Axial heterogeneity and filtered-load dependence of proximal bicarbonate reabsorption

A theoretical model was developed to examine the role of physical and chemical factors in the control of bicarbonate reabsorption in the renal proximal tubule. Included in the model were axial and radial variations in the concentrations of HCO3-, CO2 and related chemical species in the tubule lumen and epithelial cells. Relations between these concentrations and the solute fluxes across the brush border and basolateral membranes were also included, as were reaction rate and equilibrium expressions to describe the various buffering processes in the lumen and cells. The two most critical membrane parameters, the rate constant for H+ secretion at the brush border and the effective permeability of HCO3- at the basolateral membrane, were evaluated by comparing model predictions with available free-flow micropuncture data in the rat. It was found that the experimental observations could be explained only by decreasing one or both of these membrane parameters with axial position, suggesting a progressive decrease in HCO3- reabsorptive capacity along the tubule. For single nephron filtered loads of HCO3- up to about 1,400 pmol/min, absolute bicarbonate reabsorption was predicted to increase nearly in proportion to filtered load, whereas it was calculated to be relatively constant at higher filtered loads, irrespective of how filtered load was assumed to be varied. These predictions are in excellent agreement with most of the available micropuncture data in rats, as is the prediction that HCO3- reabsorption should change in parallel with CO2 partial pressure in the filtrate, at a given filtered load of HCO3–. Certain discrepancies between the model predictions and experimental observations are evident at very high filtered loads, and the implications of these are discussed in terms of possible adaptive responses of the tubule

Health claims databases used for kidney research around the world

Health claims databases offer opportunities for studies on large populations of patients with kidney disease and health outcomes in a non-experimental setting. Among others, their unique features enable studies on healthcare costs or on longitudinal, epidemiological data with nationwide coverage. However, health claims databases also have several limitations. Because clinical data and information on renal function are often lacking, the identification of patients with kidney disease depends on the actual presence of diagnosis codes only. Investigating the validity of these data is therefore crucial to assess whether outcomes derived from health claims data are truly meaningful. Also, one should take into account the coverage and content of a health claims database, especially when making international comparisons. In this article, an overview is provided of international health claims databases and their main publications in the area of nephrology. The structure and contents of the Dutch health claims database will be described, as well as an initiative to use the outcomes for research and the development of the Dutch Kidney Atlas. Finally, we will discuss to what extent one might be able to identify patients with kidney disease using health claims databases, as well as their strengths and limitations

Polypharmacy and medication use in patients with chronic kidney disease with and without kidney replacement therapy compared to matched controls

BACKGROUND: This study aims to examine polypharmacy (PP) prevalence in patients with chronic kidney disease (CKD) Stage G4/G5 and patients with kidney replacement therapy (KRT) compared with matched controls from the general population. Furthermore, we examine risk factors for PP and describe the most commonly dispensed medications. METHODS: Dutch health claims data were used to identify three patient groups: CKD Stage G4/G5, dialysis and kidney transplant patients. Each patient was matched to two controls based on age, sex and socio-economic status (SES) score. We differentiated between ‘all medication use’ and ‘chronic medication use’. PP was defined at three levels: use of ≥5 medications (PP), ≥10 medications [excessive PP (EPP)] and ≥15 medications [hyper PP (HPP)]. RESULTS: The PP prevalence for all medication use was 87, 93 and 95% in CKD Stage G4/G5, dialysis and kidney transplant patients, respectively. For chronic medication use, this was 66, 70 and 75%, respectively. PP and comorbidity prevalence were higher in patients than in controls. EPP was 42 times more common in young CKD Stage G4/G5 patients (ages 20–44 years) than in controls, while this ratio was 3.8 in patients ≥75 years. Older age (64–75 and ≥75 years) was a risk factor for PP in CKD Stage G4/G5 and kidney transplant patients. Dialysis patients ≥75 years of age had a lower risk of PP compared with their younger counterparts. Additional risk factors in all patients were low SES, diabetes mellitus, vascular disease, hospitalization and an emergency room visit. The most commonly dispensed medications were proton pump inhibitors (PPIs) and statins. CONCLUSIONS: CKD Stage G4/G5 patients and patients on KRT have a high medication burden, far beyond that of individuals from the general population, as a result of their kidney disease and a large burden of comorbidities. A critical approach to medication prescription in general, and of specific medications like PPIs and statins (in the dialysis population), could be a first step towards more appropriate medication use

