Levels of retinol and retinyl esters in plasma and urine of dogs with urolithiasis

Vitamin A (VA) deficiency and Tamm-Horsfall glycoprotein (THP), a protein that binds retinol and retinyl esters in canine urine, might be involved in the pathogenesis of urolithiasis in dogs. In the present study, we assessed levels of retinol, retinyl esters, retinol-binding protein (RBP) and THP in plasma and urine of dogs with a history of urolithiasis (n = 25) compared with clinically healthy controls (n = 18). Plasma retinol concentrations were higher in dogs with uroliths of struvit (P < 0.01), calcium oxalate (P < 0.05), urate (P < 0.01) and cysteine, but there were no differences in the concentrations of plasma RBP and retinyl esters. Excretion of urinary retinol and retinyl esters were tentatively, but not significantly higher in the stone-forming groups, which was accompanied by increased levels of urinary RBP (P < 0.01) and lower excretions in THP (P < 0.01). The results show that VA deficiency may be excluded as a potential cause for canine urolithiasis. However, the occurrence of RBP and a concomitant reduction of THP in urine indicates a disturbed kidney function as cause or consequence of stone formation in dogs.

Contrasting Effects of Ethylene Biosynthesis on Induced Plant Resistance against a Chewing and a Piercing-Sucking Herbivore in Rice

Ethylene is a stress hormone with contrasting effects on herbivore resistance. However, it remains unknown whether these differences are plant- or herbivore-specific. We cloned a rice 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene, OsACS2, whose transcripts were rapidly up-regulated in response to mechanical wounding and infestation by two important pests: the striped stem borer (SSB) Chilo suppressalis and the brown planthopper (BPH) Nilaparvata lugens. Antisense expression of OsACS2 (as-acs) reduced elicited ethylene emission, SSB-elicited trypsin protease inhibitor (TrypPI) activity, SSB-induced volatile release, and SSB resistance. Exogenous application of ACC restored TrypPI activity and SSB resistance. In contrast to SSB, BPH infestation increased volatile emission in as-acs lines. Accordingly, BPH preferred to feed and oviposit on wild-type (WT) plants—an effect that could be attributed to two repellent volatiles, 2-heptanone and 2-heptanol, that were emitted in higher amounts by as-acs plants. BPH honeydew excretion was reduced and natural enemy attraction was enhanced in as-acs lines, resulting in higher overall resistance to BPH. These results demonstrate that ethylene signaling has contrasting, herbivore-specific effects on rice defense responses and resistance against a chewing and a piercing-sucking insect, and may mediate resistance trade-offs between herbivores of different feeding guilds in rice.

Glomerular filtration rate, urine production, and fractional clearance of electrolytes in acute kidney injury in dogs and their association with survival.

BACKGROUND Acute kidney injury (AKI) is common in dogs. Few studies have assessed sequential changes in indices of kidney function in dogs with naturally occurring AKI. OBJECTIVE To document sequential changes of conventional indices of renal function, to better define the course of AKI, and to identify a candidate marker for recovery. ANIMALS Ten dogs with AKI. METHODS Dogs were prospectively enrolled and divided into surviving and nonsurviving dogs. Urine production was measured with a closed system for 7 days. One and 24-hour urinary clearances were performed daily to estimate solute excretion and glomerular filtration rate (GFR). Solute excretion was calculated as an excretion ratio (ER) and fractional clearance (FC) based on both the 1- and 24-hour urine collections. RESULTS Four dogs survived and 6 died. At presentation, GFR was not significantly different between the outcome groups, but significantly (P = .03) increased over time in the surviving, but not in the nonsurviving dogs. Fractional clearance of Na decreased significantly over time (20.2-9.4%, P < .0001) in the surviving, but not in the nonsurviving dogs. The ER and FC of solutes were highly correlated (r, 0.70-0.95). CONCLUSION AND CLINICAL IMPACT Excretion ratio might be used in the clinical setting as a surrogate marker to follow trends in solute excretion. Increased GFR, urine production, and decreased FC of Na were markers of renal recovery. The FC of Na is a simple, noninvasive, and cost-effective method that can be used to evaluate recovery of renal function.

