Methionine and Choline Supply during the Periparturient Period Alter Plasma Amino Acid and One-Carbon Metabolism Profiles to Various Extents: Potential Role in Hepatic Metabolism and Antioxidant Status.

The objective of this study was to profile plasma amino acids (AA) and derivatives of their metabolism during the periparturient period in response to supplemental rumen-protected methionine (MET) or rumen-protected choline (CHOL). Forty cows were fed from -21 through 30 days around parturition in a 2 × 2 factorial design a diet containing MET or CHOL. MET supply led to greater circulating methionine and proportion of methionine in the essential AA pool, total AA, and total sulfur-containing compounds. Lysine in total AA also was greater in these cows, indicating a better overall AA profile. Sulfur-containing compounds (cystathionine, cystine, homocystine, and taurine) were greater in MET-fed cows, indicating an enriched sulfur-containing compound pool due to enhanced transsulfuration activity. Circulating essential AA and total AA concentrations were greater in cows supplied MET due to greater lysine, arginine, tryptophan, threonine, proline, asparagine, alanine, and citrulline. In contrast, CHOL supply had no effect on essential AA or total AA, and only tryptophan and cystine were greater. Plasma 3-methylhistidine concentration was lower in response to CHOL supply, suggesting less tissue protein mobilization in these cows. Overall, the data revealed that enhanced periparturient supply of MET has positive effects on plasma AA profiles and overall antioxidant status.

Association of Hyperhomocysteinemia with Stroke Recurrence after Initial Stroke.

BACKGROUND AND PURPOSE: Homocysteine (Hcy) is closely associated with stroke. Despite the fact that Hcy has consistently been shown to predict development of recurrent stroke, prior studies on the association of Hcy and stroke subtypes have been inconclusive. METHODS: Data from the Ege Stroke Registry were examined and 5-year follow-up data were analyzed. Multivariate survival analyses were undertaken using Cox proportional hazards models to determine the prognostic value of Hcy in different ischemic stroke subtypes. RESULTS: Of the 9522 patients with stroke, 307 (27%) with hyperhomocysteinemia (hHcy) had recurrent stroke. Univariate Cox regression model showed that hHcy group was associated with recurrent stroke (crude hazard ratio [HR] 1.16; 95% CI 1.02-1.30). But there was no such association in multivariate regression models (adjusted HR 1.11; 95% CI .97-1.26). hHcy was not associated with any ischemic stroke subtypes at 5 years. Univariate Cox regression model showed that hHcy group was associated with overall cardiovascular events (crude HR 1.44; 95% CI 1.32-1.57). However, this association no longer existed in multivariate regression models (adjusted HR 1.01; 95% CI .93-1.12). Higher plasma Hcy group was significantly associated with higher mortality compared with normal plasma Hcy group (OR 1.83; 95% CI .45-2.32). CONCLUSIONS: Our results showed that elevated Hcy is not associated independently with stroke recurrence and overall cardiovascular events in patients with ischemic stroke. There was no association between the hHcy and stroke recurrence in the stroke subtypes within 5 years.

Buccal Cell Cytokeratin 14 Correlates with Multiple Blood Biomarkers of Alzheimer's Disease Risk.

Mild cognitive impairment (MCI) may reflect early stages of neurodegenerative disorders such as Alzheimer's disease (AD). Our hypothesis was that cytokeratin 14 (CK14) expression could be used with blood-based biomarkers such as homocysteine, vitamin B12, and folate to identify individuals with MCI or AD from the Australian Imaging, Biomarkers and Lifestyle (AIBL) flagship study of aging. Buccal cells from 54 individuals were analyzed by a newly developed method that is rapid, automated, and quantitative for buccal cell CK14 expression levels. CK14 was negatively correlated with plasma Mg²âº and LDL, while positively correlated with vitamin B12, red cell hematocrit/volume, and basophils in the MCI group and positively correlated with insulin and vitamin B12 in the AD group. The combined biomarker panel (CK14 expression, plasma vitamin B12, and homocysteine) was significantly lower in the MCI (p = 0.003) and AD (p = 0.0001) groups compared with controls. Receiver-operating characteristic curves yielded area under the curve (AUC) values of 0.829 for the MCI (p = 0.002) group and 0.856 for the AD (p = 0.0003) group. These complex associations of multiple related parameters highlight the differences between the MCI and AD cohorts and possibly an underlying metabolic pathology associated with the development of early memory impairment. The changes in buccal cell CK14 expression observed in this pilot study supports previous results suggesting the peripheral biomarkers and metabolic changes are not restricted to brain pathology alone in MCI and AD and could prove useful as a potential biomarker in identifying individuals with an increased risk of developing MCI and eventually AD.

