Establishing normal values of total testosterone in adult healthy men by the use of four immunometric methods and liquid chromatography-mass spectrometry

BACKGROUND

The total testosterone (T) cutoffs clinically adopted to define late-onset hypogonadism (LOH) do not consider the differences that exist between different analytical platforms, nor do they consider the body mass index (BMI) or age of the patient. We aimed at providing method, age and BMI-specific normal values for total T in European healthy men.

METHODS

A total of 351 eugonadal healthy men were recruited, and total T was measured with four automated immunometric assays (IMAs): ARCHITECT i1000SR (Abbott), UniCel DxI800 (Beckman Coulter), Cobas e601 (Roche), IMMULITE 2000 (Siemens) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Reference ranges (RRs) were calculated for each method.

RESULTS

Passing and Bablok regression analysis and Bland-Altman plot showed an acceptable agreement between Abbott and LC-MS/MS, but a poor one between LC-MS/MS and the other IMAs. Age-specific T concentrations in non-obese (BMI <29.9 kg/m2) men were greater than in all men. The total T normal range, in non-obese men aged 18-39 years, measured with LC-MS/MS was 9.038-41.310 nmol/L. RRs calculated with LC-MS/MS statistically differed from the ones calculated with all individual IMAs, except Abbott and among all IMAs. Statistically significant differences for both upper and lower reference limits between our RRs and the ones provided by the manufacturers were also noticed.

CONCLUSIONS

We calculated normal ranges in a non-obese cohort of European men, aged 18-39 years, with four commercially available IMAs and LC-MS/MS and found statistically significant differences according to the analytical method used. Method-specific reference values can increase the accuracy of LOH diagnosis and should be standardly used.

Antibodies as biomarker candidates for response and survival to checkpoint inhibitors in melanoma patients

Background

Long-term survival of stage IV melanoma patients has improved significantly with the development of immune checkpoint inhibitors (CIs). Reliable biomarkers to predict response and clinical outcome are needed.

Methods

We investigated the role of melanoma-associated antibodies as predictive markers for CI therapy in two independent cohorts. In cohort 1, a prospective study, we measured specific antibodies before treatment, after one week and after six to nine weeks of treatment. Cohort 2 consisted of serum samples prior to CI therapy initiation. ELISA assays were performed to quantify specific IgG directed against melanocyte differentiation antigens tyrosinase-related proteins 1 and 2 (TRP1/TYRP1 and TRP2/TYRP2), glycoprotein 100 (gp100), MelanA/MART1, and the cancer-testis antigen NY-ESO-1. Response was defined as either complete or partial remission on CT scan according to RECIST 1.1.

Results

In cohort 1, baseline levels of these antibodies were higher in the responder group, although statistical significance was only reached for NY-ESO-1 (p = 0.007). In cohort 2, significantly higher antibody baseline levels for MelanA/MART1 (p = 0.003) and gp100 (p = 0.029) were found. After pooling the results from both cohorts, higher levels of MelanA/MART1 (p = 0.013), TRP1/TYRP1 (p = 0.048), TRP2/TYRP2 (p = 0.047) and NY-ESO-1 (p = 0.005) specific antibodies at baseline were independently associated with response.

Conclusions

Melanoma-associated antibodies may be candidate biomarkers for response and survival in metastatic melanoma patients being treated with CIs. These markers may be used to complement patient assessment, in combination with PD-L1 status, tumor-infiltrating lymphocytes and tumor mutational burden, with the aim to predict outcome of CI treatment in patients with metastatic melanoma.

Trial registration

Ethikkommission Ostschweiz, EKOS 16/079 https://ongoingprojects.swissethics.ch/runningProjects_list.php?q=%28BASECID~contains~2016-00998%29&orderby=dBASECID.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0523-2) contains supplementary material, which is available to authorized users.

Publisher Correction: Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits

In the version of this article originally published, the name of author Martin H. de Borst was coded incorrectly in the XML. The error has now been corrected in the HTML version of the paper.

Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits

High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic and pulse pressure) to date in over 1 million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also highlight shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future.

