Endothelium and angiogenesis in white coat hypertension

Tutorial review for peptide assays: An ounce of pre-analytics is worth a pound of cure

The recent increase in peptidomimetic-based medications and the growing interest in peptide hormones has brought new attention to the quantification of peptides for diagnostic purposes. Indeed, the circulating concentrations of peptide hormones in the blood provide a snapshot of the state of the body and could eventually lead to detecting a particular health condition. Although extremely useful, the quantification of such molecules, preferably by liquid chromatography coupled to mass spectrometry, might be quite tricky. First, peptides are subjected to hydrolysis, oxidation, and other post-translational modifications, and, most importantly, they are substrates of specific and nonspecific proteases in biological matrixes. All these events might continue after sampling, changing the peptide hormone concentrations. Second, because they include positively and negatively charged groups and hydrophilic and hydrophobic residues, they interact with their environment; these interactions might lead to a local change in the measured concentrations. A phenomenon such as nonspecific adsorption to lab glassware or materials has often a tremendous effect on the concentration and needs to be controlled with particular care. Finally, the circulating levels of peptides might be low (pico- or femtomolar range), increasing the impact of the aforementioned effects and inducing the need for highly sensitive instruments and well-optimized methods. Thus, despite the extreme diversity of these peptides and their matrixes, there is a common challenge for all the assays: the need to keep concentrations unchanged from sampling to analysis. While significant efforts are often placed on optimizing the analysis, few studies consider in depth the impact of pre-analytical steps on the results. By working through practical examples, this solution-oriented tutorial review addresses typical pre-analytical challenges encountered during the development of a peptide assay from the standpoint of a clinical laboratory. We provide tips and tricks to avoid pitfalls as well as strategies to guide all new developments. Our ultimate goal is to increase pre-analytical awareness to ensure that newly developed peptide assays produce robust and accurate results.

Diagnosis and Monitoring of White Coat Hypertension in Pregnancy: an ISSHP Consensus Delphi Procedure

BACKGROUND

There is no accepted definition or standardized monitoring for white coat hypertension in pregnancy. This Delphi procedure aimed to reach consensus on out-of-office blood pressure (BP) monitoring, and white coat hypertension diagnostic criteria and monitoring.

METHOD

Relevant international experts completed three rounds of a modified Delphi questionnaire. For each item, the predefined cutoff for group consensus was ≥70% agreement, with 60% to 70% considered to warrant reconsideration at the subsequent round, and <60% considered insufficient to warrant consideration.

RESULTS

Of 230 experts, 137 completed the first round and 114 (114/137, 83.2%) completed all three. For out-of-office BP monitoring, there was consensus that home BP monitoring (HBPM) should be chosen; instructions given, pairs of BP values taken, opportunity given for women to qualify values they do not regard as valid, and BP considered evaluated when ≥25% of values are above a cutoff. For HBPM, BP should be taken at least 2 to 3 d/wk, at minimum in the morning; however, many factors may affect frequency and timing. Experts endorsed a clinic BP <140/90 mm Hg as normal. While not reaching consensus, most agreed that HBPM values should be lower than clinic BP. Among those, HBPM <135/85 mm Hg was considered normal. There was consensus that white coat hypertension warrants: HBPM at least 1 d/wk before 20 weeks, 2 to 3 d/wk after 20 weeks or if persistent hypertension develops, and symptom monitoring (ie, headache, visual symptoms, and right upper quadrant/epigastric pain).

CONCLUSIONS

Consensus-based diagnostic criteria and monitoring strategies should inform clinical care and research, to facilitate evaluation of out-of-office BP monitoring on pregnancy outcomes.

Metabolic syndrome and subchondral bone alterations: The rise of osteoarthritis - A review

Metabolic syndrome (MS) has become one of the top major health burdens for over three decades not only due to its effects on cardiovascular health but also its implications in orthopedics. Extensive research has shown that MS is tightly linked to osteoarthritis and inflammation, a process which appears to primarily occur in the subchondral bone via the incidence of bone-marrow lesions (BMLs). Numerous studies identify obesity, dyslipidemia, insulin resistance and hypertension as the top metabolic risk factors, the so-called "deadly quartet". These factors are responsible for the disruptive physiological processes that culminate in detrimental alterations within the subchondral bone, cartilage damage and, overall, the predominant pro-inflammatory joint microenvironment. Although it has long been thought that osteoarthritis was limited to the cartilage component of the joint, other studies indicate that the disease may originate from the harmful alterations that occur primarily in the subchondral bone, especially via means of vascular pathology. Since metabolic risk factors are manageable to a certain extent, it is therefore possible to decelerate the progression of OA and mitigate its devastating effects on the subchondral bone and subsequent articular cartilage damage.

