Peripheral and central vascular conductance influence on post-exercise hypotension

Background

Post-exercise hypotension (PEH) following prolonged dynamic exercise arises from increased total vascular conductance (TVC) via skeletal muscle vasodilation. However, arterial vasodilation of skeletal musculatures does not entirely account for the rise in TVC. The aim of the present study was to determine the contribution of vascular conductance (VC) of the legs, arms, kidneys and viscera to TVC during PEH.

Methods

Eight subjects performed a single period of cycling at 60% of heart rate (HR) reserve for 60 minutes. Blood flow in the right renal, superior mesenteric, right brachial and right femoral arteries was measured by Doppler ultrasonography in a supine position before exercise and during recovery. HR and mean arterial pressure (MAP) were measured continuously. MAP decreased significantly from approximately 25 minutes after exercise cessation compared with pre-exercise baseline. TVC significantly increased (approximately 23%; P <0.05) after exercise compared with baseline, which resulted from increased VC in the leg (approximately 33%) and arm (approximately 20%), but not in the abdomen.

Conclusion

PEH was not induced by decreased cardiac output, but by increased TVC, two-thirds of the rise in which can be attributed to increased VC in active and inactive limbs.     

Ocular blood flow decreases during passive heat stress in resting humans

Background

Heat stress induces various physiological changes and so could influence ocular circulation. This study examined the effect of heat stress on ocular blood flow.

Findings

Ocular blood flow, end-tidal carbon dioxide (P_ETCO₂) and blood pressure were measured for 12 healthy subjects wearing water-perfused tube-lined suits under two conditions of water circulation: (1) at 35°C (normothermia) for 30 min and (2) at 50°C for 90 min (passive heat stress). The blood-flow velocities in the superior temporal retinal arteriole (STRA), superior nasal retinal arteriole (SNRA), and the retinal and choroidal vessels (RCV) were measured using laser-speckle flowgraphy. Blood flow in the STRA and SNRA was calculated from the integral of a cross-sectional map of blood velocity. P_ETCO₂ was clamped at the normothermia level by adding 5% CO₂ to the inspired gas. Passive heat stress had no effect on the subjects’ blood pressures. The blood-flow velocity in the RCV was significantly lower after 30, 60 and 90 min of passive heat stress than the normothermic level, with a peak decrease of 18 ± 3% (mean ± SE) at 90 min. Blood flow in the STRA and SNRA decreased significantly after 90 min of passive heat stress conditions, with peak decreases of 14 ± 3% and 14 ± 4%, respectively.

Conclusion

The findings of this study suggest that passive heat stress decreases ocular blood flow irrespective of the blood pressure or arterial partial pressure of CO₂.     

Influence of the ABCG2 gout risk 141?K allele on urate metabolism during a fructose challenge

Introduction

Both genetic variation in ATP-binding cassette sub-family G member 2 (ABCG2) and intake of fructose-containing beverages are major risk factors for hyperuricemia and gout. This study aimed to test the hypothesis that the ABCG2 gout risk allele 141 K promotes the hyperuricaemic response to fructose loading.

Methods

Healthy volunteers (n = 74) provided serum and urine samples immediately before and 30, 60, 120 and 180 minutes after ingesting a 64 g fructose solution. Data were analyzed based on the presence or absence of the ABCG2 141 K gout risk allele.

Results

The 141 K risk allele was present in 23 participants (31%). Overall, serum urate (SU) concentrations during the fructose load were similar in those with and without the 141 K allele (P_SNP = 0.15). However, the 141 K allele was associated with a smaller increase in SU following fructose intake (P_SNP <0.0001). Those with the 141 K allele also had a smaller increase in serum glucose following the fructose load (P_SNP = 0.002). Higher fractional excretion of uric acid (FEUA) at baseline and throughout the fructose load was observed in those with the 141 K risk allele (P_SNP <0.0001). However, the change in FEUA in response to fructose was not different in those with and without the 141 K risk allele (P_SNP = 0.39). The 141 K allele effects on serum urate and glucose were more pronounced in Polynesian participants and in those with a body mass index ≥25 kg/m².