Fibroblast growth factor 23 and renal function among young and healthy individuals

BACKGROUND

Fibroblast growth factor 23 (FGF-23), an osteocyte hormone involved in the regulation of phosphate metabolism, is associated with incident and progressive chronic kidney disease. We aimed to assess the association of FGF-23 with renal parameters, vascular function and phosphate metabolism in a large cohort of young and healthy individuals.

METHODS

Healthy individuals aged 25-41 years were included in a prospective population-based study. Fasting venous blood and morning urinary samples were used to measure plasma creatinine, cystatin C, endothelin-1, phosphate and plasma FGF-23 as well as urinary creatinine and phosphate. Multivariable regression models were constructed to assess the relationship of FGF-23 with parameters of renal function, endothelin-1 and fractional phosphate excretion.

RESULTS

The median age of 2077 participants was 37 years, 46% were males. The mean estimated glomerular filtration rate (eGFR - CKD-EPI creatinine-cystatin C equation) and fractional phosphate excretion were 110 mL/min/1.73 m2 and 8.7%, respectively. After multivariable adjustment, there was a significant inverse relationship of FGF-23 with eGFR (β per 1 log-unit increase -3.81; 95% CI [-5.42; -2.20]; p<0.0001). Furthermore, we found a linear association between FGF-23 and endothelin-1 (β per 1 log-unit increase 0.06; [0.01, 0.11]; p=0.01). In addition, we established a significant relationship of FGF-23 with fractional phosphate excretion (β per 1 log-unit increase 0.62; [0.08, 1.16]; p=0.03).

CONCLUSIONS

Increasing plasma FGF-23 levels are strongly associated with decreasing eGFR and increasing urinary phosphate excretion, suggesting an important role of FGF-23 in the regulation of kidney function in young and healthy adults.

Whole blood omega-3 fatty acid concentrations are inversely associated with blood pressure in young, healthy adults

BACKGROUND

Omega-3 fatty acids (n - 3 FA) may have blood pressure (BP)-lowering effects in untreated hypertensive and elderly patients. The effect of n - 3 FA on BP in young, healthy adults remains unknown. The Omega-3 Index reliably reflects an individuals' omega-3 status. We hypothesized that the Omega-3 Index is inversely associated with BP levels in young healthy adults.

METHODS

The current study (n = 2036) is a cross-sectional study investigating the baseline characteristics of a cohort, which includes healthy adults, age 25-41 years. Individuals with cardiovascular disease, known diabetes or a BMI higher than 35 kg/m were excluded. The Omega-3 Index was determined in whole blood using gas chromatography. Association with office and 24-h BP was assessed using multivariable linear regression models adjusted for potential confounders.

RESULTS

Median Omega-3 Index was 4.58% (interquartile range 4.08; 5.25). Compared with individuals in the lowest Omega-3 Index quartile, individuals in the highest had a SBP and DBP that was 4 and 2 mmHg lower, respectively (P < 0.01). A significant linear inverse relationship of the Omega-3 Index with 24-h and office BP was observed. Per 1-U increase in log-transformed Omega-3 Index the lowering in BP (given as multivariable adjusted β coefficients; 95% confidence interval) was -2.67 mmHg (-4.83; -0.51; P = 0.02) and -2.30 mmHg (-3.92; -0.68; P = 0.005) for 24-h SBP and DBP, respectively.

CONCLUSION

A higher Omega-3 Index is associated with statistically significant, clinically relevant lower SBP and DBP levels in normotensive young and healthy individuals. Diets rich in n - 3 FA may be a strategy for primary prevention of hypertension.

Multi-ethnic genome-wide association study for atrial fibrillation

Atrial fibrillation (AF) affects more than 33 million individuals worldwide1 and has a complex heritability2. We conducted the largest meta-analysis of genome-wide association studies (GWAS) for AF to date, consisting of more than half a million individuals, including 65,446 with AF. In total, we identified 97 loci significantly associated with AF, including 67 that were novel in a combined-ancestry analysis, and 3 that were novel in a European-specific analysis. We sought to identify AF-associated genes at the GWAS loci by performing RNA-sequencing and expression quantitative trait locus analyses in 101 left atrial samples, the most relevant tissue for AF. We also performed transcriptome-wide analyses that identified 57 AF-associated genes, 42 of which overlap with GWAS loci. The identified loci implicate genes enriched within cardiac developmental, electrophysiological, contractile and structural pathways. These results extend our understanding of the biological pathways underlying AF and may facilitate the development of therapeutics for AF.

