Inadequate dietary magnesium intake increases atherosclerotic plaque development in rabbits

Effects of lacto-ovo-vegetarian diet vs. standard-weight-loss diet on obese and overweight adults with non-alcoholic fatty liver disease: a randomised clinical trial

The aim of the study was to compare the effects of a lacto-ovo-vegetarian diet (LOV-D) vs. a standard weight-loss diet (SWL-D) on obese/overweight adults with NAFLD. Present randomised clinical trial recruited 75 overweight/obese adults with NAFLD, who were randomly assigned into LOV-D and SWL-D groups for 3 months. The LOV-D was designed based on eliminating meat, poultry, and fish; while including dairy products and eggs. The SWL-D was planned according to the standard food pyramid, which was free in all sources of food. Adherence to LOV-D significantly outperformed SWL-D in reducing levels of alanine aminotransferase (ALT), body weight, waist circumference, BMI, fasting blood sugar, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triacylglycerol (TG), cholesterol, low-density lipoprotein cholesterol (LDL-C), and systolic blood pressure (SBP). Furthermore, ultrasonography revealed a higher alleviation in NAFLD grade among LOV-D, compared with SWL-D. This study suggests that adherence to LOV-D for 3 months has beneficial effects on NAFLD improvement, anthropometric measures, glycaemic-related markers, and lipid profiles.

The effect of the dietary approaches to stop hypertension diet on total antioxidant capacity, superoxide dismutase, catalase, and body composition in patients with non-alcoholic fatty liver disease: a randomized controlled trial

Aim

Non-alcoholic fatty liver disease (NAFLD) is a condition characterized by the accumulation of fat in the liver without excessive alcohol consumption. Lifestyle modifications, such as adopting a healthy diet, represent the standard treatment for NAFLD. However, the impact of the Dietary Approaches to Stop Hypertension (DASH) diet on oxidative stress biomarkers in patients with NAFLD remains unclear. Therefore, this study aimed to determine the effect of the DASH diet on total antioxidant capacity (TAC), catalase (CAT), superoxide dismutase (SOD) levels, and body composition in overweight and obese patients with NAFLD.

Methods

A total of 70 overweight and obese patients aged 1870 years were randomly assigned to either the intervention (DASH diet, n = 35) or the control group (control diet, n = 35) for 12 weeks, with both groups following a calorie-restricted diet.

Results

The mean age of participants was 43.1 ± 8.1 years in the DASH group and 45.1 ± 8.6 years in the control group. At the end of the study, a significant difference was observed in the mean TAC and SOD levels between the two groups (p = 0.02). After adjusting for potential confounding factors, such as age, sex, diabetes, smoking, physical activity, and baseline values, the DASH diet maintained its significant effects on TAC and SOD compared to the control diet (p = 0.03). However, there were no significant differences in CAT levels between the two groups. Moreover, a significant reduction in visceral fat (p = 0.01) and a marginally significant decrease in BMI (p = 0.06) were observed in the DASH group compared to the control group after adjusting for potential confounders.

Conclusion

In conclusion, our study showed that following the DASH diet for 12 weeks in overweight and obese patients with NAFLD has beneficial effects on TAC, SOD, and visceral fat. These findings support the use of the DASH diet as a potential therapeutic intervention for the improvement of oxidative biomarkers in patients with NAFLD.

Clinical trial registration

www.irct.ir/, identifier IRCT20170117032026N3.

The effect of the Dietary Approaches to Stop Hypertension (DASH) diet on body composition, complete blood count, prothrombin time, inflammation and liver function in haemophilic adolescents

There is no dietary strategy that has yet been specifically advocated for haemophilia. Therefore, we sought to assess the effect of the Dietary Approaches to Stop Hypertension (DASH) diet in adolescents with haemophilia. In this parallel trial, forty male adolescents with haemophilia were dichotomised into the DASH group or control group for 10 weeks. The serum high sensitivity C-reactive protein, IL-6, complete blood count (CBC), serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, partial thromboplastin time (PTT), waist circumference (WC), percentage of body fat, fat-free mass and liver steatosis were measured at the beginning and end of the study. Serum vitamin C was measured as a biomarker of compliance with the DASH diet. The DASH diet was designed to include high amounts of whole grains, fruits, vegetables and low-fat dairy products, as well as low amounts of saturated fats, cholesterol, refined grains, sweets and red meat. Serum vitamin C in the DASH group was significantly increased compared with the control (P = 0·001). There was a significant reduction in WC (P = 0·005), fat mass (P = 0·006), hepatic fibrosis (P = 0·02) and PTT (P = 0·008) in the DASH group, compared with the control. However, there were no significant differences regarding other selected outcomes between groups. Patients in the DASH group had significantly greater increase in the levels of erythrocyte, Hb and haematocrit, as compared with the control. Adherence to the DASH diet in children with haemophilia yielded significant beneficial effects on body composition, CBC, inflammation and liver function.