Conclusions

In contrast to the predicted responses for a hyperuricemia/gout risk allele, the 141 K allele is associated with smaller increases in SU and higher FEUA following a fructose load. The results suggest that ABCG2 interacts with extra-renal metabolic pathways in a complex manner to regulate SU and gout risk.

Clinical Trials Registration

The study was registered by the Australian Clinical Trials Registry (ACTRN12610001036000).     

A Technique for Performing Electrical Impedance Myography in the Mouse Hind Limb: Data in Normal and ALS SOD1 G93A Animals

Objective

To test a method for performing electrical impedance myography (EIM) in the mouse hind limb for the assessment of disease status in neuromuscular disease models.

Methods

An impedance measuring device consisting of a frame with electrodes embedded within an acrylic head was developed. The head was rotatable such that data longitudinal and transverse to the major muscle fiber direction could be obtained. EIM measurements were made with this device on 16 healthy mice and 14 amyotrophic lateral sclerosis (ALS) animals. Repeatability was assessed in both groups.

Results

The technique was easy to perform and provided good repeatability in both healthy and ALS animals, with intra-session repeatability (mean ± SEM) of 5% ±1% and 12% ±2%, respectively. Significant differences between healthy and ALS animals were also identified (e.g., longitudinal mean 50 kHz phase was 18±0.6° for the healthy animals and 14±1.0° for the ALS animals, p = 0.0025).

Conclusions

With this simple device, the EIM data obtained is highly repeatable and can differentiate healthy from ALS animals.

Significance

EIM can now be applied to mouse models of neuromuscular disease to assess disease status and the effects of therapy.     

The Supplementary Motor Area Exerts a Tonic Excitatory Influence on Corticospinal Projections to Phrenic Motoneurons in Awake Humans

Introduction

In humans, cortical mechanisms can interfere with autonomic breathing. Respiratory-related activation of the supplementary motor area (SMA) has been documented during voluntary breathing and in response to inspiratory constraints. The SMA could therefore participate in the increased resting state of the respiratory motor system during wake (i.e. "wakefulness drive to breathe").

Methods

The SMA was conditioned by continuous theta burst magnetic stimulation (cTBS, inhibitory) and 5 Hz conventional rTMS (5 Hz, excitatory). The ensuing effects were described in terms of the diaphragm motor evoked response (DiMEPs) to single-pulse transcranial magnetic stimulation over the motor cortex. DiMEPs were recorded at baseline, and at 3 time-points ("post1", "post2", "post3") up to 15 minutes following conditioning of the SMA.

Results

cTBS reduced the amplitude of DiMEPs from 327.5±159.8 µV at baseline to 243.3±118.7 µV, 217.8±102.9 µV and 240.6±123.9 µV at post 1, post 2 and post 3, respectively (F = 6.341, p = 0.002). 5 Hz conditioning increased the amplitude of DiMEPs from 184.7±96.5 µV at baseline to 270.7±135.4 µV at post 3 (F = 4.844, p = 0.009).

Conclusions

The corticospinal pathway to the diaphragm can be modulated in both directions by conditioning the SMA. This suggests that the baseline respiratory activity of the SMA represents an equipoise from which it is possible to move in either direction. The resting corticofugal outflow from the SMA to phrenic motoneurones that this study evidences could putatively contribute to the wakefulness drive to breathe.     

Assessment of Dynamic Cerebral Autoregulation in Patients with Basilar Artery Stenosis

Background and Aims

Previous studies have shown impaired cerebral autoregulation (CA) in carotid and middle cerebral artery (MCA) stenosis/occlusion. Little is known about CA in patients with basilar artery (BA) stenosis. We therefore investigated dynamic CA patterns in BA stenosis using transfer function analysis (TFA).

Methods

We measured spontaneous oscillations of blood flow velocity (CBFV) in the right posterior cerebral artery (PCA), and left MCA and mean arterial pressure (ABP) continuously in 25 patients with BA stenosis (moderate n=16 with 50-69% occlusion and severe n=9 with ≥70% occlusion) and 22 healthy volunteers in supine position during 6 circles per minute deep breath. Analysis was based on the ‘black-box’ model of transfer function deriving phase and gain in both PCA and MCA.

