Development of New Targeted Inulin Complex Nanoaggregates for siRNA Delivery in Antitumor Therapy.

Here, a novel strategy of formulating efficient polymeric carriers based on the already described INU-IMI-DETA for gene material whose structural, functional, and biological properties can be modulated and improved was successfully investigated. In particular, two novel derivatives of INU-IMI-DETA graft copolymer were synthesized by chemical functionalisation with epidermal growth factor (EGF) or polyethylenglycol (PEG), named INU-IMI-DETA-EGF and INU-IMI-DETA-PEG, respectively, in order to improve the performance of already described "inulin complex nanoaggregates" (ICONs). The latter were thus prepared by appropriately mixing the two copolymers, by varying each component from 0 to 100 wt% on the total mixture, named EP-ICONs. It was seen that the ability of the INU-IMI-DETA-EGF/INU-IMI-DETA-PEG polymeric mixture to complex siGL3 increases with the increase in the EGF-based component in the EP-ICONs and, for each sample, with the increase in the copolymer:siRNA weight ratio (R). On the other hand, the susceptibility of loaded siRNA towards RNase decreases with the increase in the pegylated component in the polymeric mixture. At all R values, the average size and the zeta potential values are suitable for escaping from the RES system and suitable for prolonged intravenous circulation. By means of biological characterisation, it was shown that MCF-7 cells are able to internalize mainly the siRNA-loaded into EGF-decorated complexes, with a significant difference from ICONs, confirming its targeting function. The targeting effect of EGF on EP-ICONs was further demonstrated by a competitive cell uptake study, i.e., after cell pre-treatment with EGF. Finally, it was shown that the complexes containing both EGF and PEG are capable of promoting the internalisation and therefore the transfection of siSUR, a siRNA acting against surviving mRNA, and to increase the sensitivity to an anticancer agent, such as doxorubicin.

Maternal Hypercholesterolemia Associated with Nicotine Exposure in Adulthood May Induce Kidney Injury in Male Rats if Hypomagnesemia Occurs.

BACKGROUND/AIMS: Maternal hypercholesterolemia is a risk factor to renal injury in rat pups at adulthood, especially if they feed a cholesterol-enriched diet after weaning. However, the renal function of male pups of dams with hypercholesterolemia (PH) that were fed a regular chow from weaning to adulthood needs investigation, particularly those exposed to an adverse risk such as nicotine. METHODS: We evaluated the renal function of PH animals and we compared the data with those found in male pups of control dams (PC) at 3- and 6-month-old by inulin clearance. Moreover, we investigated the effect of nicotine treatment for 8 days in both PH and PC animals at 6 months old via metabolic function studies and by renal histological analysis. RESULTS: Inulin clearance and other renal function parameters were similar in PH and PC animals at 3 and 6 months old. Nevertheless, the PH group showed significant differences with regard to histological analysis despite a similar number of glomeruli. The glomerular area of PH animals was significantly smaller than that measured in PC animals, and the fractional interstitial area was significantly larger in PH animals than that measured in PC animals at 3 months old. With regard to nicotine treatment, we observed a trend for a reduction in creatinine clearance in both PC and PH groups, but only PH animals showed hypomagnesemia and the highest fractional interstitial area. CONCLUSIONS: The offspring exposed to a high cholesterol milieu during intrauterine and neonatal life may show a silent kidney injury at adulthood that may be aggravated by nicotine exposure if hypomagnesemia occurs.

Design, synthesis and evaluation of biotin decorated inulin-based polymeric micelles as long-circulating nanocarriers for targeted drug delivery.

