Implication of N-Methyl-d-Aspartate Receptor in Homocysteine-Induced Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is a leading cause of vision loss. Elevated homocysteine (Hcy) (Hyperhomocysteinemia) (HHcy) has been reported in AMD. We previously reported that HHcy induces AMD-like features. This study suggests that N-Methyl-d-aspartate receptor (NMDAR) activation in the retinal pigment epithelium (RPE) is a mechanism for HHcy-induced AMD. Serum Hcy and cystathionine-ß-synthase (CBS) were assessed by ELISA. The involvement of NMDAR in Hcy-induced AMD features was evaluated (1) in vitro using ARPE-19 cells, primary RPE isolated from HHcy mice (CBS), and mouse choroidal endothelial cells (MCEC); (2) in vivo using wild-type mice and mice deficient in RPE NMDAR (NMDARR-/-) with/without Hcy injection. Isolectin-B4, Ki67, HIF-1α, VEGF, NMDAR1, and albumin were assessed by immunofluorescence (IF), Western blot (WB), Optical coherence tomography (OCT), and fluorescein angiography (FA) to evaluate retinal structure, fluorescein leakage, and choroidal neovascularization (CNV). A neovascular AMD patient's serum showed a significant increase in Hcy and a decrease in CBS. Hcy significantly increased HIF-1α, VEGF, and NMDAR in RPE cells, and Ki67 in MCEC. Hcy-injected WT mice showed disrupted retina and CNV. Knocking down RPE NMDAR improved retinal structure and CNV. Our findings underscore the role of RPE NMDAR in Hcy-induced AMD features; thus, NMDAR inhibition could serve as a promising therapeutic target for AMD.

Long-term functional correction of cystathionine ß-synthase deficiency in mice by adeno-associated viral gene therapy.

Cystathionine ß-synthase (CBS) deficiency is a recessive inborn error of sulfur metabolism characterized by elevated blood levels of total homocysteine (tHcy). Patients diagnosed with CBS deficiency are currently treated by a combination of vitamin supplementation and restriction of foods containing the homocysteine precursor methionine, but the effectiveness of this therapy is limited due to poor compliance. A mouse model for CBS deficiency (Tg-I278T Cbs-/- ) was used to evaluate a potential gene therapy approach to treat CBS deficiency utilizing an AAVrh.10-based vector containing the human CBS cDNA downstream of the constitutive, strong CAG promoter (AAVrh.10hCBS). Mice were administered a single dose of virus and followed for up to 1 year. The data demonstrated a dose-dependent increase in liver CBS activity and a dose-dependent decrease in serum tHcy. Liver CBS enzyme activity at 1 year was similar to Cbs+/- control mice. Mice given the highest dose (5.6 × 1011 genomes/mouse) had mean serum tHcy decrease of 97% 1 week after injection and an 81% reduction 1 year after injection. Treated mice had either full- or substantial correction of alopecia, bone loss, and fat mass phenotypes associated with Cbs deficiency in mice. Our findings show that AAVrh.10-based gene therapy is highly effective in treating CBS deficiency in mice and supports additional pre-clinical testing for eventual use human trials.

Treatment of Cystathionine ß-Synthase Deficiency in Mice Using a Minicircle-Based Naked DNA Vector.

Cystathionine ß-synthase (CBS) deficiency is a recessive inborn error of metabolism characterized by extremely elevated total homocysteine (tHcy) in the blood. Patients diagnosed with CBS deficiency have a variety of clinical problems, including dislocated lenses, osteoporosis, cognitive and behavioral issues, and a significantly increased risk of thrombosis. Current treatment strategies involve a combination of vitamin supplementation and restriction of foods containing the homocysteine precursor methionine. Here, a mouse model for CBS deficiency (Tg-I278T Cbs-/-) was used to evaluate the potential of minicircle-based naked DNA gene therapy to treat CBS deficiency. A 2.3 kb DNA-minicircle containing the liver-specific P3 promoter driving the human CBS cDNA (MC.P3-hCBS) was delivered into Tg-I278T Cbs-/- mice via a single hydrodynamic tail vein injection. Mean serum tHcy decreased from 351 µM before injection to 176 µM 7 days after injection (p = 0.0005), and remained decreased for at least 42 days. Western blot analysis reveals significant minicircle-directed CBS expression in the liver tissue. Liver CBS activity increased 34-fold (12.8 vs. 432 units; p = 0.0004) in MC.P3-hCBS-injected animals. Injection of MC.P3-hCBS in young mice, subsequently followed for 202 days, showed that the vector can ameliorate the mouse homocystinuria alopecia phenotype. The present findings show that minicircle-based gene therapy can lower tHcy in a mouse model of CBS deficiency.