METHODS

Literature was reviewed using PubMed and Google Scholar in order to find a correlation between metabolic syndrome and osteoarthritic progression. The investigation included a combination of nomenclature such as: "metabolic syndrome", "obesity", "insulin resistance", "hypertension", "dyslipidemia", "low-grade systemic inflammation", "osteoarthritis", "subchondral bone", "cartilage" and "inflammatory biomarkers".

CONCLUSION

Based on several studies, there seems to be a significant association between The Deadly Quartet (metabolic syndrome), dysregulation of both pro- and anti-inflammatory biomarkers, and osteoarthritic progression arising from unbridled systemic inflammation.

Examining the Association of Knee Pain with Modifiable Cardiometabolic Risk Factors

OBJECTIVE

There is a well-established link between obesity and knee osteoarthritis, and recent research has implicated diabetes as a potential cause of cartilage degeneration. This study uses the National Health and Nutrition Examination Survey (NHANES) database to examine the association between knee pain and various metabolic factors.

METHODS

A retrospective cross-sectional study of the NHANES database from 1999 to 2004 was performed. The main outcome was any knee pain and bilateral knee pain. Main effects of interest were body mass index (BMI), and hemoglobin A1c (HbA1c). We additionally assessed various patient factors including age, race, poverty, gender and smoking status. Multivariable logistic regression models and interaction terms were analyzed.

RESULTS

Data on 12,900 patients was included. In the main adjusted analysis, the modifiable risk factors associated with any knee pain were: overweight (OR 0.91; 95% CI 0.85, 0.97), obesity (OR 1.54; 95% CI 1.42, 1.66), glycemic control (OR 1.20; 95% CI 1.03, 1.38), and current smokers (OR 1.15; 95% CI 1.05, 1.27), all p<0.05. These same factors remain significant for bilateral knee pain. Subgroup analysis showed patients under 65 years old have a 5% increase in risk of any knee pain as their body mass index increases, but patients 65 years and older have a 10% increase in risk.

CONCLUSION

This study confirms the association of knee pain with increased weight, glycemic control, current smoking and age. Most of these risk factors can be modified in patients with knee pain and should be discussed when providing conservative treatment options.

Ambulatory blood pressure monitoring in living kidney donors: What changes in 10 years?

In renal transplantation, living donations have more significant benefits compared to cadaveric donations. However, a probable increase in blood pressure following donation should also be kept in mind. In this study, we investigated the long-term changes in blood pressure in living kidney donors using ambulatory blood pressure monitoring and we explored the e-GFR and albuminuria/proteinuria measurements at 3 time points. Twenty-eight living kidney donors and 39 healthy individuals were evaluated and compared at the baseline and later at the 10th year. At the 10th year, creatinine levels were higher and eGFR levels were lower in the donors, whereas the systolic and diastolic measurements of the donors and controls and the prevalence of nondipping in the donors and controls were similar. Our study may be underpowered due to its small population size. However, our results at the 10th year follow-up indicated that the risk of hypertension might not seem to have increased in the well-selected donors. In addition, the majority of our donors had preserved their GFR values. Therefore, we can suggest that living kidney donation appears to be safe in well-selected patients over a 10-year time frame.

The impact of protein oxidation on sustained and white coat hypertension

Objective:

The present study compared the unfavorable effects of protein oxidation and deoxyribonucleic acid damage on patients with white coat hypertension (WCH), sustained hypertension (HT), and normotensives.

Methods:

Participants were allocated into 3 groups: 40 healthy controls, 36 patients with WCH, and 40 patients with sustained HT. Patients with risk factors for atherosclerosis, endocrine diseases, alcoholism, or masked hypertension were excluded. Plasma level of protein carbonyl (PCO), ischemia modified albumin (IMA), total thiol (T-SH), prooxidant-antioxidant balance (PAB), advanced protein oxidation products (AOPPs), and urinary level of 8-hydroxy-2’-deoxyguanosine (8-OHdG) were measured and relationship between these oxidative stress parameters and WCH and sustained HT was analyzed.

