Excretion Ratio Research Articles

Clinical and Pharmacotherapeutic Relevance of the Double-Chain Domain of the Angiotensin II Type 1 Receptor Blocker Olmesartan

We previously reported that the angiotensin II type 1 (AT1) receptor blocker (ARB) olmesartan has two important interactions to evoke inverse agonism (IA). We refer to these interactions as the “double-chain domain (DCD).” Since the clinical pharmacotherapeutic relevance of olmesartan is still unclear, we examined these effects in rats and humans. We analyzed the effects at an advanced stage of renal insufficiency in Dahl salt-sensitive hypertensive rats (Study 1). Rats were fed a high-salt diet from age 9 weeks and arbitrarily assigned to three treatment regimens at age 16 to 21 weeks: olmesartan (2 mg/kg/day) with DCD, a compound related to olmesartan without DCD (6 mg/kg/day, R-239470) or placebo. We also compared the depressor effects of olmesartan to those of other ARBs in patients with essential hypertension (Study 2). Thirty essential hypertensive outpatients who had been receiving ARBs other than olmesartan were recruited for this study. Our protocol was approved by the hospital ethics committee and informed consent was obtained from all patients 12 weeks prior to switching from ARBs other than olmesartan to olmesartan. In Study 1, olmesartan induced a more prominent suppression of the ratio of urinary protein excretion to creatinine at age 21 weeks without lowering blood pressure among the three groups. In Study 2, the depressor effect of olmesartan was significantly stronger than those of other ARBs, which do not contain the DCD. These additive effects by olmesartan may be due to DCD.

Vitamin D homeostasis is disrupted in a type II diabetic rat model due to aberrant reuptake in kidney

Alterations of serum levels of the major circulating form of vitamin D (25‐hydroxycholecalciferol, 25D3) and its active hormone derivative (1,25‐dihydroxycholecalciferol, 1,25D3) have been associated with type II diabetes, but a mechanism for this occurrence has not been fully elucidated. In this study, we used the Zucker Diabetic Fatty (ZDF) rat model to characterize the role of renal reabsorption in vitamin D homeostasis in diabetic and non‐diabetic rats fed vitamin D sufficient (1000 IUs/kg), deficient (0 IUs/kg), and supplemented diets (10000 IUs/kg). Using ELISA, we analyzed serum and urinary 25D3, 1,25D3 and vitamin D binding protein (DBP) levels in 16 wk old ZDF and lean rats. Serum levels of both 25D3 and 1,25D3 were significantly lower in diabetic animals than their non‐diabetic controls fed either vitamin D deficient or sufficient diets. Furthermore, diabetic rats excreted greater proportions of DBP and 25D3 in urine than their respective controls. Vitamin D supplementation markedly increased serum 25D3 in diabetic rats, but had no effect on serum 1,25D3 or urinary excretion ratios. Taken together, these data suggest that compromised renal reabsorption of 25D3 and DBP may be a significant contributing mechanism leading to reduced vitamin D status in diabetes. Supported by USDA (Iowa State University Nutrition and Wellness Center SRPG to MR) and the Iowa State University Experiment Station.

Renal excretion of clofarabine: Assessment of dose-linearity and role of renal transport systems on drug excretion

The renal excretion of clofarabine was studied in vitro in the isolated perfused rat kidney (IPK) model and in vivo in rats. Clofarabine excretion was studied at four doses (160, 800, 2000 and 4000microg) in the IPK, targeting perfusate levels of 2, 10, 25, 50microg/mL, respectively. Clofarabine (2microg/mL) was also co-perfused with known inhibitors of the, organic cation (cimetidine, ranitidine and tyramine) and organic anion (probenecid, ellagic acid) transport systems. Additionally, the effect of medications including, itraconazole, digoxin, fludarabine and cytarabine (Ara-C) on clofarabine excretion was, evaluated. Based on IPK results, in vivo studies were performed to assess the plasma, pharmacokinetics and urinary recovery of clofarabine (6.5mg/kg, IV) pretreatment, with cimetidine (250mg/kg, IV). Clofarabine clearance was non-linear in the IPK, although at concentrations that were approximately 10- to 100-fold higher than maximum concentrations observed in humans. Excretion ratio data indicated a shift from net, secretion (XR=1.2+/-0.33) to net reabsorption (XR=0.78+/-0.40) at the highest dose, tested. Clofarabine clearance was significantly reduced upon co-administration with, cimetidine (0.83+/-0.22-->0.32+/-0.058mL/min). In vivo data correlated with IPK results as clofarabine clearance decreased 61% (20.2-7.80mL/min/kg), upon co-administration with cimetidine in rats. The results suggest that clofarabine is a substrate for a cimetidine-sensitive organic cation transporter system in the kidney, presumably OCT2. The magnitude of the cimetidine-clofarabine interaction was similar, in IPK and in vivo, demonstrating the utility of the IPK model in characterizing renal, drug excretion and assessing potential drug-drug interactions.