Results

Though changes of phase shift and gain between the patients and healthy controls were observed in MCA, the differences are however not significant. Phase shift in PCA was significantly decreased in severe stenosis when comparing with healthy controls and moderate stenosis (4.2±34.2° VS 41.1±40.4°, 4.2±34.2° VS 34.2±27.2°, both p<0.05), whilst the gain in PCA is increased for moderate BA stenosis and decreased for severe BA stenosis. Furthermore, we found that phase shift were almost abolished in patients with ischemic stroke who developed unfavorable clinical outcome (mRs>2) on the 90 days after stroke onset.

Conclusion

Dynamic CA in PCA reduces in patients with severe BA stenosis and those with ischemic stroke who present poor outcome in 90 days after stroke onset. Phase shift might be a sensitive index prompting impaired CA in posterior circulation.     

Impact of Metformin on Endothelial Ischemia-Reperfusion Injury in Humans In Vivo: A Prospective Randomized Open,Blinded-Endpoint Study

Introduction

Large prospective studies in patients with type 2 diabetes mellitus have demonstrated that metformin treatment improves cardiovascular prognosis, independent of glycemic control. Administration of metformin potently limits infarct size in murine models of myocardial infarction. This study examined, for the first time in humans, whether metformin limits ischemia-reperfusion (IR) injury in vivo using a well-validated forearm model of endothelial IR-injury.

Methods

Twenty-eight healthy volunteers (age 41±6 years, 10 male/16 female) were randomized between pretreatment with metformin (500 mg three times a day for 3 days) or no treatment in a Prospective Randomized Open Blinded Endpoint study. Brachial artery flow mediated dilation (FMD) was measured before and after 20 minutes of forearm ischemia and 20 minutes of reperfusion. FMD analysis was performed offline by investigators blinded for the treatment arm.

Results

Baseline FMD did not differ between metformin pretreatment and no pretreatment (6.9±3.6% and 6.1±3.5%, respectively, p = 0.27, n = 26). FMD was significantly lower after forearm IR in both treatment arms (4.4±3.3% and 4.3±2.8%, respectively, P<0.001 in both conditions). A linear mixed model analysis revealed that metformin treatment did not prevent the decrease in FMD by IR.

Conclusion

A 3 day treatment with metformin in healthy, middle-aged subjects does not protect against endothelial IR-injury, measured with brachial artery FMD after forearm ischemia. Further studies are needed to clarify what mechanism underlies the cardiovascular benefit of metformin treatment.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01610401","term_id":"NCT01610401"}}NCT01610401     

Effect of timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men

Background

Resistance exercise alters the post-exercise response of anabolic and catabolic hormones. A previous study indicated that the turnover of muscle protein in trained individuals is reduced due to alterations in endocrine factors caused by resistance training, and that muscle protein accumulation varies between trained and untrained individuals due to differences in the timing of protein and carbohydrate intake. We investigated the effect of the timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men.

Methods

Subjects were 10 trained healthy men (mean age, 23 ± 4 years; height, 173.8 ± 3.1 cm; weight, 72.3 ± 4.3 kg) and 10 untrained healthy men (mean age, 23 ± 1 years; height, 171.8 ± 5.0 cm; weight, 64.5 ± 5.0 kg). All subjects performed four sets of 8 to 10 repetitions of a resistance exercise (comprising bench press, shoulder press, triceps pushdown, leg extension, leg press, leg curl, lat pulldown, rowing, and biceps curl) at 80% one-repetition maximum. After each resistance exercise session, subjects were randomly divided into two groups with respect to intake of protein (0.3 g/kg body weight) and carbohydrate (0.8 g/kg body weight) immediately after (P0) or 6 h (P6) after the session. All subjects were on an experimental diet that met their individual total energy requirement. We assessed whole-body protein metabolism by measuring nitrogen balance at P0 and P6 on the last 3 days of exercise training.

Results

The nitrogen balance was significantly lower in the trained men than in the untrained men at both P0 (P <0.05) and P6 (P <0.01). The nitrogen balance in trained men was significantly higher at P0 than at P6 (P <0.01), whereas that in the untrained men was not significantly different between the two periods.

Conclusion

The timing of protein and carbohydrate intake after resistance exercise influences nitrogen balance differently in trained and untrained young men.     

