The increase of plasma homocysteine concentrations with age is partly due to the deterioration of renal function as determined by plasma cystatin C

Hypertension and cystatin C account for sex differences in serum homocysteine levels in acute coronary syndrome subjects with normal serum creatinine

BACKGROUND

Hyperhomocysteinemia is one of cardiovascular disease risk factors and fasting homocysteine levels are significantly elevated in male compared to female acute coronary syndrome (ACS) patients with normal renal function. However, it is not known the sex related determinants of plasma homocysteine levels in ACS subjects without renal dysfunction.

METHODS

A total of 165 ACS participants with normal plasma creatinine who underwent coronary angiography were included in the present study. Clinical parameters, homocysteine, fasting glucose and lipid profile, hemoglobin, white blood cell, platelets, creatinine, cystatin C, blood urea nitrogen, uric acid (UA), and albumin were measured. Multivariate linear regression analyses were used to recognize the predictive factors for homocysteine.

RESULTS

The levels of plasma homocysteine were significantly higher in men than in women (P < 0.0001). In males, homocysteine (log10) was positively associated with hypertension (r = 0.569, P < 0.001), creatinine (r = 0.367, P < 0.001) and cystatin C (log10) (r = 0.333, P = 0.001). In females, homocysteine (log10) was positively correlated with age (r = 0.307, P = 0.107), hypertension (r = 0.456, P < 0.001), creatinine (r = 0.341, P = 0.008), cystatin C (log10) (r = 0.429, P = 0.001) and UA (r = 0.569, P < 0.001) whereas was negatively associated with LDL-C (r =  - 0.298, P = 0.021) and ApoB (r =  - 0.273, P = 0.033). Parameters up to statistical significance in males or females were incorporated into the stepwise linear regression models. In men, hypertension (P < 0.001) and creatinine (P = 0.031) were independently related to homocysteine. Most of the variability of homocysteine levels in males were only determined by hypertension. In women, cystatin C (log10) (P = 0.004) and hypertension (P = 0.005) were independently related to homocysteine (log10). Plasma cystatin C had a higher explanatory value than hypertension in females.

CONCLUSIONS

Hypertension and cystatin C could explain most of the sex differences in serum homocysteine levels in ACS subjects with normal serum creatinine. This finding suggested the importance of making different strategies in males and females to manage hyperhomocysteinemia effectively in ACS subjects without renal dysfunction.

Plasma homocysteine is associated with nonproliferative retinopathy in patients with type 2 diabetes without renal disease

BACKGROUND AND AIMS

This study aimed to assess the role of plasma homocysteine (Hcy) in the development of nonproliferative diabetic retinopathy (NPDR) in patients with type 2 diabetes (T2DM) without chronic kidney disease.

METHODS

This was a cross-sectional study that included 94 T2DM. Hcy, serum 25-hydroxy (25-OH) vitamin D, vitamin B12, and folate were determined by the CMIA method. NPDR was determined according to the EURODIAB retinal photography methodology and optical coherence tomography (OCT) of the macula.

RESULTS

Compared to patients without NPDR, patients with NPDR had longer diabetes duration (p < 0.001), higher Hcy (p < 0.001), lower vitamin B12 (p = 0.028) and lower estimated glomerular filtration rate (eGFR) (p = 0.004). NPDR was positively associated with diabetes duration (p < 0.001), HbA₁c (p = 0.049) and Hcy (p < 0.001), and negatively with vitamin B12 (p = 0.027) and eGFR (p = 0.005). Logistic regression analyses showed that diabetes duration (OR = 1.13, p < 0.001), Hcy (OR = 1.06, p = 0.047), and eGFR (OR = 0.96, p = 0.004) were the main predictors of NPDR in T2DM. Stepwise regression analyses showed that the best model for predicting Hcy (R2 = 0.104) included vitamins B12 and D.

CONCLUSIONS

Higher Hcy is associated with NPDR and may play a role as a risk factor for its development in T2DM. Vitamins B12 and D seem to modify this association.

Ability of dietary factors to affect homocysteine levels in mice: a review

Homocysteine is associated with several diseases, and a series of dietary factors are known to modulate homocysteine levels. As mice are often used as model organisms to study the effects of dietary hyperhomocysteinemia, we collected data about concentrations of vitamin B₁₂, vitamin B₆, folate, methionine, cystine, and choline in mouse diets and the associated plasma/serum homocysteine levels. In addition, we more closely examined the composition of the control diet, the impact of the mouse strain, sex and age, and the duration of the dietary intervention on homocysteine levels. In total, 113 out of 1103 reviewed articles met the inclusion criteria. In the experimental and control diets, homocysteine levels varied from 0.1 to 280 µmol/l. We found negative correlations between dietary vitamin B₁₂ (rho = − 0.125; p < 0.05), vitamin B₆ (rho = − 0.191; p < 0.01) and folate (rho = − 0.395; p < 0.001) and circulating levels of homocysteine. In contrast, a positive correlation was observed between dietary methionine and homocysteine (methionine: rho = 0.146; p < 0.05). No significant correlations were found for cystine or choline and homocysteine levels. In addition, there was no correlation between the duration of the experimental diets and homocysteine levels. More importantly, the data showed that homocysteine levels varied widely in mice fed control diets as well. When comparing control diets with similar nutrient concentrations (AIN-based), there were significant differences in homocysteine levels caused by the strain (ANOVA, p < 0.05) and age of the mice at baseline (r = 0.47; p < 0.05). When comparing homocysteine levels and sex, female mice tended to have higher homocysteine levels than male mice (9.3 ± 5.9 µmol/l vs. 5.8 ± 4.5 µmol/l; p = 0.069). To conclude, diets low in vitamin B₁₂, vitamin B₆, or folate and rich in methionine are similarly effective in increasing homocysteine levels. AIN recommendations for control diets are adequate with respect to the amounts of homocysteine-modulating dietary parameters. In addition, the mouse strain and the age of mice can affect the homocysteine level.

The effect of physical activity on total homocysteine concentrations and cardiovascular risk in older Brazilian adults with type 2 diabetes

A low level of physical activity has a potential association with high levels of homocysteine, which implies an increased chance of older adults with type 2 diabetes mellitus developing cardiovascular disease (CVD). However, the effects of physical activity on homocysteine levels have been poorly explored in the literature. Therefore, this study compared homocysteine levels and cardiovascular risk among physically active and inactive older women with type 2 diabetes mellitus. Fifty-nine women with type 2 diabetes mellitus, between 60 and 91 years old, were evaluated. The level of physical activity was assessed using the International Physical Activity Questionnaire (IPAQ) long version to identify active and inactive older women. Blood samples were collected and anthropometric, body composition, and blood pressure measurements were performed to determine homocysteine levels and cardiovascular risk. The results demonstrated that active older women with type 2 diabetes mellitus have lower homocysteine values (F = 17.79, p < 0.001, ηp² = 0.238), cardiovascular risk scores (F = 15.84, p = p < 0.001, ηp² = 0.217), and waist circumferences (F = 2.95, p = 0.013, ηp² = 0.049) when compared with inactive older women. It was concluded that there was a difference in the levels of homocysteine, cardiovascular risk, and waist circumference between active and inactive older women with type 2 diabetes. Active older women are less likely to have cardiovascular risk than inactive older women.