Here, long-circulating behaviors of Inulin-based nanomicelles are demonstrated for the first time in vivo. We show the synthesis and evaluation of biotin (BIO)-decorated polymeric INVITE micelles constituted of substances of natural origin, Inulin (INU) and Vitamin E (VITE), as long-circulating carriers for receptor-mediated targeted drug delivery. The resulting INVITE or INVITE-BIO micelles, nanometrically sized, did not reveal any cytotoxicity after 24h of incubation with Caco-2 cells. Moreover, in vitro studies on Caco-2 cells monolayers indicated that the transport of INVITE-BIO micelles was faster than surface unmodified INVITE micelles. In vivo optical imaging studies evidenced that, upon intravenous administration, INVITE-BIO micelles were quantitatively present in the body up to 48h. Instead, after oral administration, the micelles were not found in the systemic circulation but eliminated with the normal intestinal content. In conclusion, INVITE-BIO micelles may enhance drug accumulation in tumor-cells over-expressing the receptor for biotin through receptor mediated endocytosis.

The kidneys play an important role in the clearance of rFVIIa in rats.

INTRODUCTION: Previous distribution and histological studies have indicated that the kidneys and renal proximal tubular cells play a role in clearance of rFVIIa. However, the relative importance of the kidneys in clearance of rFVIIa has not previously been addressed. The objective of the present study was to evaluate the importance of the kidneys in the clearance process of rFVIIa after iv administration to rats using a nephrectomy model. MATERIALS AND METHODS: A nephrectomized rat model was established and validated using inulin, a compound primarily cleared by the kidneys, as a test substance and several physiological parameters were monitored to ensure viability and robustness of the model. The model was then used for pharmacokinetic evaluation of renal clearance of rFVIIa. The pharmacokinetic parameters for rFVIIa were evaluated both by use of standard non-compartmental methods and by use of mixed effects methods, where a pharmacokinetic model was used to simultaneously model all data from healthy, sham operated, and nephrectomized rats. RESULTS: Nephrectomized animals showed stable rectal temperature, SpO2 and pulse and as expected, clearance of inulin was essentially abolished compared to control animals (p<0.001). For rFVIIa, nephrectomy resulted in a clearance and terminal half-life of 34mL/h/kg and 2.8h compared to 68mL/h/kg and1.9h in rats exposed to sham surgery (p<0.0001 for both parameters). CONCLUSION: The present data show that about 50% of the total clearance of rFVIIa from circulation in rats under isoflurane anaesthesia is due to renal clearance.

Combined serum creatinine and cystatin C Schwartz formula predicts kidney function better than the combined CKD-EPI formula in children.

BACKGROUND: The combined serum creatinine (SCreat) and cystatin C (CysC) CKD-EPI formula constitutes a new advance for glomerular filtration rate (GFR) estimation in adults. Using inulin clearances (iGFRs), the revised SCreat and the combined Schwartz formulas, this study aims to evaluate the applicability of the combined CKD-EPI formula in children. METHOD: 201 iGFRs for 201 children were analyzed and divided by chronic kidney disease (CKD) stages (iGFRs ≥90 ml/min/1.73 m(2), 90 > iGFRs > 60, and iGFRs ≤59), and by age groups (<10, 10-15, and >15 years). Medians with 95% confidence intervals of bias, precision, and accuracies within 30% of the iGFRs, for all three formulas, were compared using the Wilcoxon signed-rank test. RESULTS: For the entire cohort and for all CKD and age groups, medians of bias for the CKD-EPI formula were significantly higher (p < 0.001) and precision was significantly lower than the solely SCreat and the combined SCreat and CysC Schwartz formulas. We also found that using the CKD-EPI formula, bias decreased and accuracy increased while the child age group increased, with a better formula performance above 15 years of age. However, the CKD-EPI formula accuracy is 58% compared to 93 and 92% for the SCreat and combined Schwartz formulas in this adolescent group. CONCLUSIONS: The performance of the combined CKD-EPI formula improves in adolescence compared with younger ages. Nevertheless, the CKD-EPI formula performs more poorly than the SCreat and the combined Schwartz formula in pediatric population.

pH-responsive hydrogels containing PMMA nanoparticles: an analysis of controlled release of a chemotherapeutic conjugate and transport properties.