Association of 24-Hour Blood Pressure With Urinary Sodium Excretion in Healthy Adults

BACKGROUND

While the positive relationship between urinary sodium excretion and blood pressure (BP) is well established for middle-aged to elderly individuals using office BP, data are limited for younger individuals and ambulatory BP measurements.

METHODS

Our analysis included 2,899 individuals aged 18 to 90 years from 2 population-based studies (GAPP, Swiss Kidney Project on Genes in Hypertension [SKIPOGH]). Participants with prevalent cardiovascular disease, diabetes, or on BP-lowering treatment were excluded. In SKIPOGH, 24-hour urinary sodium excretion was used as a measure of sodium intake, while in GAPP it was calculated from fasting morning urinary samples using the Kawasaki formula. Multivariable linear regression models were used to assess the relationships of 24-hour urinary salt excretion with office and ambulatory BP measurements.

RESULTS

Mean age, ambulatory BP, sodium excretion, and estimated glomerular filtration rate in GAPP and SKIPOGH were 35 and 44 years, 123/78 and 118/77 mm Hg, 4.2 and 3.3 g/d, and 110 and 99 ml/min/1.73 m2, respectively. A weak linear association was observed between 24-hour ambulatory systolic BP and urinary sodium excretion (β (95% confidence interval [CI]) per 1 g increase in sodium excretion (0.33 % (0.09; 0.57); P = 0.008). No significant relationships were observed for 24-hour ambulatory diastolic BP (β (95% CI) (0.13 % (-0.15; 0.40) P = 0.37). When repeating the analyses in different age groups, all BP indices appeared to have stronger relationships in the older age groups (>40 years).

CONCLUSIONS

In these large cohorts of healthy adults, urinary sodium excretion was only weakly associated with systolic 24-hour ambulatory BP.

Osteoporosis, diabetes, and hypertension are major risk factors for mortality in older adults: an intermediate report on a prospective survey of 1467 community-dwelling elderly healthy pensioners in Switzerland

BACKGROUND

Osteoporosis is an important morbidity factor for ageing populations in developed countries. However, compared to the amount of information available on diabetes and cardiovascular disease, little is known about the direct impact of osteoporosis on general mortality in older age.

METHODS

We obtained data from a prospective population-based cohort of pensioners from the SENIORLAB study who were subjectively healthy. The inclusion criteria were an age of at least 60 years and Swiss residence. We assessed and analysed clinical measures, voluntary reports, and laboratory values.

RESULTS

In total, 1467 subjects were included in the cohort. The mean follow-up time was 3.68 years (95% confidence interval, 3.64-3.71). The ages of the included participants ranged from 60 to 99 years. At follow-up, there were 1401 survivors, and 66 participants had died. According to the multivariate analysis (Cox regression), osteoporosis was the most important risk factor for all-cause mortality (hazard ratio, 4.46; 95% confidence interval, 1.82-10.91), followed by diabetes (hazard ratio, 2.17; 95% confidence interval, 1.04-4.52) and hypertension (hazard ratio, 1.81; 95% confidence interval, 1.09-3.03).

CONCLUSIONS

Osteoporosis is a major risk factor for all-cause mortality in a subjectively healthy senior population, followed by type 2 diabetes mellitus and hypertension. Osteoporosis should be more actively diagnosed in healthy pensioners before they develop osteoporosis-associated health incidents.

TRIAL REGISTRATION

The present study was registered in the International Standard Randomized Controlled Trial Number registry: ISRCTN53778569 .

Anemia in tuberculosis cases and household controls from Tanzania: Contribution of disease, coinfections, and the role of hepcidin

Background

Tuberculosis (TB) induces a systemic inflammatory state affecting iron homeostasis. Patients with TB often have additional comorbidities such as anemia which can result in poorer treat outcomes. We studied the contribution of anemia and the role of the iron regulatory hormone hepcidin among TB patients and household contacts.