Sex differences in acetylcholine-induced sweating responses due to physical training

Purpose

The present study examined sex differences in the sweat gland response to acetylcholine (ACh) in physically trained and untrained male and female subjects.

Methods

Sweating responses were induced on the forearm and thigh in resting subjects by ACh iontophoresis using a 10% solution at 2 mA for 5 min at 26°C and 50% relative humidity.

Results

The ACh-induced sweating rate (SR) on the forearm and thigh was greater in physically trained male (P < 0.001 for the forearm and thigh, respectively) and female (P = 0.08 for the forearm, P < 0.001 for the thigh) subjects than in untrained subjects of both sexes. The SR was also significantly greater in physically trained males compared to females at both sites (P < 0.001) and in untrained males compared to females on the thigh (P < 0.02) only, although the degree of difference was greater in trained subjects than in untrained subjects. These sex differences can be attributed to the difference in sweat output per gland rather than the number of activated sweat glands.

Conclusion

We conclude that physical training enhances the ACh-induced SR in both sexes but that the degree of enhancement is greater in male than in female subjects. The effects of physical training and sex on the SR may be due to changes in peripheral sensitivity to ACh and/or sweat gland size.     

Aging Is Accompanied by a Blunted Muscle Protein Synthetic Response to Protein Ingestion

Purpose

Progressive loss of skeletal muscle mass with aging (sarcopenia) forms a global health concern. It has been suggested that an impaired capacity to increase muscle protein synthesis rates in response to protein intake is a key contributor to sarcopenia. We assessed whether differences in post-absorptive and/or post-prandial muscle protein synthesis rates exist between large cohorts of healthy young and older men.

Procedures

We performed a cross-sectional, retrospective study comparing in vivo post-absorptive muscle protein synthesis rates determined with stable isotope methodologies between 34 healthy young (22±1 y) and 72 older (75±1 y) men, and post-prandial muscle protein synthesis rates between 35 healthy young (22±1 y) and 40 older (74±1 y) men.

Findings

Post-absorptive muscle protein synthesis rates did not differ significantly between the young and older group. Post-prandial muscle protein synthesis rates were 16% lower in the older subjects when compared with the young. Muscle protein synthesis rates were >3 fold more responsive to dietary protein ingestion in the young. Irrespective of age, there was a strong negative correlation between post-absorptive muscle protein synthesis rates and the increase in muscle protein synthesis rate following protein ingestion.

Conclusions

Aging is associated with the development of muscle anabolic inflexibility which represents a key physiological mechanism underpinning sarcopenia.     

Hyperfractionated high-dose rate brachytherapy in the treatment of oral tongue cancer

Background

Low-dose rate brachytherapy is a well established treatment modality of oral cancer. Data about high-dose rate (HDR) brachytherapy are still sparse with various fractionation schedules and heterogeneous results.

Aim

The aim of our retrospective study was to evaluate the results of HDR brachytherapy with doses of 3 Gy twice daily.

Patients and methods

Twenty patients with squamous cell tongue cancer were treated in the years 2001–2009 by exclusive HDR BT 18 × 3 Gy twice daily. The plastic tube technique was used. Median follow up was 47 months (7.8–118) since brachytherapy.

Results

The local and locoregional control was 85% and 68%, respectively. Bone necrosis developed in one case treated without mandibular shielding and soft tissue necrosis in 2 cases.

Conclusion

It can be concluded that HDR brachytherapy with 18 × 3 Gy twice daily is safe with promising local control. The risk of nodal recurrences is substantial.     

Measurement of body composition in response to a short period of overfeeding

Background

Obesity and overweight are increasing in prevalence in developed countries as a result of changing dietary habits and a lack of physical activity. The purpose of the present study was to evaluate the changes in body composition during short-term overfeeding using the three-component model, which is composed of fat mass (FM), total body water (TBW), and fat-free dry solids (FFDS).

Methods

Ten healthy men completed 3 days of overfeeding during which they consumed 1,500 kcal/day more energy than consumed in their normal diets. Body composition was evaluated at three time points: the day before and after their normal diets and the day after the 3-day overfeeding diet.