The Relation between Homocysteine Levels in Patients with Acute Coronary Syndrome and Grace Score

Objectives

This study investigated the correlation between homocysteine levels in patients with Acute Coronary Syndrome and GRACE Score.

Methods

This study included 191 cases -140 Non-ST MI cases and 51 MI with ST-elevation cases in Şişli Etfal Training and Research Hospital Coronary Intensive Care Unit between December 2008 and March 2010. Homocysteine was measured by immulite 2000 device, using kemiluminesans method and competitive immunoassay principle and a kit by DPC was used during the measurement. The reference range given by the producing company was between 5-15 Mmol/L for male and female adults. The patients were classified into three risk groups as low, medium and high on the basis of the criteria identified in GRACE risk score: age, heart rate, systolic blood pressure, serum creatine levels, Killip classification, cardiac arrest on admission, increased cardiac enzymes and ST segment depression. The relation between homocysteine levels in patients with Acute Coronary Syndrome and GRACE risk score was evaluated.

Results

In the Non-ST MI group, a statistically-moderate positive correlation was seen between homocysteine and GRACE risk score during the study (p<0.05). However, in the MI with ST-elevation group, no correlation was found between homocysteine and GRACE risk score (p>0.05). Overall, despite the low figures, a meaningful positive relation was observed between homocysteine and GRACE risk score in all cases.

Conclusion

Homocysteine is independent of other classic risk factors for cardiovascular diseases. Therefore, we believe that routine plasma homocysteine levels should be checked when evaluating risk factors for Atherosclerotic Coronary Artery disease.

Aberrant cystatin-C expression in blood from patients with breast cancer is a suitable marker for monitoring tumor burden

The present study was performed to evaluate the efficacy of circulating cystatin-C as a tumor monitoring biomarker at different clinical time points in patients with breast cancer over a long-term follow-up period. In addition, the secretory rate of circulating cystatin-C from cancer tissue was investigated by comparing the blood and tissue expression levels of cystatin-C. Blood samples from healthy volunteers (40 males and 40 females) were obtained at yearly health examinations if laboratory and imaging abnormalities were not detected. Blood samples from 34 patients with breast cancer were obtained at 205 different time points of clinical progression. Blood levels of cystatin-C were measured using ELISA and the tissue levels were measured using immunohistochemistry. No age-associated effect was observed in male and female blood cystatin-C levels. The positivity rate was 46% in patients (38/83) and 40% in samples collected at different time points (82/205). Blood cystatin-C levels were lowest following surgery compared with patients with systemic metastasis (P<0.001). The sensitivity, specificity and accuracy rates of ELISA were 53.6, 63.6 and 53.9%, respectively. The concordance rate between blood and tissue expression was 38%. The main reason for discordance between tissue and serum expression of cytostatin-C came from low serum positivity in samples showing tissue cytostatin-C (3/11, 27%). The specificity between cytostatin-C and CA-125 was highest in tumor absence state. In conclusion, elevated blood levels of cystatin-C were observed in 40% of breast cancer cases and were tumor-volume dependent. However, the concordance rate between tissue and blood was quite low, suggesting tumor heterogeneity of cystatin-C expression or co-acting pathway activation, such as cathepsin D. As one-third of breast cancer tissues express cystatin-C without cancer antigen 15-3 elevation, cystatin-C may represent a good tumor-monitoring marker in breast cancer.

Cysteine Proteinases and Their Inhibitors in Extracellular Fluids: Markers for Diagnosis and Prognosis in Cancer

Cathepsins B, H and L have been shown to participate in processes of tumor growth, vascularization, invasion and metastasis. Their levels in tumor tissue extracts can provide useful clinical information to predict disease-free and overall survival in breast, lung, colorectal, brain and head and neck cancer patients. Recently we have found that both cysteine cathepsins and their endogenous protein inhibitors stefins and cystatin C can also predict prognosis when measured extracellularly. In melanoma and colorectal cancer patients high serum levels of cathepsins B and H correlated with shorter survival. Similarly, increased extracellular levels of stefins A and B and cystatin C correlated significantly with high risk of adverse outcome in cancer patients. However, the cathepsin B/cystatin C complex was found to be less abundant in sera of patients with malignant tumors than in those with benign diseases or in healthy controls, suggesting an imbalance between the enzyme and its inhibitor in cancer patients.

Serum Cystatin C Level Is Not a Promising Biomarker for Predicting Clinicopathological Characteristics of Bladder Urothelial Tumors

The role of cystatin C (Cys-C) in tumorigenesis and progression of bladder urothelial tumors (BUT) is still indefinite. We retrospectively collected the clinical information from the records of 425 BUT patients. Pretreatment serum Cys-C levels were compared across the various groups. Then we subgroup the patients with GFR ≥ 90 mg/min/1.73 m², to exclude the effects of lower renal function on cystatin C. No statistically significant differences in the levels of serum Cys-C were found among the tumor characteristics (all P > 0.05). In conclusion, circulating Cys-C was not a reliable predictor for clinicopathological characteristics of BUT patients.

Contribution of guanine nucleotide exchange factor Vav2 to NLRP3 inflammasome activation in mouse podocytes during hyperhomocysteinemia

NADPH oxidase (NOX)-derived reactive oxygen species (ROS) have been demonstrated to mediate the activation of NOD-like receptor protein 3 (NLRP3) inflammasomes in podocytes in response to elevated levels of homocysteine (Hcys). However, it remains unknown how NLRP3 inflammasome activation is triggered by NOX. The present study tested whether the guanine nucleotide exchange factor Vav2 mediates Rac1-mediated NOX activation in response to elevated Hcys leading to NLRP3 inflammasome activation in podocytes and consequent glomerular injury. In a mouse model of hyperhomocysteinemia (hHcys), we found that mice with hHcys (on the FF diet) or oncoVav2 (a constitutively active form of Vav2) transfection in the kidney exhibited increased colocalization of NLRP3 with apoptosis-associated speck-like protein (ASC) or caspase-1 and elevated IL-1β levels in glomeruli, indicating the formation and activation of the NLRP3 inflammasome. This glomerular NLRP3 inflammasome activation was accompanied by podocyte dysfunction and glomerular injury, even sclerosis. Local transfection of Vav2 shRNA plasmids significantly attenuated hHcys-induced NLRP3 inflammasome activation, podocyte injury, and glomerular sclerosis. In cultured podocytes, Hcys treatment and oncoVav2 transfection were also found to increase NLRP3 inflammasome formation and activation, which were all inhibited by Vav2 shRNA. Furthermore, Vav2 shRNA prevented Hcys-induced podocyte damage as shown by restoring Hcys-impaired VEGF secretion and podocin production. This inhibitory action of Vav2 shRNA on Hcys-induced podocyte injury was associated with reduction of Rac1 activity and ROS production. These results suggest that elevated Hcys levels activate Vav2 and thereby increase NOX activity leading to ROS production, which triggers NLRP3 inflammasome activation, podocyte dysfunction and glomerular injury.