Metabolomics reveals that aldose reductase activity due to AKR1B10 is upregulated in hepatitis C virus infection

To understand the changes in the metabolome of hepatitis C virus (HCV)-infected persons, we conducted a metabolomic investigation in both plasma and urine of 30 HCV-positive individuals using plasmas from 30 HCV-negative blood donors and urines from 30 healthy volunteers. Samples were analysed by gas chromatography-mass spectrometry and data subjected to multivariate analysis. The plasma metabolomic phenotype of HCV-positive persons was found to have elevated glucose, mannose and oleamide, together with depressed plasma lactate. The urinary metabolomic phenotype of HCV-positive persons comprised reduced excretion of fructose and galactose combined with elevated urinary excretion of 6-deoxygalactose (fucose) and the polyols sorbitol, galactitol and xylitol. HCV-infected persons had elevated galactitol/galactose and sorbitol/glucose urinary ratios, which were highly correlated. These observations pointed to enhanced aldose reductase activity, and this was confirmed by real-time quantitative polymerase chain reaction with AKR1B10 gene expression elevated sixfold in the liver. In contrast, AKR1B1 gene expression was reduced 40% in HCV-positive livers. Interestingly, persons who were formerly HCV infected retained the metabolomic phenotype of HCV infection without reverting to the HCV-negative metabolomic phenotype. This suggests that the effects of HCV on hepatic metabolism may be long lived. Hepatic AKR1B10 has been reported to be elevated in hepatocellular carcinoma and in several premalignant liver diseases. It would appear that HCV infection alone increases AKR1B10 expression, which manifests itself as enhanced urinary excretion of polyols with reduced urinary excretion of their corresponding hexoses. What role the polyols play in hepatic pathophysiology of HCV infection and its sequelae is currently unknown.

Copeptin Is Associated with Kidney Length, Renal Function, and Prevalence of Simple Cysts in a Population-Based Study.

Arginine vasopressin (AVP) has a key role in osmoregulation by facilitating water transport in the collecting duct. Recent evidence suggests that AVP may have additional effects on renal function and favor cyst growth in polycystic kidney disease. Whether AVP also affects kidney structure in the general population is unknown. We analyzed the association of copeptin, an established surrogate for AVP, with parameters of renal function and morphology in a multicentric population-based cohort. Participants from families of European ancestry were randomly selected in three Swiss cities. We used linear multilevel regression analysis to explore the association of copeptin with renal function parameters as well as kidney length and the presence of simple renal cysts assessed by ultrasound examination. Copeptin levels were log-transformed. The 529 women and 481 men had median copeptin levels of 3.0 and 5.2 pmol/L, respectively (P<0.001). In multivariable analyses, the copeptin level was associated inversely with eGFR (β=-2.1; 95% confidence interval [95% CI], -3.3 to -0.8; P=0.002) and kidney length (β=-1.2; 95% CI, -1.9 to -0.4; P=0.003) but positively with 24-hour urinary albumin excretion (β=0.11; 95% CI, 0.01 to 0.20; P=0.03) and urine osmolality (β=0.08; 95% CI, 0.05 to 0.10; P<0.001). A positive association was found between the copeptin level and the presence of renal cysts (odds ratio, 1.6; 95% CI, 1.1 to 2.4; P=0.02). These results suggest that AVP has a pleiotropic role in renal function and may favor the development of simple renal cysts.

Associations of ambulatory blood pressure with urinary caffeine and caffeine metabolite excretions.

Intake of caffeinated beverages might be associated with reduced cardiovascular mortality possibly via the lowering of blood pressure. We estimated the association of ambulatory blood pressure with urinary caffeine and caffeine metabolites in a population-based sample. Families were randomly selected from the general population of Swiss cities. Ambulatory blood pressure monitoring was conducted using validated devices. Urinary caffeine, paraxanthine, theophylline, and theobromine excretions were measured in 24 hours urine using ultrahigh performance liquid chromatography tandem mass spectrometry. We used mixed models to explore the associations of urinary excretions with blood pressure although adjusting for major confounders. The 836 participants (48.9% men) included in this analysis had mean age of 47.8 and mean 24-hour systolic and diastolic blood pressure of 120.1 and 78.0 mm Hg. For each doubling of caffeine excretion, 24-hour and night-time systolic blood pressure decreased by 0.642 and 1.107 mm Hg (both P values <0.040). Similar inverse associations were observed for paraxanthine and theophylline. Adjusted night-time systolic blood pressure in the first (lowest), second, third, and fourth (highest) quartile of paraxanthine urinary excretions were 110.3, 107.3, 107.3, and 105.1 mm Hg, respectively (P trend <0.05). No associations of urinary excretions with diastolic blood pressure were generally found, and theobromine excretion was not associated with blood pressure. Anti-hypertensive therapy, diabetes mellitus, and alcohol consumption modify the association of caffeine urinary excretion with systolic blood pressure. Ambulatory systolic blood pressure was inversely associated with urinary excretions of caffeine and other caffeine metabolites. Our results are compatible with a potential protective effect of caffeine on blood pressure.