Results

Before and after their normal diets, there were no significant differences in body weight and composition, but after 3 days of overfeeding, body weight, TBW, and FFDS increased 0.7, 0.7, and 0.2 kg, respectively (P <0.0001). There was no significant difference in FM between the normal and overfeeding diets.

Conclusion

This study suggests that TBW gain contributes to weight gain following a short-term overfeeding.     

The Effect of Eplerenone on Adenosine Formation in Humans In Vivo: A Double-Blinded Randomised Controlled Study

Background

It has been suggested that mineralocorticoid receptor antagonists have direct cardioprotective properties, because these drugs reduce mortality in patients with heart failure. In murine models of myocardial infarction, mineralocorticoid receptor antagonists reduce infarct size. Using gene deletion and pharmacological approaches, it has been shown that extracellular formation of the endogenous nucleoside adenosine is crucial for this protective effect. We now aim to translate this finding to humans, by investigating the effects of the selective mineralocorticoid receptor antagonist eplerenone on the vasodilator effect of the adenosine uptake inhibitor dipyridamole, which is a well-validated surrogate marker for extracellular adenosine formation.

Methods and Results

In a randomised, double-blinded, placebo-controlled, cross-over study we measured the forearm blood flow response to the intrabrachial administration of dipyridamole in 14 healthy male subjects before and after treatment with placebo or eplerenone (50 mg bid for 8 days). The forearm blood flow during administration of dipyridamole (10, 30 and 100 µg·min⁻¹·dl⁻¹) was 1.63 (0.60), 2.13 (1.51) and 2.71 (1.32) ml·dl⁻¹·min⁻¹ during placebo use, versus 2.00 (1.45), 2.68 (1.87) and 3.22 (1.94) ml·dl⁻¹·min⁻¹ during eplerenone treatment (median (interquartile range); P = 0.51). Concomitant administration of the adenosine receptor antagonist caffeine attenuated dipyridamole-induced vasodilation to a similar extent in both groups. The forearm blood flow response to forearm ischemia, as a stimulus for increased formation of adenosine, was similar during both conditions.

Conclusion

In a dosage of 50 mg bid, eplerenone does not augment extracellular adenosine formation in healthy human subjects. Therefore, it is unlikely that an increased extracellular adenosine formation contributes to the cardioprotective effect of mineralocorticoid receptor antagonists.

Trial Registration

ClinicalTrials.gov, {"type":"clinical-trial","attrs":{"text":"NCT01837108","term_id":"NCT01837108"}}NCT01837108     

Distribution characteristics of salivary cortisol measurements in a healthy young male population

Background

Salivary cortisol has been used in various fields of science as a non-invasive biomarker of stress levels. This study offers the normative reference values of cortisol measurement for healthy young males.

Findings

Salivary cortisol levels were measured in 267 healthy young males (age: 21.7 ± 1.5 years) in the early morning on two consecutive days and were analyzed by radioimmunoassay. Frequency distribution analysis was conducted with mean values of the measurements taken on the 2 days. The mean salivary cortisol level was 20.39 ± 7.74 nmol/l (median: 19.31 nmol/l). The skewness and kurtosis of the distribution of the raw data were 0.72 and 0.68, respectively. They were both improved by a square root transformation but not by a logarithmic transformation.

Conclusions

The skewness of the distribution for salivary cortisol measured in the early morning is considerably smaller than that previously reported from afternoon measurements. A “floor effect” may be an explanation for the difference in the distribution characteristics of salivary cortisol.     

A Self-Report Risk Index to Predict Occurrence of Dementia in Three Independent Cohorts of Older Adults: The ANU-ADRI

Background and Aims

The Australian National University AD Risk Index (ANU-ADRI, http://anuadri.anu.edu.au) is a self-report risk index developed using an evidence-based medicine approach to measure risk of Alzheimer''s disease (AD). We aimed to evaluate the extent to which the ANU-ADRI can predict the risk of AD in older adults and to compare the ANU-ADRI to the dementia risk index developed from the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study for middle-aged cohorts.