Metabolism of sulphobromophthalein II. Species differences between rats, guinea-pigs and rabbits.

Interesting species differences in the metabolism of sulphobromophthalein sodium have been observed between rats, guinea-pigs and rabbits. The species difference was measured in terms of sulphobromophthalein monoglutathione conjugate (mGSH) positional isomer formation. After an intravenous injection of sulphobromophthalein to rats, 92% of sulphobromophthalein-mGSH excreted into bile was the alpha-isomer. In contrast, in guinea-pigs the three isomers alpha, beta and delta were excreted in equivalent amounts. In rabbits, the majority of sulphobromophthalein-mGSH was excreted as the beta-isomer. The formation ratio of glutathione (GSH) conjugates in-vitro using cytosolic glutathione S-transferases (GSTs) prepared from livers generally accounted for the biliary excretion ratio of alpha-, beta- and delta-monomercaptide isomers in-vivo. GSTs from the livers of rat, guinea-pig, and rabbit were purified and characterized. Although their main GSTs produced different isomers, their 20 amino acid residues showed that they belonged to the same class mu of GSTs. The results suggested differences of the three-dimensional structure of GSTs that formed sulphobromophthalein-mGSH isomers between the three animal species.

The Disposition of Pravastatin in a Rat Model of Streptozotocin-Induced Diabetes and Organic Anion Transporting Polypeptide 2 and Multidrug Resistance-Associated Protein 2 Expression in the Liver

The combination of diabetes and hyperlipidemia promotes the development of atherosclerosis. Therefore, it is important for diabetic patients to control blood fat. 3-Hydroxy-3-methylglutaryl enzyme A (HMG-CoA) reductase inhibitors (statins), like pravastatin, are frequently administered to diabetic patients for this purpose. Although the alterations of metabolic enzymes and transporters in the diabetic liver maybe change the disposition of pravastatin, the effect has not been fully investigated. In the present study, we investigated the disposition of pravastatin and the mRNA expression of transporters in the liver. Pravastatin (5 mg.kg(-1) body weight) was administered intravenously to diabetic rats, and the pravastatin concentrations in the plasma, urine, and bile were measured by high-performance liquid chromatography. Changes in the mRNA expressions of multidrug resistance-associated protein 2 (MRP2) and organic anion transporting polypeptide 2 (OATP2) in the liver were also estimated using reverse transcriptase-polymerase chain reaction (RT-PCR). We found that the plasma pravastatin concentration was lower in the diabetic rat because the transportation of pravastatin into hepatocytes was promoted along with increased expression of OATP2. The biliary excretion ratio of pravastatin was significantly lower in the diabetic rat because the pravastatin transportation into bile was reduced along with the decreased expression of MRP2. To clarify these phenomena, the analysis of mRNA expression using real-time PCR and the measurement of the amount and the activity of proteins are necessary in future study.

Stoichiometry of benthic invertebrate nutrient recycling: interspecific variation and the role of body mass

Ecological stoichiometry (ES) and allometry offer frameworks for predicting how nutrient recycling varies within and among animal species. Despite the importance of benthic-derived nutrients in most aquatic systems, predictions based on ES and allometry have been poorly tested among benthic invertebrate consumers. Here, we show that the rates and ratios at which three freshwater benthic invertebrate species (a crustacean, an insect, and a polychaeta) recycled nitrogen (N) and phosphorus (P) can be partially predicted by ES and allometry depending on whether data are analyzed intra- or interspecifically. Mass-specific N and P excretion rates were negatively correlated with invertebrate body size both among and within taxa, supporting allometric predictions. However, mass-specific N and P excretion rates were positively and negatively correlated to invertebrate body N and P, respectively, but only when data were analyzed intraspecifically. As a corollary, the mass-specific N:P excretion ratio was positively related to body N:P ratio. Such a contrasting pattern on excretion-mediated N and P recycling suggests that stoichiometric constraints regarding consumer-resource imbalances for the three species utilized in this study may be stronger for P than for N. Our results indicate that the variation in nutrient recycling, which is mediated by taxonomic constraints on stoichiometry and allometry, may substantially help us to understand the importance of benthic detritivorous species to the functioning of aquatic ecosystems.