Results:

Ambulatory 24-hour, daytime and night-time systolic and diastolic blood pressure readings of sustained HT group were significantly higher than those of WCH and control groups (p<0.001, all). AOPPs, PCO, IMA, 8-OHdG, and PAB levels were significantly higher in HT group than WCH and control groups (p<0.001, all). Additionally, T-SH level was significantly lower in HT group than WCH and control groups (p<0.001). A similar statistically significant relationship was detected between WCH and control groups.

Conclusion:

Results indicate that increased level of AOPPs, PCO, IMA, 8-OHdG, PAB, and decreased level of T-SH are likely to be indicators of oxidative stress, which may play a key role both in WCH and sustained HT.

Vitamin D levels in white coat and sustained hypertension

OBJECTIVE

The plasma levels of vitamin D in patients with white coat hypertension (WCHT) have not been studied previously. The aim of this study was to evaluate vitamin D levels in WCHT and compare with sustained hypertension (SHT) and with normotension (NT).

PATIENTS AND METHODS

Fifty-three normotensive, 42 WCHT, and 59 SHT patients were recruited in this study. The participants were matched for age, sex, and BMI. The vitamin D levels were determined using the electrochemiluminescence immunoassay method.

RESULTS

Plasma vitamin D levels were significantly lower in SHT than in the WCHT and NT groups (26.4±4.9, 34.3±3.6, and 36±5 ng/ml, respectively), and were similar in the WCHT and NT groups. There was a negative correlation between vitamin D levels and blood pressure parameters such as clinic systolic blood pressure (SBP), clinic diastolic blood pressure (DBP), 24-h SBP, 24-h DBP, daytime SBP, daytime DBP, night-time SBP, and night-time DBP (r=-0.554, -0.419, -0.629, -0.427, -0.559, -0.534, -0.607, -0.462, respectively, and all P<0.001) in the entire study group. Clinic SBP (B±SE=-0.97±0.037, P=0.009) and 24-h SBP (B±SE=-0.138±0.055, P=0.013) were identified as predictors for vitamin D levels in the entire study group.

CONCLUSION

Our data show that sustained hypertensive patients have lower vitamin D levels than white coat hypertensive and normotensive individuals. White coat hypertensive patients without other cardiovascular risk factors have higher vitamin D levels than sustained hypertensive patients, suggesting that they have a lower cardiovascular risk.

Circulating miR-21 and eNOS in subclinical atherosclerosis in patients with hypertension

OBJECTIVES

The aim of this study is to evaluate the relationship of miR-21, nitric oxide (NOx) and endothelial nitric oxide synthase (eNOS) with subclinical atherosclerosis in carotid arteries by measuring carotid intima media thickness (CIMT) in patients with hypertension and healthy controls.

DESIGN AND METHODS

A total of 28 hypertensive and 28 healthy controls were enrolled. MiR-21 expression was analyzed by quantitative reverse transcription-PCR and NOx, and eNOS levels were measured by ELISA assay. CIMT was evaluated by ultrasonography and CIMT ≥ 0.8 mm was accepted as increased CIMT (iCIMT).

RESULTS

C-reactive protein (CRP) level, plasma miR-21 expression level and CIMT were found to be significantly higher in the hypertension group when compared to the control group (p = 0.009, p = 0.002 and p < 0.001, respectively). NOx and eNOS levels were significantly lower in the hypertension group compared to the control group (p < 0.001, both). MiR-21 level was positively correlated with the clinical systolic blood pressure, clinical diastolic blood pressure, CRP and CIMT. MiR-21 was also negatively correlated with NOx and eNOS. Eighteen patients with hypertension had iCIMT. MiR-21 and CRP levels were significantly higher (p < 0.001 and p = 0.001), whereas NOx and eNOS levels were significantly lower in patients with iCIMT (p < 0.001, both).

CONCLUSION

The decreased levels of NOx and eNOS found in this study indicate the co-existence of endothelial dysfunction and hypertension once more. In the absence of microalbuminuria, the increased miR-21 expression in patients with iCIMT made us conclude that this miRNA might be involved in the early stages of atherosclerotic process in hypertensive patients.