Maternal vitamin D deficiency increases the thromboxane/prostacyclin ratio through alterations in the one-carbon cycle in Wistar rats.

This study aims to test the hypothesis that vitamin D deficiency can influence long-chain polyunsaturated fatty acid metabolism through alterations in the one-carbon cycle. Wistar rats (n = 8 per group) were given either a control (1,000 IU D3/kg diet) or a vitamin D deficient (VDD) (0 IU D3/kg diet) diet from pre-pregnancy to delivery. On day 20 of gestation, pregnant female rats were delivered by C-section to collect placenta and blood. VDD group demonstrated high serum parathyroid hormone, low serum phosphate, low plasma folate, higher plasma homocysteine, and higher plasma malondialdehyde levels (P < 0.05 for all) as compared to control. Lower protein levels of placental cystathionine-ß-synthase enzyme (P < 0.05) were observed in the VDD group as compared to control. VDD group demonstrated higher placental mRNA levels of the enzymes phospholipase A2 and cyclooxygenase-2 (P < 0.05 for both) as compared to control. Protein levels of the enzymes phospholipase A2 and cyclooxygenase-2 were lower (P < 0.05 for both) in the VDD group as compared to the control group. The ratio of thromboxane B2 and 6-keto prostaglandin F1α in serum was higher (P < 0.05) in the VDD group as compared to control; although the serum levels of 6-keto prostaglandin F1α and thromboxane B2 were similar in both the groups. Our findings suggest that increased oxidative stress due to maternal vitamin D deficiency results in the imbalance between the vasoconstrictor (thromboxane B2 ) and vasodilator (6-keto prostaglandin F1α ) eicosanoids, which may lead to endothelial dysfunction and poor pregnancy outcome. © 2019 BioFactors, 45 (4):548-555, 2019.

Hepatoprotective effects of lycopene on liver enzymes involved in methionine and xenobiotic metabolism in hyperhomocysteinemic rats.

Hyperhomocysteinemia, defined by an increased plasma homocysteine level, is commonly associated with chronic liver diseases. A link between the elevated homocysteine level and oxidative stress has been demonstrated. Indeed the pathogenesis of liver diseases in the case of hyperhomocysteinemia could be due to this production of oxidative stress. Many studies have demonstrated the antioxidative properties of lycopene, a carotenoid. Therefore, the present study was designed to induce hyperhomocysteinemia in male Wistar rats in order to analyze the effect of lycopene supplementation on homocysteine metabolism, on phase I and phase II xenobiotic-metabolizing enzyme activities, and on liver injury by histological examination and analysis of biochemical markers. We found that rats with a high methionine diet showed abnormal histological features, with an increase of serum homocysteine, alanine aminotransferase and aspartate aminotransferase levels, decreased hepatic cystathionine beta synthase and S-adenosyl-homocysteine hydrolase activities and an increased hepatic malondialdehyde level. We demonstrated the reversal effect of lycopene supplementation on hyperhomocysteinemia. Taken together, these findings provide additional clues on the hepatoprotective effects of lycopene.

Molecular and biochemical investigations of patients with intermediate or severe hyperhomocysteinemia.

