Asymmetric Dimethylarginine and Augmentation Index in Newly Diagnosed Patients With Hypertension

Does hyperglycemia affect arginine metabolites in critically ill patients? A prospective cohort and in vitro study

BACKGROUND

Changes in the arginine metabolites asymmetric dimethyl-L-arginine (ADMA) and L-homoarginine and acute blood glucose concentrations have been shown to cause endothelial dysfunction and be independently associated with mortality in Intensive Care Unit (ICU) patients. The aim of this study was to investigate whether hyperglycemia potentially modulates these arginine metabolite concentrations to provide a mechanism that may link hyperglycemia and mortality in this patient group.

METHODS

A clinical and in vitro study were undertaken. Glucose, glycosylated hemoglobin-A1c (HbA1c) and the stress hyperglycemia ratio (SHR) (to quantify absolute, chronic and relative hyperglycemia respectively) were measured in 1155 acutely unwell adult patients admitted to a mixed medical-surgical ICU. SHR was calculated by dividing the admission glucose by the estimated average glucose over the last 3 months, which was derived from HbA1c. ADMA and L-homoarginine were measured in a plasma sample collected at admission to ICU by liquid chromatography tandem mass spectrometry. The activity of dimethylarginine-dimethylaminohydrolase 1 (DDAH1), the main enzyme regulating ADMA concentrations, was assessed at varying glucose concentrations in vitro by quantifying the conversion of ADMA to citrulline in HEK293 cells that overexpress DDAH1.

RESULTS

In the clinical study, plasma ADMA was not significantly associated with any measure of hyperglycemia. L-homoarginine was positively associated with glucose (β = 0.067, p = 0.018) and SHR (β = 0.107, p < 0.001) after correction for glomerular filtration rate. However, as L-homoarginine is a negative predictor of mortality, the direction of these associations are the opposite of those expected if hyperglycemia was affecting mortality via changes in L-homoarginine. In vitro DDAH1 activity was not significantly influenced by glucose concentrations (p = 0.506).

CONCLUSION

In critically ill patients the association between relative hyperglycemia and mortality is not mediated by changes in ADMA or L-homoarginine. Trial registration ANZCTR Trial ID ACTRN12615001164583.

COVID-19 and Inflammatory Markers

Coronavirus disease-2019 (COVID-19) causes mild illness to serious infection with lung involvement, thrombosis, and other complications potentially resulting in fatal outcomes. Recognised inflammatory biomarkers play important roles in managing patients with COVID-19; for example, diagnosis, follow-up, assessment of treatment response, and risk stratification. Inflammatory markers in COVID-19 disease were analysed in two categories. Well-known inflammatory markers include complete blood count, C-reactive protein, albumin, cytokines, and erythrocyte sedimentation rate. Asymmetric dimethylarginine, endocan, pentraxin 3, serum amyloid A, soluble urokinase plasminogen activator receptor, total oxidant status and total antioxidant status, and galectin-3 are considered among the emerging inflammatory markers. This brief narrative review assesses the relationship between these inflammatory markers and COVID-19 infection.

Evaluation of Subclinical Atherosclerosis by Ultrasound Radiofrequency Data Technology in Patients With Familial Mediterranean Fever

OBJECTIVES

The aim of this study was to noninvasively demonstrate the presence of early risk associated with subclinical inflammatory activity in patients with familial Mediterranean fever (FMF) who had stable disease, using ultrasound (US) radiofrequency data technology.

METHODS

A total of 110 participants, including 55 patients with FMF and 55 healthy control participants, were evaluated with Doppler US. The intima-media thickness and arterial stiffness were measured from bilateral common carotid arteries (CCAs) by the radiofrequency method.

