-0.47, P<0.001). After 3 months of intervention, the relation between the PML increase in tHcy and PML betaine was weakened (beta=-0.33, P=0.007). CONCLUSIONS: Plasma betaine is a strong determinant of the PML increase in tHcy in subjects not supplemented with B-vitamins.

Predictors of outcome and comparison of different drug regimens for the prevention of relapse in patients with Graves' disease.

OBJECTIVE: To investigate the effect of different antithyroid drug (ATD) regimens on relapse rates of Graves' disease, and to look for predictors of relapse. DESIGN AND METHODS: In a prospective two-way factorial randomized clinical trial, 218 patients with Graves' disease were assigned to ATD combined with l-thyroxine (l-T(4)) or ATD alone for 12 Months. After discontinuation of antithyroid therapy, each group was stratified to either 12 Months further treatment with l-T(4) or no treatment. Clinical and biochemical assessments were carried out before treatment, after 3 and 6 weeks, and every third Month for 12 Months. If the patients lacked symptoms of relapse, laboratory tests were performed every third Month for the second Year, and thereafter annually. RESULTS: The proportion of all patients with relapse was 47.7% 2 Years after withdrawal of ATD. There was no difference in relapse rates between the treatment groups (P=0.217, log--rank test). Smokers had a higher relapse rate than non-smokers (58.4% vs 38.8%, P=0.009). Patients who were thyrotropin-receptor antibody (TRAb) positive after 12 Months of antithyroid therapy had a higher relapse rate than those who were negative (72.5% vs 36.8%, P<0.0001). Similarly, relapse was more frequent (55.5%) in patients having large goiter compared with subjects with small goiter (36.3%, P=0.0007). CONCLUSIONS: Relapse rates of Graves' disease were independent of ATD regimen whether followed by l-T(4) therapy or not. Smoking, large goiter and presence of TRAb at the end of ATD therapy were strong predictors of relapse.

Neurological features and enzyme therapy in patients with endocrine and exocrine pancreas dysfunction due to CEL mutations.

OBJECTIVE: To further define clinical features associated with the syndrome of diabetes and pancreatic exocrine dysfunction due to mutations in the carboxyl-ester lipase (CEL) gene and to assess the effects of pancreatic enzyme substitution therapy. RESEARCH DESIGN AND METHODS: Nine patients with CEL gene mutation, exocrine deficiency, and diabetes were treated and followed for 30 months. RESULTS: Treatment improved symptoms in seven of nine patients. Exocrine and endocrine function assessed by fecal elastase and A1C were not affected, although fecal lipid excretion was reduced. Vitamin E was low in all patients but increased with treatment (P < 0.001 at 30 months) and improved in five subjects. A predominantly demyelinating neuropathy was seen in a majority of patients, and carpal tunnel syndrome was common. CONCLUSIONS: Pancreatic enzyme substitution alleviated symptoms and malabsorption and normalized vitamin E levels. Glycemic control was not significantly affected. The CEL syndrome seems associated with a demyelinating neuropathology.

Betaine: a key modulator of one-carbon metabolism and homocysteine status.

Betaine serves as a methyl donor in a reaction converting homocysteine to methionine, catalysed by the enzyme betaine-homocysteine methyltransferase. It has been used for years to lower the concentration of plasma total homocysteine (tHcy) in patients with homocystinuria, and has recently been shown to reduce fasting and in particular post-methionine load (PML) tHcy in healthy subjects. Betaine exists in plasma at concentrations of about 30 micromol/L; it varies 10-fold (from 9 to 90 micromol/L) between individuals, but the intra-individual variability is small. Major determinants are choline, dimethylglycine and folate in plasma, folic acid intake and gender. Recent studies have demonstrated that plasma betaine is a stronger determinant of PML tHcy than are vitamin B6 and folate. The betaine-PML tHcy relationship is attenuated after supplementation with B-vitamins, and is most pronounced in subjects with low folate. Betaine shows a weaker association with fasting tHcy (than with PML tHcy), and also this association is most pronounced in subjects with low folate. In pregnancy, plasma betaine declines until gestational week 20, and thereafter remains constant. From gestational week 20 onwards, fasting tHcy shows a strong inverse association with plasma betaine, and betaine becomes a stronger predictor than folate of fasting tHcy. To conclude, betaine status is a component of an individual's biochemical make-up with ramifications to one-carbon metabolism. Betaine status should be investigated in pathologies related to altered metabolism of homocysteine and folate, including cardiovascular disease, cancer and neural tube defects.

A Scandinavian case of domestically acquired human fascioliasis.

A 30-y-old farmhand was admitted to our clinic in September 2000 with a 6-week history of increasing fatigue and polydipsia/polyuria after an initial short spell of gastroenteritis. No evidence of disease was discovered. During follow-up he developed leucocytosis with prominent eosinophilia, leading to the discovery of multiple liver abscesses and subsequently to the diagnosis of human fascioliasis of domestic origin. Although not uncommon in Europe, the infestation has hitherto not been reported from Scandinavia. The patient was successfully treated with praziquantel.

Determination of choline, betaine, and dimethylglycine in plasma by a high-throughput method based on normal-phase chromatography-tandem mass spectrometry.

BACKGROUND: The quaternary ammonium compounds, choline and betaine, and dimethylglycine (DMG) reside along a metabolic pathway linked to the synthesis of neurotransmitters and membrane phospholipids and to homocysteine remethylation and, therefore, folate status. Lack of a convenient, high-throughput method for the determination of these compounds has prevented population-based studies of their possible associations with lifestyle, nutrition, and chronic diseases. METHODS: Serum or plasma samples were deproteinized by mixing with three volumes of acetonitrile that contained d(9)-choline and d(9)-betaine as internal standards. We used a normal-phase silica column for the separation of choline (retention time, 2.8 min), betaine (1.3 min), DMG (1.15 min), and internal standards, which were detected as positive ions by tandem mass spectroscopy in the multiple-reaction monitoring mode, using the molecular transitions m/z 104-->60 (choline), m/z 113-->69 (d(9)-choline), m/z 118-->59 (betaine), m/z 127-->68 (d(9)-betaine), and m/z 104-->58 (DMG). RESULTS: For all three metabolites, the assay was linear in the range 0.4-400 micromol/L, and the lower limit of the detection (signal-to-noise ratio = 5) was < or =0.3 micromol/L. The within- and between-day imprecision (CVs) was 2.1-7.2% and 3.5-8.8%, respectively. The analytical recovery was 87-105%. The fasting plasma concentrations (median, 25th-75th percentiles) were 8.0 (7.0-9.3) micromol/L for choline, 31.7 (27.0-41.1) micromol/L for betaine, and 1.66 (1.30-2.02) micromol/L for DMG in 60 healthy blood donors. In individuals who had eaten a light breakfast, plasma concentrations of all three metabolites were significantly (25-30%) higher than in fasting individuals. CONCLUSION: This is the first method for the combined measurement of choline, betaine, and DMG in human plasma or serum. The assay is characterized by simple sample preparation, no derivatization, high throughput, imprecision (CV) <10%, detection limits below the values seen in volunteers, and the high specificity provided by tandem mass spectroscopy.