Normotensive blood pressure in pregnancy – the role of salt and aldosterone

A successful pregnancy requires an accommodating environment. Salt and water availability are critical for plasma volume expansion. Any changes in sodium intake would alter aldosterone, a hormone previously described beneficial in pregnancy. To date, it remains ambiguous whether high aldosterone or high salt intake is preferable. We hypothesized that increased aldosterone is a rescue mechanism and appropriate salt availability is equally effective in maintaining a normotensive blood pressure (BP) phenotype in pregnancy. We compared normotensive pregnant women (n=31) throughout pregnancy with young healthy female individuals (n=31–62) and performed salt sensitivity testing within the first trimester. Suppression of urinary tetrahydro-aldosterone levels by salt intake as measured by gas chromatography–mass spectrometry and urinary sodium excretion corrected for creatinine, respectively, was shifted toward a higher salt intake in pregnancy (P<0.0001). In pregnancy, neither high urinary tetrahydro-aldosterone nor sodium excretion was correlated with higher BP. In contrast, in nonpregnant women, systolic BP rose with aldosterone (P<0.05). Testing the impact of salt on BP, we performed salt sensitivity testing in a final cohort of 19 pregnant and 24 nonpregnant women. On salt loading, 24-hour mean arterial pressure rose by 3.6±1.5 and dropped by –2.8±1.5 mm Hg favoring pregnant women (P<0.01; χ2=6.04; P<0.02). Our data suggest first that salt responsiveness of aldosterone is alleviated in conditions of pregnancy without causing aldosterone-induced hypertension. Second, salt seems to aid in BP lowering in pregnancy for reasons incompletely elucidated, yet involving renin suppression and potentially placental sensing mechanisms. Further research should identify susceptible individuals and clarify effector mechanisms.

Effect of large doses of parenteral vitamin D on glycaemic control and calcium/phosphate metabolism in patients with stable type 2 diabetes mellitus: a randomised, placebo-controlled, prospective pilot study.

OBJECTIVE Vitamin D (D₃) status is reported to correlate negatively with insulin production and insulin sensitivity in patients with type 2 diabetes mellitus (T2DM). However, few placebo-controlled intervention data are available. We aimed to assess the effect of large doses of parenteral D3 on glycosylated haemoglobin (HbA(₁c)) and estimates of insulin action (homeostasis model assessment insulin resistance: HOMA-IR) in patients with stable T2DM. MATERIALS AND METHODS We performed a prospective, randomised, double-blind, placebo-controlled pilot study at a single university care setting in Switzerland. Fifty-five patients of both genders with T2DM of more than 10 years were enrolled and randomised to either 300,000 IU D₃ or placebo, intramuscularly. The primary endpoint was the intergroup difference in HbA(₁c) levels. Secondary endpoints were: changes in insulin sensitivity, albuminuria, calcium/phosphate metabolism, activity of the renin-aldosterone axis and changes in 24-hour ambulatory blood pressure values. RESULTS After 6 months of D₃ supply, there was a significant intergroup difference in the change in HbA(₁c) levels (relative change [mean ± standard deviation] +2.9% ± 1.5% in the D₃ group vs +6.9% ± 2.1% the in placebo group, p = 0.041) as HOMA-IR decreased by 12.8% ± 5.6% in the D₃ group and increased by 10% ± 5.4% in the placebo group (intergroup difference, p = 0.032). Twenty-four-hour urinary albumin excretion decreased in the D₃ group from 200 ± 41 to 126 ± 39, p = 0.021). There was no significant intergroup difference for the other secondary endpoints. CONCLUSIONS D₃ improved insulin sensitivity (based on HOMA-IR) and affected the course of HbA(₁c) positively compared with placebo in patients with T2DM.