Closer look at white-coat hypertension

This review aims to clarify novel concepts regarding the clinical and laboratory aspects of white-coat hypertension (WCHT). Recent studies on the clinical and biological implications of WCHT were compared with existing knowledge. Studies were included if the WCHT patients were defined according to the 2013 European Society of Hypertension guidelines, i.e., an office blood pressure (BP) of ≥ 140/90 mmHg, a home BP of ≤ 135/85 mmHg, and a mean 24-h ambulatory BP of ≤ 130/80 mmHg. WCHT studies published since 2000 were selected, although a few studies performed before 2000 were used for comparative purposes. True WCHT was defined as normal ABPM and home BP readings, and partial WCHT was defined as an abnormality in one of these two readings. The reported prevalence of WCHT was 15%-45%. The incidence of WCHT tended to be higher in females and in non-smokers. Compared with normotensive (NT) patients, WCHT was associated with a higher left ventricular mass index, higher lipid levels, impaired fasting glucose, and decreased arterial compliance. The circadian rhythm in WCHT patients was more variable than in NT patient’s, with a higher pulse pressure and non-dipping characteristics. Compared with sustained hypertension patients, WCHT patients have a better 10-year prognosis; compared with NT patients, WCHT patients have a similar stroke risk, but receive more frequent drug treatment. There are conflicting results regarding WCHT and markers of endothelial damage, oxidative stress and inflammation, and the data imply that WCHT patients may have a worse prognosis. Nitric oxide levels are lower, and oxidative stress parameters are higher in WCHT patients than in NT patients, whereas the antioxidant capacity is lower in WCHT patients than in NT patients. Clinicians should be aware of the risk factors associated with WCHT and patients should be closely monitored especially to identify target organ damage and metabolic syndrome.

White-coat hypertension

1. Numerous studies have examined whether white-coat hypertension (WCHT) is associated with increased cardiovascular risk, but with definitions of WCHT that were not sufficiently robust, results have been inconsistent. The aim of the present review was to standardize the evidence by only including studies that used a definition of WCHT consistent with international guidelines. 2. Published studies were reviewed for data on vascular dysfunction, target organ damage, risk of future sustained hypertension and cardiovascular events. 3. White-coat hypertension has a population prevalence of approximately 15% and is associated with non-smoking and slightly elevated clinic blood pressure. Compared with normotensives, subjects with WCHT are at increased cardiovascular risk due to a higher prevalence of glucose dysregulation, increased left ventricular mass index and increased risk of future diabetes and hypertension. 4. In conclusion, management of a patient with WCHT should focus on cardiovascular risk factors, particularly glucose intolerance, not blood pressure alone.

Endothelial damage in white coat hypertension: role of lectin-like oxidized low-density lipoprotein-1

The aims of this study included an examination of soluble lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (sLOX-1) levels in hypertensive (HT) patients. Another aim examined sLOX-1 associations with oxidized LDL (oxLDL), nitric oxide synthase (eNOS) and nitric oxide (NOx). A final aim was to compare these parameters between HT patients, white-coat hypertensive (WCH) patients and healthy controls. The three groups, HT, WCH and controls, were comprised of 35 patients each. sLOX-1 and oxLDL levels were significantly increased in WCH and HT patients compared with controls. The eNOS activation was significantly lower in HT than in the control group. sLOX-1 and oxLDL levels were significantly negatively correlated with eNOS levels in the WCH and HT groups. Carotid intima-media thickness (CIMT) measurements were significantly higher in the WCH and HT groups compared with controls. There was a significant positive correlation between CIMT and sLOX-1 and oxLDL; however, there was a negative correlation with eNOS in WCH. Regression analysis revealed that sLOX-1 was the variable that had a significant effect on blood pressure (P<0.001, odds ratio (95% confidence interval=23.273 (5.843-92.688)). A possible endothelial impairment may act as a cardiovascular risk factor in WCH. Necessary measures should be considered in terms of atherosclerosis risk with HT, especially in early identification of endothelial damage by looking at sLOX-1 levels. We believe sLOX-1 levels are strong biomarkers for determining early endothelial damage in HT, and especially in WCH patients.

Metabolic syndrome meets osteoarthritis

Metabolic osteoarthritis (OA) has now been characterized as a subtype of OA, and links have been discovered between this phenotype and metabolic syndrome (MetS)--both with individual MetS components and with MetS as a whole. Hypertension associates with OA through subchondral ischaemia, which can compromise nutrient exchange into articular cartilage and trigger bone remodelling. Ectopic lipid deposition in chondrocytes induced by dyslipidemia might initiate OA development, exacerbated by deregulated cellular lipid metabolism in joint tissues. Hyperglycaemia and OA interact at both local and systemic levels; local effects of oxidative stress and advanced glycation end-products are implicated in cartilage damage, whereas low-grade systemic inflammation results from glucose accumulation and contributes to a toxic internal environment that can exacerbate OA. Obesity-related metabolic factors, particularly altered levels of adipokines, contribute to OA development by inducing the expression of proinflammatory factors as well as degradative enzymes, leading to the inhibition of cartilage matrix synthesis and stimulation of subchondral bone remodelling. In this Review, we summarize the shared mechanisms of inflammation, oxidative stress, common metabolites and endothelial dysfunction that characterize the aetiologies of OA and MetS, and nominate metabolic OA as the fifth component of MetS. We also describe therapeutic opportunities that might arise from uniting these concepts.