Homocysteine as a predictor of early neurological deterioration in acute ischemic stroke.

BACKGROUND AND PURPOSE: Hyperhomocysteinemia is a well-known risk factor for vascular disease. However, its action, mechanism, and role in the acute phase of stroke have not been determined. We tried to determine whether an association existed between elevated serum homocysteine levels and early neurological deterioration (END) in patients with acute ischemic stroke. METHODS: We performed a secondary analysis from the Cilostazol in Acute Ischemic Stroke Treatment (CAIST) trial, which was a double-blinded, randomized, multicenter trial, assessing the noninferiority of cilostazol over aspirin within 48 hours of an acute ischemic stroke. END was defined as an increase of ≥1 point in motor power or an increase of ≥2 points in the total National Institute of Health Stroke Scale score within 7 days. RESULTS: The mean (±SD) serum homocysteine level was 11.4±4.7 µmol/L. Of the 396 patients studied, 57 (14.4%) patients worsened during the 7 days after inclusion. Most (68%) of the END cases occurred within the first 24 hours after treatment. High levels (>10.3 µmol/L) of serum homocysteine were independent predictors for END (third quartile odds ratio, 3.45; 95% confidence intervals, 1.25-9.50; P=0.016; fourth quartile odds ratio, 3.36; 95% confidence intervals 1.18-9.52; P=0.023) in multivariate analysis. CONCLUSIONS: Patients with acute stroke with elevated serum homocysteine levels are at an increased risk for END.

Determination of cysteine, homocysteine, cystine, and homocystine in biological fluids by HPLC using fluorosurfactant-capped gold nanoparticles as postcolumn colorimetric reagents.

We have demonstrated for the first time the suitability of fluorosurfactant-capped spherical gold nanoparticles as HPLC postcolumn colorimetric reagents for the direct assay of cysteine, homocysteine, cystine, and homocystine. The success of this work was based on the use of an on-line tris(2-carboxyethyl)phosphine reduction column for cystine and homocystine. Several parameters affecting the separation efficiency and the postcolumn colorimetric detection were thoroughly investigated. Under the optimized conditions, cysteine, homocysteine, cystine, and homocystine in human urine and plasma samples were determined. Detection limits for cysteine, homocysteine, cystine, and homocystine ranged from 0.16-0.49 µM. The accuracy in terms of recoveries ranged between 94.0-102.1%. This proposed method was rapid, inexpensive, and simple.

Plasma homocysteine levels in patients with multiple sclerosis in the Greek population.

BACKGROUND: In recent years, there has been increasing interest in the role of plasma homocysteine (Hcy) as a possible risk factor for several diseases of the central nervous system. The aim of this study was to determine the plasma levels of Hcy in a group of multiple sclerosis (MS) patients from a Greek population and the possible correlation with age, disability status, activity or duration of disease, sex, and treatment. METHODS: The MS group that was studied consisted of 46 patients and a total of 42 healthy individuals served as a control group. Plasma Hcy levels were determined by means of high-performance liquid chromatography coupled with fluorescence detection, after precolumn derivatization with 4-Fluoro-7-aminosulfonylbenzofurazan (ABD-F). RESULTS: Statistical analysis revealed that, in the MS patients, Hcy levels were not significantly different as compared to those in the controls. Men presented with higher Hcy levels than women in the MS group; however, age, disease subtype, disease duration, relapse rate, and Expanded Disability Status Scale score/Multiple Sclerosis Severity Score did not significantly affect Hcy levels in MS patients. CONCLUSION: The preliminary data suggest that Hcy levels were not elevated in our sample of Greek MS patients, which does not support previous findings of a significant correlation between elevated serum Hcy levels and MS. Further studies to establish a possible association between MS and Hcy levels in the context of different ethnic groups with different habits are needed.

[Outcomes of patients with combined methylmalonic acidemia and homocystinuria after treatment].