Understanding measurements of intestinal permeability in healthy humans with urine lactulose and mannitol excretion

Our aim was to understand the information from differential two-sugar excretion (2-SE) in measuring intestinal permeability. In a crossover study in 12 healthy volunteers, we compared urinary excretion ratios of lactulose (L) to mannitol [(M) LMR] after ingestion in liquid formulation (LF) or in delayed-release, methacrylate-coated capsules (CAP). Both formulations were radiolabelled. Urine was collected every 2 h from 0 to 8 h, and from 8 to 24 h. Two hours after LF, gastric residual was 15.9 +/- 6.2% (SEM), and the percentage in colon was 49.6 +/- 7.8%; in 11/12 participants, liquid had entered colon within 2 h. Average CAP arrival time in colon was 5.16 +/- 0.46 h (mode 6 h). After LF, mannitol was extensively absorbed in the first 8 h; lactulose absorption was low throughout the 24 h. After the LF, the LMR (geometric mean, 95% CI per h) in the 0-2 h urine was [0.08 (0.05, 0.11)], which was lower than in 8-24 h urine [0.32 (0.16, 0.46); P < 0.05]. Urine LMRs at 8-24 h were similar after LF or CAP. We concluded that, after LF, sugar excretion in 0-2 h urine may reflect both SI and colon permeability. Colonic permeability is reflected by urine sugar excretion between 6 and 24 h. CAP delivery reduces mannitol excreted at 0-6 h, compared with LF. The 0-5 or 6 h 2-SE urine likely reflects both SI and colon permeability; the higher LMR in the 8-24 h urine relative to 0-2 h urine should be interpreted with caution and does not mean that colon is more permeable than SI.

Renoprotective effect of rosuvastatin in DOCA-salt hypertensive rats

Pleiotropic effects of statins represent potential mechanisms for the treatment of end organ damage in hypertension. This study has investigated the effects of rosuvastatin (10 mg/kg/day) on renal function impairment, glomerulosclerosis and tubulointerstitial fibrosis in deoxycorticosterone acetate (DOCA)-salt hypertensive (DSH) rat. Rats were implanted with DOCA strips (200 mg/kg) on 1 week after unilateral nephrectomy. Rats received a controlled diet with or without rosuvastatin. Three weeks after DOCA implantation, systolic blood pressure (SBP) was measured by tail-cuff method. The glomerulosclerosis and tubulointerstitial fibrosis was determined by Masson's trichrome stain. The tumour necrosis factor (TNF-alpha), interleukin-1beta (IL-1beta), interferon-gamma (IFN-gamma), monocyte chemoattractant protein1 (MCP1), intercellular adhesion molecule-1 (ICAM-1) and endothelin-1 (ET-1) were determined by real-time polymerase chain reaction. The expression of ED-1, transforming growth factor-beta1 (TGF-beta1) and connective tissue growth factor (CTGF) was determined in the kidney by immunoblotting and immunohistochemistry. In DSH rats, SBP was increased, which was not affected by rosuvastatin treatment. Creatinine clearance was decreased while urinary albumin excretion ratio was increased in DSH rats compared with controls, which were attenuated by rosuvastatin treatment. Glomerulosclerosis and tubulointerstitial fibrosis in DSH rats were attenuated by rosuvastatin treatment. The messenger RNA expression of TNF-alpha, IL-1beta, IFN-gamma, MCP1, ICAM-1 and ET-1 was increased in DSH, which was attenuated by rosuvastatin treatment. The expression of ED-1, TGF-beta and CTGF was increased in the kidney of DSH, which was counteracted by rosuvastatin treatment. Rosuvastatin is effective in preventing progression of renal injury in DSH, the mechanism of which is associated with anti-inflammatory and anti-fibrotic effects.

