The kidney plays a key role in the correction of systemic acid-base imbalances. Central for this regulation are the intercalated cells in the distal nephron, which secrete acid or base into the ...urine. How these cells sense acid-base disturbances is a long-standing question. Intercalated cells exclusively express the Na
-dependent Cl
/HCO
exchanger AE4 (Slc4a9). Here we show that AE4-deficient mice exhibit a major dysregulation of acid-base balance. By combining molecular, imaging, biochemical and integrative approaches, we demonstrate that AE4-deficient mice are unable to sense and appropriately correct metabolic alkalosis and acidosis. Mechanistically, a lack of adaptive base secretion via the Cl
/HCO
exchanger pendrin (Slc26a4) is the key cellular cause of this derailment. Our findings identify AE4 as an essential part of the renal sensing mechanism for changes in acid-base status.
Background and Purpose
Specific, high potency receptor antagonists are valuable tools when evaluating animal and human physiology. Within the glucose‐dependent, insulinotropic polypeptide (GIP) ...system, considerable attention has been given to the presumed GIP receptor antagonist, (Pro3)GIP, and its effect in murine studies. We conducted a pharmacological analysis of this ligand including interspecies differences between the rodent and human GIP system.
Experimental Approach
Transiently transfected COS‐7 cells were assessed for cAMP accumulation upon ligand stimulation and assayed in competition binding using 125I‐human GIP. Using isolated perfused pancreata both from wild type and GIP receptor‐deficient rodents, insulin‐releasing, glucagon‐releasing and somatostatin‐releasing properties in response to species‐specific GIP and (Pro3)GIP analogues were evaluated.
Key Results
Human (Pro3)GIP is a full agonist at human GIP receptors with similar efficacy (Emax) for cAMP production as human GIP, while both rat and mouse(Pro3)GIP were partial agonists on their corresponding receptors. Rodent GIPs are more potent and efficacious at their receptors than human GIP. In perfused pancreata in the presence of 7 mM glucose, both rodent (Pro3)GIP analogues induced modest insulin, glucagon and somatostatin secretion, corresponding to the partial agonist activities observed in cAMP production.
Conclusions and Implications
When evaluating new compounds, it is important to consider interspecies differences both at the receptor and ligand level. Thus, in rodent models, human GIP is a comparatively weak partial agonist. Human (Pro3)GIP was not an antagonist at human GIP receptors, so there is still a need for a potent antagonist in order to elucidate the physiology of human GIP.
To identify predictors of radiographic progression in a 2-year randomised, double-blind, clinical study (CIMESTRA) of patients with early rheumatoid arthritis (RA).
Patients with early RA (n = 130) ...were treated with methotrexate, intra-articular betamethasone and ciclosporin/placebo-ciclosporin. Baseline magnetic resonance imaging (MRI) of the wrist (wrist-only group, n = 130) or MRI of wrist and metacarpophalangeal (MCP) joints (wrist+MCP group, n = 89) (OMERACT RAMRIS), x-ray examination of hands, wrists and forefeet (Sharp/van der Heijde Score (TSS)), Disease Activity Score (DAS28), anti-cyclic citrullinated peptide antibodies (anti-CCP), HLA-DRB1-shared epitope (SE) and smoking status were assessed. Multiple regression analysis was performed with delta-TSS (0-2 years) as dependent variable and baseline DAS28, TSS, MRI bone oedema score, MRI synovitis score, MRI erosion score, anti-CCP, smoking, SE, age and gender as explanatory variables.
Baseline values: median DAS28 5.6 (range 2.4-8.0); anti-CCP positive 61%; radiographic erosions 56%. At 2 years: DAS28 2.0 (0.5-5.7), in DAS remission: 56%, radiographic progression 26% (wrist+MCP group, similar for wrist-only group). MRI bone oedema score was the only independent predictor of delta-TSS (wrist+MCP group: coefficient = 0.75 (95% CI 0.55 to 0.94), p<0.001; wrist-only group: coefficient = 0.59 (95% CI 0.40 to 0.77), p<0.001). Bone oedema score explained 41% of the variation in the progression of TSS (wrist+MCP group), 25% in wrist-only group (Pearson's r = 0.64 and r = 0.50, respectively). Results were confirmed by sensitivity analyses.
In a randomised controlled trial aiming at remission in patients with early RA, baseline RAMRIS MRI bone oedema score of MCP and wrist joints (and of wrist only) was the strongest independent predictor of radiographic progression in hands, wrists and forefeet after 2 years. MRI synovitis score, MRI erosion score, DAS28, anti-CCP, SE, smoking, age and gender were not independent risk factors.
NCT00209859.
