Differences in heart rate responses to upright posture are associated with variations in the high-frequency power of heart rate variability.

High resting heart rate is a cardiovascular risk factor, but limited data exist on the underlying hemodynamics and reproducibility of supine-to-upright increase in heart rate. We recorded noninvasive hemodynamics in 574 volunteers [age, 44.9 yr; body mass index (BMI), 26.4 kg/m2; 49% male] during passive head-up tilt (HUT) using whole body impedance cardiography and radial artery tonometry. Heart rate regulation was evaluated using heart rate variability (HRV) analyses. Comparisons were made between quartiles of supine-to-upright heart rate changes, in which heart rate at rest ranged 62.6-64.8 beats/min (P = 0.285). The average upright increases in heart rate in the quartiles 1-4 were 4.7, 9.9, 13.5, and 21.0 beats/min, respectively (P < 0.0001). No differences were observed in the low-frequency power of HRV, whether in the supine or upright position, or in the high-frequency power of HRV in the supine position. Upright high-frequency power of HRV was highest in quartile 1 with lowest upright heart rate and lowest in quartile 4 with highest upright heart rate. Mean systolic blood pressure before and during HUT (126 vs. 108 mmHg) and the increase in systemic vascular resistance during HUT (650 vs. 173 dyn·s/cm5/m2) were highest in quartile 1 and lowest in quartile 4. The increases in heart rate during HUT on three separate occasions several weeks apart were highly reproducible (r = 0.682) among 215 participants. To conclude, supine-to-upright increase in heart rate is a reproducible phenotype with underlying differences in the modulation of cardiac parasympathetic tone and systemic vascular resistance. As heart rate at rest influences prognosis, future research should elucidate the prognostic significance of these phenotypic differences.NEW & NOTEWORTHY Subjects with similar supine heart rates are characterized by variable increases in heart rate during upright posture. Individual heart rate increases in response to upright posture are highly reproducible as hemodynamic phenotypes and present underlying differences in the modulation of cardiac parasympathetic tone and systemic vascular resistance. These results indicate that resting heart rate obtained in the supine position alone is not an optimal means of classifying people into groups with differences in cardiovascular function.

Presence of gastrointestinal symptoms in IgA nephropathy: a cross-sectional study.

BACKGROUND: Gastrointestinal (GI) symptoms are common in end-stage kidney disease. Mounting evidence indicates that the intestine plays an important role in the pathogenesis of IgA nephropathy (IgAN). However, no studies have addressed the obvious question; do IgAN patients suffer from GI symptoms? METHODS: Presence of GI symptoms and health-related quality of life were evaluated using the validated Gastrointestinal Symptom Rating Scale (GSRS) and Psychological General Well-Being (PGWB) questionnaires in 104 patients with kidney biopsy-verified IgAN and in 147 healthy controls. A person was regarded to experience 'increased GI symptoms' if the GSRS score exceeded plus 1 standard deviation of the mean of the corresponding score in the healthy controls. RESULTS: According to the GSRS total score, the IgAN patients had more GI symptoms than the healthy controls (2.0 vs. 1.7, p < 0.001). Female IgAN patients had higher GSRS total score than male patients (2.2 vs. 1.7, p = 0.001). More IgAN patients with preserved kidney function (eGFR > 60ml/min/1.73m2) suffered from increased symptoms of diarrhoea (76 vs. 25%, p = 0.028), constipation (81 vs. 19%, p = 0.046) and reflux (85 vs. 15%, p = 0.004) than did IgAN patients with reduced kidney function (eGFR < 60ml/min/1.73m2). CONCLUSIONS: IgAN patients and especially female IgAN patients experienced more GI symptoms than healthy controls. More prevalent GI symptoms were already observed before kidney function was clearly reduced. Systematic enquiry of GI symptoms might increase the standard of care among IgAN patients. Moreover, GI symptoms may provide clues for future studies that examine the pathophysiology of IgAN.

Plasma uric acid is related to large arterial stiffness but not to other hemodynamic variables: a study in 606 normotensive and never-medicated hypertensive subjects.