OBJECTIVE: Combined methylmalonic acidemia with homocystinuria is a common form of methylmalonic acidemia in China. Patients with this disease can progress to death without timely and effective treatment. This study aimed to analyze the treatment outcomes of patients with combined methylmalonic acidemia and homocystinuria. METHOD: From September 2004 to April 2012, 58 patients with combined methylmalonic acidemia and homocystinuria (34 males and 24 females) were diagnosed and treated in our hospital. Fifty cases were from clinical patients including 42 early-onset cases and 8 late-onset cases. Their age when they were diagnosed ranged from 18 days to 30.8 years. The other 8 cases were from newborn screening. All the patients were treated with vitamin B12, betaine, folic acid, vitamin B6, and L-carnitine. The physical and neuropsychological development, general laboratory tests, the levels of amino acids, acylcarnitines, and homocysteine in blood, and organic acids in urine were followed up. RESULT: The follow-up period ranged from 1 month to 7.1 years. Three cases died (all were early-onset cases). In the other patients after treatment, the symptoms such as recurrent vomiting, seizures, lethargy, and poor feeding disappeared, muscle strength and muscle tension were improved, and general biochemical abnormalities such as anemia and metabolic acidosis were corrected. Among the surviving 55 cases, 49 had neurological impairments such as developmental delay and mental retardation. The median levels of blood propionylcarnitine and its ratio with acetylcarnitine, serum homocysteine, and urine methylmalonic acid were significantly decreased (P < 0.01), from 7.73 µmol/L (ranged from 1.5 to 18.61 µmol/L), 0.74 (ranged from 0.29 to 2.06), 97.3 µmol/L (ranged from 25.1 to 250 µmol/L) and 168.55 (ranged from 3.66 to 1032.82) before treatment to 2.74 µmol/L (ranged from 0.47 to 12.09 µmol/L), 0.16 (ranged from 0.03 to 0.62), 43.8 µmol/L (ranged from 17 to 97.8 µmol/L) and 6.81 (ranged from 0 to 95.43) after treatment, respectively. CONCLUSION: Patients with combined methylmalonic acidemia and homocystinuria respond to a combined treatment consisting of supplementation of hydroxycobalamin, betaine, folic acid, vitamin B6 and L-carnitine with clinical and biochemical improvement. But the long-term outcomes are unsatisfactory, with neurological sequelae in most patients.

Detailed analysis of gene polymorphisms associated with ischemic stroke in South Asians.

The burden of stroke is disproportionately high in the South Asian subcontinent with South Asian ethnicity conferring a greater risk of ischemic stroke than European ancestry regardless of country inhabited. While genes associated with stroke in European populations have been investigated, they remain largely unknown in South Asians. We conducted a comprehensive meta-analysis of known genetic polymorphisms associated with South Asian ischemic stroke, and compared effect size of the MTHFR C677T-stroke association with effect sizes predicted from homocysteine-stroke association. Electronic databases were searched up to August 2012 for published case control studies investigating genetic polymorphisms associated with ischemic stroke in South Asians. Pooled odds ratios (OR) for each gene-disease association were calculated using a random-effects model. We identified 26 studies (approximately 2529 stroke cases and 2881 controls) interrogating 33 independent genetic polymorphisms in 22 genes. Ten studies described MTHFR C677T (108 with TT genotype and 2018 with CC genotype) -homocysteine relationship and six studies (735 stroke cases and 713 controls) described homocysteine-ischemic stroke relationship. Risk association ORs were calculated for ACE I/D (OR 5.00; 95% CI, 1.17-21.37; p = 0.03), PDE4D SNP 83 (OR 2.20; 95% CI 1.21-3.99; p = 0.01), PDE4D SNP 32 (OR 1.57; 95% CI 1.01-2.45, p = 0.045) and IL10 G1082A (OR 1.44; 95% CI, 1.09-1.91, p = 0.01). Significant association was observed between elevated plasma homocysteine levels and MTHFR/677 TT genotypes in healthy South Asians (Mean difference (ΔX) 5.18 µmol/L; 95% CI 2.03-8.34: p = 0.001). Our results demonstrate that the genetic etiology of ischemic stroke in South Asians is broadly similar to the risk conferred in Europeans, although the dataset is considerably smaller and warrants the same clinical considerations for risk profiling.

Complementary effects of multivitamin and omega-3 fatty acid supplementation on indices of cardiovascular health in individuals with elevated homocysteine.