Methods

This study included three validation cohorts, i.e., the Rush Memory and Aging Study (MAP) (n = 903, age ≥53 years), the Kungsholmen Project (KP) (n = 905, age ≥75 years), and the Cardiovascular Health Cognition Study (CVHS) (n = 2496, age ≥65 years) that were each followed for dementia. Baseline data were collected on exposure to the 15 risk factors included in the ANU-ADRI of which MAP had 10, KP had 8 and CVHS had 9. Risk scores and C-statistics were computed for individual participants for the ANU-ADRI and the CAIDE index.

Results

For the ANU-ADRI using available data, the MAP study c-statistic was 0·637 (95% CI 0·596–0·678), for the KP study it was 0·740 (0·712–0·768) and for the CVHS it was 0·733 (0·691–0·776) for predicting AD. When a common set of risk and protective factors were used c-statistics were 0.689 (95% CI 0.650–0.727), 0.666 (0.628–0.704) and 0.734 (0.707–0.761) for MAP, KP and CVHS respectively. Results for CAIDE ranged from c-statistics of 0.488 (0.427–0.554) to 0.595 (0.565–0.625).

Conclusion

A composite risk score derived from the ANU-ADRI weights including 8–10 risk or protective factors is a valid, self-report tool to identify those at risk of AD and dementia. The accuracy can be further improved in studies including more risk factors and younger cohorts with long-term follow-up.     

Effects of Sodium Bicarbonate on High-Intensity Endurance Performance in Cyclists: A Double-Blind,Randomized Cross-Over Trial

Background

While the ergogenic effect of sodium bicarbonate (BICA) on short-term, sprint-type performance has been repeatedly demonstrated, little is known about its effectiveness during prolonged high-intensity exercise in well-trained athletes. Therefore, this study aims to examine the influence of BICA on performance during exhaustive, high-intensity endurance cycling.

Methods

This was a single-center, double-blind, randomized, placebo-controlled cross-over study. Twenty-one well-trained cyclists (mean ± SD: age 24±8 y, BMI 21.3±1.7, VO_2peak 67.3±9.8 ml·kg⁻¹·min⁻¹) were randomly allocated to sequences of following interventions: oral ingestion of 0.3 g·kg⁻¹ BICA or 4 g of sodium chloride (placebo), respectively. One h after ingestion subjects exercised for 30 min at 95% of the individual anaerobic threshold (IAT) followed by 110% IAT until exhaustion. Prior to these constant load tests stepwise incremental exercise tests were conducted under both conditions to determine IAT and VO_2peak. Analysis of blood gas parameters, blood lactate (BLa) and gas exchange measurements were conducted before, during and after the tests. The main outcome measure was the time to exhaustion in the constant load test.

Results

Cycling time to exhaustion was improved (p<0.05) under BICA (49.5±11.5 min) compared with placebo (45.0±9.5 min). No differences in maximal or sub-maximal measures of performance were observed during stepwise incremental tests. BICA ingestion resulted in an increased pH, bicarbonate concentration and BLa before, throughout and after both exercise testing modes.

Conclusion

The results suggest that ingestion of BICA may improve prolonged, high-intensity cycling performance.

Trial Registration

German Clinical Trials Register (DRKS) DRKS00006198.     

Serum sclerostin in high-activity adult patients with juvenile idiopathic arthritis

Introduction

Juvenile idiopathic arthritis (JIA) is a disease associated with loss of bone mass, deterioration in bone mass quality and an increased risk of fractures. The objective of this study was to evaluate factors that predict bone mineral density (BMD) alterations in young adult patients with active JIA before and during therapy with tumour necrosis factor α (TNFα) inhibitors.

Methods

Thirty-one patients (twelve males and nineteen females; mean age =25.1 ± 6.1 years) with active JIA (mean Disease Activity Score in 28 joints (DAS28) =6.36 ± 0.64; mean high-sensitivity C-reactive protein (hsCRP) =18.36 ± 16.95 mg/L) were investigated. The control group consisted of 84 healthy individuals matched by sex and age. BMD, bone turnover markers and serum concentrations of soluble receptor activator of nuclear factor κB ligand, osteoprotegerin, dickkopf Wnt signalling pathway inhibitor 1 (Dkk1) and sclerostin were evaluated.