BACKGROUND: Elevated level of plasma uric acid (PUA) has been associated with cardiovascular disease, but whether uric acid is an independent risk factor or merely a marker remains controversial. METHODS: We investigated in a cross-sectional setting the association of PUA with hemodynamics in 606 normotensive and never-medicated hypertensive subjects (295 men, 311 women, age range 19-73 years) without cardiovascular disease or gout. In all except 15 individuals, PUA was within the normal range. Supine hemodynamics were recorded using whole-body impedance cardiography and radial tonometric pulse wave analysis. RESULTS: The mean concentrations of PUA in age, sex and body mass index adjusted quartiles were 234, 278, 314, and 373 µmol/l, respectively. The highest PUA quartile presented with higher aortic to popliteal pulse wave velocity (PWV) than the lowest quartile (8.7 vs. 8.2 m/s, p = 0.026) in analyses additionally adjusted for plasma concentrations of C-reactive protein, low density lipoprotein cholesterol, triglycerides, and mean aortic blood pressure. No differences in radial and aortic blood pressure, wave reflections, heart rate, cardiac output, and systemic vascular resistance were observed between the quartiles. In linear regression analysis, PUA was an independent explanatory factor for PWV (ß = 0.168, p < 0.001, R2 of the model 0.591), but not for systolic or diastolic blood pressure. When the regression analysis was performed separately for men and women, PUA was an independent predictor of PWV in both sexes. CONCLUSIONS: PUA concentration was independently and directly associated with large arterial stiffness in individuals without cardiovascular disease and PUA levels predominantly within the normal range. Trial registration ClinicalTrials.gov NCT01742702.

Central wave reflection is associated with peripheral arterial resistance in addition to arterial stiffness in subjects without antihypertensive medication.

BACKGROUND: Augmentation index, a marker of central wave reflection, is influenced by age, sex, height, blood pressure, heart rate, and arterial stiffness. However, the detailed haemodynamic determinants of augmentation index, and their relations, remain uncertain. We examined the association of augmentation index with vascular resistance and other haemodynamic and non-haemodynamic factors. METHODS: Background information, laboratory values, and haemodynamics of 488 subjects (239 men, 249 women) without antihypertensive medication were obtained. Indices of central wave reflection, systemic vascular resistance, cardiac function, and pulse wave velocity were measured using continuous radial pulse wave analysis and whole-body impedance cardiography. RESULTS: In a regression model including only haemodynamic variables, augmentation index in males and female subjects, respectively, was associated with systemic vascular resistance (ß = 0.425, ß = 0.336), pulse wave velocity (ß = 0.409, ß = 0.400) (P < 0.001 for all), stroke volume (ß = 0.256, ß = 0.278) (P = 0.001 for both) and heart rate (ß = -0.150, ß = -0.156) (P = 0.049 and P = 0.036). When age, height, weight, smoking habits, and laboratory values were included in the regression model, the most significant explanatory variables for augmentation index in males and females, respectively, were age (ß = 0.577, ß = 0.557) and systemic vascular resistance (ß = 0.437, ß = 0.295) (P < 0.001 for all). In the final regression model, pulse wave velocity was not a significant explanatory variable for augmentation index, probably due to the high correlation of this variable with age (Spearman's correlation ≥0.617). CONCLUSION: Augmentation index is strongly associated with systemic vascular resistance in addition to arterial stiffness. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01742702 .

The type of the functional cardiovascular response to upright posture is associated with arterial stiffness: a cross-sectional study in 470 volunteers.