Abstract 4875: Obstructive Sleep Apnea is Associated With Increased Aortic Stiffening, Microalbuminuria and Endothelial Dysfunction in Hypertensives: A Double Enemy to the Vasculature

Introduction: Incriminating evidence of an adverse effect of obstructive sleep apnea (OSA) on the vasculature is increasing. We investigated the degree of vascular impairment in the high risk population of hypertensives with OSA by diverse atherosclerotic surrogates. Methods : We studied 62 consecutive patients [49 men, aged 48±7 years, 31 smokers, body mass index (BMI) 32±4kg/m 2 ) with untreated hypertension and OSA diagnosed by polysomnography (PSG) [apnea/hypopnea index (AHI)≥5], and a control group of 70 untreated hypertensives without OSA (AHI&lt;5) matched for age, sex, body mass index, smoking status and 24h systolic blood pressure (BP). All subjects underwent 24h ambulatory BP monitoring, echocardiography and aortic stiffness evaluation by means of carotid - femoral pulse wave velocity (PWV) using an automatic device (Complior SP). Metabolic profile, serum creatinine levels (sCr), glomerular filtration rate (eGFR), and asymmetric dimethyl-arginine (ADMA) were assessed from a morning blood sample. The albumin/creatinine excretion ratio (ACR) was calculated from two non consecutive urine morning samples. Results : Hypertensives with OSA had similar 24h systolic BP (140±9 vs. 138±6 mmHg, p=NS) but higher 24h diastolic BP levels (87±6 vs. 84±7 mmHg, p=0.03) compared to the control group. Left ventricle mass index was greater in the OSA group (109±23 vs. 100±25 gr/m 2 , p=0.04), while relative wall thickness (0.43±0.07 vs. 0.43±0.08) and metabolic profile did not differ (p=NS for all). Although sCr and eGFR were similar between the two groups (0.96±0.18 vs. 0.94±0.18mg/dl and 114±30 vs. 116±27 ml/min/1.73m 2 , p=NS for both), patients with OSA exhibited higher levels of logACR and logADMA compared to those without (1.07±0.31 vs. 0.66±0.38 mg/g, −0.25±0.1 vs. −0.31±0.1 μ mol/l, respectively, p&lt;0.0001 for both) even after adjustment for confounders. Furthermore, PWV was elevated in OSA patients compared to the control group. (8.2±0.7vs.7.2±0.9m/sec, p&lt;0.001). In the entire study population logAHI was correlated with PWV (r=0.35, p&lt;0.001), logADMA (r=0.30, p=0.001) and logACR (r=0.34, p&lt;0.0001). Conclusions : Elevated values of ADMA, PWV and ACR in hypertensives with OSA reveal an atherosclerotic state enhanced by sleep disordered breathing.

Abstract 4856: Nighttime Sodium Excretion Following Acute Sodium Loading Predicts Blood Pressure Dipping and Aortic Augmentation Index

Background: In subjects who are in sodium (Na) balance, chronically increased night:day urinary Na excretion ratio is associated with arterial stiffening and nocturnal blood pressure non-dipping; less is known about these relationships following acute Na loading. Methods: We studied 11 young (24±5 yrs, 8 male/3 female), non obese, otherwise healthy prehypertensives over 6 days. Subjects ate a 20 mMol Na diet for 4 days. On day 5, they received 2 liters of 0.9% saline (308 mMol Na) over 2 hours, then an additional 130 mMol Na over 2 meals. Between days 4 and 6, subjects performed complete urine collections and ambulatory blood pressure monitoring, and underwent SphygmoCor assessment of aortic augmentation index (AIx75; in %, standardized to heart rate 75) on days 4 and 6. We defined the increase in nighttime urinary Na excretion following Na loading as: Nighttime-Na Excretion Ratio (NNER) = mMol Na/hr (rate night 5, post-Na load)/mMol Na/hr (rate night 4, pre-Na load). We also defined the change in nocturnal blood pressure dipping between night 4 (pre-Na load) and night 5 (post-Na load) as: ChgDip = nocturnal decrease in mean arterial pressure [mmHg, night 4] - nocturnal decrease in mean arterial pressure [mmHg, night 5] We then explored how the NNER related to ChgDip and AIx75 post-Na loading with linear regression. Results: The nighttime Na excretion rate increased following Na loading (.9±.9 to 8±4 mMol/hr, p &lt; .001); the mean NNER was 13±9. After stepwise regression including age, gender, body mass index, daytime Na excretion, post-Na mean arterial pressure, and pre-Na blood pressure dip, higher NNER predicted less effect of Na loading on ChgDip ( β = −0.4, p = .005). In a stepwise regression model including age, gender, height, mean arterial pressure, left ventricular mass, aortic augmentation index in low-Na balance, and daytime Na excretion, the NNER was the only significant predictor of post-Na loading AIx75 ( β = −1.3, p= .009). Blood pressure dipping and AIx75 did not correlate with daytime Na excretion. Conclusions : Following an acute Na load, prehypertensive subjects who increase their nighttime Na excretion rate the most preserve nocturnal blood pressure dipping and have lower aortic augmentation index.