Results

Baseline BMD values in the lumbar spine, proximal femur, femoral neck and distal radius were significantly lower in patients with JIA compared to healthy control participants. Baseline sclerostin serum concentrations were significantly higher in patients with JIA compared to control participants. After 2 years of treatment with TNFα inhibitors, BMD was significantly increased in the lumbar spine. This increase correlated with a drop in DAS28 score. A statistically significant correlation between hsCRP and Dkk1 was found at baseline, as well as during the 2-year follow-up period. A significant reduction in serum sclerostin after 1 year of therapy was predictive of a drop in DAS28 score observed with a 1-year delay after reduction of serum sclerostin.

Conclusion

A significant correlation between the sclerostin serum concentration and the number of tender and swollen joints, but not BMD, supports the hypothesis that chondrocytes and cells of the subchondral bone may contribute to circulating sclerostin in JIA.     

Inter-daily variability in body composition among young men

Background

The present study analyses changes in body composition over the course of a working week. The purpose of the study is to identify the size of the changes in the observed parameters by means of typical error of measurement (TE) as the initial value for the interpretation of the detected changes in the repeated measurement in diagnostic practice.

Methods

The researched group consisted of 86 males, aged 21.4 ± 1.0 years. All the participants were free of any medical conditions. The measurement of each participant took place over 1 week from Monday till Friday, in the morning hours. Parameters measured: body mass (BM), total body water (TBW), and body fat (BF). The measurement employed two devices using the bioelectric impedance analysis. These devices were the analyzers Tanita BC 418 MA and Nutriguard MS. In order to assess the differences between the average values, the analysis of repeated measurements was used. To assess the material significance, eta squared was used. TE was used to express the size of the changes in the observed parameters.

Results

A statistically significant difference between the average values of the observed parameters was only detected when using the Tanita BC 418 MA analyzer. Based on the post-hoc tests, these differences in the average values were always detected on Monday and Friday. No material significance was proved, however. The highest TE values were also detected in measurements carried out on Monday and Friday. For BM, the value of TE was 0.6 kg, for TBW 1.0–1.1 %, 0.8–0.9 kg, and for BF 1.2–1.6 %, 1.1–1.3 kg depending on the analyzer used.

Conclusions

The results of the present study demonstrate the stability of parameters of body composition throughout a working week, with the provision that standard measuring conditions are fulfilled. For the purpose of diagnostic practice, when interpreting the results of the repeated measurements, it is advisable to take as provable change caused by the observed factors only the ones whose values exceed the value of a weekly TE or the upper limit of the interval of the measurement reliability.     

Pulmonary vasoreactivity in spontaneously hypertensive rats - Effects of endothelin-1 and leptin

Background

Systemic hypertension may be associated with an increased pulmonary vascular resistance, which we hypothesized could be, at least in part, mediated by increased leptin.

Methods

Vascular reactivity to phenylephrine (1 μmol/L), endothelin-1 (10 nmol/L) and leptin (0.001–100 nmol/L) was evaluated in endothelium-intact and -denuded isolated thoracic aorta and pulmonary arteries from spontaneously hypertensive versus control Wistar rats. Arteries were sampled for pathobiological evaluation and lung tissue for morphometric evaluation.

Results

In control rats, endothelin-1 induced a higher level of contraction in the pulmonary artery than in the aorta. After phenylephrine or endothelin-1 precontraction, leptin relaxed intact pulmonary artery and aortic rings, while no response was observed in denuded arteries. Spontaneously hypertensive rats presented with increased reactivity to phenylephrine and endothelin-1 in endothelium-intact pulmonary arteries. After endothelin-1 precontraction, endothelium-dependent relaxation to leptin was impaired in pulmonary arteries from hypertensive rats. In both strains of rats, aortic segments were more responsive to leptin than pulmonary artery. In hypertensive rats, pulmonary arteries exhibited increased pulmonary artery medial thickness, associated with increased expressions of preproendothelin-1, endothelin-1 receptors type A and B, inducible nitric oxide synthase and decreased endothelial nitric oxide synthase, together with decreased leptin receptor and increased suppressor of cytokine signaling 3 expressions.

Conclusions

Altered pulmonary vascular reactivity in hypertension may be related to a loss of endothelial buffering of vasoconstriction and decreased leptin-induced vasodilation in conditions of increased endothelin-1.