The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Ansofie Goessaert - One of the best experts on this subject based on the ideXlab platform.
-
phenotyping nocturnal polyuria circadian and age related variations in diuresis rate Free Water Clearance and sodium Clearance
Age and Ageing, 2020Co-Authors: Thomas F Monaghan, Ansofie Goessaert, Donald L Bliwise, Marieastrid Denys, Veerle Decalf, Candy Kumps, Johan Vande Walle, Jeffrey P Weiss, Matthew Epstein, Jeremy WeedonAbstract:Abstract Background this study compares diuresis rate, sodium Clearance and Free Water Clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP. Methods post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium Clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium Clearance and FWC using four predictor variables: NP status (present [nocturnal urine production g90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification. Results subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium Clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium Clearance and daytime sodium Clearance. FWC showed a complex age effect, which was independent of time of day or NP status. Conclusions age-related increases in nighttime/daytime diuresis rate, 24-h sodium Clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium Clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or Free Water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to Water Clearance.
-
nocturnal polyuria excess of nocturnal urine production excess of definitions influence on renal function profile
The Journal of Urology, 2016Co-Authors: Ansofie Goessaert, J. Vande Walle, Ruud Bosch, Piet Hoebeke, Karel EveraertAbstract:Purpose: This study aimed to identify important differences in renal function profile, and potential Water and sodium diuresis cutoffs among participants with nocturnal polyuria according to nocturnal polyuria definitions.Materials and Methods: This post hoc analysis was based on a prospective study in which participants completed a bladder diary, collected urine and provided a blood sample. With an age dependent nocturnal polyuria index greater than 20% to 33% as the referent 4 definitions of nocturnal polyuria were compared, including 1) nocturnal polyuria index greater than 33%, 2) nocturnal urine production greater than 90 ml per hour and 3) greater than 10 ml/kg, and 4) nocturia index greater than 1.5.Results: In 112 male and female participants significant differences in baseline characteristics and bladder diary parameters were found according to definition. Diuresis rate, Free Water Clearance and sodium Clearance had similar 24-hour courses in the subgroups with and without polyuria by each defini...
Jeremy Weedon - One of the best experts on this subject based on the ideXlab platform.
-
phenotyping nocturnal polyuria circadian and age related variations in diuresis rate Free Water Clearance and sodium Clearance
Age and Ageing, 2020Co-Authors: Thomas F Monaghan, Ansofie Goessaert, Donald L Bliwise, Marieastrid Denys, Veerle Decalf, Candy Kumps, Johan Vande Walle, Jeffrey P Weiss, Matthew Epstein, Jeremy WeedonAbstract:Abstract Background this study compares diuresis rate, sodium Clearance and Free Water Clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP. Methods post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium Clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium Clearance and FWC using four predictor variables: NP status (present [nocturnal urine production g90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification. Results subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium Clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium Clearance and daytime sodium Clearance. FWC showed a complex age effect, which was independent of time of day or NP status. Conclusions age-related increases in nighttime/daytime diuresis rate, 24-h sodium Clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium Clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or Free Water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to Water Clearance.
Willem Van Oeveren - One of the best experts on this subject based on the ideXlab platform.