Methods

We analyzed serum samples from 102 TB cases and 98 controls without TB, matched by age/sex, for hepcidin, iron, and inflammation parameters. Five controls developed TB within 12 months. We used linear regression to assess associations.

Results

Anemia of chronic disease (ACD) was more frequent among cases than controls (59.8% vs. 26.1%), but iron-deficiency anemia more frequent in controls (10% vs. 1%). The median hepcidin level was higher in cases than controls (63.7 vs. 14.2 ng/mL), but coinfections with HIV, helminths, and respiratory pathogens did not show cumulative effects. Hepcidin was associated with more severe TB symptom scoring (coefficient 0.8, 95% confidence interval [CI] 0.5–1.2) and higher mycobacterial load (0.7, 95% CI 0.4–1.0). Hepcidin was higher in TB cases and controls who developed TB compared to controls without TB (p<0.001), even when restricting to HIV-negative study participants.

Conclusions

ACD was the predominate etiology in TB patients suggesting limited benefit from iron supplementation. Increased hepcidin levels long before active disease, indicating altered iron metabolism, may be a marker for developing disease among TB-exposed individuals. Clinical management of anemia and nutrition interventions in TB patients need to be considered to improve the clinical course and outcomes.

The –11377 C>G promoter variant of the adiponectin gene, prevalence of coronary atherosclerosis, and incidence of vascular events in men

No prospective data demonstrating an association between the –11377 C>G adiponectin gene promoter variant and cardiovascular risk are available. We therefore prospectively evaluated the cardiovascular risk associated with adiponectin gene single nucleotide polmorphisms (SNPs) including SNP –11377 in a consecutive series of men undergoing coronary angiography. We recorded vascular events over four years in 402 men undergoing coronary angiography for the evaluation of coronary artery disease. No significant associations of SNPs +276 G>T and +45 T>G with serum adiponectin, with significant coronary stenoses >50%, or with vascular events were observed. However, for SNP –11377 C>G, serum adiponectin levels significantly decreased (Ptrend = 0.003), and the prevalence of significant coronary stenoses significantly increased from the CC over the GC to the GG genotype (ptrend = 0.004). Prospectively, the risk of vascular events significantly increased from the CC over the CG to the GG genotype of this SNP (adjusted hazard ratios 1.555 [0.957-2.525] and 2.309 [1.067–4.998], respectively; ptrend = 0.014). The –11377 C>G adiponectin gene promoter variant is i) associated with decreased serum adiponectin levels, ii) correlated with the presence of coronary atherosclerosis and iii) significantly predictive of vascular events among men undergoing coronary angiography.

Relationships of kidney injury molecule-1 with renal function and cardiovascular risk factors in the general population

BACKGROUND

Kidney injury molecule-1 (KIM-1) has been associated with kidney damage in patients with preexisting renal disease. However, little is known about the relationships of KIM-1 with renal function and cardiovascular risk factors in healthy individuals from the general population.

METHODS

Healthy individuals aged 25-41years were enrolled in a population-based study. Main exclusion criteria were a BMI >35kg/m², preexisting kidney disease or established cardiovascular disease. KIM-1 was measured from frozen plasma samples using a high-sensitivity assay. Multivariable linear regression models were constructed to assess the relationships of KIM-1 with renal function and various cardiovascular risk factors.

RESULTS

We included 2060 individuals (47% men, median (interquartile range) age: 37 (31-40) years) in this analysis. Median KIM-1 levels were 82.5 (IQR 59.4-112.7) pg/ml. We found no significant relationship of KIM-1 with creatinine (adjusted β-coefficient (95% confidence interval) 0.0005 (-0.002; 0.003), p=0.61) and cystatin C (-0.02 (-0.21; 0.17), p=0.84). There were significant linear relationships of log-transformed KIM-1 with systolic blood pressure (adjusted β-coefficient (95% confidence interval) 0.07 (0.04; 0.09), p<0.0001), diastolic blood pressure (0.04 (0.02; 0.07), p=0.001), low-density lipoprotein cholesterol (0.09 (0.06; 0.11), p<0.0001), high-density lipoprotein cholesterol (0.07 (0.05; 0.1), p<0.0001), high-sensitivity C-reactive protein (0.05 (0.03; 0.07), p<0.0001), age (0.09 (0.07; 0.11), p<0.0001), BMI (0.04 (0.01; 0.06), p=0.005) and current smoking (0.12 (0.07; 0.17), p<0.0001).