Chronic prescription of antidepressant medication in patients with chronic kidney disease with and without kidney replacement therapy compared with matched controls in the Dutch general population

BACKGROUND: Chronic kidney disease (CKD) is associated with a higher prevalence of depression, neuropathic pain and insomnia. These conditions are often treated pharmaceutically. In this study we aimed to determine the prevalence of chronic antidepressant use among CKD patients with and without kidney replacement therapy (KRT). METHODS: By using the Dutch health claims database, we were able to determine the prevalence, type and dosage of chronic antidepressant prescriptions in patients with CKD Stage G4/G5 without KRT (n = 14 905), patients on dialysis (n = 3872) and patients living on a functioning graft (n = 8796) and compared these to age-, sex- and socio-economic status (SES)-matched controls from the general population. RESULTS: Our data show that the prevalence of chronic antidepressant prescription is 5.6%, 5.3% and 4.2% in CKD Stage G4/G5, dialysis and kidney transplant patients, respectively, which is significantly higher than in matched controls. Although our data revealed more prescriptions in female patients and in the age category 45–64 years, our data did not show any association between antidepressant prescriptions and SES. Selective serotonin reuptake inhibitors were the most prescribed drugs in all patient groups and controls. Tricyclic antidepressants were more often used in patients compared with controls. CONCLUSION: This nationwide analysis revealed that chronic antidepressant prescription in the Netherlands is higher in CKD patients with and without KRT than in controls, higher in middle-aged patients and women, unrelated to socio-economic status and lower than chronic use reported in other countries

The validity of Dutch health claims data for identifying patients with chronic kidney disease:a hospital-based study in the Netherlands

Background. Health claims data may be an efficient and easily accessible source to study chronic kidney disease (CKD) prevalence in a nationwide population. Our aim was to study Dutch claims data for their ability to identify CKD patients in different subgroups. Methods. From a laboratory database, we selected 24 895 adults with at least one creatinine measurement in 2014 ordered at an outpatient clinic. Of these, 15 805 had >= 2 creatinine measurements at least 3 months apart and could be assessed for the chronicity criterion. We estimated the validity of a claim-based diagnosis of CKD and advanced CKD. The estimated glomerular filtration rate (eGFR)-based definitions for CKD (eGFR = 75 years. The specificity of CKD and advanced CKD was >= 99%. Positive predictive values ranged from 72% to 99% and negative predictive values ranged from 40% to 100%. Conclusion. When using health claims data for the estimation of CKD prevalence, it is important to take into account the characteristics of the population at hand. The younger the subjects and the more advanced the stage of CKD the higher the sensitivity of such data. Understanding which patients are selected using health claims data is crucial for a correct interpretation of study results

Structure-Specific Fermentation of Galacto-Oligosaccharides, Isomalto-Oligosaccharides and Isomalto/Malto-Polysaccharides by Infant Fecal Microbiota and Impact on Dendritic Cell Cytokine Responses