Thymoquinone Protects Neurons in the Cerebellum of Rats through Mitigating Oxidative Stress and Inflammation Following High-Fat Diet Supplementation

High-fat diet (HFD) is a major problem causing neuronal damage. Thymoquinone (TQ) could regulate oxidative stress and the inflammatory process. Hence, the present study elucidated the significant role of TQ on oxidative stress, inflammation, as well as morphological changes in the cerebellum of rats with HFD. Rats were divided into three groups as (1) control, (2) saturated HFD for eight weeks and (3) HFD supplementation (four weeks) followed by TQ 300 mg/kg/day treated (four weeks). After treatment, blood samples were collected to measure oxidative stress markers glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), and inflammatory cytokines. Furthermore, neuronal morphological changes were also observed in the cerebellum of the rats. HFD rats show higher body weight (286.5 ± 7.4 g) as compared with the control group (224.67 ± 1.78 g). TQ treatment significantly (p < 0.05) lowered the body weight (225.83 ± 13.15 g). TQ produced a significant (p < 0.05) reduction in cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL). The antioxidative enzymes significantly reduced in HFD rats (GSH, 1.46 ± 0.36 mol/L and SOD, 99.13 ± 5.41 µmol/mL) as compared with the control group (GSH, 6.25 ± 0.36 mol/L and SOD, 159.67 ± 10.67 µmol/mL). MDA was increased significantly in HFD rats (2.05 ± 0.25 nmol/L) compared to the control group (0.695 ± 0.11 nmol/L). Surprisingly, treatment with TQ could improve the level of GSH, MDA, and SOD. TQ treatment significantly (p < 0.05) reduced the inflammatory markers as compared with HFD alone. TQ treatment minimizes neuronal damage as well as reduces inflammation and improves antioxidant enzymes. TQ can be considered as a promising agent in preventing the neuronal morphological changes in the cerebellum of obese populations.

Magnesium intake in a Longitudinal Study of Adult Health: associated factors and the main food sources

This study aimed to identify the sociodemographic and lifestyle factors associated with magnesium intake and describe the main food sources in the Brazilian Longitudinal Study of Adult Health (ELSA-Brazil). This observational, cross-sectional study was conducted using the baseline data from the ELSA-Brazil (2008-2010). Associations between usual magnesium intake and sociodemographic and lifestyle factors were analyzed using multiple linear regression. Food sources were identified by calculating the percentage contribution of each FFQ item to the amount of magnesium provided by all foods. The analysis was performed using Stata® software (version 12), assuming a statistical significance level of 5%. The top food sources to magnesium intake were as follows: beans, oats, nuts, white rice, orange, French bread, cooked fish, boneless meat, whole milk, and whole wheat bread. There were positive associations between magnesium intake and female sex; age ≥60 years; self-reported black, indigenous, or brown skin colors; per capita income ≥3 minimum wages, and moderate or vigorous physical activity levels. Sociodemographic and lifestyle factors were associated with magnesium intake among the evaluated individuals.

Optimization of hypomagnesemia diagnostics as an integral element in paroxysmal atrial fibrillation management strategy

Purpose. To study magnesium status of patients having paroxysmal atrial fibrillation (AF) based on the use of an integrated clinical and laboratory approach. Methods. A prospective cohort study included 58 patients of the cardiology department of New Hospital Medical Association. The main group consisted of 32 patients having frequently recurring paroxysmal AF, the control group consisted of 26 patients without paroxysmal rhythm disturbance. The clinical status, Holter ECG monitoring data, the test results for magnesium deficiency (MD) clinical evidence, laboratory evidence of calcium, magnesium in blood plasma and formed elements, magnesium in whole blood, free fatty acids (FFA) and osmolality in blood plasma were assessed. Results. The score obtained when assessing MD clinical evidence was significantly higher in the main group patients compared with the control group (16.5 (11÷21) vs. 13 (8÷15), p<0.001). A statistically significant magnesium decrease in whole blood was revealed in patients having paroxysmal AF (0.54 (0.46÷0.60) vs. 0.61 (0.59÷0.64), p<0.001) and inside formed elements (0.68 (0.53÷1.07) vs. 1.31 (1.07÷1.44), p<0.001), which reflected changes in their magnesium status to a greater extent than the measured plasma cation concentrations. A close correlation between magnesium content in formed elements (intracellularly) and AF paroxysms frequency (Spearman’s rank correlation -0.51, p<0.001) was established. A violation of calcium to magnesium ratio in blood plasma (2.6 (2.5÷2.9) vs. 3.0 (2.8÷3.1), p=0.004) and intracellularly (4.85 (2.62÷9.3) vs. 1.85 (1.57÷2.07), p<0.001) was revealed in patients having AF. It has been shown that complex forming interactions with free fatty acids may affect intracellular calcium and magnesium content.

Associations of serum magnesium levels and calcium-magnesium ratios with mortality in patients with coronary artery disease

AIMS

Low magnesium (Mg) and high calcium (Ca) levels are linked to increased cardiovascular disease (CVD) risk in the general population. This prospective study assessed whether there are any independent associations of serum Mg levels and Ca-Mg ratios with mortality in patients with coronary artery disease (CAD).

METHODS

This prospective cohort study included 3380 CAD patients. Cox regression models were used to estimate associations of serum Mg and Ca-Mg ratio with risk of mortality.

RESULTS

A total of 562 deaths (331 due to CVD) were recorded during a 7.59-year (median) follow-up. Spline plots displayed U-shaped associations between serum Mg levels and Ca-Mg ratios and risk of mortality. When compared with a moderate group, adjusted hazard ratios (95% confidence intervals) for low Mg levels and high Ca-Mg ratios were 1.59 (1.30-1.95) and 1.31 (1.06-1.61) for all-cause mortality, and 1.71 (1.32-2.22) and 1.44 (1.09-1.89) for CVD mortality, respectively. There was also a tendency to increase risk of mortality in patients with high serum Mg levels and low Ca-Mg ratios. Associations of low serum Mg and high Ca-Mg ratio with risk of mortality did not change when stratified by gender, body mass index, CAD type, estimated glomerular filtration rate, use of diuretics, or history of diabetes or hypertension.