CONCLUSION

Among healthy adults from the general population, plasma levels of KIM-1 were not associated with renal function but were independently related to multiple cardiovascular risk factors.

High first-trimester maternal blood cystatin C levels despite normal serum creatinine predict pre-eclampsia in singleton pregnancies

Early biochemical identification of women at high risk for the development of pre-eclampsia (PE) is still unsatisfactory. Renal markers measured during the first trimester were analysed to predict later occurrence of PE. A nested case-control study was conducted within the prospective predictive markers for the diagnosis of preeclampsia study. Pregnant women were included at the end of the first trimester and followed up until birth. Controls were matched to PE cases. Renal markers [i.e. creatinine, cystatin C (CysC), β₂ microglobulin (B2M), β-trace protein (BTP), glomerular filtration rate estimations (eGFR) of the aforementioned markers, uric acid (UA), urea, and serum uromodulin (sUMOD)] were compared to placental growth factor (PlGF), a marker known to predict PE later in pregnancy. Reference intervals were determined for the different markers. In the 183 women (PE, n = 39; controls, n = 144), CysC, the CysC/PlGF ratio (p < .01) and UA were higher, whereas the eGFR_CysC/eGFR_Crea ratio (a marker of glomerular endothelial integrity and shrunken pore syndrome) and PlGF were lower in women who developed PE (p < .05 for all). Compromised filtration of the larger molecule CysC together with a normal creatinine, in a subset of PE cases (15.3%) was a unique, strong and independent predictor of later PE if the baseline CysC concentration was >0.85 mg/l. In conclusion, CysC and its derivatives as well as UA, indicating volume expansion, measured at the end of the first trimester are predictive of PE. Thus, women can be easily identified and followed as an early reduction in glomerular filtration quality poses a high risk for a subsequent development of PE.

Are patients affected by mitochondrial disorders at nutritional risk?

OBJECTIVES

Patients with mitochondrial disorders (MD) frequently present with gastrointestinal complaints, mainly gastrointestinal dysmotility, that interfere with their food intake. A deterioration of their nutritional state may worsen the course of the disease. Our study aimed to evaluate a simple screening tool to identify nutritional risk and perform an extended nutritional assessment to explore the potential presence of deficiencies in this population compared with controls.

METHODS

A prospective cohort study was conducted to compare outpatients with MD to matched healthy controls. Nutritional screening and full nutritional assessments were performed, including quantitative and qualitative dietary habits (7-d food log), body function and composition, and resting energy expenditure and quality of life (QoL) measurements. Blood and 24-h urine sample analyses were performed in the patient group.

RESULTS

Twenty-six subjects were included in the study, with 11 in the patient group and 15 in the control group. No patient was deemed malnourished according to the nutritional risk score NRS-2002. When compared with the controls, however, the patients with MD had significantly lower muscle mass (P = 0.04), reduced handgrip strength (P = 0.07), and significant changes in QoL and pathologic creatinine height index, which indicate malnutrition. The patients with MD also had a significantly lower protein intake (P = 0.01).

CONCLUSIONS

According to the current definition by the European Society of Clinical Nutrition and Metabolism (ESPEN) and the American Society of Parenteral and Enteral Nutrition (ASPEN), all patients fulfilled the criteria for malnutrition. Thus, the usual nutritional screening tool is less sensitive for chronically ill outpatients. These results provide a rationale to increase protein intake and adapt patients' energy stores to improve symptoms and QoL.