Hyperhomocysteinemia increases the risk of chronic kidney disease in a Chinese middle-aged and elderly population-based cohort

BACKGROUND

Patients either with hyperhomocysteinemia or chronic kidney disease (CKD) have an increased risk of cardiovascular disease. Little is known regarding whether hyperhomocysteinemia can increase the risk of CKD in a Chinese middle-aged and elderly population. To help clarify this we conducted a prospective cohort study to measure the association of hyperhomocysteinemia with CKD.

METHODS

A total of 5917 adults aged 56.4 ± 9.6 years without CKD at baseline were enrolled. The highest homocysteine quartile (≥15 μmol/L) was defined as hyperhomocysteinemia. CKD was defined as decreased estimated glomerular filtration rate (eGFR < 60 mL/min/1.73 m²) or presence of proteinuria (urine protein ≥ 1+) assessed using a repeated dipstick method.

RESULTS

During 3 years of follow-up, 143 (2.4%) patients developed CKD, 85 (1.4%) patients with proteinuria and 59 (1.0%) patients with decreased eGFR. After adjusted for potential confounders, both homocysteine (per 1 μmol/L increase) and hyperhomocysteinemia were independently associated with increased risk of decreased eGFR [with a fully adjusted OR of 1.07 (95% CI 1.04-1.10) and 3.05 (95% CI 1.71-5.46)] and CKD [with a fully adjusted OR of 1.04 (95% CI 1.02-1.07) and 1.62 (95% CI 1.11-2.35)], respectively. By contrast, neither homocysteine (per 1 μmol/L increase) nor hyperhomocysteinemia were associated with proteinuria in the multivariable logistic regression analysis.

CONCLUSIONS

The study revealed that hyperhomocysteinemia increases the risk of decreased eGFR. This suggests that homocysteine could be considered as a useful molecular markers for delaying the development of CKD.

Effect of physical activity on levels of homocysteine, folate, and vitamin B12 in the elderly

OBJECTIVES

Homocysteine (Hcy) has emerged as a risk factor for cardiovascular diseases (CVD). However the relationship of physical activity (PA) with Hcy levels in the elderly is controversial. Accordingly, the current study examined the effect of low and high participation in PA on serum Hcy in young (n = 77; 18-50 years) and old (n = 207; > 65 years) males (n = 141) and females (n = 142).

METHODS

Level of PA was obtained in a 1-to-1 interview and participants divided into low and high groups. Serum Hcy, folate, and vitamin B12 were obtained after 12 hour fast drawn by venipuncture.

RESULTS

Levels of Hcy correlated with folate (r = -0. 5; p = 0.000) and vitamin B12 (r = -0.3; p = 0.000). The ANOVA revealed a main effect of PA for Hcy (p = 0.04) but not for folate (p = 0.2) and vitamin B12 (p = 0.2). Main effects were found also of age for Hcy (p = 0.000) and folate (p = 0.005) as well as of gender for Hcy (p = 0.000) and vitamin B12 (p = 0.000). Subsequent ANCOVA showed lower levels of Hcy in the participants with greater versus lower PA even after controlling for B12 vitamin.

CONCLUSION

These results confirm the importance of the vitamins for regulating Hcy levels. Additionally, the data suggests that PA affects Hcy levels without affecting and independent of B vitamins in the elderly.

A high thyroid stimulating hormone level is associated with diabetic peripheral neuropathy in type 2 diabetes patients

AIM

The association between thyroid stimulating hormone (TSH) and type 2 diabetes mellitus (T2DM) is well known. However, whether TSH is related to diabetic peripheral neuropathy (DPN) has not been studied. The aim of this study was to explore the relationship between TSH and DPN in Chinese patients with T2DM.

METHODS

In this cross-sectional study, 605 patients with T2DM were enrolled. Subclinical hypothyroidism (SCH) was defined as an elevated TSH level (>4.0mIU/L) and a normal free thyroxine level. DPN was evaluated by neurological symptoms, neurological signs, and electromyogram.

RESULTS

Serum TSH levels were significantly higher in DPN and signs of DPN compared with non-DPN T2DM patients (both P<0.01).The prevalence of DPN and signs of DPN in SCH subjects was higher than that in euthyroid subjects (both P<0.01). Spearman's correlation analysis showed that the serum TSH level was positively associated with DPN (r=0.172, P<0.01). A significant independent association between TSH and DPN was found by multiple logistic regression analysis after adjusting for potential confounding variables [odds ratio (OR)=1.365, P<0.01]. The patients were sequentially assigned to quartiles according to TSH level. Compared with quartile 1, patients in quartile 2 (P<0.01), quartile 3 (P=0.01), and quartile 4 (P<0.01) had a higher risk of DPN. Receiver-operating characteristic curve analysis revealed that the optimal cutoff point of TSH to indicate DPN was 3.045mIU/L in men and 2.94mIU/L in women.

CONCLUSION

TSH level is independently associated with DPN in Chinese population with T2DM. A high serum TSH level may be a potential risk factor for DPN.

Relationship between High Serum Cystatin C Levels and the Risk of Gestational Diabetes Mellitus

Aims

Serum cystatin C (CysC) has recently been shown to be associated with the incidence of type 2 diabetes mellitus (T2DM) and progression to the pre-diabetic state. The aim of this study was to explore the relationship between serum CysC and the risk of gestational diabetes mellitus (GDM) in Chinese pregnant women.

Methods

This cross-sectional study consisted of 400 pregnant women including111 with GDM and 289 with normal glucose tolerance at 24–28 weeks of gestation. The subjects were further divided into four groups according to the CysC quartiles, and their clinical characteristics were compared. The serum CysC concentration was measured using immunoturbidimetry and the degree of insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMA-IR).

Results

Serum CysC levels were significantly higher in pregnant women with GDM than in the healthy pregnant women[1.0(0.8–1.8) vs 0.7(0.6–1.0), P<0.01). The Spearman’s correlation analysis showed that serum CysC was positively associated with HOMA-IR(r = 0.118, P<0.05) and the occurrence of GDM(r = 0.348, P<0.01). The pregnant women were divided into quartiles according to their serum CysC concentrations. Compared to the first quartile, pregnant women in Q2 (OR, 2.441; P = 0.025), Q3 (OR, 3.383; P = 0.001) and Q4 (OR, 5.516; P<0.001) had higher risk of GDM after adjusted for age, BMI, HbA1c and HOMA-IR. Further, with a rise in the serum CysC, there was an increasing trend in the HOMA-IR levels (P<0.05). A binary logistic regression analysis after adjusting for other confounding variables revealed a significant and independent association between serum CysC and GDM [OR = 14.269; 95% confidence interval, 4.977–40.908, P<0.01].The receiver operating characteristic curve analysis revealed that the optimal cutoff point for serum CysC to indicate GDM was 0.95mg/L.