Deficiency of ECHS1 causes mitochondrial encephalopathy with cardiac involvement.

OBJECTIVE Short-chain enoyl-CoA hydratase (ECHS1) is a multifunctional mitochondrial matrix enzyme that is involved in the oxidation of fatty acids and essential amino acids such as valine. Here, we describe the broad phenotypic spectrum and pathobiochemistry of individuals with autosomal-recessive ECHS1 deficiency. METHODS Using exome sequencing, we identified ten unrelated individuals carrying compound heterozygous or homozygous mutations in ECHS1. Functional investigations in patient-derived fibroblast cell lines included immunoblotting, enzyme activity measurement, and a palmitate loading assay. RESULTS Patients showed a heterogeneous phenotype with disease onset in the first year of life and course ranging from neonatal death to survival into adulthood. The most prominent clinical features were encephalopathy (10/10), deafness (9/9), epilepsy (6/9), optic atrophy (6/10), and cardiomyopathy (4/10). Serum lactate was elevated and brain magnetic resonance imaging showed white matter changes or a Leigh-like pattern resembling disorders of mitochondrial energy metabolism. Analysis of patients' fibroblast cell lines (6/10) provided further evidence for the pathogenicity of the respective mutations by showing reduced ECHS1 protein levels and reduced 2-enoyl-CoA hydratase activity. While serum acylcarnitine profiles were largely normal, in vitro palmitate loading of patient fibroblasts revealed increased butyrylcarnitine, unmasking the functional defect in mitochondrial β-oxidation of short-chain fatty acids. Urinary excretion of 2-methyl-2,3-dihydroxybutyrate - a potential derivative of acryloyl-CoA in the valine catabolic pathway - was significantly increased, indicating impaired valine oxidation. INTERPRETATION In conclusion, we define the phenotypic spectrum of a new syndrome caused by ECHS1 deficiency. We speculate that both the β-oxidation defect and the block in l-valine metabolism, with accumulation of toxic methacrylyl-CoA and acryloyl-CoA, contribute to the disorder that may be amenable to metabolic treatment approaches.

Iron uptake and ferrokinetics in healthy male subjects of an iron-based oral phosphate binder (SBR759) labeled with the stable isotope 58 Fe

SBR759 is a novel polynuclear iron(III) oxide–hydroxide starch·sucrose·carbonate complex being developed for oral use in chronic kidney disease (CKD) patients with hyperphosphatemia on hemodialysis. SBR759 binds inorganic phosphate released by food uptake and digestion in the gastro-intestinal tract increasing the fecal excretion of phosphate with concomitant reduction of serum phosphate concentrations. Considering the high content of ∼20% w/w covalently bound iron in SBR759 and expected chronic administration to patients, absorption of small amounts of iron released from the drug substance could result in potential iron overload and toxicity. In a mechanistic iron uptake study, 12 healthy male subjects (receiving comparable low phosphorus-containing meal typical for CKD patients: ≤1000 mg phosphate per day) were treated with 12 g (divided in 3 × 4 g) of stable 58Fe isotope-labeled SBR759. The ferrokinetics of [58Fe]SBR759-related total iron was followed in blood (over 3 weeks) and in plasma (over 26 hours) by analyzing with high precision the isotope ratios of the natural iron isotopes 58Fe, 57Fe, 56Fe and 54Fe by multi-collector inductively coupled mass spectrometry (MC-ICP-MS). Three weeks following dosing, the subjects cumulatively absorbed on average 7.8 ± 3.2 mg (3.8–13.9 mg) iron corresponding to 0.30 ± 0.12% (0.15–0.54%) SBR759-related iron which amounts to approx. 5-fold the basal daily iron absorption of 1–2 mg in humans. SBR759 was well-tolerated and there was no serious adverse event and no clinically significant changes in the iron indices hemoglobin, hematocrit, ferritin concentration and transferrin saturation.