A discrepancy has been identified between numbers of expected and identified patients with homocystinuria due to cystathionine beta-synthase (CBS) deficiency. Patients homozygous for the frequent c.833T>C (p.I278T) are most often responsive to vitamin B6, and can present with a total-homocysteine (tHcy) <100 µM on a normal diet. In Denmark, patients with tHcy <100 µM are not routinely sequenced for CBS(2) mutations. This study investigated the prevalence of CBS mutations and the common methylenetetrahydrofolate reductase (MTHFR) c.677C>T polymorphism in patients with tHcy ≥ 50 µM and the association with clinical manifestations. We studied a cohort of patients with intermediate and severe hyperhomocysteinemia (tHcy ≥ 50 µM) determined between 1996 and 2011. Among the 413 eligible patients, 184 (45%) patients agreed to participate in the present follow-up study. A MTHFR(3)c.677TT genotype was found in 49% of the patients. Eight patients were found to have mutations in CBS(2). Of those, two were homozygous for c.833T>C (p.I278T), and four were compound heterozygous for c.833T>C. One c.833T>C (p.I278T) compound heterozygote was identified by lowering the threshold for sequencing from tHcy at 100 µM to 50 µM. The most prominent clinical presentation among patients with a CBS(2) mutation was thrombosis presenting at a median age of 25 years. In case of arterial or venous thrombosis without any explanation in individuals below 40 years, tHcy should be part of the thrombophilia screening. When tHcy is between 50 and 100 µM genotyping for the MTHFR(3) c.677TT is relevant, and when tHcy >100 µM CBS should be genotyped.

[Serum cystathionine ß-synthase (CBS), cystathionine γ-lyase (CSE ) and cytochrome c oxidase (COX) in copper mine miners potentially expose d to hydrogen sulfide]. / ß-syntaza cystationiny (CBS), γ-liaza cystationiny (CSE) i oksydaza cytochromu c (COX) w surowicy górników kopalni miedzi potencjalnie narazonych na emisje siarkowodoru.

BACKGROUND: The aim of the study was to evaluate serum levels of the target enzyme for H2S toxicity--cytochrome c oxidase (COX) and enzymes involved in the synthesis of H2S--cystathionine ß-synthase (CBS) and cystathionine γ-lyase (CSE) in copper mine miners. MATERIAL AND METHODS: The initial and basic study was conducted respectively in 237 and 88 miners, working in 2 mining shafts: I--no H2S emissions recorded in the last 10 years (study group A) and II--H2S emissions occurred (study group B). A medical examination was performed and 10 ml of blood was collected from miners immediately after exiting the mine. RESULTS: There were no clinical or biochemical changes typical for H2S toxicity. Sulfhemoglobine was undetectable and there were no changes in the red-ox system. However, in group B, regulatory changes were found; a tendency to higher concentration of CBS and CSE, a higher activity of angiotensin converting enzyme (ACE) compared to group A (p<0.05) and a linear relationship between ACE and CSE (r=0.6927; p<0.001). It has been shown that cigarette smoking decreases COX (p<0.05), however, in miners working in shaft II, the decreased level of COX may result also from the presence of H2S in the gaseous emissions. CONCLUSIONS: COX concentration can be a sensitive indicator of exposure to H2S. The measurements of blood H2S concentrations carried out in workplaces should explain the cause of the changes observed in the COX, CBS and CSE activity.

Acute psychosis in an adolescent with undiagnosed homocystinuria.

Homocystinuria due to cystathionine-ß-synthase deficiency (CBS deficiency) usually presents with ectopia lentis, myopia, intellectual disability, skeletal anomalies resembling Marfan syndrome, and thromboembolic events. Whereas neurodevelopment impairments have been often described in untreated homocystinuria adult patients, acute psychosis has rarely been reported as a presenting symptom of the disease. Here, we describe a 17-year-old girl affected by CBS deficiency presenting acute onset of visual hallucinations, behavioral perseverance, psychomotor hyperactivity, and affective inappropriateness. Ectopia lentis, diagnosed several years before, didn't have been considered as possible sign of a metabolic disorder. Psychotic symptoms were unresponsive to the conventional antipsychotic drugs and relieved after pyridoxine and folic acid treatment. CONCLUSION: A diagnosis of homocystinuria due to CBS deficiency should be considered in patients presenting, as target signs, ectopia lentis with or without learning difficulties, and should also be taken into account as a potentially treatable cause of acute psychosis in childhood and adolescence. WHAT IS KNOWN: • Homocystinuria frequently present with ectopia lentis, myopia, cognitive impairment, Marfan-like phenotype, osteoporosis, cerebrovascular, or cardiac thrombosis. • Acute psychosis has rarely been reported as a presenting symptom of the disease. WHAT IS NEW: • The complete psychotic symptoms' remission with pharmacological doses of pyridoxine and folic acid, without antipsychotic drugs.