Conclusions

Serum CysC is significantly and independently associated with insulin resistance and GDM. It may be a helpful biomarker to identify the risk of GDM in Chinese pregnant women.

The potential physiological crosstalk and interrelationship between two sovereign endogenous amines, melatonin and homocysteine

The antioxidant melatonin and the non-proteinogenic excitotoxic amino acid homocysteine (Hcy) are very distinct but related reciprocally to each other in their mode of action. The elevated Hcy level has been implicated in several disease pathologies ranging from cardio- and cerebro-vascular diseases to neurodegeneration owing largely to its free radical generating potency. Interestingly, melatonin administration potentially normalizes the elevated Hcy level, thereby protecting the cells from the undesired Hcy-induced excitotoxicity and cell death. However, the exact mechanism and between them remain obscure. Through literature survey we have found an indistinct but a vital link between melatonin and Hcy i.e., the existence of reciprocal regulation between them, and this aspect has been thoroughly described herein. In this review, we focus on all the possibilities of co-regulation of melatonin and Hcy at the level of their production and metabolism both in basal and in pathological conditions, and appraised the potential of melatonin in ameliorating homocysteinemia-induced cellular stresses. Also, we have summarized the differential mode of action of melatonin and Hcy on health and disease states.

Homocysteine levels in normotensive children of hypertensive parents

OBJECTIVE

There are several studies showing an association between an increase in the plasma levels of homocysteine and the pathogenesis of hypertension. In this study, we assessed normotensive children of hypertensive adult parents to determine whether there is any change in homocysteine levels prior to the onset of hypertension.

METHODS

A total of 79 normotensive children of essential hypertensive parents who were followed-up at the cardiology department and 72 healthy children of normotensive parents who presented to the department of pediatrics at our clinic with complaints such as nonspecific chest pain and innocent murmur were included in the study. The participants' complete blood count and low-density lipoprotein, high-density lipoprotein, triglyceride, total cholesterol, folic acid, vitamin B12, and homocysteine levels were noted.

RESULTS

No statistically significant differences were noted between the two groups in terms of age, gender, height, weight, body mass index, or levels of fasting lipids, folic acid, and vitamin B12 (p>0.05). Although the mean systolic and diastolic blood pressures were within the normal limits in both groups, they were significantly higher in children with a family history of hypertension than in controls (p<0.05). Similarly, homocysteine levels of children with a family history of hypertension were significantly higher than those of controls (p<0.01).

CONCLUSION

Homocysteine levels of normotensive children of hypertensive parents are elevated before they develop hypertension. Homocysteine levels may be predictive of the subsequent development of hypertension in normotensive children of hypertensive parents.

B12 deficiency increases with age in hospitalized patients: a study on 14,904 samples

BACKGROUND

Cobalamin deficiency is responsible for hematological, neurological, neurocognitive, and neuropsychiatric impairments and is a risk factor for cardiovascular diseases, particularly in the elderly people.

METHODS

In order to determine B12 status in old inpatients, a total number of 14,904 hospitalized patients in whom B12 measurements were performed in five hospitals in the Paris metropolitan area were included from January 1, 2011 to December 31, 2011. The aims of the study were to determine whether age had an impact on B12 and folate deficiencies and to evaluate correlations between B12 and biological parameters-folate, hemoglobin, mean cell volume, homocystein (tHcy)-and age.

RESULTS

Patients were aged 70.3±19.5 years. Low B12 concentration (<200ng/L) was observed in 4.6% of cases, 24.2% had middle B12 concentration (200-350ng/L), 12.6% were functional B12 deficient (B12 < 350 ng/L associated to high tHcy level, tHcy > 17 µmol/L), 20.4% had low folate concentration (folate < 4 µg/L), 10.6% were functional folate deficient (folate < 4 µg/L associated to tHcy > 17 µmol/L), and 4.7% of patients were both functional B12 and folate deficient. The B12 or folate deficient patients had lower mean cell volume level than nondeficient patients. Increase in mean cell volume and tHcy concentrations with age and decrease in B12, folate, and hemoglobin levels with age were observed. Frequency of functional B12 deficiency was 9.6% in patients aged 30-60 years and 14.2% in patients over 90 years. Frequency of functional folate deficiency was 9.5% in 30-60 years and 12.1% in >90 years.

CONCLUSIONS

In inpatients, functional B12 deficiency and functional folate deficiency increase with age and are not associated with anemia or macrocytosis. False vitamin B deficiencies are frequent.

Plasma Homocysteine is Associated with Retinopathy in Type 1 Diabetic Patients in the Absence of Nephropathy

INTRODUCTION

Previous cross-sectional studies suggested that plasma total homocysteine (tHcy) is associated with retinopathy in patients with type 1 diabetes (T1DM) only in cases of impaired renal function. The objective of this study was to examine whether there is an independent relationship between tHcy and retinopathy in normoalbuminuric T1DM patients with normal estimated glomerular filtration rate (eGFR).

METHODS

The study included 163 normoalbuminuric patients with T1DM and normal renal function (eGFR >60 ≤ 125 ml min(-1) 1.73 m(-2)). Urinary albumin excretion rate (UAE) was measured from at least two 24 h urine samples. Photodocumented retinopathy status was made according to the EURODIAB protocol. tHcy level was measured with the chemiluminescent immunoassay.

RESULTS

Retinopathy was present in 48% of normoalbuminuric patients. Patients with retinopathy were older (49 vs 42 years, p = 0.001), had higher systolic blood pressure (130 vs 120 mmHg, p = 0.001), triglycerides (0.89 vs 0.77 mmol/L, p = 0.01), tHcy (9.8 vs 9.1 µmol/L, p = 0.04), and lower eGFR (100 vs 106 ml min(-1) 1.73 m(-2), p = 0.03). In multivariate logistic regression analysis, after adjustment for variables that reached statistical significance in the univariate analysis, only tHcy was significantly associated with a risk of retinopathy in our subjects (p = 0.02), with odds ratios of 1.02 to 1.43.

CONCLUSION

These data suggest that tHcy is independently associated with retinopathy in normoalbuminuric T1DM with normal eGFR. The mechanisms relating tHcy and retinopathy in T1DM are not clear. Prospectives studies are needed to confirm whether higher tHcy in normoalbuminuric T1DM patients has predictive value for development of retinopathy.

Serum homocysteine level is positively associated with chronic kidney disease in a Taiwan Chinese population

BACKGROUND

Both hyperhomocysteinemia and chronic kidney disease (CKD) increase risk of cardiovascular disease. In this study, we investigated the association between serum homocysteine level and CKD.