BACKGROUND: In a cross-sectional study we examined whether the haemodynamic response to upright posture could be divided into different functional phenotypes, and whether the observed phenotypes were associated with known determinants of cardiovascular risk. METHODS: Volunteers (n = 470) without medication with cardiovascular effects were examined using radial pulse wave analysis, whole-body impedance cardiography, and heart rate variability analysis. Based on the passive head-up tilt induced changes in systemic vascular resistance and cardiac output, the principal determinants of blood pressure, a cluster analysis was performed. RESULTS: The haemodynamic response could be clustered into 3 categories: upright increase in vascular resistance and decrease in cardiac output were greatest in the first (+45 % and -27 %, respectively), smallest in the second (+2 % and -2 %, respectively), and intermediate (+22 % and -13 %, respectively) in the third group. These groups were named as 'constrictor' (n = 109), 'sustainer' (n = 222), and 'intermediate' (n = 139) phenotypes, respectively. The sustainers were characterized by male predominance, higher body mass index, blood pressure, and also by higher pulse wave velocity, an index of large arterial stiffness, than the other groups (p < 0.01 for all). Heart rate variability analysis showed higher supine and upright low frequency/high frequency (LF/HF) ratio in the sustainers than constrictors, indicating increased sympathovagal balance. Upright LF/HF ratio was also higher in the sustainer than intermediate group. In multivariate analysis, independent explanatory factors for higher pulse wave velocity were the sustainer (p < 0.022) and intermediate phenotypes (p < 0.046), age (p < 0.001), body mass index (p < 0.001), and hypertension (p < 0.001). CONCLUSIONS: The response to upright posture could be clustered to 3 functional phenotypes. The sustainer phenotype, with smallest upright decrease in cardiac output and highest sympathovagal balance, was independently associated with increased large arterial stiffness. These results indicate an association of the functional haemodynamic phenotype with an acknowledged marker of cardiovascular risk. TRIAL REGISTRATION: ClinicalTrials.gov NCT01742702.

Spleen enlargement is a common finding in acute Puumala hantavirus infection and it does not associate with thrombocytopenia.

The pathogenesis of thrombocytopenia in Puumala hantavirus (PUUV) infection is probably multifactorial. We aimed to evaluate the possible spleen enlargement during acute PUUV infection, and to determine its association with thrombocytopenia and disease severity. Magnetic resonance imaging (MRI) of the spleen was performed in 20 patients with acute PUUV infection. MRI was repeated 5-8 months later. The change in spleen length was compared with markers describing the severity of the disease. In all patients, the spleen length was increased in the acute phase compared with the control phase (median 129 mm vs 111 mm, p < 0.001). The change correlated with maximum C-reactive protein value (r = 0.513, p = 0.021) and inversely with maximum leukocyte count (r = -0.471, p = 0.036), but not with maximum serum creatinine level or minimum platelet count. Enlarged spleen, evaluated by MRI, was shown to be a common finding during acute PUUV infection. However, it does not associate with thrombocytopenia and acute kidney injury.

Association of resting heart rate with cardiovascular function: a cross-sectional study in 522 Finnish subjects.

BACKGROUND: High resting heart rate (HR) is associated with increased cardiovascular risk in general populations, possibly due to elevated blood pressure (BP) or sympathetic over-activity. We studied the association of resting HR with cardiovascular function, and examined whether the hemodynamics remained similar during passive head-up tilt. METHODS: Hemodynamics were recorded using whole-body impedance cardiography and continuous radial pulse wave analysis in 522 subjects (age 20-72 years, 261 males) without medication influencing HR or BP, or diagnosed diabetes, coronary artery, renal, peripheral arterial, or cerebrovascular disease. Correlations were calculated, and results analysed according to resting HR tertiles. RESULTS: Higher resting HR was associated with elevated systolic and diastolic BP, lower stroke volume but higher cardiac output and work, and lower systemic vascular resistance, both supine and upright (p < 0.05 for all). Subjects with higher HR also showed lower supine and upright aortic pulse pressure and augmentation index, and increased resting pulse wave velocity (p < 0.001). Upright stroke volume decreased less in subjects with highest resting HR (p < 0.05), and cardiac output decreased less in subjects with lowest resting HR (p < 0.009), but clear hemodynamic differences between the tertiles persisted both supine and upright. CONCLUSIONS: Supine and upright hemodynamic profile associated with higher resting HR is characterized by higher cardiac output and lower systemic vascular resistance. Higher resting HR was associated with reduced central wave reflection, in spite of elevated BP and arterial stiffness. The increased cardiac workload, higher BP and arterial stiffness, may explain why higher HR is associated with less favourable prognosis in populations.

Alcohol Consumption and Its Influence on the Clinical Picture of Puumala Hantavirus Infection.