Healthy lifestyle and glucagon-like peptide-1 in young and healthy adults: A population-based study

A healthy lifestyle is associated with a lower risk of cardiovascular events and mortality, but underlying mechanisms are not fully understood. The aim of our study was to investigate the relationships between a healthy lifestyle and glucagon-like peptide-1 (GLP-1), an incretin hormone with both glycemic and cardiovascular properties. Healthy participants aged 25-41years without cardiovascular disease, diabetes or a body mass index (BMI) >35kg/m² were enrolled in a population-based study. The following metrics were used to build a lifestyle score ranging from 0 to 7 (a higher score indicating a healthier lifestyle): blood pressure (BP) (<120/80mmHg), plasma levels of glycated hemoglobin (<5.7%), total cholesterol levels (<200mg/dl), BMI (<25kg/m²), not smoking cigarettes, moderate (≥150min/week) or vigorous (≥75min/week) physical activity and a healthy diet. Among 2133 participants median age was 36.7years and 53.3% were female. GLP-1 levels decreased significantly from 39.5 to 30.9ng/l (p<0.0001) across increasing lifestyle score categories. This linear relationship persisted in multivariable adjusted linear regression models (B for GLP-1 per 1-unit increase of the lifestyle score -0.06; 95% confidence intervals -0.07, -0.04; p<0.0001). Individual health metrics that were significantly associated with GLP-1 were a normal BMI (-0.07; -0.12, -0.03; p=0.001), low total cholesterol levels (-0.07; -0.12, -0.03; p=0.001), normal BP (-0.05; -0.10, -0.00; p=0.047) and not smoking (-0.06; -0.10, -0.01; p=0.01). A healthy lifestyle is strongly associated with lower GLP-1 levels in young and healthy adults.

Plasma levels of endothelin-1 and renal function among young and healthy adults

Background:

Endothelin-1 (ET-1), a vasoconstrictive and pro-inflammatory peptide, is associated with several cardiovascular risk factors and outcomes. We aimed to investigate the association of plasma ET-1 levels and renal function among young and healthy adults.

Methods:

Individuals aged 25–41 years were enrolled in a population-based cohort study. Main exclusion criteria were established kidney disease, cardiovascular diseases, diabetes mellitus and a body mass index>35 kg/m2. Fasting venous plasma samples were used to measure creatinine, cystatin C and ET-1. The estimated glomerular filtration rate (eGFR) was calculated using the creatinine based chronic kidney disease epidemiology collaboration (CKD-EPI) formula. Multivariable regression models were constructed to assess interrelationships of plasma ET-1 with parameters of renal function.

Results:

Median age of the 2139 participants was 37 years, 47% males. Median creatinine and eGFR were 67 μmol/L and 112 mL/min/1.73 m2, respectively. Using quartile one as the reference group, the β-coefficients (95% confidence intervals [CIs]) for eGFR were 0.06 (− 1.22 to 1.35),−0.66 (− 1.95 to 0.62) and−1.70 (− 3.01 to−0.39) for quartiles 2–4 (p-for-trend=0.0056), respectively and β-coefficients (95% CIs) for cystatin C were 0.002 (− 0.01 to 0.02), 0.02 (0.003–0.03) and 0.03 (0.01–0.04) for quartiles 2–4 (p-for-trend<0.0001), respectively. Using ET-1 as a continuous variable, the β-coefficient (95% CI) for eGFR per 1-unit increase was−1.82 (− 3.19 to−0.44, p=0.0095) and 0.02 (0.01–0.04, p=0.0003) for cystatin C. Similar results were found between creatinine and ET-1 levels.

Conclusions:

ET-1 levels are strongly associated with parameters of renal function among young and healthy adults, suggesting an important role of ET-1 and endothelial function in the regulation of kidney function.

Healthy Lifestyle and Blood Pressure Variability in Young Adults

BACKGROUND

The aim of this study was to assess the relationships between healthy lifestyle metrics and blood pressure variability (BPV) in young and healthy adults.

METHODS

A population-based sample of 1,999 individuals aged 25-41 years was investigated. A lifestyle-score from 0 (most unhealthy) to 7 (most healthy) was calculated by giving one point for each of the following components: never smoking cigarettes, adhering to a healthy diet, performing moderate or intense physical activity, having a body mass index <25 kg/m2, a total cholesterol <200 mg/dl, a glycated hemoglobin <5.7%, or a conventional BP <120/80 mm Hg. Standardized ambulatory 24-hour BP measurements were obtained in all individuals. BPV was defined as the SD of all individual ambulatory BP recordings. We constructed multivariable linear regression models to assess the relationships between the lifestyle-score and BPV. None of the results were adjusted for multiple testing.