MATERIALS AND METHODS

A total of 1,581 participants were recruited from a health check-up center in a tertiary hospital in Taiwan between 2006 and 2008. Two groups were created based on serum homocysteine levels above or below 12.24 μmol/l. Estimated glomerular filtration rate (eGFR) was calculated by the Modification of Diet in Renal Disease equation; we defined CKD as an eGFR below 60 ml/min/1.73 m(2). Multivariate logistic and linear regression analyses were used to estimate the associations between serum homocysteine levels and kidney function.

RESULTS

Subjects with elevated homocysteine levels were older and had higher body mass index, blood pressures, fasting plasma glucose, total cholesterol, triglycerides, and eGFR than those with normal serum homocysteine level. Using multiple logistic regression analyses after adjustment for age, sex, lifestyle habits (smoking, alcohol consumption, and betel nut chewing) and chronic diseases (hypertension, diabetes, dyslipidemia), the odds ratio (95 % confidence interval) of having CKD was 5.76 (2.99-11.1) among subjects with elevated serum homocysteine levels compared to subjects with normal serum homocysteine levels. The significant increase in odds ratios for CKD in progressive homocysteine levels reveals a dose-response effect. After adjustment for confounders, at multiple linear regression analyses serum homocysteine level resulted significantly and negatively correlated to eGFR.

CONCLUSIONS

Elevated serum homocysteine levels appear to be closely associated with CKD. Serum homocysteine levels are negatively associated with eGFR.

A prospective controlled study of kidney donors: baseline and 6-month follow-up

BACKGROUND

Most previous studies of living kidney donors have been retrospective and have lacked suitable healthy controls. Needed are prospective controlled studies to better understand the effects of a mild reduction in kidney function from kidney donation in otherwise healthy individuals.

STUDY DESIGN

Prospective, controlled, observational cohort study.

SETTING & PARTICIPANTS

Consecutive patients approved for donation at 8 transplant centers in the United States were asked to participate. For every donor enrolled, an equally healthy control with 2 kidneys who theoretically would have been suitable to donate a kidney also was enrolled.

PREDICTOR

Kidney donation.

MEASUREMENTS

At baseline predonation and at 6 months after donation, medical history, vital signs, measured (iohexol) glomerular filtration rate, and other measurements were collected. There were 201 donors and 198 controls who completed both baseline and 6-month visits and form the basis of this report.

RESULTS

Compared with controls, donors had 28% lower glomerular filtration rates at 6 months (94.6 ± 15.1 [SD] vs 67.6 ± 10.1 mL/min/1.73 m(2); P < 0.001), associated with 23% greater parathyroid hormone (42.8 ± 15.6 vs 52.7 ± 20.9 pg/mL; P < 0.001), 5.4% lower serum phosphate (3.5 ± 0.5 vs 3.3 ± 0.5 mg/dL; P < 0.001), 3.7% lower hemoglobin (13.6 ± 1.4 vs 13.1 ± 1.2 g/dL; P < 0.001), 8.2% greater uric acid (4.9 ± 1.2 vs 5.3 ± 1.1 mg/dL; P < 0.001), 24% greater homocysteine (1.2 ± 0.3 vs 1.5 ± 0.4 mg/L; P < 0.001), and 1.5% lower high-density lipoprotein cholesterol (54.9 ± 16.4 vs 54.1 ± 13.9 mg/dL; P = 0.03) levels. There were no differences in albumin-creatinine ratios (5.0 [IQR, 4.0-6.6] vs 5.0 [IQR, 3.3-5.4] mg/g; P = 0.5), office blood pressures, or glucose homeostasis.

LIMITATIONS

Short duration of follow-up and possible bias resulting from an inability to screen controls with kidney and vascular imaging performed in donors.

CONCLUSIONS

Kidney donors have some, but not all, abnormalities typically associated with mild chronic kidney disease 6 months after donation. Additional follow-up is warranted.

Elevated plasma homocysteine level in vascular dementia reflects the vascular disease process

Background

Patients with vascular dementia (VaD) exhibit particularly elevated levels of plasma total homocysteine (tHcy) compared to patients with other psychogeriatric diseases.

Methods

We investigated the main determinants (age, renal impairment, cobalamin/folate status and presence of extracerebral vascular disease) of plasma tHcy in 525 patients with VaD. Furthermore, 270 patients with depression were used as a reference group to reveal the potential specificity of elevated plasma tHcy in patients with VaD.

Results

Elevated plasma tHcy levels in patients with VaD could only partly be attributed to cobalamin/folate deficiency or renal impairment. Plasma tHcy might also be related to the vascular disease process since patients with depression and vascular disease exhibited similar plasma tHcy levels to patients with VaD.

Conclusion

Our findings suggest that elevated plasma tHcy might be a sensitive marker for the vascular disease process in patients with VaD and that the level also is a reflection of changes in the other main determinants of plasma tHcy.

Elevated plasma homocysteine level is not primarily related to Alzheimer's disease

BACKGROUND

A moderate elevation of plasma total homocysteine (tHcy) is considered a potential risk factor for Alzheimer's disease (AD).

METHODS

We have investigated the main determinants (age, renal impairment, cobalamin/folate status and the presence of vascular disease) of plasma tHcy in 326 patients with AD, and also in 281 patients with mild cognitive impairment (MCI), since about half of these patients develop AD during the first 5 years.

RESULTS

Elevated plasma tHcy in patients with AD could mainly be attributed to cobalamin/folate deficiency or renal impairment. Younger patients (below 75 years) with AD and patients with MCI without cobalamin/folate deficiency or renal impairment showed normal levels of plasma tHcy.

CONCLUSION

Our findings suggest that plasma tHcy is not primarily involved in the pathogenesis of AD but rather a reflection of changes of the main determinants of plasma tHcy in AD patients.

Association of plasma homocysteine with self-reported sleep apnea is confounded by age: results from the national health and nutrition examination survey 2005-2006

High levels of plasma homocysteine are implicated in the pathogenesis of cardiovascular diseases especially if accompanied by sleep apnea, but a direct pathogenetic link between plasma homocysteine levels and obstructive sleep apnea is debatable. This association can have far-reaching public health implications considering the inverse association between folate and plasma homocysteine. We used data from the 2005-2006 cycle of the National Health and Nutrition Examination Survey (NHANES) to test the hypothesized associations. Of the 4490 subjects included in analysis, 177 reported sleep apnea. Age-standardized and design-effect-corrected prevalence rates were differential across gender, plasma homocysteine, and red cell folate status. Plasma homocysteine was positively correlated with age (r = 0.38, P < 0.0001). Multivariate analyses using sociodemographic and clinical covariates demonstrated that plasma homocysteine levels retained their respective associations with self-reported sleep apnea in all models except when age was included as a covariate. Our results demonstrate that the claimed association of plasma homocysteine with sleep apnea may be confounded by age.

Association between kidney and cardiac diastolic function in Chinese subjects without overt disease: correlation with ageing and inflammatory markers

BACKGROUND

Age-related changes in kidney structure and function have been well documented. This study aimed to assess the relationship between declines of normal ageing-related kidney function and cardiac diastolic function in a healthy Chinese population.