Biopolymers composed of a pH-responsive, hydrophilic poly(methacrylic acid-grafted-ethylene glycol) network polymerized in the presence of poly(methyl methacrylate) nanoparticles were designed for the oral delivery of chemotherapeutics for the treatment of colon cancer. An inulin-doxorubicin conjugate, designed to target the colon and improve doxorubicin efficacy, was loaded into these polymer carriers at an efficiency of 54%. Release studies indicated these polymer carriers minimized conjugate release in low pH conditions and released the conjugate at neutral pH conditions using a two-step pH experiment modeling the stomach and the small intestine. At lower concentration levels, the presence of the polymer carriers did not disrupt tight junctions as determined by transepithelial electrical resistance studies using Caco-2 and HT29-MTX cell lines which are an accurate model of the GI tract epithelia. Permeability values of unmodified doxorubicin and the inulin-doxorubicin conjugate in the presence of the polymer carriers were also determined using the same cell models and ranged from 1.87 to 3.80 × 10 (-6) cm/s.

N-acetylcysteine protects rats with chronic renal failure from gadolinium-chelate nephrotoxicity.

The aim of this study was to evaluate the effect of Gd-chelate on renal function, iron parameters and oxidative stress in rats with CRF and a possible protective effect of the antioxidant N-Acetylcysteine (NAC). Male Wistar rats were submitted to 5/6 nephrectomy (Nx) to induced CRF. An ionic-cyclic Gd (Gadoterate Meglumine) was administrated (1.5 mM/KgBW, intravenously) 21 days after Nx. Clearance studies were performed in 4 groups of anesthetized animals 48 hours following Gd- chelate administration: 1--Nx (n = 7); 2--Nx+NAC (n = 6); 3--Nx+Gd (n = 7); 4--Nx+NAC+Gd (4.8 g/L in drinking water), initiated 2 days before Gd-chelate administration and maintained during 4 days (n = 6). This group was compared with a control. We measured glomerular filtration rate, GFR (inulin clearance, ml/min/kg BW), proteinuria (mg/24 hs), serum iron (µg/dL); serum ferritin (ng/mL); transferrin saturation (%), TIBC (µg/dL) and TBARS (nmles/ml). Normal rats treated with the same dose of Gd-chelate presented similar GFR and proteinuria when compared with normal controls, indicating that at this dose Gd-chelate is not nephrotoxic to normal rats. Gd-chelate administration to Nx-rats results in a decrease of GFR and increased proteinuria associated with a decrease in TIBC, elevation of ferritin serum levels, transferrin oversaturation and plasmatic TBARS compared with Nx-rats. The prophylactic treatment with NAC reversed the decrease in GFR and the increase in proteinuria and all alterations in iron parameters and TBARS induced by Gd-chelate. NAC administration to Nx rat did not modify the inulin clearance and iron kinetics, indicating that the ameliorating effect of NAC was specific to Gd-chelate. These results suggest that NAC can prevent Gd-chelate nephrotoxicity in patients with chronic renal failure.

Pharmacokinetic study of S-1 in patients in whom inulin clearance was measured.

OBJECTIVE: This pharmacokinetic study of S-1 was conducted in patients in whom glomerular filtration rate (GFR) was directly measured to explore the possibility of adjusting the S-1 dose on the basis of GFR in patients with normal or nearly normal renal function. METHODS: S-1 was given to 12 patients twice daily for 28 consecutive days followed by 14 days of rest, repeated every 6 weeks. GFR was measured on the basis of inulin clearance (CLin) before the first day of treatment. RESULTS: The area under the time-concentration curve (AUC) of 5-fluorouracil (5-FU) correlated with that of 5-chloro-2,4-dihydroxypyridine (CDHP, r = 0.750, p = 0.005). The AUC of CDHP correlated with the measured 24-hour creatinine clearance (CLcr) per subject (r = -0.620, p = 0.032), but not with the CLin (r = -0.356, p = 0.257). The AUC of 5-FU did not correlate with either the 24-hour CLcr per subject (r = -0.401, p = 0.187) or with the CLin (r = -0.300, p = 0.351). CONCLUSION: Dosage adjustment based on the GFR does not reduce individual variations in 5-FU concentrations among patients with normal or nearly normal renal function who receive S-1.