CONCLUSION

This study demonstrated that a moderate Ca-Mg ratio (range: 3.91-4.70) had the lowest mortality risk, and that low serum Mg and high Ca-Mg ratio were independent risk factors of mortality in CAD patients. Nevertheless, the optimal dose-response of Mg and Ca for mitigating CAD risk still requires further investigation.

Ingestion of magnesium was not associated with coronary calcium score in a cross-sectional study

Background and aims: Magnesium plays a key role in glucose metabolism, vascular tone, and inflammation. Therefore, it might be a dietary risk factor for cardiovascular diseases. In vitro and animal studies have suggested a decrease in vascular calcification with an increase in the magnesium intake. The objective of the present study was to investigate the association between magnesium intake and coronary artery calcium (CAC) score among participants of the ELSA-Brasil. Methods: This is an observational, cross-sectional study undertaken with a sub-sample from the ELSA-Brasil baseline data. In this sub-sample, only participants with CAC examination data were included (n = 4,306). Dietary intake was assessed by a validated food frequency questionnaire. The association between magnesium intake and presence of CAC (0 versus > 0) was investigated using multiple logistic regression models. Results: The participants were predominantly female (54.4 %), with self-reported white skin color (59.1 %), no smoking habit (53.7 %) and undergraduate or postgraduate education (44.4 %). The range of magnesium consumption was 37.24 - 1266.31 mg/day. CAC prevalence was 28.4 %. No significant association was found between magnesium intake and CAC after adjustments for diet, lifestyle, and clinical characteristics. In a first univariate model, the fifth quintile of magnesium intake, in comparison to the first quintile (lowest intake), resulted in an OR = 1.25, 95 % CI: 1.01 - 1.54 (P-linear trend = 0.005). However, in the last fully adjusted model, the fifth quintile of magnesium intake resulted in OR = 0.86, 95 % CI: 0.64 - 1.17 (P-linear trend = 0.239). Conclusions: In ELSA-Brasil, the intake of magnesium was not associated with the presence of coronary artery calcification.

Characterizing Fatty Liver in vivo in Rabbits, Using Quantitative Ultrasound

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and can often lead to fibrosis, cirrhosis, cancer and complete liver failure. Liver biopsy is the current standard of care to quantify hepatic steatosis, but it comes with increased patient risk and only samples a small portion of the liver. Imaging approaches to assess NAFLD include proton density fat fraction estimated via magnetic resonance imaging (MRI) and shear wave elastography. However, MRI is expensive and shear wave elastography is not proven to be sensitive to fat content of the liver (Kramer et al. 2016). On the other hand, ultrasonic attenuation and the backscatter coefficient (BSC) have been observed to be sensitive to levels of fat in the liver (Lin et al. 2015; Paige et al. 2017). In this study, we assessed the use of attenuation and the BSC to quantify hepatic steatosis in vivo in a rabbit model of fatty liver. Rabbits were maintained on a high-fat diet for 0, 1, 2, 3 or 6 wk, with 3 rabbits per diet group (total N = 15). An array transducer (L9-4) with a center frequency of 4.5 MHz connected to a SonixOne scanner was used to gather radio frequency (RF) backscattered data in vivo from rabbits. The RF signals were used to estimate an average attenuation and BSC for each rabbit. Two approaches were used to parameterize the BSC (i.e., the effective scatterer diameter and effective acoustic concentration using a spherical Gaussian model and a model-free approach using a principal component analysis [PCA]). The 2 major components of the PCA from the BSCs, which captured 96% of the variance of the transformed data, were used to generate input features to a support vector machine for classification. Rabbits were separated into two liver fat-level classes, such that approximately half of the rabbits were in the low-lipid class (≤9% lipid liver level) and half of the rabbits in the high-lipid class (>9% lipid liver level). The slope and the midband fit of the attenuation coefficient provided statistically significant differences (p value = 0.00014 and p value = 0.007, using a two-sample t test) between low and high-lipid fat classes. The proposed model-free and model-based parameterization of the BSC and attenuation coefficient parameters yielded classification accuracies of 84.11 %, 82.93 % and 78.91 % for differentiating low-lipid versus high-lipid classes, respectively. The results suggest that attenuation and BSC analysis can differentiate low-fat versus high-fat livers in a rabbit model of fatty liver disease.

Magnesium and Cardiovascular Disease

Magnesium is the most abundant intracellular divalent cation and essential for maintaining normal cellular physiology and metabolism, acting as a cofactor of numerous enzymes, regulating ion channels and energy generation. In the heart, magnesium plays a key role in modulating neuronal excitation, intracardiac conduction, and myocardial contraction by regulating a number of ion transporters, including potassium and calcium channels. Magnesium also has a role in regulating vascular tone, atherogenesis and thrombosis, vascular calcification, and proliferation and migration of endothelial and vascular smooth muscle cells. As such, magnesium potentially has a major influence on the pathogenesis of cardiovascular disease. As the kidney is a major regulator of magnesium homeostasis, kidney disorders can potentially lead to both magnesium depletion and overload, and as such increase the risk of cardiovascular disease. Observational data have shown an association between low serum magnesium concentrations or magnesium intake and increased atherosclerosis, coronary artery disease, arrhythmias, and heart failure. However, major trials of supplementation with magnesium have reported inconsistent benefits and also raised potential adverse effects of magnesium overload. As such, there is currently no firm recommendation for routine magnesium supplementation except when hypomagnesemia has been proven or suspected as a cause for cardiac arrhythmias.

Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis

Because serum magnesium does not reflect intracellular magnesium, the latter making up more than 99% of total body magnesium, most cases of magnesium deficiency are undiagnosed. Furthermore, because of chronic diseases, medications, decreases in food crop magnesium contents, and the availability of refined and processed foods, the vast majority of people in modern societies are at risk for magnesium deficiency. Certain individuals will need to supplement with magnesium in order to prevent suboptimal magnesium deficiency, especially if trying to obtain an optimal magnesium status to prevent chronic disease. Subclinical magnesium deficiency increases the risk of numerous types of cardiovascular disease, costs nations around the world an incalculable amount of healthcare costs and suffering, and should be considered a public health crisis. That an easy, cost-effective strategy exists to prevent and treat subclinical magnesium deficiency should provide an urgent call to action.

Dose-response relationship between lower serum magnesium level and higher prevalence of knee chondrocalcinosis

Background

The aim was to assess serum magnesium levels in relation to prevalence of knee chondrocalcinosis in two population-based Chinese studies.

Methods

Data included in this analysis consisted of two population-based cross-sectional studies, i.e., the Xiangya Hospital Health Management Center Study and the Xiangya Osteoarthritis (XO) Study I. A bilateral knee anteroposterior radiograph was obtained from each subject. Radiographic knee chondrocalcinosis was present if there was definite linear cartilage calcification. Serum magnesium concentration was measured using the chemiluminescence method. We examined the relation of serum magnesium levels to prevalence of knee chondrocalcinosis using generalized estimating equations.

Results

The prevalence of knee chondrocalcinosis was 1.4% in the Xiangya Hospital Health Management Center Study (n = 12,631). Compared with the lowest tertile, the age, sex and body mass index (BMI)-adjusted odds ratios (ORs) of chondrocalcinosis were 0.59 (95% CI 0.40–0.87) and 0.49 (95% CI 0.33–0.72) in the second and the third tertiles of serum magnesium, respectively (P for trend <0.001). The prevalence of knee chondrocalcinosis in the XO Study I (n = 1316) was 4.1%. The age, sex and BMI-adjusted ORs of chondrocalcinosis were 0.67 (95% CI 0.34–1.30) in the second and 0.45 (95% CI 0.21–0.94) in the third tertile of serum magnesium when compared with the lowest tertile (P for trend = 0.030). Similar results were observed in men and women in both studies. Adjusting for additional potential confounders did not change the results materially.

Conclusions

Subjects with lower levels of serum magnesium, even within the normal range, had higher prevalence of knee chondrocalcinosis in a dose-response relationship manner, suggesting that magnesium may have a preventive or therapeutic potential for knee chondrocalcinosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1450-6) contains supplementary material, which is available to authorized users.

Magnesium deficiency and oxidative stress: an update

Magnesium deficiency (MgD) has been shown to impact numerous biological processes at the cellular and molecular levels. In the present review, we discuss the relationship between MgD and oxidative stress (OS). MgD is accompanied by increased levels of OS markers such as lipid, protein and DNA oxidative modification products. Additionally, a relationship was detected between MgD and a weakened antioxidant defence. Different mechanisms associated with MgD are involved in the development and maintenance of OS. These mechanisms include systemic reactions such as inflammation and endothelial dysfunction, as well as changes at the cellular level, such as mitochondrial dysfunction and excessive fatty acid production.

Effects of Dietary Approach to Stop Hypertension diet on androgens, antioxidant status and body composition in overweight and obese women with polycystic ovary syndrome: a randomised controlled trial

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrine disease in reproductive age women. The present study aimed to determine the effects of Dietary Approaches to Stop Hypertension (DASH) diet on reproductive hormones, plasma total antioxidant status and anthropometric indices in overweight and obese PCOS women.

METHODS

In this randomised controlled clinical trial, 60 women with PCOS were randomly assigned to one of two diets with energy restriction: the DASH diet and a control diet. The DASH and control diets consisted of 50-55% carbohydrate, 15-20% protein and 25-30% total fat. The DASH diet was designed to be rich in vegetables, fruits, whole grains and low-fat dairy products, as well as low in saturated fats, cholesterol, refined grains and sweets. In the present study, the anthropometric indices, body composition, total testosterone, androstenedione, sex hormone binding globulin (SHBG), free androgen index and 2,2'-diphenyl-1-picryylhydrazyl (DPPH) scavenging activity were measured before and after 3 months.

RESULTS

The consumption of DASH diet compared to the control diet was associated with a significant reduction in weight [-5.78 (1.91) kg versus -4.34 (2.87) kg, P = 0.032], body mass index (BMI) [-2.29 (0.15) kg m^-2 versus -1.69 (0.20) kg m^-2 , P = 0.02], fat mass [-3.23(1.66) kg versus -2.13 (1.26) kg, P = 0.008] and serum androstenedione [-1.75 (1.39) ng mL^-1 versus -1.02 (0.72) ng mL^-1 , P-value = 0.019]. Increased concentrations of SHBG [28.80 (21.71) versus 11.66(18.82) nmol L^-1 , P = 0.003) and DPPH scavenging activity [30.23% (19.09) versus 12.97% (25.12) were also found in the DASH group.

CONCLUSIONS

The DASH diet could improve weight loss, BMI and fat mass. Furthermore, it could result in a significant reduction in serum androstenedione and a significant increase in antioxidant status and SHBG.