MATERIALS AND METHODS

A total of 852 healthy adults aged 30-98 years were enrolled and divided into four groups according to quartiles of estimated glomerular filtration rate (eGFR) and cystatin C (CYSC). Cardiac diastolic function was measured by ratio of peak velocity of early filling to peak velocity of atrial filling (E/A), which was derived by B-mode echocardiography. Lower E/A was defined as measures under the 25th percentile of sample distribution (0·784).

RESULTS

Age was significantly associated with eGFR (r = -0·102, P < 0·01), CYSC (r = 0·544, P < 0·01) and E/A (r = -0·381, P < 0·01). Binary logistic regression analysis revealed that second, third and fourth quartile groups of CYSC and fourth quartile of eGFR were significantly associated with lower E/A in an unadjusted model. However, these associations were lost after full adjustment.

CONCLUSIONS

Our results confirm that ageing is a major factor contributing to declines in both kidney and cardiac diastolic function in a healthy population. Adjustment for covariates, however, showed that normal ageing-related declines in kidney function and cardiac diastolic function are not independently linked.

Metabolic footprint of diabetes: a multiplatform metabolomics study in an epidemiological setting

BACKGROUND

Metabolomics is the rapidly evolving field of the comprehensive measurement of ideally all endogenous metabolites in a biological fluid. However, no single analytic technique covers the entire spectrum of the human metabolome. Here we present results from a multiplatform study, in which we investigate what kind of results can presently be obtained in the field of diabetes research when combining metabolomics data collected on a complementary set of analytical platforms in the framework of an epidemiological study.

METHODOLOGY/PRINCIPAL FINDINGS

40 individuals with self-reported diabetes and 60 controls (male, over 54 years) were randomly selected from the participants of the population-based KORA (Cooperative Health Research in the Region of Augsburg) study, representing an extensively phenotyped sample of the general German population. Concentrations of over 420 unique small molecules were determined in overnight-fasting blood using three different techniques, covering nuclear magnetic resonance and tandem mass spectrometry. Known biomarkers of diabetes could be replicated by this multiple metabolomic platform approach, including sugar metabolites (1,5-anhydroglucoitol), ketone bodies (3-hydroxybutyrate), and branched chain amino acids. In some cases, diabetes-related medication can be detected (pioglitazone, salicylic acid).

CONCLUSIONS/SIGNIFICANCE

Our study depicts the promising potential of metabolomics in diabetes research by identification of a series of known and also novel, deregulated metabolites that associate with diabetes. Key observations include perturbations of metabolic pathways linked to kidney dysfunction (3-indoxyl sulfate), lipid metabolism (glycerophospholipids, free fatty acids), and interaction with the gut microflora (bile acids). Our study suggests that metabolic markers hold the potential to detect diabetes-related complications already under sub-clinical conditions in the general population.

Non-invasive estimation of glomerular filtration rate (GFR). The Lund model: Simultaneous use of cystatin C- and creatinine-based GFR-prediction equations, clinical data and an internal quality check

Knowledge of glomerular filtration rate (GFR) is required to detect and follow impairment of renal function, to allow correct dosage of drugs cleared by the kidneys, and for the use of nephrotoxic contrast media. Correct determination of GFR requires invasive techniques, which are expensive, slow and not risk-free. Therefore, GFR-prediction equations based solely upon cystatin C or creatinine and anthropometric data or upon cystatin C, creatinine and anthropometric data have been developed. The combined prediction equations display the best diagnostic performance, but in several easily identifiable clinical situations (e.g. abnormal muscle mass, treatment with large doses of glucocorticoids) prediction equations based upon either cystatin C or creatinine are better than the combined equations. In Lund, where cystatin C has been used as a GFR-marker in the clinical routine since 1994, a strategy based upon this knowledge has therefore been developed. This comprises simultaneous use of a cystatin C-based and a creatinine-based GFR-prediction equation. If the GFRs predicted agree, the mean value is used as a reliable GFR-estimate. If the GFRs predicted do not agree, clinical data is evaluated to identify reasons for not using one of the two prediction equations and the GFR predicted by the other one is used. If no reasons for the difference in predicted GFRs are found, an invasive gold standard determination of GFR is performed. If the GFRs predicted agree for a patient, the creatinine value is reliably connected to a specific GFR and can be used to follow changes in GFR of that patient.

Demographic, lifestyle, and health characteristics and serum B vitamin status are determinants of plasma total homocysteine concentration in the post-folic acid fortification period, 1999-2004

Elevated circulating total homocysteine (tHcy) concentrations are related to increased risk for cardiovascular disease. Folic acid fortification resulted in a significant decrease in circulating tHcy in the United States. In the post-folic acid fortification period, associations between plasma tHcy and demographic, health, and lifestyle factors and B vitamin status were investigated. Data from the 3 recent NHANES cycles (1999-2004) were used to study the associations among plasma tHcy and sex, race/ethnicity, age, BMI, blood pressure (BP), serum creatinine, serum cotinine, vitamin/mineral supplement use, and folate and cobalamin status in 16,254 persons (8329 men, 7925 women). Multivariate-adjusted plasma tHcy was approximately 9.7% higher in men than in women (P < 0.0001), approximately 5.3% higher in non-Hispanic whites than in non-Hispanic blacks (P < 0.0001), approximately 64.5% higher in individuals aged >or=60 y than in individuals aged <20 y (P < 0.0001), and approximately 5% higher in supplement nonusers than in supplement users (P < 0.0001). Persons in the 4th quartile for serum creatinine, serum cotinine, systolic BP, and serum methylmalonic acid (MMA) had approximately 36.1, approximately 13.4, approximately 5.6, and approximately 16.2%, respectively, higher tHcy than those in the 1st quartile (P < 0.0001). Plasma tHcy was inversely associated with serum folate (P < 0.0001), RBC folate (P < 0.0001), and serum cobalamin (P < 0.0001). In the post-folic acid fortification period, sex, race/ethnicity, age, systolic BP, supplement use, RBC folate, and serum creatinine, cotinine, folate, and cobalamin are significant determinants of plasma tHcy. Serum MMA was strongly associated with plasma tHcy.