Prognostic relevance of clinical and histological features in IgA nephropathy treated with steroid and angiotensin receptor blockers

The prognostic relevance of clinical and histological features on renal outcome has not been assessed in patients with IgA nephropathy (IgAN) treated with the combination therapy of steroid and angiotensin receptor blockers (ARB). A prospective trial of a combination of steroid and ARB was performed in 50 patients with IgAN, proteinuria and serum creatinine levels < 2 mg/dl. Over a mean follow-up period of 4 years, the combination therapy reduced proteinuria and hematuria and improved renal function in most patients. The mean change in estimated GFR (eGFR) was + 0.30 +/- 0.74 ml/min/1.73 m2/month. Forty-three patients (86%) exhibited stable renal function and 7 patients (14%) reached the primary end point of a (3) 20% decrease in eGFR from baseline levels. Between the nonprogressive and progressive patients, there were significant differences in the levels of urine protein/ creatinine excretion ratio (PCR) at baseline and throughout the follow-up period as well as baseline eGFR and degree of glomerular crescents (p < 0.05). Forty (80%) and 24 patients (48%) had a urine PCR < 1 and < 0.3 g/g, respectively, at their last follow-up. Renal survival was better in patients who had initial urine PCR < 3 g/g as well as final PCR < 1 g/g. Regression analysis revealed that the final urine PCR and age were critical determinants of slope of the eGFR by both univariate and multivariate analyses. However, eGFR, pathologic findings, systolic BP, proteinuria, and body mass index at the initial presentation were not predictive of slope. Our results indicate that achieving a low urinary protein excretion is the main determinant for the good outcome in patients treated with combination therapy.

Renoprotective effect of rosuvastatin in DOCA-salt hypertensive rats

BACKGROUND Pleiotropic effects of statins represent potential mechanisms for the treatment of end organ damage in hypertension. This study has investigated the effects of rosuvastatin (10 mg/kg/day) on renal function impairment, glomerulosclerosis and tubulointerstitial fibrosis in deoxycorticosterone acetate (DOCA)-salt hypertensive (DSH) rat. METHODS Rats were implanted with DOCA strips (200 mg/kg) on 1 week after unilateral nephrectomy. Rats received a controlled diet with or without rosuvastatin. Three weeks after DOCA implantation, systolic blood pressure (SBP) was measured by tail-cuff method. The glomerulosclerosis and tubulointerstitial fibrosis was determined by Masson's trichrome stain. The tumour necrosis factor (TNF-alpha), interleukin-1beta (IL-1beta), interferon-gamma (IFN-gamma), monocyte chemoattractant protein1 (MCP1), intercellular adhesion molecule-1 (ICAM-1) and endothelin-1 (ET-1) were determined by real-time polymerase chain reaction. The expression of ED-1, transforming growth factor-beta1 (TGF-beta1) and connective tissue growth factor (CTGF) was determined in the kidney by immunoblotting and immunohistochemistry. RESULTS In DSH rats, SBP was increased, which was not affected by rosuvastatin treatment. Creatinine clearance was decreased while urinary albumin excretion ratio was increased in DSH rats compared with controls, which were attenuated by rosuvastatin treatment. Glomerulosclerosis and tubulointerstitial fibrosis in DSH rats were attenuated by rosuvastatin treatment. The messenger RNA expression of TNF-alpha, IL-1beta, IFN-gamma, MCP1, ICAM-1 and ET-1 was increased in DSH, which was attenuated by rosuvastatin treatment. The expression of ED-1, TGF-beta and CTGF was increased in the kidney of DSH, which was counteracted by rosuvastatin treatment. CONCLUSION Rosuvastatin is effective in preventing progression of renal injury in DSH, the mechanism of which is associated with anti-inflammatory and anti-fibrotic effects.