Enhanced brain amyloid-ß clearance by rifampicin and caffeine as a possible protective mechanism against Alzheimer's disease.

Rifampicin and caffeine are widely used drugs with reported protective effect against Alzheimer's disease (AD). However, the mechanism underlying this effect is incompletely understood. In this study, we have hypothesized that enhanced amyloid-ß (Aß) clearance from the brain across the blood-brain barrier (BBB) of wild-type mice treated with rifampicin or caffeine is caused by both drugs potential to upregulate low-density lipoprotein receptor related protein-1 (LRP1) and/or P-glycoprotein (P-gp) at the BBB. Expression studies of LRP1 and P-gp in brain endothelial cells and isolated mice brain microvessels following treatment with rifampicin or caffeine demonstrated both drugs as P-gp inducers, and only rifampicin as an LRP1 inducer. Also, brain efflux index (BEI%) studies conducted on C57BL/6 mice treated with either drug to study alterations in Aß clearance demonstrated the BEI% of Aß in rifampicin (82.4 ± 4.3%) and caffeine (80.4 ± 4.8%) treated mice were significantly higher than those of control mice (62.4 ± 6.1%, p < 0.01). LRP1 and P-gp inhibition studies confirmed the importance of both proteins to the clearance of Aß, and that enhanced clearance following drugs treatment was caused by LRP1 and/or P-gp upregulation at the mouse BBB. Furthermore, our results provided evidence for the presence of a yet to be identified transporter/receptor that plays significant role in Aß clearance and is upregulated by caffeine and rifampicin. In conclusion, our results demonstrated the upregulation of LRP1 and P-gp at the BBB by rifampicin and caffeine enhanced brain Aß clearance, and this effect could explain, at least in part, the protective effect of rifampicin and caffeine against AD.

[How to evaluate renal function in cancer patients]. / Évaluation de la fonction rénale chez le patient atteint de cancer.

The evaluation of renal function in patients with cancer is necessary. Measuring the actual glomerular filtration rate of the patient is the gold standard. This is usually done using a measure of the renal clearance of a marker of glomerular filtration rate (inulin) or a radio-marker (EDTA Chrome 51, (51)Cr-EDTA). However, these measures are complex and very constraining for the patient and in terms of organization and equipment. It is possible to estimate renal function by calculation. There are in the literature many evaluation formulae available. However, it is essential to use a tool reliable enough to determine an appropriate estimate of renal function, and adjust the doses of treatment if necessary. The choice of the abreviated MDRD (aMDRD) formula is so far the recommended option in oncology.

Comparison of plasma clearance of iohexol and urinary clearance of inulin for measurement of GFR in children.

BACKGROUND: Very few studies have been published that compare plasma clearance of iohexol (Cio) with renal clearance of inulin (Cin). STUDY DESIGN: Diagnostic test study. SETTING & PARTICIPANTS: 60 children aged 11.6 ± 4.5 years with different kidney disorders were investigated. INDEX TEST: Plasma Cio calculated from the slope and a single point. REFERENCE TEST: Renal Cin with continuous infusion during water diuresis. Results were compared with the correlation coefficients, bias and precision, accuracy percentage, root mean square error, and intraclass correlation. OTHER MEASUREMENTS: Measured creatinine clearance and estimated glomerular filtration rate based on serum creatinine level and height. RESULTS: Mean Cin was 70.7 ± 41.3 (SD) mL/min/1.73 m². Mean differences between Cio and Cin were 2.65 and 2.00 mL/min/1.73 m² for the slope and single-point methods, respectively. Precision was ±16 mL/min/1.73 m² and intraclass correlation was 0.92 in both methods. Proportions of Cio within 30% of Cin were 83.3% and 86.7% for the slope and single-point methods, respectively. LIMITATIONS: A limited number of patients; no adults were studied. CONCLUSIONS: Plasma Cio shows good agreement with renal Cin.