Puumala hantavirus (PUUV) causes hemorrhagic fever with renal syndrome. Characteristic clinical findings include acute kidney injury (AKI), thrombocytopenia, and capillary leakage. Smoking increases the risk of severe AKI, but it is not known whether alcohol consumption predisposes patients to a more severe infection. Liver and pancreatic enzymes, as well as biomarkers of alcohol consumption (gamma-glutamyl transferase, GGT; carbohydrate-deficient transferrin, CDT; GGT-CDT combination; and ethyl glucuronide, EtG), were measured from 66 patients with acute PUUV infection during hospitalization and at the convalescence phase. Alcohol consumption was present in 41% of the study population, 15% showing signs of heavy drinking. Alcohol use did not affect the severity of PUUV induced AKI nor the overall clinical picture of the infection. Liver enzyme levels (GGT or alanine aminotransferase, ALT) were elevated in 64% of the patients, but the levels did not associate with the markers reflecting the severity of the disease. Serum amylase activities at the convalescent stage were higher than those at the acute phase (p < 0.001). No cases with acute pancreatitis were found. In conclusion, our findings indicate that alcohol consumption does not seem to affect the clinical course of an acute PUUV infection.

High activity of indoleamine 2,3-dioxygenase is associated with renal insufficiency in Puumala hantavirus induced nephropathia epidemica.

Nephropathia epidemica (NE) is a hemorrhagic fever with renal syndrome caused by Puumala hantavirus. The severity of NE varies greatly. The aim of the present study was to evaluate whether serum indoleamine 2,3-dioxygenase (IDO) activity is associated with the severity of NE. A prospectively collected cohort of 102 consecutive patients with acute serologically confirmed NE was examined. Serum kynurenine, tryptophan, creatinine, CRP, and blood cell count were measured for up to 5 consecutive days after admission. The kynurenine to tryptophan (kyn/trp) ratio reflecting IDO activity was calculated. A maximum kyn/trp ratio >202 µmol/mmol had a sensitivity of 85% and a specificity of 75% for detecting maximum serum creatinine values >250 µmol/L by receiver operating characteristic (ROC) analysis. A maximum kyn/trp ratio >202 µmol/mmol (high IDO level) was also associated with other parameters reflecting the severity of the disease and renal impairment. Patients with high IDO levels had higher maximum serum creatinine (379 vs. 102 µmol/L, P<0.001), plasma C-reactive protein (104.1 vs. 72.1 mg/L, P=0.029), and blood leukocyte values (11.9 vs. 9.0 × 10(9) /L, P<0.001) compared to patients with kyn/trp ratio ≤ 202 µmol/mmol. They also had lower minimum urinary output (1,100 vs. 1,900 ml/day, P<0.001) and longer hospital stays (8 vs. 5 days, P<0.001). In conclusion, high serum IDO activity was associated with increased disease severity and renal impairment in NE.

Individual changes of central blood pressure in response to upright posture: different hemodynamic phenotypes.

OBJECTIVES: Most studies about upright regulation of blood pressure have focused on orthostatic hypotension despite the diverse hemodynamic changes induced by orthostatic challenge. We investigated the effect of passive head-up tilt on aortic blood pressure. METHODS: Noninvasive peripheral and central hemodynamics in 613 volunteers without cardiovascular morbidities or medications were examined using pulse wave analysis, whole-body impedance cardiography and heart rate variability analysis. RESULTS: In all participants, mean aortic SBP decreased by -4 (-5 to -3) mmHg [mean (95% confidence intervals)] and DBP increased by 6 (5--6) mmHg in response to upright posture. When divided into tertiles according to the supine-to-upright change in aortic SBP, two tertiles presented with a decrease [-15 (-14 to -16) and -4 (-3 to -4) mmHg, respectively] whereas one tertile presented with an increase [+7 (7-- 8) mmHg] in aortic SBP. There were no major differences in demographic characteristics between the tertiles. In regression analysis, the strongest explanatory factors for upright changes in aortic SBP were the supine values of, and upright changes in systemic vascular resistance and cardiac output, and supine aortic SBP. CONCLUSION: In participants without cardiovascular disease, the changes in central SBP during orthostatic challenge are not uniform. One-third presented with higher upright than supine aortic SBP with underlying differences in the regulation of systemic vascular resistance and cardiac output. These findings emphasize that resting blood pressure measurements give only limited information about the blood pressure status.