Estimation of reference curves for the urinary steroid metabolome in the first year of life in healthy children: tracing the complexity of human postnatal steroidogenesis

CONTEXT Complex steroid disorders such as P450 oxidoreductase deficiency or apparent cortisone reductase deficiency may be recognized by steroid profiling using chromatographic mass spectrometric methods. These methods are highly specific and sensitive, and provide a complete spectrum of steroid metabolites in a single measurement of one sample which makes them superior to immunoassays. The steroid metabolome during the fetal-neonatal transition is characterized by a) the metabolites of the fetal-placental unit at birth, b) the fetal adrenal androgens until its involution 3-6 months postnatally, and c) the steroid metabolites produced by the developing endocrine organs. All these developmental events change the steroid metabolome in an age- and sex-dependent manner during the first year of life. OBJECTIVE The aim of this study was to provide normative values for the urinary steroid metabolome of healthy newborns at short time intervals in the first year of life. METHODS We conducted a prospective, longitudinal study to measure 67 urinary steroid metabolites in 21 male and 22 female term healthy newborn infants at 13 time-points from week 1 to week 49 of life. Urine samples were collected from newborn infants before discharge from hospital and from healthy infants at home. Steroid metabolites were measured by gas chromatography-mass spectrometry (GC-MS) and steroid concentrations corrected for urinary creatinine excretion were calculated. RESULTS 61 steroids showed age and 15 steroids sex specificity. Highest urinary steroid concentrations were found in both sexes for progesterone derivatives, in particular 20α-DH-5α-DH-progesterone, and for highly polar 6α-hydroxylated glucocorticoids. The steroids peaked at week 3 and decreased by ∼80% at week 25 in both sexes. The decline of progestins, androgens and estrogens was more pronounced than of glucocorticoids whereas the excretion of corticosterone and its metabolites and of mineralocorticoids remained constant during the first year of life. CONCLUSION The urinary steroid profile changes dramatically during the first year of life and correlates with the physiologic developmental changes during the fetal-neonatal transition. Thus detailed normative data during this time period permit the use of steroid profiling as a powerful diagnostic tool.

Insulin activates Na(+)/H(+) exchanger 3: biphasic response and glucocorticoid dependence.

Insulin is an important regulator of renal salt and water excretion, and hyperinsulinemia has been implicated to play a role in hypertension. One of the target proteins of insulin action in the kidney is Na(+)/H(+) exchanger 3 (NHE3), a principal Na(+) transporter responsible for salt absorption in the mammalian proximal tubule. The molecular mechanisms involved in activation of NHE3 by insulin have not been studied so far. In opossum kidney (OK) cells, insulin increased Na(+)/H(+) exchange activity in a time- and concentration-dependent manner. This effect is due to activation of NHE3 as it persisted after pharmacological inhibition of NHE1 and NHE2. In the early phase of stimulation (2-12 h), NHE3 activity was increased without changes in NHE3 protein and mRNA. At 24 h, enhanced NHE3 activity was accompanied by an increase in total and cell surface NHE3 protein and NHE3 mRNA abundance. All the effects of insulin on NHE3 activity, protein, and mRNA were amplified in the presence of hydrocortisone. These results suggest that insulin stimulates renal tubular NHE3 activity via a biphasic mechanism involving posttranslational factors and an increase in NHE3 gene expression and the effects are dependent on the permissive action of hydrocortisone.

CYP17A1 Enzyme Activity Is Linked to Ambulatory Blood Pressure in a Family-Based Population Study

BACKGROUND Genome-wide association studies have linked CYP17A1 coding for the steroid hormone synthesizing enzyme 17α-hydroxylase (CYP17A1) to blood pressure (BP). We hypothesized that the genetic signal may translate into a correlation of ambulatory BP (ABP) with apparent CYP17A1 activity in a family-based population study and estimated the heritability of CYP17A1 activity. METHODS In the Swiss Kidney Project on Genes in Hypertension, day and night urinary excretions of steroid hormone metabolites were measured in 518 participants (220 men, 298 women), randomly selected from the general population. CYP17A1 activity was assessed by 2 ratios of urinary steroid metabolites: one estimating the combined 17α-hydroxylase/17,20-lyase activity (ratio 1) and the other predominantly 17α-hydroxylase activity (ratio 2). A mixed linear model was used to investigate the association of ABP with log-transformed CYP17A1 activities exploring effect modification by urinary sodium excretion. RESULTS Daytime ABP was positively associated with ratio 1 under conditions of high, but not low urinary sodium excretion (P interaction <0.05). Ratio 2 was not associated with ABP. Heritability estimates (SE) for day and night CYP17A1 activities were 0.39 (0.10) and 0.40 (0.09) for ratio 1, and 0.71 (0.09) and 0.55 (0.09) for ratio 2 (P values <0.001). CYP17A1 activities, assessed with ratio 1, were lower in older participants. CONCLUSIONS Low apparent CYP17A1 activity (assessed with ratio 1) is associated with elevated daytime ABP when salt intake is high. CYP17A1 activity is heritable and diminished in the elderly. These observations highlight the modifying effect of salt intake on the association of CYP17A1 with BP.