Out-of-office and central blood pressure for risk stratification: a cross-sectional study in patients treated for hypertension

BACKGROUND

Central blood pressure (BP) predicts mortality independent of office brachial BP. Whether central BP may be useful to differentiate BP control requires examination and was the first aim of this study. Secondly, we sought to determine the variability in central BP among patients from different categories of BP control [controlled hypertension (CH), masked hypertension (MH), white coat (WCHT) and uncontrolled hypertension (UH)].

MATERIALS AND METHODS

We assessed patients with uncomplicated hypertension using measurement of central BP (SphygmoCor 8.1), brachial BP and 24-h ambulatory BP monitoring. BP control was defined according to guidelines using office BP and 24-h BP.

RESULTS

Of the 201 patients (63 ± 8 years, 51% men), 67 (33%) were classified as CH; 59 (29%) with MH; 31 (15%) with WCHT; and 44 (22%) with UH. There were no differences in central BP parameters (augmentation pressure, augmentation index, pulse pressure) between patients with CH and MH or between patients with WCHT and UH (P > 0·05 for all). However, there was significant overlap in central systolic BP between BP control categories. For example, 27% of patients with normal brachial systolic BP had central systolic BP above age- and gender-specific normal values, including patients from three classifications of BP control (CH: n = 27; MH: n = 22; and WCHT: n = 4).

CONCLUSION

Office central BP alone cannot delineate categories of BP control. However, given the high degree of variability in central BP among patients from different categories of BP control, measurement of central BP may result in significant reclassification of risk related to BP.

Mechanical and circulating biomarkers in isolated clinic hypertension

1. This review examines the current evidence for altered mechanical and circulating biomarkers in isolated clinic hypertension and their potential significance. 2. Arterial stiffness, as assessed by central pulse wave velocity, is influenced by multiple cardiovascular risk factors; however, an independent association with isolated clinic hypertension (ICHT) has not been convincingly shown in four small studies. 3. Endothelial dysfunction, as assessed by brachial artery flow-mediated vasodilation, circulating levels of endothelial markers (e.g. nitrite/nitrate, von Willebrand factor, endothelin-1) and/or circulating levels of inhibitors of vascular nitric oxide (plasma asymmetric dimethylarginine, homocysteine), has been shown to be present in established hypertension and to a variable and inconsistent extent in subjects with ICHT. 4. Evidence of increased oxidative stress in ICHT versus normotensive subjects was found in two of three studies. 5. Circulating inflammatory markers C-reactive protein and plasminogen activator inhibitor-1 were significantly increased in two of three and two of two studies, respectively, in ICHT compared with normotensive subjects. 6. Urinary albumin excretion is a marker of both arterial and renal disease. The consensus from seven studies in patients with ICHT is that albuminuria is not an independent marker for ICHT. 7. Studies to date assessing biomarkers in ICHT have been small and cross-sectional. Larger, long-term longitudinal studies of arterial functional and circulating biomarkers are required to assess the potential vascular impact of ICHT.

Endothelial progenitor cells in pregnancy

The discovery of endothelial progenitor cells has generated considerable interest in the field of vascular biology. These cells arise from a population of circulating mononuclear cells and have the capacity to form new blood vessels and contribute to vascular repair. Circulating endothelial progenitor cell numbers are reduced in patients with cardiovascular risk factors and in the presence of endothelial dysfunction, but are increased in response to ischaemia, oestrogens and drug therapy. They have been studied in pathologies from cardiovascular and renal disease to rheumatoid arthritis and pre-eclampsia. Pregnancy is a challenge to the maternal vascular system, requiring systemic adaptation and pronounced local changes in the uterus. Diseases of pregnancy such as pre-eclampsia and gestational diabetes increase the risk of pregnancy complications and are associated with endothelial dysfunction. We propose that endothelial progenitor cells have an important role in the regulation and maintenance of the vasculature during pregnancy. This review summarises our current understanding of endothelial progenitor cells, with specific reference to their role in angiogenesis and human pregnancy.