The effects of DASH diet on weight loss and metabolic status in adults with non-alcoholic fatty liver disease: a randomized clinical trial

BACKGROUND & AIMS

This study was designed to determine the effects of the Dietary Approaches to Stop Hypertension (DASH) diet on weight loss and metabolic status in overweight patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

This randomized controlled clinical trial was done among 60 overweight and obese patients with NAFLD. Patients were randomly allocated to consume either the control (n = 30) or the DASH eating pattern (n = 30) for 8 weeks. Both diets were designed to be calorie-restricted. Both diets were consisted of 52-55% carbohydrates, 16-18% proteins and 30% total fats; however, the DASH diet was designed to be rich in fruits, vegetables, whole grains, and low-fat dairy products and low in saturated fats, cholesterol and refined grains.

RESULTS

Adherence to the DASH eating pattern, compared to the control diet, weight (P = 0.006), BMI (P = 0.01), alanine aminotransferase (ALT) (P = 0.02), alkalin phosphatase (ALP) (P = 0.001), insulin levels (P = 0.01), homoeostasis model of assessment-estimated insulin resistance (HOMA-IR) (P = 0.01) significantly decreased and quantitative insulin sensitivity check index (QUICKI) (P = 0.004) significantly increased. Compared with the control diet, the DASH diet has resulted in significant reductions in serum triglycerides (P = 0.04) and total-/HDL-cholesterol ratio (P = 0.01). Finally, decreased concentrations of serum high-sensitivity C-reactive protein (hs-CRP) (P = 0.03), malondialdehyde (MDA) (P = 0.04), increased levels of nitric oxide (NO) (P = 0.01) and glutathione (GSH) (P = 0.009) were found in the DASH group compared with the control group.

CONCLUSIONS

Consumption of DASH diet for 8 weeks among patients with NAFLD had beneficial effects on weight, BMI, ALT, ALP, triglycerides, markers of insulin metabolism, inflammatory markers, GSH and MDA.

Intravascular magnetomotive optical coherence tomography of targeted early-stage atherosclerotic changes in ex vivo hyperlipidemic rabbit aortas

We report the development of an intravascular magnetomotive optical coherence tomography (IV-MM-OCT) system used with targeted protein microspheres to detect early-stage atherosclerotic fatty streaks/plaques. Magnetic microspheres (MSs) were injected in vivo in rabbits, and after 30 minutes of in vivo circulation, excised ex vivo rabbit aorta samples specimens were then imaged ex vivo with our prototype IV-MM-OCT system. The alternating magnetic field gradient was provided by a unique pair of external custom-built electromagnetic coils that modulated the targeted magnetic MSs. The results showed a statistically significant MM-OCT signal from the aorta samples specimens injected with targeted MSs.

Contrast Ultrasound Imaging of the Aorta Does Not Affect Progression of Atherosclerosis or Cardiovascular Biomarkers in ApoE-/- Mice

OBJECTIVES

Ultrasound contrast agents (UCAs) enhance cardiovascular ultrasound imaging. Adverse biological effects have occurred after administration of UCAs, and more research is needed for a comprehensive understanding of the risks involved. We used the ApoE(-/-) mouse model of atherosclerosis to characterize the effects of ultrasound and UCAs on atherosclerosis and plasma biomarkers.

METHODS

Male ApoE(-/-) mice (8 weeks old; n = 24) were intravenously infused with a UCA (2 × 10(10) Definity microbubbles per hour; Lantheus Medical Imaging, North Billerica, MA) and exposed to 2.8-MHz center frequency ultrasound (10 Hz pulse repetition frequency, 1.4 microseconds pulse duration, 2 minutes exposure duration, and 2 sites) at 1 of 3 derated peak rarefactional pressure amplitudes (0, 1.9, or 3.8 MPa), and then consumed either a chow or Western diet for 4 weeks (n = 4 per group). Blood plasma samples were collected before ultrasound exposure and at 2 and 4 weeks after exposure and assayed for total cholesterol and von Willebrand Factor (vWF). A pathologist measured atheroma thickness in formalin-fixed, hematoxylin-eosin-stained transverse aorta sections and scored them for severity of atherosclerosis.

RESULTS

Plasma total cholesterol initially averaged 286 mg/dL in the Western diet group and increased to 861 mg/dL after 4 weeks on the diet (P < .0001). Total cholesterol did not increase significantly in the chow diet group. Plasma vWF increased after 2 weeks on the Western diet (P < .0001). Atheroma thickness was greater in animals consuming the Western diet than in chow-fed animals (P < .05). Ultrasound had no significant effect on plasma total cholesterol, plasma vWF, or atheroma thickness.

CONCLUSIONS

Contrast ultrasound did not increase the severity of atherosclerosis or alter cardiovascular biomarkers in the ApoE(-/-) mouse model.

Role of magnesium in cardiovascular diseases

Magnesium, the fourth most abundant cation in the human body, is involved in several essential physiological, biochemical, and cellular processes regulating cardiovascular function. It plays a critical role in modulating vascular smooth muscle tone, endothelial cell function, and myocardial excitability and is thus central to the pathogenesis of several cardiovascular disorders such as hypertension, atherosclerosis, coronary artery disease, congestive heart failure, and cardiac arrhythmias. This review discusses the vasodilatory, anti-inflammatory, anti-ischemic, and antiarrhythmic properties of magnesium and its current role in the prevention and treatment of cardiovascular disorders.