The severity of Puumala hantavirus induced nephropathia epidemica can be better evaluated using plasma interleukin-6 than C-reactive protein determinations.

BACKGROUND: Nephropathia epidemica (NE) is a Scandinavian type of hemorrhagic fever with renal syndrome caused by Puumala hantavirus. The clinical course of the disease varies greatly in severity. The aim of the present study was to evaluate whether plasma C-reactive protein (CRP) and interleukin (IL)-6 levels associate with the severity of NE. METHODS: A prospectively collected cohort of 118 consecutive hospital-treated patients with acute serologically confirmed NE was examined. Plasma IL-6, CRP, and creatinine, as well as blood cell count and daily urinary protein excretion were measured on three consecutive days after admission. Plasma IL-6 and CRP levels higher than the median were considered high. RESULTS: We found that high IL-6 associated with most variables reflecting the severity of the disease. When compared to patients with low IL-6, patients with high IL-6 had higher maximum blood leukocyte count (11.9 vs 9.0 x 10(9)/l, P = 0.001) and urinary protein excretion (2.51 vs 1.68 g/day, P = 0.017), as well as a lower minimum blood platelet count (55 vs 80 x 10(9)/l, P < 0.001), hematocrit (0.34 vs 0.38, P = 0.001), and urinary output (1040 vs 2180 ml/day, P < 0.001). They also stayed longer in hospital than patients with low IL-6 (8 vs 6 days, P < 0.001). In contrast, high CRP did not associate with severe disease. CONCLUSIONS: High plasma IL-6 concentrations associate with a clinically severe acute Puumala hantavirus infection, whereas high plasma CRP as such does not reflect the severity of the disease.

The severity of acute Puumala hantavirus infection does not predict the long-term outcome of patients.

BACKGROUND/AIMS: We have found greater urinary protein excretion and higher glomerular filtration rate (GFR) and blood pressure in patients 6 years after acute nephropathia epidemica (NE) compared with seronegative controls. The present aim was to establish whether the long-term outcome is determined by the severity of acute illness. METHODS: Serial plasma interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), creatinine, C-reactive protein, blood cell count as well as 24-hour urinary protein and overnight α(1)-microglobulin and albumin excretions were measured in 37 patients with acute NE. Human leucocyte antigen (HLA)-B, HLA-DRB1, TNF-α(-308) and IL-6(-174) alleles were also analyzed. After 6 years, GFR, blood pressure and urinary protein excretion were examined. RESULTS: There were no associations between the clinical severity of acute NE or the genetic factors determined and the increased GFR, hypertension or 24-hour urinary protein excretion observed 6 years later. The degree of inflammation during the acute phase was higher in patients who had increased urinary excretion of α(1)-microglobulin 6 years later compared with those with no α(1)-microglobulin excretion. CONCLUSION: Neither the severity of acute NE nor the host genetic factors determined the predicted renal function, blood pressure or 24-hour urinary protein excretion 6 years later.

Adverse influence of bisoprolol on central blood pressure in the upright position: a double-blind placebo-controlled cross-over study.