-
short term effects of tolvaptan in individuals with autosomal dominant polycystic kidney disease at various levels of kidney function
American Journal of Kidney Diseases, 2015Co-Authors: Wendy E Boertien, Esther Meijer, Paul E De Jong, Gert J Ter Horst, Remco J Renken, Eric J Van Der Jagt, Peter Kappert, John Ouyang, Gerwin E Engels, Willem Van OeverenAbstract:Background A recent study showed that tolvaptan, a vasopressin V 2 receptor antagonist, decreased total kidney volume (TKV) growth and estimated glomerular filtration rate (GFR) loss in autosomal dominant polycystic kidney disease (ADPKD) with creatinine Clearance≥60mL/min. The aim of our study was to determine whether the renal hemodynamic effects and pharmacodynamic efficacy of tolvaptan in ADPKD are dependent on GFR. Study Design Clinical trial with comparisons before and after treatment. Setting & Participants Patients with ADPKD with a wide range of measured GFRs (mGFRs; 18-148 mL/min) in a hospital setting. Intervention Participants were studied at baseline and after 3 weeks of treatment with tolvaptan given in increasing dosages, if tolerated (doses of 60, 90, and 120mg/d in weeks 1, 2, and 3, respectively). Outcomes Change in markers for aquaresis (Free-Water Clearance, urine and plasma osmolality, 24-hour urine volume, and plasma copeptin) and kidney injury (TKV and kidney injury biomarkers). Measurements GFR was measured by 125 I-iothalamate Clearance; TKV, by magnetic resonance imaging; biomarker excretion, by enzyme-linked immunosorbent assay; and osmolality, by Freezing point depression. Results In 27 participants (52% men; aged 46±10 years; mGFR, 69±39mL/min; TKV, 2.15 [IQR, 1.10-2.77] L), treatment with tolvaptan led to an increase in urine volume and Free-Water Clearance and a decrease in urine osmolality, TKV, and kidney injury marker excretion. Changes in urine volume and osmolality with treatment were less in participants with lower baseline mGFRs (both P P =0.001), suggesting that participants with decreased GFRs responded more to tolvaptan per functioning nephron. Limitations Limited sample size, no control group. Conclusions In patients with ADPKD with decreased kidney function, response to tolvaptan is lower for TKV, urinary volume, and osmolality, but larger for fractional Free-Water Clearance. This latter finding suggests that patients with ADPKD with lower GFRs might benefit from long-term treatment with tolvaptan, as has been observed for patients with preserved GFRs.
Donald D Smyth - One of the best experts on this subject based on the ideXlab platform.
-
renal denervation altered the hemodynamic and renal effects following intracerebroventricular administration of the i1 imidazoline receptor agonist rilmenidine in pentobarbital anaesthetized rats
Neurochemistry International, 1997Co-Authors: Brian S Penner, Donald D SmythAbstract:Abstract Previous studies have reported on the effects of intracerebroventricular (icv) administration of the I1-imidazoline receptor agonist moxonidine. In the present study, the relationship between increasing doses of the I1-agonist rilmenidine (administered icv) with blood pressure and renal function has been determined. Moreover, the importance of the renal nerves in this response have also been assessed. In pentobarbitone anesthetized rats, icv rilmenidine (30, 100, 300 nmol in 5μl) produced a dose related decrease in blood pressure and heart rate. Urine flow was not altered at the lower doses although at the highest dose (300 nmol) the increase approached significance (p = 0.06). Sodium excretion and osmolar Clearance were not altered. Free Water Clearance was increased at 100 and 300 nmol rilmenidine (p
-
clonidine induced increase in osmolar Clearance and Free Water Clearance via activation of two distinct α2 adrenoceptor sites
British Journal of Pharmacology, 1996Co-Authors: H D Intengan, Donald D SmythAbstract:1. Clonidine, an alpha 2-adrenoceptor agonist, will increase urine flow rate in the anaesthetized rat by increasing both Free Water and osmolar Clearance. In the present study, we investigated whether these effects of clonidine were mediated at two sites which could be distinguished pharmacologically in uninephrectomized male Sprague-Dawley rats. 2. Clonidine (1.0 nmol kg-1 min-1) infused into the renal artery increased osmolar and Free Water Clearance. Following pretreatment with prazosin (0.15 mg kg-1, i.v.), an antagonist with reported selectivity for the alpha 2b-adrenoceptor subtype, the increase in Free Water but not osmolar Clearance was decreased. Pretreatment with the opioid receptor antagonist, naltrexone (3.0 mg kg-1, i.v.) attenuated the increase in osmolar but not Free Water Clearance. This disparate antagonism of clonidine by prazosin and naltrexone was consistent with two distinct sites. 3. We submit the hypothesis that the alpha 2a- and alpha 2b-adrenoceptor subtypes mediated the clonidine-induced osmolar and Free Water Clearance. The blockade in Free Water Clearance by prazosin indicated a possible role of the alpha 2b-adrenoceptor subtype whereas the alpha 2a-adrenoceptor subtype was considered as the site mediating the clonidine-induced increase in osmolar Clearance. UK-14,304 (1.0 nmol kg-1 min-1), a mixed alpha 2-adrenoceptor/imidazoline receptor agonist with selectivity for the alpha 2a-subtype increased only osmolar Clearance. This increase was blocked by naltrexone but not prazosin pretreatment. The imidazoline receptor was not involved, as naltrexone failed to alter the moxonidine (3.0 nmol kg-1-min-1) induced increase in osmolar Clearance. These data suggested to us that the alpha 2a-/alpha 26-subtype hypothesis should be investigated more closely in future studies. 4. These findings indicate that the increase in osmolar and Free Water Clearance following clonidine can be distinguished pharmacologically indicating that two sites were involved. Furthermore, we propose the hypothesis that the alpha 2a-adrenoceptor subtype mediated osmolar Clearance whereas the alpha 2b-subtype mediated Free Water Clearance. The prazosin-sensitive increase in Free Water Clearance following clonidine suggested a possible role for the alpha 2b-subtype. The naltrexone-sensitive increase in osmolar Clearance following clonidine and UK-14,304 (but not moxonidine) suggested a possible role of the alpha 2a-subtype. Clearly, this postulate requires further study.