RESULTS

No statistically significant difference was found between the patients with FMF and controls in terms of the right and left CCA intima-media thickness, distensibility coefficient, compliance coefficient, α and β stiffness indices, and pulsed wave velocity (P > .05). Symptom duration and diagnosis and treatment time of the patients with FMF had a negative correlation with the distensibility and compliance measurements obtained by Doppler US (r = -0.324 and -0.303), and a positive (r = 0.380 and 0.339) and statistically significant relationship was detected between the α stiffness index, β stiffness index, and pulsed wave velocity (P < .05).

CONCLUSIONS

Common carotid artery intima-media thickness and arterial stiffness measurements can aid in early prediction of cardiovascular disease development in patients with FMF. Radiofrequency data technology provides a noninvasive method for accurately and quantitatively showing the CCA intima-media thickness elevation and the decrease in vascular elasticity in patients with FMF.

Angiotensin-converting Enzyme Inhibition Improves the Effectiveness of Transcutaneous Carbon Dioxide Treatment

AIM

To study the effect of carbon dioxide (CO₂) therapy on the nitric oxide (NO) pathway by monitoring plasma asymmetric dimethylarginine (ADMA) concentrations.

PATIENTS AND METHODS

Forty-seven hypertensive patients who underwent transcutaneous CO₂ therapy were enrolled. Thirty healthy individuals were recruited for the control group. Blood samples were taken one hour before, as well as one hour, 24 hours and 3 weeks after the first CO₂ treatment. Controls did not undergo CO₂ treatment. Plasma ADMA levels were measured by ELISA.

RESULTS

ADMA levels decreased significantly one hour after the first CO2 treatment compared to the baseline concentrations (p=0.003). Significantly greater reduction was found among patients in whom angiotensin converting enzyme inhibitors (ACEIs) were administered (p=0.019).

CONCLUSION

The short- and long-term decrease of ADMA levels suggests that CO₂ is not only a vasodilator, but also has a beneficial effect on the NO pathway. ACE inhibition seems to enhance the effect of CO₂ treatment.

Investigation of the arterial stiffness and associated factors in patients with familial Mediterranean fever

Objective:

Because of the ongoing and recurring inflammatory state in familial Mediterranean fever (FMF), patients may experience a high risk of cardiovascular events. Our aim was to investigate the arterial stiffness and associated factors in patients with FMF.

Methods:

Sixty-nine consecutive FMF patients (including 11 females) and 35 controls (including 5 females) were enrolled in the study. The demographical, clinical, and laboratory data and genetic mutations of the patients were recorded. In the study, FMF patients according to the Tel-Hashomer criteria were included, whereas patients with other known inflammatory rheumatologic disease, atherosclerotic cardiovascular disease, hypertension, diabetes, those under the age of 18 years, or those refusing to participate in the study were excluded. Arterial stiffness measurements were performed using the TensioMed device (TensoMed Ltd, Budapest, Hungary).

Results:

The patient and control groups were similar in terms of the mean ages, BMIs, gender, systolic blood pressures, and smoking. FMF patients had a higher pulse wave velocity (PWV) (7.73±1.3 and 7.18±1.1 m/s; p=0.03) and lower brachial and aortic augmentation indexes (–64.6±14.6% and –54.6±25.9%, p=0.041 and 4.9±7.4% and 14.0±11.5%, p=0.025, respectively) compared with the controls. Thirty-one (45%) patients were in the “during-attack” state and had higher PWV (8.17±1.6 and 7.38±0.9 m/s; p=0.027) compared with the asymptomatic patients. PWV was correlated to serum CRP, WBC, ESR, fibrinogen, and neutrophil/lymphocyte ratios (r=0.666, 0.429, 0.441, 0.388, and 0.460, respectively). The genetic mutation and predominant attack type had no effect on arterial stiffness.

Conclusion:

FMF patients have increased arterial stiffness during attacks compared with asymptomatic patients and controls. The impaired arterial stiffness is correlated to the severity of the inflammatory state rather than to the attack type or genetic mutations.

Age and gender differences in the influences of eNOS T-786C polymorphism on arteriosclerotic parameters in general population in Japan

OBJECTIVE

The influence of T-786C polymorphism in the promoter region of endothelial nitric oxide synthase (eNOS) on arteriosclerotic parameters by age and gender were examined.