Magnetomotive optical coherence tomography for the assessment of atherosclerotic lesions using αvβ3 integrin-targeted microspheres

PURPOSE

We investigated the early-stage fatty streaks/plaques detection using magnetomotive optical coherence tomography (MM-OCT) in conjunction with αvβ3 integrin-targeted magnetic microspheres (MSs). The targeting of functionalized MSs was investigated by perfusing ex vivo aortas from an atherosclerotic rabbit model in a custom-designed flow chamber at physiologically relevant pulsatile flow rates and pressures.

PROCEDURES

Aortas were extracted and placed in a flow chamber. Magnetic MS contrast agents were perfused through the aortas and MM-OCT, fluorescence confocal, and bright field microscopy were performed on the ex vivo aorta specimens for localizing the MSs.

RESULTS

The results showed a statistically significant and stronger MM-OCT signal (3.30 ± 1.73 dB) from the aorta segment perfused with targeted MSs, compared with the nontargeted MSs (1.18 ± 0.94 dB) and control (0.78 ± 0.41 dB) aortas. In addition, there was a good co-registration of MM-OCT signals with confocal microscopy.

CONCLUSIONS

Early-stage fatty streaks/plaques have been successfully detected using MM-OCT in conjunction with αvβ3 integrin-targeted magnetic MSs.

Short-term magnesium deficiency downregulates telomerase, upregulates neutral sphingomyelinase and induces oxidative DNA damage in cardiovascular tissues: relevance to atherogenesis, cardiovascular diseases and aging

1) short-term dietary deficiency of magnesium (Mg; 21 days) in rats (MgD) would result in a downregulation of telomerase in cardiac and aortic smooth muscle cells, 2) low levels of Mg(2+) added to drinking water (DW) would either prevent or greatly reduce the downregulation of telomerase in MgD, 3) MgD in rats would cause an upregulation of neutral-sphingomyelinase (N-SMAse) and p53, 4) short-term MgD would result in oxidation of DNA in diverse cardiac muscle and aortic smooth muscle cells as exemplified by measurement of 8-hydroxydeoxyguanosine (8-OH-dG), and 5) cross-talk between telomerase, N-SMase, p53, and 8-OH-dG would be evident in left ventricular (LV), right ventricular (RV), atrial and aortic smooth muscle obtained from rats subjected to short-term MgD. The data indicated that short-term MgD (10% normal dietary intake) resulted in downregulation of telomerase in LV, RV, atrial and aortic muscle cells; even very low levels of water-bourne Mg(2+) (e.g., 15-40 mg/lday) either prevented or ameliorated the downregulation of telomerase. Our experiments also showed that MgD resulted in a 7-10 fold increased formation of 8-OH-dG in the cardiac and aortic muscle cells. The experiments also confirmed that short-term dietary deficiency of Mg resulted in greatly increased upregulation of N-SMAse and p53 in the cardiac and aortic muscle tissues. These new experiments point to a sizeable cross-talk among telomerase, N-SMAse, and p53 in rat cardiac and peripheral vascular muscle exposed to a short-term MgD. These studies would be compatible with the idea that even short-term MgD could cause alterations of the genome in diverse cell types leading to mutations of cardiac, vascular, and endothelial cells seen in aging and atherogenesis. Since we have shown, previously, that activation of N-SMAse in MgD leads to synthesis and release of ceramide in cardiovascular tissues and cells, we believe this pathway, most likely, helps to result in downregulation of telomerase, upregulation of transcription factors (e.g., p53; NF-kB), cytokine release, mutations, transformations, and dysfunctional growth seen in the cardiac and vascular cells observed in the normal aging process, atherogenesis, hypertension, and cardiac failure. Lastly, we suggest ways in which this hypothesis can be tested.

Magnesium intake is inversely associated with coronary artery calcification: the Framingham Heart Study

OBJECTIVES

The aim of this study was to examine whether magnesium intake is associated with coronary artery calcification (CAC) and abdominal aortic calcification (AAC).

BACKGROUND

Animal and cell studies suggest that magnesium may prevent calcification within atherosclerotic plaques underlying cardiovascular disease. Little is known about the association of magnesium intake and atherosclerotic calcification in humans.

METHODS

We examined cross-sectional associations of self-reported total (dietary and supplemental) magnesium intake estimated by food frequency questionnaire with CAC and AAC in participants of the Framingham Heart Study who were free of cardiovascular disease and underwent Multi-Detector Computed Tomography (MDCT) of the heart and abdomen (n = 2,695; age: 53 ± 11 years), using multivariate-adjusted Tobit regression. CAC and AAC were quantified using modified Agatston scores (AS). Models were adjusted for age, sex, body mass index, smoking status, systolic blood pressure, fasting insulin, total-to-high-density lipoprotein cholesterol ratio, use of hormone replacement therapy (women only), menopausal status (women only), treatment for hyperlipidemia, hypertension, cardiovascular disease prevention, or diabetes, as well as self-reported intake of calcium, vitamins D and K, saturated fat, fiber, alcohol, and energy. Secondary analyses included logistic regressions of CAC and AAC outcomes as cut-points (AS >0 and AS ≥90th percentile for age and sex), as well as sex-stratified analyses.

RESULTS

In fully adjusted models, a 50-mg/day increment in self-reported total magnesium intake was associated with 22% lower CAC (p < 0.001) and 12% lower AAC (p = 0.07). Consistent with these observations, the odds of having any CAC were 58% lower (p trend: <0.001) and any AAC were 34% lower (p trend: 0.01), in those with the highest compared to those with the lowest magnesium intake. Stronger inverse associations were observed in women than in men.