Treatment with beta-blockers is characterized by inferior reduction of central versus peripheral blood pressure. We examined changes in blood pressure, cardiac function, and vascular resistance after 3 weeks of bisoprolol treatment (5 mg/day) during passive head-up tilt in 16 never-treated Caucasian males with grade I-II primary hypertension. A double-blind, randomized, placebo-controlled cross-over design was applied, and hemodynamics were recorded using continuous tonometric pulse wave analysis and whole-body impedance cardiography. Bisoprolol decreased blood pressure in the aorta (~8/10 mmHg, p ≤ 0.032) and radial artery (~10/9 mmHg, p ≤ 0.037), but upright aortic systolic blood pressure was not significantly reduced (p = 0.085). Bisoprolol reduced heart rate and left cardiac work, and increased subendocardial viability index in supine and upright positions (p ≤ 0.044 for all). Bisoprolol increased stroke volume in the supine (~11 ml, p = 0.02) but not in the upright position, while only upright (~1 l/min, p = 0.007) but not supine cardiac output was reduced. Upright elevation in systemic vascular resistance was increased 2.7-fold (p = 0.002), while upright pulse pressure amplification was decreased by ~20% (p = 0.002) after bisoprolol. Aortic augmentation index, augmentation pressure, and pulse pressure were not changed in the supine position but were increased in the upright position (from 9% to 17%, 3-6 mmHg, and 30-34 mmHg, respectively, p ≤ 0.016 for all). In conclusion, although bisoprolol treatment reduced peripheral blood pressure, central systolic blood pressure in the upright position was not decreased. Importantly, the harmful influences of bisoprolol on central pulse pressure and pressure wave reflection were manifested in the upright position.

Tubular proteinuria and glomerular filtration 6 years after puumala hantavirus-induced acute interstitial nephritis.

BACKGROUND/AIMS: We previously found increased urinary protein excretion, glomerular filtration rate (GFR) and blood pressure in a retrospective analysis of patients with previous nephropathia epidemica (NE). Here, we evaluated the long-term outcome after NE in a prospectively recruited patient group. METHODS: Proteinuria, GFR and ambulatory 24-hour blood pressure were assessed 4-7 years (mean 6) after acute NE in 37 patients, and these values were compared to those from 38 seronegative controls. RESULTS: Six years after NE, the prevalence of elevated urinary alpha(1)-microglobulin excretion was higher in the patients than controls (9/35 vs. 1/38; p = 0.005). The patients also had higher urinary protein excretion (0.17 +/- 0.05 vs. 0.14 +/- 0.04 g/day; p = 0.006), GFR (119 +/- 19 vs. 109 +/- 14 ml/min/1.73 m(2); p = 0.016) and mean systolic (123 +/- 11 vs. 117 +/- 9 mm Hg; p = 0.012), nighttime systolic (109 +/- 11 vs. 100 +/- 9 mm Hg; p = 0.001) and nighttime diastolic blood pressure (70 +/- 7 vs. 66 +/- 7 mm Hg; p = 0.035) than the controls. CONCLUSIONS: These results confirm our previous findings of a higher prevalence of tubular proteinuria and increased urinary protein excretion, GFR and systolic blood pressure 6 years after acute NE.

Treatment of experimental renal osteodystrophy with pamidronate.

We evaluated the effects of the bisphosphonate pamidronate on bone histomorphometry, structure and strength in male rats with uninephrectomy or with chronic renal disease induced by 5/6 nephrectomy. In rats with chronic renal disease the plasma urea, phosphate and parathyroid hormone levels were significantly increased compared to rats with a uninephroctomy and none of these parameters was affected by pamidronate treatment. In the femoral midshaft, chronic renal disease reduced cortical bone mineral density and content. No difference was observed in the breaking load of the femoral midshaft. In the distal femur, a high-turnover renal osteodystrophy was found but pamidronate suppressed this bone turnover and increased bone mineral content. Treatment had no effect on chronic disease-induced augmentation of osteoid volume or fibroblast surface. These studies show that in this model of stage 3 renal disease, pamidronate increased mineral content in the femoral midshaft and distal metaphysis primarily by adding bone to endocortical and trabecular surfaces but did not reduce osteitis fibrosa.

Oxonic acid-induced hyperuricemia elevates plasma aldosterone in experimental renal insufficiency.