Peroxisome proliferator-activated receptor alpha and alpha/gamma agonists do not cause impairment in renal function in the rat.

BACKGROUND/AIMS: Patients treated with peroxisome proliferator-activated receptor analogs (PPAR) alpha or alpha/gamma may develop a transient and reversible increase in serum creatinine, the mechanism of which remains obscure. This study evaluates whether treatment with either PPAR-alpha or -alpha/gamma analogs, fenofibrate or tesaglitazar, may cause deterioration in renal hemodynamics or exert direct tubular or glomerular nephrotoxic effects in rats. METHODS: Male Sprague-Dawley rats (300-320 g) were treated per os with fenofibrate (300 mg/kg/day), tesaglitazar (1.2 mg/kg/day) or vehicle, for 14 days. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by inulin clearance and ultrasonic flowmetry, and cumulative excretion of sodium and creatinine were assessed. Biomarkers of glomerular and tubular injury were measured, including urinary albumin excretion and renal mRNA levels of kidney injury molecule 1 (Kim-1), lipocalin 2 (Lcn2), and osteopontin (Spp1). RESULTS: Fenofibrate and tesaglitazar improved the lipid profile, but caused no detectable decrease in GFR or RBF compared with vehicle-treated rats. Furthermore, the cumulative excretions of sodium and creatinine were not altered by the drugs. Finally, there was no significant difference between drug- and vehicle-treated groups in urinary albumin excretion or in the expression of renal injury biomarkers. CONCLUSIONS: In the rat, no direct nephrotoxic effect or deterioration in renal hemodynamics and function were observed following treatment with fenofibrate or tesaglitazar.

Dietary inulin supplementation does not promote colonic iron absorption in a porcine model.

Prebiotics may enhance iron bioavailability by increasing iron absorption in the colon. Anemic pigs fitted with cecal cannulas were fed a low-iron diet with or without 4% inulin. Over 7 days, pigs were administered 1 mg of (54)Fe in the morning feed followed by cannula infusion of 0.5 mg of (58)Fe to measure total and colonic iron absorption, respectively. Whole blood was drawn prior to the initial dosing and 14 days thereafter for hemoglobin concentration and stable isotope ratio analyses. The prebiotic role of inulin was confirmed by increases in lactobacilli and bifidobacteria with reductions in clostridia using terminal restriction fragment length polymorphism (TRFLP). Total iron absorption was 23.2 +/- 2.7 and 20.7 +/- 3.5% (mean +/- SEM; p > 0.05), while colonic iron absorption was 0.4 +/- 0.1 and 1.0 +/- 0.2% (mean +/- SEM; p > 0.05) in inulin-fed and control pigs, respectively. These results show that the colon does not make a significant contribution to total iron absorption in iron-deficient pigs and that inulin does not affect iron absorption in the colon.

Inhibition of water absorption in human proximal tubular epithelial cells in response to Shiga toxin-2.