SCOPE: Next to galacto-oligosaccharides (GOS), starch-derived isomalto-oligosaccharide preparation (IMO) and isomalto/malto-polysaccharides (IMMP) could potentially be used as prebiotics in infant formulas. However, it remains largely unknown how the specific molecular structures of these non-digestible carbohydrates (NDCs) impact fermentability and immune responses in infants. METHODS AND RESULTS: In vitro fermentation of GOS, IMO and IMMP using infant fecal inoculum of 2- and 8-week-old infants showed that only GOS and IMO were fermented by infant fecal microbiota. The degradation of GOS and IMO coincided with an increase in Bifidobacterium and production of acetate and lactate, which was more pronounced with GOS. Individual isomers with an (1↔1)-linkage or di-substituted reducing terminal glucose residue were more resistant to fermentation. GOS, IMO and IMMP fermentation digesta attenuated cytokine profiles in immature dendritic cells (DCs), but the extent was dependent on the infants age and NDC structure. CONCLUSION: The IMO preparation, containing reducing and non-reducing isomers, showed similar fermentation patterns as GOS in fecal microbiota of 2-week-old infants. Knowledge obtained on the substrate specificities of infant fecal microbiota and the subsequent regulatory effects of GOS, IMO and IMMP on DC responses might contribute to the design of tailored NDC mixtures for infants of different age groups. This article is protected by copyright. All rights reserved

Effects of intraperitoneal insulin versus subcutaneous insulin administration on sex hormone-binding globulin concentrations in patients with type 1 diabetes mellitus

Aims Elevated sex hormone-binding globulin (SHBG) concentrations have been described in patients with type 1 diabetes mellitus (T1DM), probably due to low portal insulin concentrations. We aimed to investigate whether the route of insulin administration, continuous intraperitoneal insulin infusion (CIPII), or subcutaneous (SC), influences SHBG concentrations among T1DM patients. Methods Post hoc analysis of SHBG in samples derived from a randomized, open-labeled crossover trial was carried out in 20 T1DM patients: 50% males, mean age 43 (±13) years, diabetes duration 23 (±11) years, and hemoglobin A1c (HbA1c) 8.7 (±1.1) (72 (±12) mmol/mol). As secondary outcomes, testosterone, 17-β-estradiol, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were analyzed. Results Estimated mean change in SHBG was −10.3nmol/L (95% CI: −17.4, −3.2) during CIPII and 3.7nmol/L (95% CI: −12.0, 4.6) during SC insulin treatment. Taking the effect of treatment order into account, the difference in SHBG between therapies was −6.6nmol/L (95% CI: −17.5, 4.3); −12.7nmol/L (95% CI: −25.1, −0.4) for males and −1.7nmol/L (95% CI: −24.6, 21.1) for females, respectively. Among males, SHBG and testosterone concentrations changed significantly during CIPII; −15.8nmol/L (95% CI: −24.2, −7.5) and −8.3nmol/L (95% CI: −14.4, −2.2), respectively. The difference between CIPII and SC insulin treatment was also significant for change in FSH 1.2U/L (95% CI: 0.1, 2.2) among males. Conclusions SHBG concentrations decreased significantly during CIPII treatment. Moreover, the difference in change between CIPII and SC insulin therapy was significant for SHBG and FSH among males. These findings support the hypothesis that portal insulin administration influences circulating SHBG and sex steroids

DH and JH usage in murine fetal liver mirrors that of human fetal liver

In mouse and human, the regulated development of antibody repertoire diversity during ontogeny proceeds in parallel with the development of the ability to generate antibodies to an array of specific antigens. Compared to adult, the human fetal antibody repertoire limits N addition and uses specifically positioned VDJ gene segments more frequently, including V6-1 the most DH-proximal VH, DQ52, the most JH-proximal DH, and JH2, which is DH-proximal. The murine fetal antibody repertoire also limits the incorporation of N nucleotides and uses its most DH proximal VH, VH81X, more frequently. To test whether DH and JH also follow the pattern observed in human, we used the scheme of Hardy to sort B lineage cells from BALB/c fetal and neonatal liver, RT-PCR cloned and sequenced VH7183-containing VDJCμ transcripts, and then assessed VH7183-DH-JH and complementary determining region 3 of the immunoglobulin heavy chain (CDR-H3) content in comparison to the previously studied adult BALB/c mouse repertoire. Due to the deficiency in N nucleotide addition, perinatal CDR-H3s manifested a distinct pattern of amino acid usage and predicted loop structures. As in the case of adult bone marrow, we observed a focusing of CDR-H3 length and CDR-H3 loop hydrophobicity, especially in the transition from the early to late pre-B cell stage, a developmental checkpoint associated with expression of the pre-B cell receptor. However, fetal liver usage of JH-proximal DHQ52 and DH-proximal JH2 was markedly greater than that of adult bone marrow. Thus, the early pattern of DH and JH usage in mouse feta liver mirrors that of human