Associations of Urinary Uromodulin with Clinical Characteristics and Markers of Tubular Function in the General Population

BACKGROUND AND OBJECTIVES Allelic variants in UMOD, the gene coding for uromodulin, are associated with rare tubulointerstitial kidney disorders and risk of CKD and hypertension in the general population. The factors associated with uromodulin excretion in the normal population remain largely unknown, and were therefore explored in this study. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Urinary uromodulin excretion was measured using a validated ELISA in two population-based cohorts that included more than 6500 individuals. The Swiss Kidney Project on Genes in Hypertension study (SKIPOGH) included 817 adults (mean age±SD, 45±17 years) who underwent renal ultrasonography and performed a 24-hour urine collection. The Cohorte Lausannoise study included 5706 adults (mean age, 53±11 years) with fresh spot morning urine samples. We calculated eGFRs using the CKD-Epidemiology Collaboration formula and by 24-hour creatinine clearance. RESULTS In both studies, positive associations were found between uromodulin and urinary sodium, chloride, and potassium excretion and osmolality. In SKIPOGH, 24-hour uromodulin excretion (median, 41 [interquartile range, 29-57] mg/24 h) was positively associated with kidney length and volume and with creatinine excretion and urine volume. It was negatively associated with age and diabetes. Both spot uromodulin concentration and 24-hour uromodulin excretion were linearly and positively associated (multivariate analyses) with eGFR<90 ml/min per 1.73 m(2). CONCLUSION Age, creatinine excretion, diabetes, and urinary volume are independent clinical correlates of urinary uromodulin excretion. The associations of uromodulin excretion with markers of tubular functions and kidney dimensions suggest that it may reflect tubule activity in the general population.

A picture of trends in Aujeszky's disease virus exposure in wild boar in the Swiss and European contexts.

BACKGROUND In parallel to the increase of wild boar abundance in the past decades, an increase of exposure to the Aujeszky's disease virus (ADV) has been reported in wild boar in several parts of Europe. Since high animal densities have been proposed to be one of the major factors influencing ADV seroprevalence in wild boar populations and wild boar abundance has increased in Switzerland, too, a re-evaluation of the ADV status was required in wild boar in Switzerland. We tested wild boar sera collected from 2008-2013 with a commercial ELISA for antibodies against ADV. To set our data in the European context, we reviewed scientific publications on ADV serosurveys in Europe for two time periods (1995-2007 and 2008-2014). RESULTS Seven out of 1,228 wild boar sera were positive for antibodies against ADV, resulting in an estimated seroprevalence of 0.57% (95% confidence interval CI: 0.32-0.96%). This is significantly lower than the prevalence of a previous survey in 2004-2005. The literature review revealed that high to very high ADV seroprevalences are reported from Mediterranean and Central-eastern countries. By contrast, an "island" of low to medium seroprevalences is observed in the centre of Europe with few isolated foci of high seroprevalences. We were unable to identify a general temporal trend of ADV seroprevalence at European scale. CONCLUSIONS The seroprevalence of ADV in wild boar in Switzerland belongs among the lowest documented in Europe. Considering the disparity of seroprevalences in wild boar in Europe, the fact that seroprevalences in Switzerland and other countries have decreased despite increasing wild boar densities and the knowledge that stress leads to the reactivation of latent ADV with subsequent excretion and transmission, we hypothesize that not only animal density but a range of factors leading to stress - such as management - might play a crucial role in the dynamics of ADV infections.