Homocysteine (HCY), C-reactive protein (hsCRP), and triglycerides (TG) are risk factors for cardiovascular disease (CVD). While multivitamins (MVit) may reduce HCY and hsCRP, omega-3 fatty acids (N3) reduce TG; yet, they are seldom studied simultaneously. We randomly assigned 100 participants with baseline HCY (> 8.0 umol/L) to the daily ingestion of: (1) placebo, (2) MVit (VitC: 200 mg; VitE: 400 IU; VitB6: 25 mg; Folic Acid: 400 ug; VitB12: 400 ug) + placebo, (3) N3 (2 g N3, 760 mg EPA, 440 mg DHA)+placebo, or (4) MVit + N3 for 12 weeks. At follow-up, we observed significant reductions in HCY (umol/L) for the MVit (- 1.43, 95 %CI, - 2.39, - 0.47) and MVit + N3 groups (- 1.01, 95 %CI, - 1.98, - 0.04) groups, both being significant (p < 0.05) vs. placebo (- 0.57, 95 %CI, - 1.49, 0.35) and N3 (1.11, 95 % CI, 0.07, 2.17). hsCRP (nmol/L) was significantly reduced in the MVit (- 6.00, 95 %CI, - 1.04, - 0.15) and MVit + N3 (- 0.98, 95 %CI, - 1.51, - 0.46) groups, but not vs. placebo (- 0.15, 95 %CI, - 0.74, 0.43) or N3 (- 0.53, 95 %CI, - 1.18, 0.12). Lastly, we observed significant reductions in TG for the N3 (- 0.41, 95 %CI, - 0.69, - 0.13) and MVit + N3 (- 0.71, 95 %CI, - 0.93, - 0.46) groups, both significant vs. placebo (- 0.10, 95 %CI, - 0.36, 0.17) and MVit groups (0.15, 95 %CI, - 12, 0.42). The co-ingestion of MVit + N3 provides synergistic affects on HCY, hsCRP, and plasma TG.

Does maternal Helicobacter pylori infection increase the risk of occurrence of neural tube defects in newborns in Northern Iran?

OBJECTIVE: To determine the relation between maternal Helicobacter pylori (H. pylori) infection and the occurrence of neural tube defects (NTDs) in newborns. METHODS: This hospital-based case-control study was carried out in Dezyani Teaching Hospital, Gorgan, Northern Iran from April 2007 to March 2009. Thirty-five mothers with NTD-affected newborns, and 53 mothers with healthy newborns were considered the cases and controls. A peripheral blood sample was obtained from all subjects, and H. pylori infections were tested by H. pylori serum antibody. The serum folic acid, vitamin B12, ferritin, and homocysteine concentrations were measured by laboratory tests. Data were analyzed using odds ratio (OR) and logistic regression. RESULTS: Forty-three percent of cases, and 26% of controls were positive for H. pylori IgG antibody, and this difference was not significant. The H. pylori seropositivity non significantly increased the risk of NTD-affected pregnancies (OR: 2.08; 95% confidence interval [CI]: 0.84-5.17, p=0.11). Serum vitamin B12 deficiency was detected in 17% of cases and 13% of controls, and folic acid deficiency in 17% of cases and 13% of controls (p=0.61). The H. pylori seropositivity was non significantly associated with low serum folate (OR 1.93 CI: 0.58-6.4, p=0.34) and ferritin (OR 1.24; CI: 0.42-3.60, p=0.68). CONCLUSION: Maternal H. pylori infection can increase the risk of occurrence of NTDs in newborns.

The effect of methionine supplementation of the AIN-93G semi-synthetic diet on the levels of homocysteine and lipids in experimental rats.

OBJECTIVES: The studies were carried out on 36 growing albino Wistar rats. PARTICIPANTS/MEASUREMENTS: The animals were randomly divided into six equinumerous groups (six rats per group), and were fed six different diets for 42 days. The control group (I) was fed with AIN-93G semi-synthetic diet, whereas groups II-VI were fed with AIN-93G semi-synthetic diet supplemented with: 2, 4, 8, 16 and 32 g of methionine/kg diet, respectively. There were assessed enzymatically, in rats' blood serum, the contents of homocysteine, total cholesterol, HDL fraction and triacyloglicerols. In addition, the LDL+VLDL cholesterol content was calculated. RESULTS: The methionine content of the diet was found to be highly positively correlated with the homocysteine content (r = 0.981) and negatively correlated with the triacylglycerols content (r = -0.916) of the experimental animals' blood serum. CONCLUSION: In the blood serum of rats fed the highest-methionine diet (32 g methionine/kg diet), the homocysteine content was significantly higher, as were the levels of total cholesterol and its HDL fraction, while the triacylglycerols content was lower as compared to the values obtained for rats fed other diet types.

[Cardiovascular disease prevention: results from Programma FASEN - H San Raffaele]. / La prevenzione delle malattie cardiovascolari: l'esperienza del Programma FASEN - H San Raffaele.