Heterozygous carriers of classical homocystinuria tend to have higher fasting serum homocysteine concentrations than non-carriers in the presence of folate deficiency.

BACKGROUND & AIMS: Many studies have reported that serum total homocysteine (tHcy) levels in cystathionine-beta-synthase (CBS) carriers are usually normal and only elevated after a methionine load. However, the amount of methionine required for a loading test is non-physiological and is never reached with regular feeding. Therefore, CBS carriers do not seem to be at an increased risk of cardiovascular diseases. However, the risk of cardiovascular diseases of CBS carriers with folate deficiency has not been studied. We recently found an extraordinarily high carrier rate (1/7.78) of a novel CBS mutation (p.D47E, c.T141A) in an Austronesian Taiwanese Tao tribe who live in a geographic area with folate deficiency. We evaluated if the CBS carriers tend to have higher fasting serum tHcy concentrations than non-carriers in presence of folate deficiency. METHODS: The serum tHcy and folate levels before and after folate replacement were measured in 48 adult Tao carriers, 40 age-matched Tao non-carriers and 40 age-matched Han Taiwanese controls. RESULTS: The serum tHcy level of the Tao CBS carriers (17.9 ± 3.8 µmol/l) was significantly higher than in Tao non-carriers (15.7 ± 3.5 µmol/l; p < 0.008) and Taiwanese controls (11.8 ± 2.9 µmol/l; p < 0.001). Furthermore, a high prevalence of folate deficiency in the Tao compared with the Taiwanese controls (4.9 ± 1.8 ng/ml vs. 10.6 ± 5.5 ng/ml; p < 0.001) was also noted. Of note, the difference in tHcy levels between the carriers and non-carriers was eliminated by folate supplementation. (carriers:13.65 ± 2.13 µmol/l; non-carriers:12.39 ± 3.25 µmol/l, p = 0.321). CONCLUSIONS: CBS carriers tend to have a higher tHcy level in the presence of folate deficiency than non-carriers. Although many reports have indicated that CBS carriers are not associated with cardiovascular disease, the risk for CBS carriers with folate deficiency has not been well studied. Owing to a significantly elevated level of fasting tHcy without methionine loading, it is important to evaluate the risk of cardiovascular disease in CBS carriers with folate deficiency.

Enzymatic diagnosis of homocystinuria by determination of cystathionine-ß-synthase activity in plasma using LC-MS/MS.

BACKGROUND: Cystathionine ß-synthase (CBS) is released into plasma from organs expressing this enzyme. Decreased plasma CBS activity has been demonstrated in CBS-deficient patients with 16 different genotypes. The aim of this study was to determine plasma CBS activity in patients carrying 11 additional genotypes using two LC-MS/MS methods. Patients and methods CBS activity was measured in EDTA or heparin plasma using either a previously described or a newly developed LC-MS/MS method optimized for analysis of the reaction product, 3,3-(2)H2-cystathionine, as its butyl ester derivative. We analyzed plasma samples from 26 CBS-deficient patients with known genotypes and 57 controls. RESULTS: We developed a new LC-MS/MS method for simple and sensitive determination of CBS activity. Plasma CBS activity was low (i.e., 0.001-0.036 of the multiples of median control values, MoM) in patients homozygous for the prevalent Hispanic mutation c.572C>T (p.T191M) but was highly elevated (2.95 MoM) in a single patient homozygous for the c.1330G>A (p.D444N) mutation. Patients with the remaining nine genotypes exhibited decreased activities (0.00-0.22 MoM), which did not overlap with the controls (0.29-2.10 MoM). CONCLUSIONS: The determination of CBS activity in plasma is a rapid and non-invasive procedure for detecting a subgroup of CBS-deficient patients with distinct genotypes.