METHODS

Brachial-ankle pulse wave velocity (baPWV), heart-rate adjusted augmentation index (AIx@75), pulse pressure (PP) and albumin-creatinine ratio (ACR) were assessed as arteriosclerotic parameters in addition to non-high-density lipoprotein cholesterol (non-HDL-C) to HDL-C (non-HDL-C/HDL-C) ratio in 1499 participants. T-786C polymorphism (rs2070744) was screened using a TaqMan allelic discrimination assay. Analyses of covariance were carried.

RESULTS

Women with the non-C allele showed significantly lower AIx@75 in participants aged <65 years and baPWV in participants aged ≥65 years than those with C allele. In contrast, men with the non-C allele showed significantly higher PP in participants aged <65 years, and higher ACR and non-HDL-C/HDL-C ratio in participants aged ≥65 years. In men on cholesterol-lowering medication, the non-C allele carriers showed significantly higher non-HDL-C compared to those in the C allele carriers.

CONCLUSIONS

eNOS T-786C polymorphism is significantly associated with arteriosclerotic parameters accompanied with age and gender differences, possibly involving antioxidative and/or endothelial signaling other than inflammatory signaling.

Are increased oxidative stress and asymmetric dimethylarginine levels associated with masked hypertension?

OBJECTIVE

In this study, our aim was to determine total oxidative stress and asymmetric dimethylarginine (ADMA) levels in patients with masked hypertension (MHT) and to examine their association with blood pressure.

METHODS

Fifty patients diagnosed with MHT and 48 healthy volunteers without any known chronic diseases have been included in this study.

RESULTS

When compared to the control group, patients with MHT had higher levels of mean ADMA (p < 0.001), total oxidant status (TOS) (p < 0.001), and oxidative stress index (OSI) (p < 0.001), and a lower mean total antioxidant status (TAS) (p < 0.001) level. While a positive correlation was determined between the systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels with ADMA, TOS, and OSI levels, a negative correlation was determined with the TAS level. During the stepwise multivariable logistic regression analysis, age (OR = 1.221; p = 0.003), body mass index (OR = 1.512; p = 0.005), low density lipoprotein (OR = 0.925; p = 0.016), ADMA (OR = 1.200; p = 0.002), and OSI (OR = 3.750; p = 0.002) levels were determined to be the predictors of MHT. During the linear regression analysis, it was determined that the independent risk factors of SBP and DBP are ADMA and OSI, and the independent risk factor of TOS, OSI, and ADMA is SBP. Our study found out that oxidative stress and ADMA levels of patients with MHT are higher than those of the control group. ADMA and OSI were determined to be predictors of MHT.

CONCLUSION

Based on these results, it could be said that oxidative stress, and therefore the ADMA level, could have an effect on the etiopathogenesis of MHT.

Clinical Significance of Endothelial Dysfunction in Essential Hypertension

The endothelium is recognized as a major determinant of vascular physiology and pathophysiology. Over the last few decades, a plethora of studies have implicated endothelial dysfunction in the progression of atherosclerosis and the subclinical target organ damage observed in essential hypertension. However, the clinical significance of diagnosing endothelial dysfunction in patients with essential hypertension remains under investigation. Although a number of vascular and non-vascular markers of endothelial dysfunction have been proposed, there is an ongoing quest for a marker in the clinical setting that is optimal, inexpensive, and reproducible. In addition, endothelial dysfunction emerges as a promising therapeutic target of agents that are readily available in clinical practice. In this context, a better understanding of its role in essential hypertension becomes of great importance. Here, we aim to investigate the clinical significance of endothelial dysfunction in essential hypertension by accumulating novel data on (a) early diagnosis using robust markers with prognostic value in cardiovascular risk prediction, (b) the association of endothelial dysfunction with subclinical vascular organ damage, and (c) potential therapeutic targets.