Patient controlled analgesia with remifentanil versus epidural analgesia in labour: Randomised multicentre equivalence trial

Objective To determine women’s satisfaction with pain relief using patient controlled analgesia with remifentanil compared with epidural analgesia during labour. Design Multicentre randomised controlled equivalence trial. Setting 15 hospitals in the Netherlands. Participants Women with an intermediate to high obstetric risk with an intention to deliver vaginally. To exclude a clinically relevant difference in satisfaction with pain relief of more than 10%, we needed to include 1136 women. Because of missing values for satisfaction this number was increased to 1400 before any analysis. We used multiple imputation to correct for missing data. Intervention Before the onset of active labour consenting women were randomised to a pain relief strategy with patient controlled remifentanil or epidural analgesia if they requested pain relief during labour. Main outcome measures Primary outcome was satisfaction with pain relief, measured hourly on a visual analogue scale and expressed as area under the curve (AUC), thus providing a time weighted measure of total satisfaction with pain relief. A higher AUC represents higher satisfaction with pain relief. Secondary outcomes were pain intensity scores, mode of delivery, and maternal and neonatal outcomes. Analysis was done by intention to treat. The study was defined as an equivalence study for the primary outcome. Results 1414 women were randomised, of whom 709 were allocated to patient controlled remifentanil and 705 to epidural analgesia. Baseline characteristics were comparable. Pain relief was ultimately used in 65% (447/687) in the remifentanil group and 52% (347/671) in the epidural analgesia group (relative risk 1.32, 95% confidence interval 1.18 to 1.48). Cross over occurred in 7% (45/687) and 8% (51/671) of women, respectively. Of women primarily treated with remifentanil, 13% (53/402) converted to epidural analgesia, while in women primarily treated with epidural analgesia 1% (3/296) converted to remifentanil. The area under the curve for total satisfaction with pain relief was 30.9 in the remifentanil group versus 33.7 in the epidural analgesia group (mean difference −2.8, 95% confidence interval −6.9 to 1.3). For who actually received pain relief the area under the curve for satisfaction with pain relief after the start of pain relief was 25.6 in the remifentanil group versus 36.1 in the epidural analgesia group (mean difference −10.4, −13.9 to −7.0). The rate of caesarean section was 15% in both groups. Oxygen saturation was significantly lower (SpO2 <92%) in women who used remifentanil (relative risk 1.5, 1.4 to 1.7). Maternal and neonatal outcomes were comparable between both groups. Conclusion In women in labour, patient controlled analgesia with remifentanil is not equivalent to epidural analgesia with respect to scores on satisfaction with pain relief. Satisfaction with pain relief was significantly higher in women who were allocated to and received epidural analgesia.L.M. Freeman, K.W. Bloemenkamp, M.T. Franssen, D.N. Papatsonis, P.J. Hajenius, M.W. Hollmann, M.D. Woiski, M. Porath, H.J. van den Berg, E. van Beek, O.W.H.M. Borchert, N. Schuitemaker, J.M. Sikkema, A.H.M. Kuipers, S.L.M. Logtenberg, P.C.M van der Salm, K.O. Rengerink, E. Lopriore, M.E. van den Akker-van Marle, S. le Cessie, J.M van Lith, M.M. Struys, B.W.J. Mol, A. Dahan, J.M. Middeldor