Homocysteine contribution to DNA damage in cystathionine ß-synthase-deficient patients.

High blood levels of homocysteine (Hcy) are found in patients affected by homocystinuria, a genetic disorder caused by deficiency of cystathionine ß-synthase (CBS) activity, as well as in nutritional deficiencies (vitamin B12 or folate) and in abnormal renal function. We previously demonstrated that lipid and protein oxidative damage is increased and the antioxidant defenses diminished in plasma of CBS-deficient patients, indicating that oxidative stress is involved in the pathophysiology of this disease. In the present work, we extended these investigations by evaluating DNA damage through the comet assay in peripheral leukocytes from CBS-deficient patients, as well as by analyzing of the in vitro effect of Hcy on DNA damage in white blood cells. We verified that DNA damage was significantly higher in the CBS-deficient patients under treatment based on a protein-restricted diet and pyridoxine, folic acid, betaine and vitamin B12 supplementation, when compared to controls. Furthermore, the in vitro study showed a concentration-dependent effect of Hcy inducing DNA damage. Taken together, the present data indicate that DNA damage occurs in treated CBS-deficient patients, possibly due to high Hcy levels.

Dynamic change of hydrogen sulfide during global cerebral ischemia-reperfusion and its effect in rats.

Hydrogen sulfide (H(2)S) is a gaseous messenger and serves as an important neuromodulator in central nervous system. In the current study, we investigated the change of H(2)S and cystathionine beta-synthase (CBS), an H(2)S-synthesizing enzyme at different time points of reperfusion following global cerebral ischemia in rats, and the effect of exogenous H(2)S on global cerebral ischemia-reperfusion injury. First, we used global cerebral ischemia-reperfusion model by occlusion of bilateral common carotid arteries and vertebral arteries. Next, we measured H(2)S levels in the hippocampus, cortex and plasma, the activity of H(2)S-synthesizing enzymes and expression of CBS mRNA and protein in the hippocampus and cortex at 12 h, 24 h, 48 h, 72 h and 7 days of reperfusion following 15 min cerebral ischemia. Second, we pretreated rats with different doses of sodium hydrogen sulfide (NaHS), an H(2)S donor and observed its effect on neuronal injury induced by 7 days of reperfusion after 15 min global cerebral ischemia. We found that when compared to sham group the amount of H(2)S in the hippocampus was increased significantly at 12 h of reperfusion after cerebral ischemia, markedly decreased at 24 h, restored to the same level as that in sham group at 48 h and maintained at 72 h and 7 days. The same change tendency in the levels of H(2)S was found in the cortex as described for the hippocampus. We found a similar change tendency in the activity of H(2)S-synthesizing enzymes, CBS mRNA and protein expression to that in the H(2)S level at different time points of reperfusion. Furthermore, while 180 micromol/kg NaHS pretreatment deteriorated the neuronal injury after global cerebral ischemia, 25 micromol/kg NaHS attenuated the neuronal injury. We suggest that a decrease of H(2)S level at 24 h of reperfusion after global cerebral ischemia may be involved in neuronal injury after cerebral ischemia and lower concentration rather than higher concentration of exogenous H(2)S may offer a protection against the neuronal injury induced by global cerebral ischemia-reperfusion.

Cystathionine beta-synthase 844Ins68 polymorphism is not associated with the levels of homocysteine and cysteine in an Indian population.

Cystathionine beta-synthase (CBS) is a key enzyme that plays a critical role in homocysteine metabolism and intracellular redox balance. We have analysed the association of the CBS 844Ins68 polymorphism alone and in combination with methylenetetrahydrofolate reductase (MTHFR C677T) and choline dehydrogenase (CHDH A119C) polymorphisms (the two polymorphisms recently shown to be associated with levels of homocysteine) with homocysteine, cysteine, folate and vitamin B(12) in 817 individuals (397 patients with coronary artery disease and 420 controls). The CBS 844Ins68 polymorphism alone or in combination with MTHFR C677T and CHDH A119C polymorphisms was not significantly associated with any of the biochemical variables studied.