Oxidative stress in human in sustained and white coat hypertension

Oxidative stress is thought to play a critical role in the pathogenesis of hypertension. Protein oxidation is defined here as the covalent modification of a protein induced either directly by reactive oxygen species or indirectly by reaction with secondary by-products of oxidative stress. The aim of our study was to evaluate the protein oxidation and to examine the function of the antioxidative system in sustained and white coat hypertensives (WCH) and compare with normotensives. This study was designed to investigate the protein oxidation parameters [protein carbonyls (PCOs)] in sustained hypertensives (17 males and 20 females) and WCH (18 males and 19 females). PCO and the endogenous antioxidant components protein thiol (P-SH), CuZn-superoxide dismutase (CuZn-SOD) and glutathione (GSH) were analysed using spectrophotometric and kinetic methods. Sustained hypertensive and WCH groups exhibited higher protein oxidation and lower P-SH, CuZn-SOD and GSH activities than normotensives. With regard to these parameters, there was no significant difference between sustained hypertensive and WCH groups. Blood pressure correlates positively with PCO groups and negatively with others. There exists an imbalance between oxidants and antioxidants in WCH because of the increase of oxidants associated with the decrease of antioxidant capacity. This may cause endothelial dysfunction just like in sustained hypertension. It may be necessary to add antioxidants to conventional antihypertensive therapy to balance the oxidative status in WCH.

Improving patient outcomes with ambulatory blood pressure monitoring in elderly with hypertension

PURPOSE

The purpose of this article is to review the current knowledge regarding ambulatory blood pressure monitoring (ABPM) use in clinical practice and to provide example cases for its use in a hypertension (HTN) specialty clinic.

DATA SOURCES

Published research trials, medical literature, and cases from the Center for Senior Hypertension.

CONCLUSIONS

The knowledge of ABPM benefits to using ABPM are substantial and improves the care and management of many conditions, including white coat HTN, white coat normotension, resistant, borderline, episodic, paroxysmal HTN, and finally orthostatic hypotension. Third-party payers only cover ABPM for "white coat" HTN.

IMPLICATIONS FOR PRACTICE

This article reviews previous studies and explains the benefit to changing our current practice to match the knowledge we have gained through research through case studies.

Increased circulating concentrations of asymmetric dimethylarginine (ADMA) in white coat hypertension

Elevated plasma levels of the endogenous nitric oxide (NO) synthase inhibitor asymmetric dimethylarginine (ADMA) contribute to endothelial dysfunction and seem to be a predictor for cardiovascular mortality. Elevated ADMA plasma concentrations have been demonstrated in patients with hypertension. However, the plasma concentrations of ADMA in white coat hypertension (WCH) has not been previously studied. The aim of this study was to evaluate ADMA in WCH and compare with normotensive (NT) and hypertensive (HT) patients. We also evaluated the relation between ADMA and NO in these three groups. For this purpose, 34 NT, 34 white coat hypertensive (clinical hypertension and ambulatory daytime blood pressure <135/85 mmHg) and 34 HT patients were recruited in this study. The subjects were matched for age, gender, body mass index (BMI) and the patients with smoking habit, dyslipidaemia and diabetes mellitus were excluded. The ADMA levels were determined by high performance liquid chromatography. Plasma ADMA levels were significantly higher in WCH group than in the NT group (3.21+/-0.49 micromol/l vs 2.84+/-0.58 micromol/l, P=0.046). It was significantly higher in the HT group than in the NTs (4.24+/-0.38 micromol/l, P<0.001). There was also a significant difference between the HT and WCH groups (P<0.001). The WCH subjects had significantly higher levels of NO than the HTs (41.68+/-2.23 vs 32.18+/-2.68 micromol/l; P<0.001) and significantly lower values than the NTs (48.24+/-4.29 micromol/l; P<0.001). In WCH and HT group, there was a negative correlation between ADMA and NO (r=-0.515, P=0.003 and r=-0.389, P=0.034, respectively). In NT subjects, there was no correlation between these two parameters (r=-0.287, P=0.124). The correlation between ADMA and NO was stronger in WCH group than in HT group. Although NO levels in HT patients were lower than WCHs and ADMA levels were higher in HT patients than WCHs, the negative correlation of these two parameters were more pronounced in WCH group. Decreased NO and increased ADMA levels in WCH may indicate endothelial dysfunction. Our data indicate also that WCH represent an intermediate group between NT and HT when endothelial dysfunction is concerned.