RESULTS

Median age was 37 years and 46.8% were men. With increasing lifestyle-score, systolic and diastolic BPV is decreasing linearly (P for trend <0.0001), even after multivariable adjustment. Per 1-point increase in lifestyle-score, the β-coefficient (95% confidence interval) for systolic and diastolic 24-hour BPV was -0.03 (-0.03; -0.02) and -0.04 (-0.05; -0.03), respectively, both P for trend <0.0001. These relationships were attenuated but remained statistically significant after additional adjustment for mean individual BP.

CONCLUSION

In this study of young and healthy adults, adopting a healthy lifestyle was associated with a lower BPV. These associations were independent of mean BP levels.

Acute effect of running exercise on physiological Achilles tendon blood flow

Sonographically detectable intratendinous blood flow (IBF) is found in 50%-88% of Achilles tendinopathy patients as well as in up to 35% of asymptomatic Achilles tendons (AT). Although IBF is frequently associated with tendon pathology, it may also represent a physiological regulation, for example, due to increased blood flow in response to exercise. Therefore, this study aimed to investigate the acute effects of a standardized running exercise protocol on IBF assessed with Doppler ultrasound (DU) "Advanced dynamic flow" in healthy ATs. 10 recreationally active adults (5 f, 5 m; 29±3 years, 1.72±0.12 m, 68±16 kg, physical activity 206±145 minute/wk) with no history of AT pain and inconspicious tendon structure performed 3 treadmill running tasks on separate days (M1-3) with DU examinations directly before and 5, 30, 60, and 120 minutes after exercise. At M1, an incremental exercise test was used to determine the individual anaerobic threshold (IAT). At M2 and M3, participants performed 30- minute submaximal constant load tests (CL₁ /CL₂ ) with an intensity 5% below IAT. IBF in each tendon was quantified by counting the number of vessels. IBF increased in five ATs from no vessels at baseline to one to four vessels solely detectable 5 minutes after CL₁ or CL₂ . One AT had persisting IBF (three vessels) throughout all examinations. Fourteen ATs revealed no IBF at all. Prolonged running led to a physiological, temporary appearance of IBF in 25% of asymptomatic ATs. To avoid exercise-induced IBF in clinical practice, DU examinations should be performed after 30 minutes of rest.

Subclinical sleep apnoea and plasma levels of endothelin-1 among young and healthy adults

Objective

Obstructive sleep apnoea (OSA) is a risk factor for vascular disease and other adverse outcomes. These associations may be at least partly due to early endothelin-1 (ET-1)-mediated endothelial dysfunction (ED). Therefore, we assessed the relationships between subclinical sleep apnoea and plasma levels of ET-1.

Methods

We performed a population-based study among 1255 young and healthy adults aged 25–41 years. Cardiovascular disease, diabetes or a body mass index >35 kg/m² were exclusion criteria. Plasma levels of ET-1 were measured using a high-sensitivity, single-molecule counting technology. The relationships between subclinical sleep apnoea (OSA indices: respiratory event index (REI), oxygen desaturation index (ODI), mean night-time blood oxygen saturation (SpO₂)) and ET-1 levels were assessed by multivariable linear regression analysis.

Results

Median age of the cohort was 35 years. Median ET-1 levels were 2.9 (IQR 2.4–3.6) and 2.5 pg/mL (IQR 2.1–3.0) among patients with (n=105; 8%) and without subclinical sleep apnoea (REI 5–14), respectively. After multivariable adjustment, subclinical sleep apnoea remained significantly associated with plasma levels of ET-1 (β=0.13 (95% CI 0.06 to 0.20) p=0.0002 for a REI 5–14; β=0.10 (95% CI 0.03 to 0.16) p=0.003 for an ODI≥5). Every 1% decrease in mean night-time SpO₂ increased ET-1 levels by 0.1 pg/mL, an association that remained significant after multivariable adjustment (β=0.02 (95% CI 0.003 to 0.033) p=0.02).

Conclusions

In this study of young and healthy adults, we found that participants with subclinical sleep apnoea had elevated plasma ET-1 levels, an association that was due to night-time hypoxaemia. Our results suggest that ED may already be an important consequence of subclinical sleep apnoea.