BACKGROUND: Hyperuricemia is associated with renal insufficiency and may predispose to Na retention and hypertension. Whether hyperuricemia plays a causal role in the pathogenesis of cardiovascular disease remains controversial. OBJECTIVE: We examined the effects of hyperuricemia on circulating and renal components of the renin-angiotensin-aldosterone system in experimental renal insufficiency. METHODS: Three weeks after 5/6 nephrectomy or sham-operation, rats were put on 2.0% oxonic acid diet for 9 weeks. Blood pressure was monitored using tail-cuff, and blood, urine, and kidney samples were taken, as appropriate. Kidney angiotensin-converting enzyme, angiotensin-converting enzyme 2 and angiotensin II receptors (AT1R, AT2R) were examined using real-time reverse transcriptase-PCR and autoradiography. RESULTS: Oxonic acid diet increased plasma uric acid by 80-90 micromol/l, while blood pressure was elevated only in hyperuricemic 5/6 nephrectomy rats (18 mmHg). Creatinine clearance was reduced by 60% in both 5/6 nephrectomy groups and by 25% in hyperuricemic Sham rats. The 5/6 nephrectomy group showed over 90% suppression of plasma renin activity, whereas the Sham + oxonic acid diet group showed 1.2 and 1.4-fold, and 5/6 nephrectomy + oxonic acid diet group 2.5 and 2.3-fold increases in plasma renin activity and plasma aldosterone, respectively. Hyperuricemia increased K and decreased Na excretion in Sham and 5/6 nephrectomy rats, leading to a more than 1.6-fold increase in urine K to Na ratio. No changes in kidney angiotensin-converting enzyme, angiotensin-converting enzyme 2, AT1R or AT2R were detected that could explain the hyperuricemia-induced alteration in Na-K balance. CONCLUSION: As oxonic acid diet increased plasma renin activity, plasma aldosterone, and urine K to Na ratio, these changes may play a significant role in the harmful cardiovascular actions of hyperuricemia.

Measurement of the kidney function in patients with rheumatoid arthritis: plasma cystatin C versus 51Cr-EDTA clearance.

BACKGROUND/AIM: Knowledge of the usefulness of cystatin C measurement in the detection of chronic kidney disease in patients with rheumatoid arthritis (RA) is scant. The purpose of this study was to evaluate the ability of plasma cystatin C- and creatinine-based methods to predict glomerular filtration rate (GFR) and classify chronic kidney disease in RA patients. METHODS: The study population consisted of 64 RA patients aged 41-86 years. Comparisons were made between measured plasma creatinine, cystatin C, creatinine clearance and GFR estimated by the Cockcroft-Gault (CG) and the Modification of Diet in Renal Disease (MDRD) formulas. The plasma clearance of (51)Cr-EDTA served as a reference. RESULTS: The Pearson correlation coefficients between plasma clearance of (51)Cr-EDTA and the markers of GFR were calculated. The correlation coefficients were 0.800 for plasma creatinine, 0.863 for cystatin C, 0.866 and 0.904 for GFR values estimated by MDRD and CG and 0.922 for plasma creatinine clearance. Statistically significant differences were detected between the correlation coefficients of plasma creatinine and GFR estimated by CG (p = 0.0412) and plasma creatinine and creatinine clearance (p = 0.0099). Creatinine clearance and the MDRD and CG formulas proved to be better at identifying GFR <90 ml/min than plasma creatinine or cystatin C. CONCLUSION: We recommend using the CG formula or creatinine clearance for the estimation of the GFR of RA patients instead of solely creatinine or cystatin C in clinical work.

Diminished coagulation capacity assessed by calibrated automated thrombography during acute Puumala hantavirus infection.

: Coagulation abnormalities are associated with Puumala-virus-induced hemorrhagic fever with renal syndrome (PUUV-HFRS). We evaluated the coagulation capacity of plasma during acute PUUV-HFRS by measuring thrombin generation using calibrated automated thrombography (CAT). The study cohort comprised 27 prospectively collected, consecutive, hospital-treated patients with acute PUUV infection. Blood samples were drawn in the acute phase and at the control visit approximately 5 weeks later. To evaluate thrombin generation, the lag time of initiation, endogenous thrombin potential (ETP), and peak and time to peak thrombin concentration were assessed by CAT in platelet poor plasma without corn trypsin inhibitor. Plasma levels of D-dimer, fibrinogen and prothrombin fragments (F1 + 2) were also evaluated. When the acute phase was compared with the control phase, ETP was decreased (median 1154 nmol/l/min, range 67-1785 vs. median 1385 nmol/l/min, range 670-1970; P < 0.001), while the lag time was prolonged (median 3.8 min, range 2.1-7.7 vs. median 2.9 min, range 2.0-4.1; P < 0.001). Low ETP correlated with low peak thrombin concentration (r = 0.833, P < 0.001). Prolonged time to peak associated with the lag time (r = 0.78, P < 0.001). ETP was associated with thrombocytopenia (r = 0.472, P = 0.015) and weakly with fibrinogen level (r = 0.386, P = 0.047). The measured CAT parameters did not associate with D-dimer and F1 + 2 levels. Decreased ETP together with low peak and prolonged lag time indicate decreased plasma potential for thrombin generation in vitro. Together with low platelet count and enhanced fibrinolysis, this further refers to altered blood coagulation and increased propensity toward bleeding in acute PUUV-HFRS.