CONCLUSIONS

In community-dwelling participants free of cardiovascular disease, self-reported magnesium intake was inversely associated with arterial calcification, which may play a contributing role in magnesium's protective associations in stroke and fatal coronary heart disease.

Deep sea water modulates blood pressure and exhibits hypolipidemic effects via the AMPK-ACC pathway: an in vivo study

Deep sea water (DSW), originally pumped from the Pacific Rim off the coast of Hualien County (Taiwan), and its mineral constituents, were concentrated by a low-temperature vacuum evaporation system to produce a hardness of approximately 400,000 mg/L of seawater mineral concentrate. The primary composition of this seawater mineral concentrate was ionic magnesium (Mg²⁺), which was approximately 96,000 mg/L. Referring to the human recommended daily allowance (RDA) of magnesium, we diluted the mineral concentrate to three different dosages: 0.1 × DSW (equivalent to 3.75 mg Mg²⁺/kg DSW); 1 × DSW (equivalent to 37.5 mg Mg²⁺/kg DSW); and 2 × DSW (equivalent to 75 mg Mg²⁺/kg DSW). Additionally, a magnesium chloride treatment was conducted for comparison with the DSW supplement. The study indicated that 0.1 × DSW, 1 × DSW and 2 × DSW decreased the systolic and diastolic pressures in spontaneous hypertensive rats in an eight-week experiment. DSW has been shown to reduce serum lipids and prevent atherogenesis in a hypercholesterolemic rabbit model. Our results demonstrated that 1 × DSW and 2 × DSW significantly suppressed the serum cholesterol levels, reduced the lipid accumulation in liver tissues, and limited aortic fatty streaks. These findings indicated that the antiatherogenic effects of DSW are associated with 5′-adenosine monophosphate-activated protein kinase (AMPK) stimulation and the consequent inhibition of phosphorylation of acetyl-CoA carboxylase (ACC) in atherosclerotic rabbits. We hypothesize that DSW could potentially be used as drinking water because it modulates blood pressure, reduces lipids, and prevents atherogenesis.

Ex vivo study of quantitative ultrasound parameters in fatty rabbit livers

Nonalcoholic fatty liver disease (NAFLD) affects more than 30% of Americans, and with increasing problems of obesity in the United States, NAFLD is poised to become an even more serious medical concern. At present, accurate classification of steatosis (fatty liver) represents a significant challenge. In this study, the use of high-frequency (8 to 25 MHz) quantitative ultrasound (QUS) imaging to quantify fatty liver was explored. QUS is an imaging technique that can be used to quantify properties of tissue giving rise to scattered ultrasound. The changes in the ultrasound properties of livers in rabbits undergoing atherogenic diets of varying durations were investigated using QUS. Rabbits were placed on a special fatty diet for 0, 3, or 6 weeks. The fattiness of the livers was quantified by estimating the total lipid content of the livers. Ultrasonic properties, such as speed of sound, attenuation, and backscatter coefficients, were estimated in ex vivo rabbit liver samples from animals that had been on the diet for varying periods. Two QUS parameters were estimated based on the backscatter coefficient: effective scatterer diameter (ESD) and effective acoustic concentration (EAC), using a spherical Gaussian scattering model. Two parameters were estimated based on the backscattered envelope statistics (the k parameter and the μ parameter) according to the homodyned K distribution. The speed of sound decreased from 1574 to 1565 m/s and the attenuation coefficient increased from 0.71 to 1.27 dB/cm/MHz, respectively, with increasing fat content in the liver. The ESD decreased from 31 to 17 μm and the EAC increased from 38 to 63 dB/cm(3) with increasing fat content in the liver. A significant increase in the μ parameter from 0.18 to 0.93 scatterers/mm(3) was observed with increasing fat content in the liver samples. The results of this study indicate that QUS parameters are sensitive to fat content in the liver.

Time domain attenuation estimation method from ultrasonic backscattered signals

Ultrasonic attenuation is important not only as a parameter for characterizing tissue but also for compensating other parameters that are used to classify tissues. Several techniques have been explored for estimating ultrasonic attenuation from backscattered signals. In the present study, a technique is developed to estimate the local ultrasonic attenuation coefficient by analyzing the time domain backscattered signal. The proposed method incorporates an objective function that combines the diffraction pattern of the source/receiver with the attenuation slope in an integral equation. The technique was assessed through simulations and validated through experiments with a tissue mimicking phantom and fresh rabbit liver samples. The attenuation values estimated using the proposed technique were compared with the attenuation estimated using insertion loss measurements. For a data block size of 15 pulse lengths axially and 15 beamwidths laterally, the mean attenuation estimates from the tissue mimicking phantoms were within 10% of the estimates using insertion loss measurements. With a data block size of 20 pulse lengths axially and 20 beamwidths laterally, the error in the attenuation values estimated from the liver samples were within 10% of the attenuation values estimated from the insertion loss measurements.

Contrast ultrasound imaging of the aorta alters vascular morphology and circulating von Willebrand factor in hypercholesterolemic rabbits

OBJECTIVES

Ultrasound contrast agents (UCAs) are intravenously infused microbubbles that add definition to ultrasonic images. Ultrasound contrast agents continue to show clinical promise in cardiovascular imaging, but their biological effects are not known with confidence. We used a cholesterol-fed rabbit model to evaluate these effects when used in conjunction with ultrasound (US) to image the descending aorta.