We studied 9145 workers allocated among Italian country employed in the same factory. Most of them were male, mean age 47,6 (20,2

[The relationship between plasma homocysteine levels and diabetic peripheral neuropathy].

OBJECTIVE: To explore the relationship between plasma homocysteine levels and diabetic peripheral neuropathy (DPNP). METHODS: A crossectional analysis was conducted on 227 patients with type 2 diabetes. Peripheral neuropathy was confirmed using electromyography (EMG). The risk factors possibly associated with diabetic neuropathy or plasma homocysteine levels were analyzed in relation to likelihood of occurrence of DPNP. RESULTS: Eighty patients with neuropathy and 147 patients without neuropathy were included. Plasma homocysteine levels were significantly higher in patients with diabetic neuropathy [(12.6 ± 3.6) µmol/L] than without diabetic neuropathy [(8.2 ± 0.9) µmol/L] (P < 0.001), and the relationship remained significant after adjusting for duration of diabetes, glycosylated hemoglobin A1c (HbA1c), age, renal status, serum folate acid and vitamin B(12), and metformin [OR 1.15 (1.02 - 1.28), P < 0.05]. In addition, per increase of 4.0 µmol/L plasma homocysteine was closely related to the occurrence of neuropathy after controlling for per unit increase of other confounding factors [OR 1.17 (0.94 - 1.33), P < 0.05]. CONCLUSIONS: Hyperhomocysteinemia was an independent risk factor for the occurrence of diabetic peripheral neuropathy.

Metabolic syndrome and serum homocysteine in patients with bipolar disorder and schizophrenia treated with second generation antipsychotics.

There is accumulating evidence for an increased prevalence of metabolic syndrome (MetS) in bipolar patients, which is comparable to the prevalence of MetS in patients with schizophrenia. Hyperhomocysteinaemia has emerged as an independent and graded risk factor for the development of cardiovascular disease (CVD), which is, at the same time, the primary clinical outcome of MetS. The aim of this study was to ascertain if the presence of MetS was associated with hyperhomocysteinaemia in patients with bipolar disorder (N=36) and schizophrenia (N=46) treated with second-generation antipsychotics (SGA). MetS was defined according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP-III) criteria and the cut-off point for hyperhomocysteinaemia was set up at 15 µmoll(-1). Results of the study indicated that the presence of the MetS is statistically significantly associated with the elevated serum homocysteine in all participants. As hyperhomocysteinaemia has emerged as an independent risk factor for psychiatric disorder and CVD, it could be useful to include fasting homocysteine serum determination in the diagnostic panels of psychiatric patients to obtain a better assessment of their metabolic risk profile.

Can high-sensitivity C-reactive protein and plasma homocysteine levels independently predict the prognosis of patients with functional disability after first-ever ischemic stroke?

BACKGROUND: The prognosis of functional disability in patients with cerebrovascular disease has not been well established. Therefore, we conducted this study to determine the prognostic significance of high-sensitivity C-reactive protein (hs-CRP) and homocysteine (Hcy) levels in patients with functional disability after acute first-ever ischemic stroke. METHOD: A total of 309 patients with first-ever stroke were examined within 24 h after symptom onset. Hcy was measured at admission, and hs-CRP measurements were made at admission and on the seventh hospital day. The correlations between the concentration of hs-CRP or Hcy and functional disability at 1, 3, 6 and 12 months after stroke onset were analyzed. RESULTS: The present study showed that both hs-CRP values on admission and on the seventh hospital day were significantly correlated with modified Rankin Scale (mRS) scores obtained at 4 times after the onset of stroke. These results also demonstrated that mRS scores are more closely associated with hs-CRP values on the seventh hospital day than on admission. However, there was no significant relationship between Hcy and mRS scores during the 12-month follow-up period. CONCLUSION: According to the present study, we cautiously suggest that hs-CRP values on the subacute phase have sufficient value as a predictor of the prognosis of functional disability after first-ever stroke.

Homocystine levels, polymorphisms and the risk of ischemic stroke in young Asian Indians.