Postdiarrhea hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children in Argentina. It is well established that Shiga toxin type 2 (Stx2) causes direct damage to glomerular endothelial cells and tubular epithelial cells, leading to a reduction in the water handling capacity of the kidney. In this study, we demonstrate that Stx2 and its B subunit (Stx2B) were able to inhibit water absorption across human renal tubular epithelial cell (HRTEC) monolayers without altering the short circuit current and the (3)H-mannitol permeability. Quantitative evaluation of (14)C-inulin transport across HRTEC monolayers showed a similar transport rate both before and after HRTEC treatment with Stx2 that confirmed the integrity of the paracellular pathway. Furthermore, Stx2 produced significant protein synthesis inhibition of HRTEC at concentrations as low as 0.001 ng/ml and 1 h of incubation, whereas Stx2B did not modify it at concentrations as high as 10,000 ng/ml and 6 h of incubation. Our findings suggest that whereas the action of Stx2 appears to be caused mainly by the inhibition of protein synthesis mediated by the A subunit, the binding of Stx2B subunit to the Gb3 receptor may affect the membrane mechanisms related to water absorption. We speculate that inhibition of water absorption may occur in proximal tubular cells in vivo in response to Stx2 and may contribute to the early event of HUS pathogenesis.

PlGF-1 and VEGFR-1 pathway regulation of the external epithelial hemato-ocular barrier. A model for retinal edema.

VEGF is considered as an important factor in the pathogenesis of macular edema. VEGF induces the rupture of the blood retinal barrier and may also influence the retinal pigment epithelial (RPE) outer retinal barrier. The aim of this work was to analyze the influence of the VEGF receptor pathways in the modulation of the RPE barrier breakdown in vitro and in vivo. The ARPE19 human junctions in culture are modulated by VEGF through VEGFR-1 but not through VEGFR-2. PlGF-1, that is a pure agonist of VEGFR-1, is produced in ARPE-19 cells under hypoxic conditions and mimics VEGF effects on the external retinal barrier as measured by TER and inulin flux. In vivo, the intravitreous injection of PlGF-1 induces a rupture of the external retinal barrier together with a retinal edema. This effect is reversible within 4 days. VEGF-E, that is a pure agonist of VEGFR-2, does not induce any acute effect on the RPE barrier. These results demonstrate that PlGF-1 can reproduce alterations of the RPE barrier occurring during diabetic retinopathy.

Inulin-type fructans: functional food ingredients.

A food (ingredient) is regarded as functional if it is satisfactorily demonstrated to affect beneficially 1 or more target functions in the body beyond adequate nutritional effects. The term inulin-type fructans covers all beta(2<--1) linear fructans including native inulin (DP 2-60, DP(av) = 12), oligofructose (DP 2-8, DP(av) = 4), and inulin HP (DP 10-60, DP(av) = 25) as well as Synergy 1, a specific combination of oligofructose and inulin HP. Inulin-type fructans resist digestion and function as dietary fiber improving bowel habits. But, unlike most dietary fibers, their colonic fermentation is selective, thus causing significant changes in the composition of the gut microflora with increased and reduced numbers of potentially health-promoting bacteria and potentially harmful species, respectively. Both oligofructose and inulin act in this way and thus are prebiotic: they also induce changes in the colonic epithelium and in miscellaneous colonic functions. In particular, the claim "inulin-type fructans enhance calcium and magnesium absorption" is scientifically substantiated, and the most active product is oligofructose-enriched inulin (Synergy 1). A series of studies furthermore demonstrate that inulin-type fructans modulate the secretion of gastrointestinal peptides involved in appetite regulation as well as lipid metabolism. Moreover, a large number of animal studies and preliminary human data show that inulin-type fructans reduce the risk of colon carcinogenesis and improve the management of inflammatory bowel diseases. Inulin-type fructans are thus functional food ingredients that are eligible for enhanced function claims, but, as more human data become available, risk reduction claims will become scientifically substantiated.

Organic anion transporter 3 (Oat3/Slc22a8) knockout mice exhibit altered clearance and distribution of penicillin G.