The Diuretic Effect in Human Subjects of an Extract ofTaraxacum officinaleFolium over a Single Day

Taraxacum officinale (L.) Weber (Asteraceae) has been extensively employed as a diuretic in traditional folk medicine and in modern phytotherapy in Europe, Asia, and the Americas without prior clinical trial substantiation. In this pilot study, a high-quality fresh leaf hydroethanolic extract of the medicinal plant T. officinale (dandelion) was ingested by volunteers to investigate whether an increased urinary frequency and volume would result. Volume of urinary output and fluid intake were recorded by subjects. Baseline values for urinary frequency and excretion ratio (urination volume:fluid intake) were established 2 days prior to dandelion dosing (8 mL TID) and monitored throughout a 1-day dosing period and 24 hours postdosing. For the entire population (n = 17) there was a significant (p < 0.05) increase in the frequency of urination in the 5-hour period after the first dose. There was also a significant (p < 0.001) increase in the excretion ratio in the 5-hour period after the second dose of extract. The third dose failed to change any of the measured parameters. Based on these first human data, T. officinale ethanolic extract shows promise as a diuretic in humans. Further studies are needed to establish the value of this herb for induction of diuresis in human subjects.

The preliminary experimental and clinical study of the relationship between the pigment gallstone and intestinal mucosal barrier

To investigate the relations between the formation of pigment gallstone and the function of the intestinal mucosal barrier, as well as the underlying mechanism. Eighty guinea pigs were randomly divided into three groups in which they were respectively given normal diet, gallstone-causing diet, and gallstone-formation diet with a supplementary intestinal mucosal protection compound known as glutamine. The model of pigment gallstone was established after 8 weeks of dietary administration. Indices about the function of the intestinal mucosal barrier and bacterial translocation were measured. Clinical cases were divided into three groups: control, cholesterol gallstone, and pigment gallstone, where the levels of plasma diamine oxidase (DAO), plasma endotoxin and the excretion rates of technetium 99m-diethylene triamine pentaacetic acid (99mTC-DTPA) in the urine of each group were measured. In the pigment gallstone group, the level of plasma DAO and endotoxin, the excretory ratio of lactulose and mannitol in urine, the bacterial translocation ratio in the celiac lymph nodes and the activities of beta-glucuronidase increased comparing to the control group. The gallstone-formation rate for the intestinal mucosal protection group (GLN) decreased, and other indices, except the activity of beta-glucuronidase, were all lower than that of gallstone-formation group. In the clinical experiment, the levels of plasma DAO and endotoxin, as well as the excretory rate of 99mTC-DTPA in urine were higher in the patients with gallstones than that in the control group. The formation of pigment gallstone was related to the abnormal function of the intestinal mucosal barrier. The abnormality in the function of the intestinal mucosal barrier probably induced the formation of gallstone by a bacterial translocation mechanism.

Pharmacokinetics of pefloxacin mesylate in human urine using capillary electrophoresis electrochemiluminescence detection

A novel and simple method to determine pharmacokinetics of pefloxacin mesylate (PM) in urine of seven healthy adults was developed. The proposed methodology was based on the electrochemiluminescence (ECL) of tris(2,2′-bipyridine)ruthenium (II) at a platinum electrode. The ECL intensity was found greatly enhanced in the presence of PM, which could directly participate in the light-emitting reaction as the reductant (in former/unchanged form). Under optimised conditions, the calibration curve was linear from 0.02 to 12 mg/L with a detection limit of 0.004 mg/L ( σ = 3). The RSD of the peak height was less than 2.4% ( n = 6). The recoveries in human urine were 96.2% to 98.3%. The highest excretion rate in urine was observed during the period 1.5–2 h after oral administration. The urinary excretion ratio of PM was 13.6% within 48 h.