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Alternative processing of the precursor protein pro-GIP results in endogenously produced GIP(1–30)NH2, that by DPP-4 cleavage in vivo results in the metabolite GIP(3–30)NH2. We showed ...previously that GIP(3–30)NH2 is a high affinity antagonist of the human GIPR in vitro. Here we determine whether it is suitable for studies of GIP physiology in rats since effects of GIP agonists and antagonists are strictly species-dependent. Transiently transfected COS-7 cells were assessed for cAMP accumulation upon ligand stimulation or assayed in competition binding using human 125I-GIP(1–42) as radioligand. In isolated perfused rat pancreata, insulin, glucagon, and somatostatin-releasing properties were evaluated. Competition binding demonstrated that on the rat GIP receptor (GIPR), rat GIP(3–30)NH2 bound with high affinity (Ki of 17nM), in contrast to human GIP(3–30)NH2 (Ki of 250nM). In cAMP studies, rat GIP(3–30)NH2 inhibited GIP(1–42)-induced rat GIPR activation and schild-plot analysis showed competitive antagonism with a pA2 of 13nM and a slope of 0.9±0.09. Alone, rat GIP(3–30)NH2 displayed weak, low-potent partial agonistic properties (EC50>1μM) with an efficacy of 9.4% at 0.32μM compared to GIP(1–42). In perfused rat pancreata, rat GIP(3–30)NH2 efficiently antagonized rat GIP(1–42)-induced insulin, somatostatin, and glucagon secretion. In summary, rat GIP(3–30)NH2 is a high affinity competitive GIPR antagonist and effectively antagonizes GIP-mediated G protein-signaling as well as pancreatic hormone release, while human GIP(3–30)NH2, despite a difference of only one amino acid between the two (arginine in position 18 in rat GIP(3–30)NH2; histidine in human), is unsuitable in the rat system. This underlines the importance of species differences in the GIP system, and the limitations of testing human peptides in rodent systems.
Background
Since 2003, care for patients with oesophageal cancer has been centralized in a few dedicated centres in Denmark. The aim of this study was to assess changes in the treatment and outcome ...of patients registered in a nationwide database.
Methods
All patients diagnosed with oesophageal cancer or cancer of the gastro‐oesophageal junction who underwent oesophagectomy in Denmark between 2004 and 2013, and who were registered in the Danish clinical database of carcinomas in the oesophagus, gastro‐oesophageal junction and stomach (DECV database) were included. Quality‐of‐care indicators, including number of lymph nodes removed, anastomotic leak rate, 30‐ and 90‐day mortality, and 2‐ and 5‐year overall survival, were assessed. To compare quality‐of‐care indicators over time, the relative risk (RR) was calculated using a multivariable log binomial regression model.
Results
Some 6178 patients were included, of whom 1728 underwent oesophagectomy. The overall number of patients with 15 or more lymph nodes in the resection specimen increased from 38·1 per cent in 2004 to 88·7 per cent in 2013. The anastomotic leak rate decreased from 14·8 to 7·6 per cent (RR 0·66, 95 per cent c.i. 0·43 to 1·01). The 30‐day mortality rate decreased from 4·5 to 1·7 per cent (RR 0·51, 0·22 to 1·15) and the 90‐day mortality rate from 11·0 to 2·9 per cent (RR 0·46, 0·26 to 0·82). There were no statistically significant changes in 2‐ or 5‐year survival rates over time.
Conclusion
Indicators of quality of care have improved since the centralization of oesophageal cancer treatment in Denmark.
Better short‐term outcome
An understanding of the underlying processes and comprehensive history of population growth after a harvest-driven depletion is necessary when assessing the long-term effectiveness of management and ...conservation strategies. The South American sea lion (SASL), Otaria flavescens, is the most conspicuous marine mammal along the South American coasts, where it has been heavily exploited. As a consequence of this exploitation, many of its populations were decimated during the early 20th century but currently show a clear recovery. The aim of this study was to assess SASL population recovery by applying a Bayesian state-space modelling framework. We were particularly interested in understanding how the population responds at low densities, how human-induced mortality interplays with natural mechanisms, and how density-dependence may regulate population growth. The observed population trajectory of SASL shows a non-linear relationship with density, recovering with a maximum increase rate of 0.055. However, 50 years after hunting cessation, the population still represents only 40% of its pre-exploitation abundance. Considering that the SASL population in this region represents approximately 72% of the species abundance within the Atlantic Ocean, the present analysis provides insights into the potential mechanisms regulating the dynamics of SASL populations across the global distributional range of the species.
Background To assess the effects of comprehensive cardiac rehabilitation compared with usual care on physical activity and mental health for patients treated with catheter ablation for atrial ...fibrillation. Methods The patients were randomized 1:1 stratified by paroxysmal or persistent atrial fibrillation and sex to cardiac rehabilitation consisting of 12 weeks physical exercise and four psycho-educational consultations plus usual care (cardiac rehabilitation group) versus usual care. The primary outcome was V o2 peak. The secondary outcome was self-rated mental health measured by the Short Form-36 questionnaire. Exploratory outcomes were collected. Results 210 patients were included (mean age: 59 years, 74% men), 72% had paroxysmal atrial fibrillation prior to ablation. Compared with usual care, the cardiac rehabilitation group had a beneficial effect on V o2 peak at four months (24.3 mL kg−1 min−1 versus 20.7 mL kg−1 min−1 , p of main effect = 0.003, p of interaction between time and intervention = 0.020). No significant difference between groups on Short Form-36 was found (53.8 versus 51.9 points, P = .20). Two serious adverse events (atrial fibrillation in relation to physical exercise and death unrelated to rehabilitation) occurred in the cardiac rehabilitation group versus one in the usual care group (death unrelated to intervention) ( P = .56). In the cardiac rehabilitation group 16 patients versus 7 in the usual care group reported non-serious adverse events ( P = .047). Conclusion Comprehensive cardiac rehabilitation had a positive effect on physical capacity compared with usual care, but not on mental health. Cardiac rehabilitation caused more non-serious adverse events.