Effects of creatine supplementation on homocysteine levels and lipid peroxidation in rats

Hyperhomocysteinaemia is an independent risk factor for CVD. Recent data show a relationship between homocysteine (Hcy) and free radical formation. Since creatine synthesis is responsible for most of the methyl group transfers that result in Hcy formation, creatine supplementation might inhibit Hcy production and reduce free radical formation. The present study investigated the effects of creatine supplementation on Hcy levels and lipid peroxidation biomarkers. Thirty rats were divided into three groups: control group; diet with creatine group (DCr; 2 % creatine in the diet for 28 d); creatine overload plus diet with creatine group (CrO + D; 5 g creatine/kg by oral administration for 5 d+2 % in the diet for 23 d). Plasma Hcy was significantly lower (P < 0.05) in DCr (7.5 (sd 1.2) micromol/l) and CrO + D (7.2 (sd 1.7) micromol/l) groups compared with the control group (12.4 (sd 2.2) micromol/l). Both plasma thiobarbituric acid-reactive species (TBARS) (control, 10 (sd 3.4); DCr, 4.9 (sd 0.7); CrO + D, 2.4 (sd 1) micromol/l) and plasma total glutathione (control, 4.3 (sd 1.9); DCr, 2.5 (sd 0.8); CrO + D, 1.8 (sd 0.5) micromol/l) were lower in the groups that received creatine (P < 0.05). In addition, Hcy showed significant negative correlation (P < 0.05) with plasma creatine (r - 0.61) and positive correlation with plasma TBARS (r 0.74). Plasma creatine was negatively correlated with plasma TBARS (r - 0.75) and total peroxide (r - 0.40). We conclude that creatine supplementation reduces plasma Hcy levels and lipid peroxidation biomarkers, suggesting a protective role against oxidative damage. Modulating Hcy formation may, however, influence glutathione synthesis and thereby affect the redox state of the cells.

Biochemistry and Clinical Role of Human Cystatin C

Low molecular-mass plasma proteins play a key role in health and disease. Cystatin C is an endogenous cysteine proteinase inhibitor belonging to the type 2 cystatin superfamily. The mature, active form of human cystatin C is a single non-glycosylated polypeptide chain consisting of 120 amino acid residues, with a molecular mass of 13,343-13,359 Da, and containing four characteristic disulfide-paired cysteine residues. Human cystatin C is encoded by the CST3 gene, ubiquitously expressed at moderate levels. Cystatin C monomer is present in all human body fluids; it is preferentially abundant in cerebrospinal fluid, seminal plasma, and milk. Cystatin C L68Q variant is an amyloid fibril-forming protein with a high tendency to dimerize. It forms self-aggregates with massive amyloid deposits in the brain arteries of young adults, leading to lethal cerebral hemorrhage. The main catabolic site of cystatin C is the kidney: more than 99% of the protein is cleared from the circulation by glomerular ultrafiltration and tubular reabsorption. The diagnostic value of cystatin C as a marker of kidney dysfunction has been extensively investigated in multiple clinical studies on adults, children, and in the elderly. In almost all the clinical studies, cystatin C demonstrated a better diagnostic accuracy than serum creatinine in discriminating normal from impaired kidney function, but controversial results have been obtained by comparing this protein with other indices of kidney disease, especially serum creatinine-based equations. In this review, we present and discuss most of the available data from the literature, critically reviewing conclusions and suggestions for the use of cystatin C in clinical practice. Despite the multitude of clinical data in the literature, cystatin C has not been widely used, perhaps because of a combination of factors, such as a general diffidence among clinicians, the absence of definitive cut-off values, conflicting results in clinical studies, no clear evidence on when and how to request the test, the poor commutability of results, and no accurate examination of costs and of its routine use in a stat laboratory.

Homocysteine in restless legs syndrome

BACKGROUND AND PURPOSE

Total plasma homocysteine (tHcy) may be a risk factor for vascular diseases and is associated with renal failure or deficiency of vitamin B12 or folate. Recently, elevated tHcy concentrations were observed in patients with Parkinson's disease (PD), particularly those under levodopa treatment. Our objective was to determine whether changes in tHcy are also found in patients with restless legs syndrome (RLS) in relation to levodopa treatment and whether folate and vitamins B6 and B12 play a role in RLS.

METHODS

In a total of 228 subjects, tHcy and B vitamin status (vitamins B6 and B12, folate) were studied: 97 patients with idiopathic RLS (40 under levodopa therapy), 39 with PD (25 under levodopa therapy), and 92 healthy controls adjusted for age and gender.

RESULTS

No significant differences were observed in tHcy levels between RLS patients and controls or between the RLS groups without treatment or with levodopa or dopamine agonist treatment. Mean tHcy was significantly higher in PD patients (13.8 micromol/l) than in either RLS patients (11.7 micromol/l) or controls (11.0 micromol/l; p<0.001). There was an inverse association between tHcy and vitamin B12 in each group.

CONCLUSIONS

RLS and, in particular, levodopa treatment in RLS are not associated with hyperhomocysteinemia. Elevated tHcy could, however, be confirmed in PD patients.

Hyperhomocysteinemia: association with renal transsulfuration and redox signaling in rats

Despite substantial evidence indicating the association of hyperhomocysteinemia (hHcys) and end-stage renal disease (ESRD), the pathogenic role of increased plasma homocysteine (Hcys) levels in the progression of ESRD remains unclear. This review will briefly summarize recent findings regarding the role of hHcys in the development of glomerulosclerosis, the association of hHcys with reduced renal transsulfuration and Hcys-induced changes of redox signaling in the development of glomerulosclerosis in rat kidneys. Based on these results, it is concluded that hHcys is implicated in glomerular sclerosis in hypertension, elevated plasma Hcys in Dahl salt-sensitive (SS) hypertensive rats is due to downregulation of cystathionine beta-synthase (CBS) expression and consequent abnormality of transsulfuration in the kidney compared with normotensive rats. Hcys-induced superoxide (O(2)(*-)) production by activation of NADPH oxidase as a triggering mechanism contributes to the effects of Hcys on the homeostasis of extracellular matrix and consequent sclerosis in the glomeruli, and NADPH oxidase activation by Hcys is associated with enhanced Rac GTPase activity.

Homocysteine, cystatin C and N-terminal-pro brain natriuretic Peptide. Vascular risk markers in elderly patients with mental illness

BACKGROUND

There is increasing evidence that vascular disease contributes to cognitive impairment and dementia. Clarification of the role of vascular risk factors in dementia is important because most are modifiable, in contrast to other risk factors such as age and genetics.

METHODS

In 451 patients with mental illness we have investigated three biochemical markers related to vascular disease, total plasma homocysteine (tHcy), cystatin C, and N-terminal-pro brain natriuretic peptide (NT-proBNP), and their association with vascular disease, diagnoses, and brain imaging findings (CT).

RESULTS

Plasma tHcy, serum cystatin C, and serum NT-proBNP showed significantly increased frequencies of elevated levels in patients with vascular disease, in patients with a pathological CT finding indicating cerebrovascular disease, and in patients above 75 years of age.

CONCLUSION

It is possible that the control of conventional vascular risk factors and therapy could be guided by the level of plasma tHcy, serum cystatin C, and serum NT-proBNP. Patients with an elevation of any of these three parameters could be selected for a lower target level of risk factors such as blood pressure, hyperlipidemia etc. than conventional target levels.