3-Hydroxybenzo(a)pyrene as a biomarker of dermal exposure to benzo(a)pyrene

The aim of this study was to determine the percutaneous absorption flux of BaP (20 microg/cm(2) in ethanol) and the usefulness of urinary 3-OHBaP as a bio-indicator of dermal exposure to BaP. The percutaneous absorbed dose and absorption flux were estimated by comparison with intravenous administration of BaP (0.01 and 0.05 mg/kg in Cremophor) as reference way. A percutaneous absorption flux of 0.37 microg/cm(2)/h was determined by killing groups of rats, following exposure time of 4.5 and 24 h. [(14)C] skin content was 3.1 microg/cm(2), after 24 h exposure to BaP. Total urinary 3-OHBaP accounted for 0.4% of the real absorbed dose, which was fourfold higher than the percentage of an intravenous dose excreted as 3-OHBaP. This finding reveals that percutaneous absorption of BaP, based on the ratio of urinary excretion of 3-OHBaP following percutaneous exposure compared to percutaneous absorption following intravenous administration of BaP, is overestimated in the rat. In vitro, BaP was intensively metabolised by rat skin. Unchanged BaP and 3-OHBaP in receptor fluid accounted for 50 and 30% of the total radioactivity. This percutaneous first past effect of BaP in rats could, in part, explain the higher urinary excretion ratio of 3-OHBaP compared to the value based on intravenous administration of BaP. Conversely, BaP was largely lower metabolised as 3-OHBaP during percutaneous absorption by humans, so BaP absorption flux should be overestimated to a lesser extent in humans than in rats.

Prediction of albuminuria by different blood pressure measurement methods in type 1 diabetes: a pilot study

In type 1 diabetes, the risk of nephropathy is strongly influenced by the level of blood pressure (BP). Ambulatory BP (ABP) monitoring has revealed an association between disturbed nocturnal BP drop and albuminuria and suggested a role of BP in microalbuminuria development. This study investigated the relationship between the urinary albumin excretion ratio (AER) and home BP (HBP) compared with ABP and clinical BP (CBP) measurements. A total of 50 adolescents and young adults with type 1 diabetes without hypertension or overt proteinuria (mean age 20+/-3.8 (s.d.) years, 21 male) had measurements of CBP (3 visits), HBP (6 days), 24-h ABP and AER (daytime and nighttime in the same 24 h with ABP monitoring). AER of 24 h was correlated with systolic 24-h (r=0.31), daytime (r=0.33) and nighttime ABP (r=0.36), without significant correlation with diastolic ABP, CBP or HBP (systolic or diastolic). Nighttime AER was correlated with 24-h (r=0.39/0.35, systolic/diastolic), daytime (r=0.36/0.32) and nighttime ABP (r=0.44/0.28). HBP was not associated with nighttime AER, but CBP was (diastolic BP only, r=0.41). No significant correlations were found between daytime AER and BP measurements. The nocturnal BP dip was not associated with any BP value. In non-dippers, nighttime AER showed strong correlations with ABP (24-h: r=0.45/0.42, systolic/diastolic; daytime: r=0.46/0.45; nighttime: r=0.49/0.35), HBP (r=0.34/0.31) and CBP (r=0.39/0.47). No such associations were found in dippers (r=0.05-0.10). These preliminary data suggest that in the early stage of diabetes-1, 24-h ABP monitoring seems to be the optimal method of revealing the association between BP and albuminuria, and cannot be replaced by HBP monitoring.

Identification of Human Metabolites of (–)-N-{2-[(R)-3-(6,7-Dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonyl)piperidino]ethyl}-4-fluorobenzamide (YM758), a Novel If Channel Inhibitor, and Investigation of the Transporter-Mediated Renal and Hepatic Excretion of These Metabolites