METHODS

Male New Zealand White rabbits (n = 41) were weaned onto an atherogenic diet containing 1% cholesterol, 10% fat, and 0.11% magnesium. At 21 days, rabbits were exposed to contrast US at 1 of 4 pressure levels using either the UCA Definity (Lantheus Medical Imaging, Inc, North Billerica, MA) or a saline control (n = 5 per group). Blood samples were collected and analyzed for lipids and von Willebrand factor (vWF), a marker of endothelial function. Animals were euthanized at 42 days, and tissues were collected for histologic analysis.

RESULTS

After adjustment for pre-exposure vWF, high-level US (in situ [at the aorta] peak rarefactional pressure of 1.4 or 2.1 MPa) resulted in significantly lower vWF 1 hour post exposure (P = .0127; P(adj) < .0762). This difference disappeared within 24 hours. Atheroma thickness in the descending aorta was lower in animals receiving the UCA compared to animals receiving saline.

CONCLUSIONS

Contrast US affected the descending aorta, as evidenced by two separate outcome measures. These results may be a first step in elucidating a previously unknown biological effect of UCAs. Further research is warranted to characterize the effects of this procedure.

Drinking deep seawater decreases serum total and low-density lipoprotein-cholesterol in hypercholesterolemic subjects

Drinking deep seawater (DSW) with high levels of magnesium (Mg) decreased serum lipids in animal studies. Therefore the effects of drinking DSW on blood lipids and its antioxidant capacity in hypercholesterolemic subjects were investigated. DSW was first prepared by a process of filtration and reverse osmosis, and then the concentrated DSW with high levels of Mg was diluted as drinking DSW. Forty-two hypercholesterolemic volunteers were randomly divided into three groups: reverse osmotic (RO) water, DSW (Mg: 395 mg/L, hardness 1410 ppm), and magnesium-chloride fortified (MCF) water (Mg: 386 mg/L, hardness 1430 ppm). The subjects drank 1050 mL of water daily for 6 weeks, and blood samples were collected and analyzed on weeks 0, 3, and 6. Drinking DSW caused a decrease in blood total cholesterol levels and this effect was progressively enhanced with time. Serum low-density lipoprotein-cholesterol (LDL-C) was also decreased by DSW. Further, total cholesterol levels of subjects in the DSW group were significantly lower than those in the MCF water or RO water groups. Compared with week 0, the DSW group had higher blood Mg level on weeks 3 and 6, but the Mg levels were within the normal range in all three groups. DSW consumption also lowered thiobarbituric acid-reactive substances (TBARS) values in serum. In conclusion, DSW was apparently effective in reducing blood total cholesterol and LDL-C, and also in decreasing lipid peroxidation in hypercholesterolemic subjects.

Temperature dependent ultrasonic characterization of biological media

Quantitative ultrasound (QUS) is an imaging technique that can be used to quantify tissue microstructure giving rise to scattered ultrasound. Other ultrasonic properties, e.g., sound speed and attenuation, of tissues have been estimated versus temperature elevation and found to have a dependence with temperature. Therefore, it is hypothesized that QUS parameters may be sensitive to changes in tissue microstructure due to temperature elevation. Ultrasonic backscatter experiments were performed on tissue-mimicking phantoms and freshly excised rabbit and beef liver samples. The phantoms were made of agar and contained either mouse mammary carcinoma cells (4T1) or chinese hamster ovary cells (CHO) as scatterers. All scatterers were uniformly distributed spatially at random throughout the phantoms. All the samples were scanned using a 20-MHz single-element f/3 transducer. Quantitative ultrasound parameters were estimated from the samples versus increases in temperature from 37 °C to 50 °C in 1 °C increments. Two QUS parameters were estimated from the backscatter coefficient [effective scatterer diameter (ESD) and effective acoustic concentration (EAC)] using a spherical Gaussian scattering model. Significant increases in ESD and decreases in EAC of 20%-40% were observed in the samples over the range of temperatures examined. The results of this study indicate that QUS parameters are sensitive to changes in temperature.

Validated sandwich ELISA for the quantification of von Willebrand factor in rabbit plasma

von Willebrand Factor (vWF) is a multimeric plasma protein important for platelet plug formation. As part of its haemostatic role, it is released from endothelial cells during vascular stress or injury and is considered an excellent biomarker of endothelial function. Currently, there are no validated kits available to measure vWF in rabbits. We developed a sensitive and reproducible sandwich enzyme-linked immunosorbent assay (ELISA) for detection of vWF in rabbit plasma using commercially available antibodies and reagents. Purified human vWF was used as a calibrator standard with a dynamic range of 1.56–100 ng/mL. The Minimum Required Dilution for rabbit plasma was 1:100. When plasma was spiked with 3.76 or 10 ng/mL vWF, recovery was 108 ± 2% and 93 ± 2%, respectively. Intra- and inter-assay precision for 8 rabbit plasma samples were 3% and 4%, respectively. The Minimum Detectable Concentration was 254 pg/mL for purified human vWF and 1:10,700 dilution of cholesterol-fed rabbit plasma, and the Reliable Detection Limits were 457 pg/mL and 1:5940. Three freeze-thaw cycles significantly decreased vWF concentrations for purified human vWF and 2 of 3 plasma samples assayed. This ELISA provides sensitive and reproducible measurements of rabbit plasma vWF, which is an important biomarker for cardiovascular research.