[Biochemical alterations in patients with Down syndrome]. / Biokémiai eltérések Down-szindromás betegekben.

UNLABELLED: Down syndrome is a chromosome abnormality with specific clinical symptoms and mental retardation caused by trisomy of chromosome 21. The basic genetic change cannot be cured, the control of the associated symptoms, however, may improve the patients' quality of life. AIMS: Authors studied the possible correlations between the Down-specific genes and the related biochemical changes. Expression of superoxide dismutase, cystathionine-beta-synthase and S100 protein was investigated. Further aim of the study was to determine the total serum antioxidant capacity (transferrin, ferritin, total protein, albumin and bilirubin) along with the extracellular antioxidants as well as concentrations of homocysteine, folic acid, and vitamin B 12 . To assess the vascular damage, the activity of NAG and S100B level was measured. METHODS: Standard laboratory methods were used to determine the antioxidant capacity (Stocks, 1974), homocysteine (HPLC), folic acid (capture, IMX-Abbott), vitamin B 12 (MEIA, IMX-Abbott), S100 B protein (chemiluminescence sandwich immunoassay) levels, and N-acetyl-beta-D-glucosaminidase (spectrophotometry). RESULTS: Plasma homocysteine value proved to be lower in 7 of the 30 and higher in 6 of the 30 patients studied than the reference range. Plasma homocysteine was found 95 +/- 21% of the reference value. Relative value of plasma folic acid - expressed in percent of the normal value - was 85 +/- 51%, and that of B 12 was 78 +/- 30%. Deficiency of folic acid was detected in 2 of the 30, decreased level of B 12 in 2 of the 30 patients enrolled. No difference was found in antioxidant activity values between Down syndrome patients and healthy controls, however, neither of them reached the adult reference range. S100 protein concentration of 4-8 times higher values (average value: 0.68 +/- 0.27 microg/l) than upper limit of the reference range was observed (> 1 year: > 0.15 microg/l). Mean value of serum N-acetyl-beta-D-glucosaminidase remained within the reference range (10-30 U/l). No statistically significant correlation between the antioxidant activity and N-acetyl-beta-D-glucosaminidase values could be observed. CONCLUSION: The lower homocysteine, folic acid and B 12 values may be considered as the consequence of an increased cystathionine-beta-synthase activity ("atheroma free model"). There was no significant alteration in antioxidant activity level. It can be supposed that the hydrogene peroxide produced due to increased expression of superoxide dismutase is metabolized by the induced glutathione-peroxidase and catalase keeping by this the balance of the antioxidant system. This hypothesis is supported by the normal N-acetyl-beta-D-glucosaminidase values not indicating any vascular damage. The high S100 values, however, reflect certain brain damage which shows a progress with the age. Based on these experiences, regular control of these parameters is recommended. Furthermore authors think that folic acid supplementation is indicated in order to improve the patients' learning capacity, inhibit the development of Alzheimer symptoms and improve the quality of life.

The many flavors of hyperhomocyst(e)inemia: insights from transgenic and inhibitor-based mouse models of disrupted one-carbon metabolism.

Mouse models that perturb homocysteine metabolism, including genetic mouse models that result in deficiencies of methylenetetrahydrofolate reductase, methionine synthase, methionine synthase reductase, and cystathionine beta-synthase, and a pharmaceutically induced mouse model with a transient deficiency in betainehomocysteine methyl transferase, have now been characterized and can be compared. Although each of these enzyme deficiencies is associated with moderate to severe hyperhomocyst(e)inemia, the broader metabolic profiles are profoundly different. In particular, the various models differ in the degree to which tissue ratios of S-adenosylmethionine to S-adenosylhomocysteine are reduced in the face of elevated plasma homocyst(e)ine, and in the distribution of the tissue folate pools. These different metabolic profiles illustrate the potential complexities of hyperhomocyst(e)inemia in humans and suggest that comparison of the disease phenotypes of the various mouse models may be extremely useful in dissecting the underlying risk factors associated with human hyperhomocyst(e)inemia.

The influence of genetic and environmental factors on plasma homocysteine concentrations in a population at high risk for coronary artery disease.