Ira Kurtz - One of the best experts on this subject based on the ideXlab platform.
-
utility of electrolyte Free Water Clearance in the analysis and treatment of the dysnatremias
2013Co-Authors: Minhtri K Nguyen, Huma Hasnain, Michael J Dibiase, Carl Schulze, Ira KurtzAbstract:Understanding the pathogenesis and treatment of hyponatremia is a challenge for medical students and experts alike. Although hyponatremia has a wide range of causes, the pathogenesis of hyponatremia is largely characterized by disorders of urinary dilution. In evaluating the renal mechanisms responsible for the pathophysiology of hyponatremia, an analysis of Free Water Clearance (FWC) and electrolyte-Free Water Clearance (EFWC) is often utilized to quantify the renal diluting defect in this disorder. In this article, the utility of Free Water Clearance (FWC) and electrolyte-Free Water Clearance (EFWC) in the diagnostic and therapeutic approach to hyponatremia is discussed.
-
whole body electrolyte Free Water Clearance derivation and clinical utility in analyzing the pathogenesis of the dysnatremias
Clinical and Experimental Nephrology, 2006Co-Authors: Minhtri K Nguyen, Ira KurtzAbstract:The total exchangeable sodium (Nae), total exchangeable potassium (Ke), and total body Water (TBW) are the major determinants of the plasma Water sodium concentration ([Na+]pw). The relationship between [Na+]pw and Nae, Ke, and TBW was empirically determined by Edelman et al., where: [Na+]pw = 1.11(Nae + Ke)/TBW − 25.6 (Eq. 1). According to Eq. 1, changes in the mass balance of Na+, K+, and H2O will therefore result in changes in the [Na+]pw. Historically, in evaluating the pathogenesis of the dysnatremias, Free Water Clearance (FWC) and electrolyte-Free Water Clearance (EFWC) have been used to evaluate the pathophysiology of the dysnatremias. However, such analyses are only valid when there is no concomitant input and non-renal output of Na+, K+, and H2O. Since the classic FWC and EFWC formulas fail to account for the input and non-renal output of Na+, K+, and H2O, these formulas cannot be used to evaluate the pathogenesis of the dysnatremias or to predict the directional change in the [Na+]pw. In this article, we have addressed this limitation by deriving a new formula, termed whole-body electrolyte-Free Water Clearance (WB-EFWC), which calculates whole-body electrolyte-Free Water Clearance for a given mass balance of Na+, K+, and H2O, rather than simply the urinary component (FWC, EFWC formulas). Unlike previous formulas, which consider only the renal component of electrolyte-Free Water Clearance, WB-EFWC accounts for all sources of input and output of Na+, K+, and H2O, and will therefore be helpful in conceptually understanding the basis for changes in the [Na+]pw in patients with the dysnatremias.
-
derivation of a new formula for calculating urinary electrolyte Free Water Clearance based on the edelman equation
American Journal of Physiology-renal Physiology, 2005Co-Authors: Minhtri K Nguyen, Ira KurtzAbstract:In evaluating the renal mechanisms responsible for the generation of the dysnatremias, an analysis of Free Water Clearance (FWC) and electrolyte-Free Water Clearance (EFWC) is often utilized to cha...