Multidisciplinary Treatment of the Metabolic Syndrome Lowers Blood Pressure Variability Independent of Blood Pressure Control

Blood pressure (BP) variability (BPV) contributes to target organ damage independent of BP. The authors examined the effect of a 1-year multidisciplinary intervention on BPV in patients with the metabolic syndrome (MetS) as defined by criteria from the Third Report of the Adult Treatment Panel. Forty-four nondiabetic patients underwent clinical and biochemical profiling, 24-hour ambulatory BP monitoring (ABPM), body composition, carotid intima-media thickness, and carotid-femoral pulse wave velocity (PWV). The intervention targeted all MetS components. BPV was assessed by the standard deviation of daytime systolic BP derived from ABPM. Patients with low and high BPV (lower or higher than the median daytime standard deviation of 11.6 mm Hg) did not differ in regards to systolic and diastolic BP, age, fasting glucose, glycated hemoglobin, and body mass index, but the high-variability group had higher values of low-density lipoprotein and leg fat. The 1-year intervention resulted in weight reduction but not BP-lowering. BPV declined in the high-variability group in association with lowering of PWV, C-reactive protein, glycated hemoglobin, alanine aminotransferase, asymmetric dimethylarginine, and increased high-density lipoprotein cholesterol. A multidisciplinary intervention independent of BP-lowering normalized BPV, lowered PWV, and enhanced metabolic control.

Novel Pathophysiological Mechanisms in Hypertension

Hypertension is the most common disease affecting humans and imparts a significant cardiovascular and renal risk to patients. Extensive research over the past few decades has enhanced our understanding of the underlying mechanisms in hypertension. However, in most instances, the cause of hypertension in a given patient continues to remain elusive. Nevertheless, achieving aggressive blood pressure goals significantly reduces cardiovascular morbidity and mortality, as demonstrated in the recently concluded SPRINT trial. Since a large proportion of patients still fail to achieve blood pressure goals, knowledge of novel pathophysiologic mechanisms and mechanism based treatment strategies is crucial. The following chapter will review the novel pathophysiological mechanisms in hypertension, with a focus on role of immunity, inflammation and vascular endothelial homeostasis. The therapeutic implications of these mechanisms will be discussed where applicable.

Effect of DDAH/ADMA/NOS regulation pathway on cavernae corporum cavernosorum rat penis of different age

The effect of DDAH/ADMA/NOS pathway in penile tissue of rats of different age was investigated to better understand the mechanism of age-related erectile dysfunction (ED). The Sprague Dawley male rats were assigned as the young group (3 month old, n = 10) and the old group (18 month old, n = 10) respectively. Intracavernous pressure (ICP) was measured before and after papaverine intracavernous injection. Pathology structure of penile tissue was evaluated under transmission electron microscope. The expression amounts of asymmetric dimethylarginine (ADMA) and cyclic guanosine monophosphate (cGMP) in penile tissue were detected by ELISA; the expression levels of isoform-specific DDAH and NOS were assessed via Western blot. Compared with the young group, the ICP in the old group rat decreased significantly (33.46 ± 5.37 versus 39.71 ± 3.67 mmHg, P = 0.02) after papaverine injection. Diffused fibrosis and impairment of endothelial cell were observed in corpus cavernosum in the old group rats. Higher level of ADMA (10.83 ± 0.96 versus 7.51 ± 1.39 μmol per gpro, P = 3.14 × 10(-4) ) and lower level of cGMP (29.42 ± 3.84 versus 47.09 ± 6.07 nmol per gpro, P = 1.57 × 10(-6) ) were detected in penile tissue of the old group compared with those of the young group. Expression of DDAH1, DDAH2, endothelial NOS (eNOS) and neuronal NOS(nNOS) all decreased significantly in penile tissue of the old group rat. The DDAH/ADMA/NOS regulation pathway changes dramatically accompanying with lower ICP in old group rat compared with those of the young group. Such findings in rats are suggestive in understanding the mechanism of age-related ED in humans.