BACKGROUND: Elevated plasma total homocysteine (tHcy) predisposes to vascular disease and results from interactions between genetic and nutritional factors. MTHFR C(677)T increases tHcy in association with low folate. CBS 844ins68 lowers tHcy and negates the raising effect of MTHFR C(677)T in healthy subjects, but it is unclear if this is the case in subjects at high risk of vascular disease. This study examines the effect on plasma tHcy of interactions between these polymorphisms in an at-risk group. METHODS: Blood samples were collected from 376 subjects at increased risk of coronary artery disease. Plasma tHcy and vitamin B(6) were measured by HPLC and red cell folate and serum vitamin B(12) were measured by immuno-luminometric assay. MTHFR C(677)T and CBS 844ins68 status was established by standard PCR techniques. RESULTS: MTHFR TT predisposed to hyperhomocysteinaemia; this was increased in the presence of low folate (P<0.05) and vitamin B(12) (P<0.01). An inverse relationship was found between tHcy and folate (r=-0.42, P<0.0001), vitamin B(12) (r=-0.26, P<0.0005) and vitamin B(6) (r=-0.25, P<0.01). There was no interaction between plasma tHcy, vitamins or MTHFR C(677)T and CBS 844ins68. DISCUSSION: In this population at high risk of coronary artery disease, plasma tHcy was determined by vitamin status. This was exacerbated by the MTHFR C(677)T mutation. CBS 844ins68 did not influence tHcy and did not negate the tHcy-raising effect of MTHFR C(677)T.

[Association of plasma homocysteine and cystathionine beta-synthase polymorphism with cerebral thrombosis].

OBJECTIVE: To study the association of plasma homocysteine (Hcy) and polymorphism and cystathionine beta-synthase (CBS) with cerebral thrombosis. METHODS: Eighty-seven patients with first-ever acute cerebral thrombosis and 80 control subjects were examined for plasma Hcy levels using high-performance liquid chromatography-fluorescence detection and for CBS polymorphism determined by amplification refractory mutation system. RESULTS: The fasting plasma Hcy level was l5.28 micromol/L (95% CI 14.37-16.19 micromol/L) in the patient group, higher than that in the control group (11.32 micromol/L, 95% C1 10.47-12.16 micromol/L, P<0.001). Plasma Hcy levels varied with different genotypes. No difference in genotype or allele frequencies was noted between patient group and control group (P>0.05). CONCLUSION: Common mutations in CBS G919A and CBS T833C lead to hyperhomocysteinemia, which, instead of common mutations in CBS, is more directly associated with increased risk of cerebral thrombosis.

Plasma albumin cysteinylation is regulated by cystathionine beta-synthase.

High homocysteine (Hcy) levels are a well-known independent risk factor for endothelial damage in atherosclerosis. We examined whether a rat intestinal model of ischemia-reperfusion was associated with high Hcy and with the modification of plasma albumin into cysteinylated species (CysAlb). The three treatment groups were as follows: midline abdominal incision (group A, n=10), followed by ligation of the superior mesenteric artery for a period of 2h (group B, n=3), and followed by reperfusion for 1h (group C, n=10). Hcy levels were 2.5-fold higher in group C than group A (p<0.05). 100% and 73.44+/-0.04% of Alb were modified into Cys species in groups C and B, respectively, compared to 51.2% in group A. A cystathionine beta-synthase (CBS) deficient mouse model, known to have high plasma Hcy levels, was also used to determine the extent of CysAlb. Hcy levels, %CysAlb, and %HcyAlb were 180.1+/-45.7 microM, 0%, and 23.4+/-4.4% in CBS deficient mice, while in control mice, those values were 5.7+/-1.8 microM, 24.2+/-4.1%, and 0%, respectively (p<0.05). High CysAlb and Hcy levels were observed in a rat model of bowel ischemia/reperfusion while high HcyAlb and Hcy levels with no CysAlb were observed in the CBS deficient mice. CysAlb may serve as a biomarker for the severity of gut ischemia, and high Hcy may explain endothelial damage associated with this model. Additionally, active CBS is essential for the formation of CysAlb.