High plasma resistin associates with severe acute kidney injury in Puumala hantavirus infection.

BACKGROUND: Puumala hantavirus (PUUV) infected patients typically suffer from acute kidney injury (AKI). Adipokines have inflammation modulating functions in acute diseases including AKI. We examined plasma levels of three adipokines (resistin, leptin, and adiponectin) in acute PUUV infection and their associations with disease severity. METHODS: This study included 79 patients hospitalized due to acute PUUV infection. Plasma resistin, leptin, adiponectin, as well as IL-6 and CRP, were measured at the acute phase, recovery phase and one year after hospitalization. RESULTS: Plasma resistin levels were significantly higher in the acute phase compared to the recovery phase and one year after (median resistin 28 pg/mL (11-107) vs. 17 pg/mL (7-36) vs. 14 pg/mL (7-31), p<0.001). Maximum resistin concentration correlated with maximum plasma creatinine levels (r = 0.63; p<0.001). The higher the amount of albuminuria in the urine dipstick test (0-1+, 2+ or 3+) at admission, the higher the median of maximum resistin (24.7 pg/mL, 25.4 pg/mL and 39.6 pg/mL, respectively, p = 0.002). High resistin was also an independent risk factor for severe AKI (creatinine ≥353.6µmol/L) (OR 1.08, 95% CI 1.02-1.14). Neither plasma leptin nor adiponectin level had any correlation with creatinine concentration or the amount of albuminuria. CONCLUSIONS: Plasma resistin independently associates with the severity of AKI in acute PUUV infection. The association of resistin with the amount of albuminuria suggests that the level of plasma resistin is not only influenced by renal clearance but could have some role in the pathogenesis of AKI during PUUV infection.

Salbutamol-induced Decrease in Augmentation Index is Related to the Parallel Increase in Heart Rate.

The change in augmentation index following salbutamol inhalation has been applied to evaluate endothelial function. We examined the contribution of salbutamol-induced increase in heart rate to the observed decrease in augmentation index. Haemodynamics were recorded using whole-body impedance cardiography and continuous pulse wave analysis from tonometric radial blood pressure. All subjects (n = 335, mean age 46, body mass index 26, 48% men) were without medications with cardiovascular influences. The effects of salbutamol inhalation (0.4 mg) versus the endothelium-independent agent nitroglycerin resoriblet (0.25 mg) were examined during passive head-up tilt, as the haemodynamic influences of these compounds depend on body position. Salbutamol decreased augmentation index by ~3-4% units in supine and upright positions. Although salbutamol moderately increased cardiac index (+4.5%) and decreased systemic vascular resistance (-8.5%), the significant haemodynamic explanatory factors for decreased augmentation index in multivariate analysis were increased supine heart rate, and increased upright heart rate and decreased ejection duration (p < 0.001 for all, r2  = 0.36-0.37). Sublingual nitroglycerin decreased supine and upright augmentation index by ~15% units and ~23% units, respectively. The haemodynamic explanatory factors for these changes in multivariate analysis were increased heart rate, reduced ejection duration and reduced systemic vascular resistance (p ≤ 0.021 for all, r2  = 0.22-0.34). In conclusion, the lowering influence of salbutamol on augmentation index may be largely explained by increased heart rate, suggesting that this effect may not predominantly reflect endothelial function.