Mechanisms of homocysteine-induced glomerular injury and sclerosis

Hyperhomocysteinemia (hHcys) has been recognized as a critical risk or pathogenic factor in the progression of end-stage renal disease (ESRD) and in the development of cardiovascular complications related to ESRD. Recently, evidence is accumulating that hHcys may directly act on glomerular cells to induce glomerular dysfunction and consequent glomerular sclerosis, leading to ESRD. In this review, we summarize recent findings that reveal the contribution of homocysteine as a pathogenic factor to the development of glomerular sclerosis or ESRD. In addition, we discuss several important mechanisms mediating the pathogenic action of homocysteine in the glomeruli or in the kidney, such as local oxidative stress, endoplasmic reticulum stress, homocysteinylation, and hypomethylation. Understanding these mechanisms may help design new approaches to develop therapeutic strategies for treatment of hHcys-associated end-organ damage and for prevention of deterioration of kidney function and ultimate ESRD in patients with hypertension and diabetes mellitus or even in aged people with hHcys.

Plasma creatinine as a determinant of plasma total homocysteine concentrations in the Hordaland Homocysteine Study: Use of statistical modeling to determine reference limits

OBJECTIVES

We established population-based reference limits for plasma total homocysteine (tHcy) according to creatinine.

DESIGN AND METHODS

In 7042 middle-aged and elderly subjects from the Hordaland Homocysteine Study, we used statistical modeling to establish nomograms for tHcy according to creatinine in the whole population and in folate-replete and healthy subgroups.

RESULTS

When plotted against creatinine, tHcy 97.5th percentile almost overlapped in men and women, and, in elderly, increased up to 8 micromol/L from the 2.5th to 97.5th creatinine percentiles. Folate-replete subjects had tHcy upper limits approximately 20% below the whole population at all creatinine levels. Healthy subjects had lower creatinine, but at a given creatinine level, tHcy was the same as in the whole population.

CONCLUSIONS

tHcy difference between men and women is mostly explained by creatinine. The tHcy-reducing effect of folate is independent of creatinine. In elderly people, creatinine should be taken into account when assessing tHcy levels.

Elevated plasma homocysteine concentration in elderly patients with mental illness is mainly related to the presence of vascular disease and not the diagnosis

BACKGROUND

Plasma total homocysteine (tHcy) is often elevated in patients with mental illness. Since patients with mental illness and vascular disease exhibit a higher plasma tHcy concentration than patients without vascular disease, it is possible that elevated plasma tHcy in mental illness is mainly due to concomitant vascular disease.

METHODS

We have investigated plasma tHcy, cobalamin/folate status, renal function and the presence of vascular disease in patients with vascular dementia (VaD, n = 501), Alzheimer's disease (AD, n = 300), depression (n = 259) and in healthy subjects (n = 144) stratified according to age (below and above 75 years).

RESULTS

Plasma tHcy concentration showed the highest increase in patients with VaD compared to patients with AD or depression. After the exclusion of patients with cobalamin/folate deficiencies and increased serum creatinine, patients with AD or depression above 75 years with vascular disease showed a similar elevation of plasma tHcy concentration as patients with VaD. Furthermore, patients with AD and depression without vascular disease showed a similar plasma tHcy concentration to healthy subjects.

CONCLUSION

The findings imply that elevated plasma tHcy concentration in elderly patients with mental illness is mainly associated with the presence of vascular disease and is not related to the specific psychogeriatric diagnosis.

Plasma homocysteine is elevated in elderly patients with memory complaints and vascular disease

BACKGROUND

There is an association between elevated plasma total homocysteine (tHcy) and vascular disease in elderly patients suffering from organic and non-organic mental disease. The main objective of the present study was to investigate the relationship between plasma tHcy concentration and vascular disease in elderly patients with memory complaints.

METHODS

In 108 patients with memory complaints the concentration of plasma tHcy was related to the presence of vascular disease. Furthermore, different determinants of plasma tHcy concentration were measured.

RESULTS

Patients with confirmed memory complaints (CMC, n = 86) which fulfilled the criteria of mild cognitive impairment were divided into two categories, with and without vascular disease. The CMC group without vascular disease showed similar biochemical and brain imaging findings to patients with subjective memory complaints (SMC, n = 22). The group of CMC patients with vascular disease had higher age, higher plasma tHcy, lower serum folate and lower renal function than patients without vascular disease.

CONCLUSION

The finding of two subgroups of patients with CMC supports the notion that mild cognitive impairment is a heterogenous clinical entity with multiple aetiological factors. The elevated plasma tHcy in the group of CMC patients with vascular disease is likely to be associated with vascular disease.

Increased homocysteine in heart failure: a result of renal impairment?

BACKGROUND

Hyperhomocysteinemia may constitute a risk factor for patients with severe heart failure. This study examines the relationship between plasma homocysteine concentration and left ventricular ejection fraction with renal function in heart failure patients free of coronary artery disease.

METHODS

Left ventricular ejection fraction was documented in 62 patients with advanced heart failure who had no proven significant coronary artery stenosis. Glomerular filtration rate was measured using the Cockroft-Gault equation.

RESULTS

Elevated homocysteine levels (>or=15 micromol/L) were detected in 22 patients. Low glomerular filtration rate was observed in patients who had normal serum creatinine concentration. Homocysteine was strongly correlated with age, duration of disease, left ventricular ejection fraction, serum creatinine, and glomerular filtration rate. Statistically significant trends were observed across respective homocysteine quartiles. However, by multivariate regression, the strongest predictor of homocysteine was the glomerular filtration rate.

CONCLUSIONS

Impaired renal function leads to a diminished clearance rate, which can be a prominent pathophysiological mechanism in the elevation of homocysteine concentration in heart failure.

Pro-thrombotic and pro-oxidant effects of diet-induced hyperhomocysteinemia

Elevated plasma homocysteine levels are associated with the risk of atherosclerosis and arterial and venous thrombosis. We have previously demonstrated that rabbits rendered hyperhomocysteinemic by parenteral administration of homocysteine develop a dysfibrinogenemia that is associated with the formation of fibrin clots that are abnormally resistant to fibrinolysis. We suggested that this acquired dysfibrinogenemia contributes to the thrombotic tendency in hyperhomocysteinemia. However, it was possible that the homocysteine-associated dysfibrinogenemia was an artifact of the parenteral administration model. Therefore, the goals of the current study were to develop a diet-induced model of homocysteinemia in rabbits and determine whether a dysfibrinogenemia and evidence of oxidative stress develop in this model as they do when homocysteine is injected. We found that rabbits fed a diet severely deficient in folate and mildly deficient in choline develop mild hyperhomocysteinemia: 14.8+/-4.0 microM in deficient rabbits compared to 9.0+/-1.7 microM in controls. The deficient rabbits also develop evidence of oxidant stress: increased lipid peroxidation in liver, impaired mitochondrial enzyme activities in liver and elevated caspase-3 levels in plasma. Most importantly, the deficient rabbits also develop a dysfibrinogenemia characterized by increased resistance to fibrinolysis. We believe that this dietary model of homocysteinemia is clinically relevant and reproduces many features associated with hyperhomocysteinemia in previous work using in vitro and in vivo models. Our findings suggest that an acquired dysfibrinogenemia could play a role in the increased risk of atherothrombotic disease in mildly hyperhomocysteinemic human subjects.