(-)-N-{2-[(R)-3-(6,7-Dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonyl)piperidino]ethyl}-4-fluorobenzamide (YM758) is a novel inhibitor of the "funny" If current channel (If channel) that is expressed in the sinus node of heart and is being developed as a treatment for stable angina and atrial fibrillation. Its metabolites were identified in human urine, plasma, and feces by radio-high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry analyses after oral administration of [(14)C]YM758. 6,7-Dimethoxy-2-[(3R)-piperidin-3-ylcarbonyl]-1,2,3,4-tetrahydroisoquinoline (YM-252124), (5R)-5-[(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)carbonyl]piperidin-2-one (YM-385459), 2-{[(3R)-1-{2-[(4-fluorobenzoyl)amino]ethyl}piperidin-3-yl]carbonyl}-7-methoxy-1,2,3,4-tetrahydroisonolin-6-yl beta-D-glucopyranosiduronic acid (AS2036329), and the unchanged drug were detected as major constituents in both urine and plasma, whereas N-(4-fluorobenzoyl)glycine (YM-385461) was detected in plasma, but not in urine. The renal and hepatic uptake transporters for these metabolites were investigated by assessing their inhibitory effect on uptake activity in human (h) organic cation transporter (OCT) 1-3/rat (r) Oct1-3, human organic anion transporter (OAT) 1/rOat1, hOAT3/rOat3, and organic anion-transporting protein 1B1/1B3-expressing HEK293 cells. IC(50) values of YM-252124 for 1-methyl-4-phenylpyridinium uptake via hOCT2 and rOct2 were 93.9 and 1700 microM, respectively, suggesting that this metabolite is secreted into urine via hOCT2/rOct2 and that the large difference in the inhibitory potentials between hOCT2 and rOct2 explains the species difference in the urinary excretion ratio of the radioactivity. The renal secretion of YM-385461, one derivative of p-aminohippuric acid, via hOAT1/rOat1, and hepatic uptake of YM-252124 via hOCT1/rOct1 was also expected. This kind of study was useful in investigating the relationship between the urinary/hepatic elimination and the transport activity for metabolites.

Ammonia emissions and dry matter of separated pig manure fractions as affected by crude protein concentration and sugar beet pulp inclusion of finishing pig diets

It was hypothesised that decreasing dietary crude protein (CP) and including sugar beet pulp (SBP) would reduce the urine:faeces nitrogen (N) excretion ratio of finisher boars and decrease ammonia emissions from separated liquid and solid manure fractions. A 2 × 2 factorial experiment was conducted to investigate the effect of dietary CP concentration (150 g kg −1 vs. 200 g kg −1) and SBP (0 g kg −1 vs. 200 g kg −1) inclusion on nutrient digestibility, N excretion and manure output from finisher boars (63 ± 1.3 kg). Urine and faeces collections were pooled in original excretion ratios. Manure samples were separated into liquid and solid fractions using separating-cloth. A 2 × 2 × 2 factorial design was used to investigate the interaction of CP concentration (150 g kg −1 vs. 200 g kg −1), SBP (0 g kg −1 vs. 200 g kg −1) and manure treatment (unseparated manure vs. cumulated separated fractions) on ammonia emissions from unseparated manure and cumulated fractions. There was an interaction between SBP and manure treatment ( P < 0.01) on manure dry matter. Dietary SBP increased the dry matter of unseparated manure compared with pigs offered diets containing no SBP. However there was no effect of dietary SBP on dry matter of the separated fractions. Dietary SBP decreased ammonia emissions from 0 to 240 h ( P < 0.05) from unseparated manure and separated fractions compared with unsupplemented diets. Decreasing dietary CP to 150 g kg −1 reduced total N excretion ( P < 0.001) and ammonia emissions from 0 to 240 h ( P < 0.1) from unseparated manure and separated fractions. There was an interaction between CP and SBP on N retention ( P < 0.05). Pigs offered the 150 g kg −1 CP diet containing SBP decreased N retention compared with pigs offered the 150 g kg −1 CP diet containing no SBP. However there was no effect of SBP in pigs offered the high CP diets on N retention. Pigs offered diets containing SBP reduced manure volume ( P < 0.05) compared with pigs offered diets containing no SBP. In conclusion, increasing dietary SBP and reducing CP concentrations decreased ammonia emissions from unseparated manure and separated liquid and solid fractions. Furthermore, dietary SBP increased the dry matter of unseparated manure however SBP inclusion had no effect on the dry matter of the separated manure fractions.

Nutrient Excretion Rates of Anadromous Alewives during Their Spawning Migration

AbstractExcretion is one of the processes through which anadromous fishes move marine‐derived nutrients into freshwater ecosystems, but no direct estimates of nutrient excretion rates by anadromous fish exist. We estimated the mass‐specific nutrient excretion rates of anadromous alewives Alosa pseudoharengus during their spring spawning migration into Bride Lake, Connecticut. Anadromous alewives excreted an average of 2.17 μg of phosphorus per gram of wet fish mass per hour and 24.71μg of nitrogen. The mean N:P ratio (by mass) of nutrient excretion was 11.7. Most of the nitrogen excreted was in the form of NH4+. Our results suggest that excretion by anadromous fish can affect local food webs and ecosystem function when ecosystems are relatively small and fish aggregate at high densities, such as at the peak of the spawning run.