Women with polycystic ovary syndrome (PCOS) often change their metabolic profile over time to decrease levels of androgens while often gaining a propensity for the development of the metabolic ...syndrome. Recent discoveries indicate that microRNAs (miRNAs) play a role in the development of PCOS and constitute potential biomarkers for PCOS. We aimed to identify miRNAs associated with the development of an impaired metabolic profile in women with PCOS, in a follow-up study, compared with women without PCOS.
Clinical measurements of PCOS status and metabolic disease were obtained twice 6 years apart in a cohort of 46 women with PCOS and nine controls. All participants were evaluated for degree of metabolic disease (hypertension, dyslipidemia, central obesity, and impaired glucose tolerance). MiRNA levels were measured using Taqman
Array cards of 96 pre-selected miRNAs associated with PCOS and/or metabolic disease.
Women with PCOS decreased their levels of androgens during follow-up. Twenty-six of the miRNAs were significantly changed in circulation in women with PCOS during the follow-up, and twenty-four of them had decreased, while levels did not change in the control group. Four miRNAs were significantly different at baseline between healthy controls and women with PCOS; miR-103-3p, miR-139-5p, miR-28-3p, and miR-376a-3p, which were decreased in PCOS. After follow-up, miR-28-3p, miR-139-5p, and miR-376a-3p increased in PCOS women to the levels observed in healthy controls. Of these, miR-139-5p correlated with total testosterone levels (rho = 0.50, p
= 0.013), while miR-376-3p correlated significantly with the waist-hip ratio at follow-up (rho = 0.43, p
= 0.01). Predicted targets of miR-103-3p, miR-139-5p, miR-28-3p, and miR-376a-3p were enriched in pathways associated with Insulin/IGF signaling, interleukin signaling, the GNRH receptor pathways, and other signaling pathways. MiRNAs altered during follow-up in PCOS patients were enriched in pathways related to immune regulation, gonadotropin-releasing hormone signaling, tyrosine kinase signaling, and WNT signaling.
These studies indicate that miRNAs associated with PCOS and androgen metabolism overall decrease during a 6-year follow-up, reflecting the phenotypic change in PCOS individuals towards a less hyperandrogenic profile.
Dehydroepiandrosterone (DHEA) is a neurosteroid with potential effects on neurogenesis and neuronal survival in humans. However, most studies on DHEA have been performed in rodents, and there is ...little direct evidence for biological effects on the human nervous system. Furthermore, the mechanism of its action is unknown. Here, we show that DHEA significantly increased the growth rates of human neural stem cells derived from the fetal cortex and grown with both epidermal growth factor (EGF) and leukemia inhibitory factor (LIF). However, it had no effect on cultures grown in either factor alone, suggesting a specific action on the EGF/LIF-responsive cell. Precursors of DHEA such as pregnenolone or six of its major metabolites, had no significant effect on proliferation rates. DHEA did not alter the small number (<3%) of newly formed neuroblasts or the large number (>95%) of nestin-positive precursors. However, the number of glial fibrillary acidic protein-positive cells, its mRNA, and protein were significantly increased by DHEA. We found both N-methyl-D-aspartate and sigma 1 antagonists, but not GABA antagonists, could completely eliminate the effects of DHEA on stem cell proliferation. Finally we asked whether the EGF/LIF/DHEA-responsive stem cells had an increased potential for neurogenesis and found a 29% increase in neuronal production when compared to cultures grown in EGF/LIF alone. Together these data suggest that DHEA is involved in the maintenance and division of human neural stem cells. Given the wide availability of this neurosteroid, this finding has important implications for future use.
Human neural precursor cells grown in culture provide a source of tissue for drug screening, developmental studies and cell therapy. However, mechanisms underlying their growth and differentiation ...are poorly understood. We show that epidermal growth factor (EGF) responsive precursors derived from the developing human cortex undergo senescence after 30–40 population doublings. Leukemia inhibitory factor (LIF) increased overall expansion rates, prevented senescence and allowed the growth of a long‐term self renewing neural stem cell (ltNSCctx) for up to 110 population doublings. We established basal gene expression in ltNSCctx using Affymetrix oligonucleotide microarrays that delineated specific members of important growth factor and signaling families consistently expressed across three separate lines. Following LIF withdrawal, 200 genes showed significant decreases. Protein analysis confirmed LIF‐regulated expression of glial fibrillary acidic protein, CD44, and major histocompatibility complex I. This study provides the first molecular profile of human ltNSCctx cultures capable of long‐term self renewal, and reveals specific sets of genes that are directly or indirectly regulated by LIF.
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