BACKGROUND: Homocysteine has been for a fairly long time been debated to be a risk factor for stroke. Opinions are divided as to whether raised levels of homocysteine seen in stroke patients are the cause or consequence of stroke. A large number of studies have been conducted in the Caucasian as well as on the Oriental population, which tend to suggest contradictory findings at many times. However, there have been no reports forthcoming from the Asian Indian population, which is a genetically different population than the previously studied populations. SUBJECTS AND METHODS: In our present study, we looked at homocysteine levels and four commonly seen polymorphisms of homocysteine metabolizing enzymes and their respective prevalence in 120 acute onset ischemic stroke patients compared with an equal number of age and gender matched healthy population. We also tested the influence of folic acid dosage (5 mg OD) on the levels of homocysteine and the allied vitamin supplements, vitamin B12 and folate in smaller groups selected from the larger group. RESULTS AND CONCLUSIONS: We found homocysteine levels to be significantly raised in the stroke population compared with healthy controls [patients: 12 micromol/L (range: 5.3-39.1 micromol/L), controls: 11.2 micromol/L (range: 6.2-14.2 micromol/L); P =0.001]. There was an almost total response to folic acid dosage as all hyperhomocysteinemic patients showed lowering of homocysteine levels in response to the dosage. The MTHFR 677 C > T polymorphisms showed association with both homocysteine levels as well as stroke (P < 0.001). Nutritional deficiency plays a dominant role in hyperhomocysteinemic conditions in our stroke population, however. Genetic determinants of homocysteine level may also have some part in determining hyperhomocysteinemic conditions in the Asian Indian populations.

Hypoxia tolerance and retinal vein occlusion: a pilot evaluation.

PURPOSE: To determine if hypoxia tolerance in patients with retinal vein occlusion (RVO) following exposure to transient hypoxia is different from the hypoxia tolerance of healthy patients without retinal vein occlusion. METHODS: Consecutive patients presenting with RVO following exposure to transient hypoxia (Group I) were compared with healthy subjects (Group II). In addition to cardiovascular and plasma tests, functional respiratory evaluation was performed at rest and during exercise at both normal oxygen levels (21% O2) and in hypoxia (11.6% O2). We used the Wilcoxon test for statistical analysis. RESULTS: Both groups of eight males had similar mean ages: Group I, 47.5 years and Group II, 53 years. In Group I, three patients had glucose or lipid abnormalities, one had hypertension, and one minor thalassanemia. In Group II, one patient had hypertension. At rest in hypoxia, the oxyhemoglobinic desaturation was significantly different (p=0.03) in Group I in comparison with Group II (-13.8 versus -9.3). At exercise in hypoxia, the oxyhemoglobinic desaturation was similar in both groups but there was a statistically significant increase in both systolic (189 versus 155 mmHg; p=0.01) and diastolic (94 versus 77 mmHg; p=0.03) blood pressure in Group I. Ventilation rate and increased heart rate during hypoxia were higher in Group I compared with Group II but were not statistically significant. CONCLUSIONS: In our pilot study, patients with RVO following exposure to transient hypoxia demonstrated intolerance to hypoxia and were significantly different from healthy subjects in their response to hypoxia. A larger study is required to confirm these preliminary results.

Cognitive impairment in folate-deficient rats corresponds to depleted brain phosphatidylcholine and is prevented by dietary methionine without lowering plasma homocysteine.

Poor folate status is associated with cognitive decline and dementia in older adults. Although impaired brain methylation activity and homocysteine toxicity are widely thought to account for this association, how folate deficiency impairs cognition is uncertain. To better define the role of folate deficiency in cognitive dysfunction, we fed rats folate-deficient diets (0 mg FA/kg diet) with or without supplemental L-methionine for 10 wk, followed by cognitive testing and tissue collection for hematological and biochemical analysis. Folate deficiency with normal methionine impaired spatial memory and learning; however, this impairment was prevented when the folate-deficient diet was supplemented with methionine. Under conditions of folate deficiency, brain membrane content of the methylated phospholipid phosphatidylcholine was significantly depleted, which was reversed with supplemental methionine. In contrast, neither elevated plasma homocysteine nor brain S-adenosylmethionine and S-adenosylhomocysteine concentrations predicted cognitive impairment and its prevention by methionine. The correspondence of cognitive outcomes to changes in brain membrane phosphatidylcholine content suggests that altered phosphatidylcholine and possibly choline metabolism might contribute to the manifestation of folate deficiency-related cognitive dysfunction.

Effect of dietary soybean protein level on the plasma homocysteine concentration in rats.

There was an inverse correlation between the plasma homocysteine concentration and dietary protein level or protein intake when a soybean protein isolate (SPI) was used as a protein source for rats. The hepatic cystathionine beta-synthase activity increased in response to the dietary SPI level. The results suggest that a high-protein diet might be an effective means to lower the plasma homocysteine concentration, probably through enhancement of the homocysteine-metabolizing activity.