The interaction of renal basolateral organic anion transporter 3 (Oat3) with commonly used pharmacotherapeutics (e.g., NSAIDs, beta-lactams, and methotrexate) has been studied extensively in vitro. However, the in vivo role of Oat3 in drug disposition, in the context of other transporters, glomerular filtration, and metabolism, has not been established. Moreover, recent investigations have identified inactive human OAT3 polymorphisms. Therefore, this investigation was designed to elucidate the in vivo role of Oat3 in the disposition of penicillin G and prototypical substrates using an Oat3 knockout mouse model. Oat3 deletion resulted in a doubling of penicillin's half-life (P < 0.05) and a reduced volume of distribution (P < 0.01), together yielding a plasma clearance that was one-half (P < 0.05, males) to one-third (P < 0.001, females) of that in wild-type mice. Inhibition of Oat3 abolished the differences in penicillin G elimination between genotypes. Hepatic accumulation of penicillin was 2.3 times higher in male knockouts (P < 0.05) and 3.7 times higher in female knockouts (P < 0.001). Female knockouts also exhibited impaired estrone-3-sulfate clearance. Oat3 deletion did not impact p-aminohippurate elimination, providing correlative evidence to studies in Oat1 knockout mice that suggest Oat1 governs tubular uptake of p-aminohippurate. Collectively, these findings are the first to indicate that functional Oat3 is necessary for proper elimination of xenobiotic and endogenous compounds in vivo. Thus Oat3 plays a distinct role in determining the efficacy and toxicity of drugs. Dysfunctional human OAT3 polymorphisms or instances of polypharmacy involving OAT3 substrates may result in altered systemic accumulation of beta-lactams and other clinically relevant compounds.

Avaliação do ritmo de filtração glomerular / Assessment of glomerular filtration rate

A medida do ritmo de filtração glomerular (RFG) é a prova laboratorial mais utilizada na avaliação da função renal. Para tanto, usam-se marcadores indiretos, como as determinações de creatinina e cistatina C no sangue, ou procede-se à determinação do RFG propriamente dito, com indicadores como inulina; contrastes iodados, marcados ou não; e outras substâncias. O exame mais solicitado para avaliação do RFG no laboratório de patologia clínica é a dosagem da creatinina sérica. Em algumas condições, entretanto, o resultado encontrado da creatinina sérica deve ser corrigido (através da utilização de fórmulas que levam em consideração características próprias do indivíduo) para ser devidamente interpretado. De fato, a inulina ainda é vista como marcador ideal de filtração glomerular, mas seu uso não se destina à prática clínica, de modo que ainda hoje persiste a busca por testes adequados para uso rotineiro.

Glomerular filtration rate (GFR) determination is the most frequently used laboratorial test to evaluate renal function. Indirect markers as blood determination of creatinine and cystatin C are used with this purpose, as well as the direct determination of GFR, with indicators like inulin; iodated contrasts, radioactive or not; and others. Serum creatinine is the test that is most commonly performed in order to evaluate GFR in the clinical pathology laboratory. However, in some conditions, aiming at the adequate interpretation of the test, the result of serum creatinine must be corrected (by using formulas that include individual characteristics of the subjects). In fact, inulin is still seen as the ideal marker of glomerular filtration, but its use is not directed to clinical practice; then the search for appropriate tests for routine use continues.

[Determination of renal function in clinical routine: which is the best method?]. / Bestimmung der Nierenfunktion im klinischen Alltag--welche Methode ist die beste?

BACKGROUND AND OBJECTIVE: Accurate quantification of renal function is important for diagnosing and monitoring progression of renal diseases and for calculating adequate doses of drugs that are excreted by the kidneys. Gold-standard procedures are too complex for routine clinical use. At the moment there are several formulae to choose from, all said to estimate renal function precisely enough for clinical purposes. It was the aim of this study to compare the accuracy of several of these in clinical routine. PATIENTS AND METHODS: The results of inulin clearance were compared with those calculated by the Cockcroft-Gault formula (CGF), abbreviated diet modification of renal disease (MDRD) formula, the Mayo formula and the cystatin C-based formula as proposed by Larsson et al. Included were 189 in-patients (aged 20-87, 40% of them women, range of inulin clearance 8-244 ml/min/1,73m). In addition, inulin clearance was compared with creatinine clearance in 142 patients (aged 20-87 years, 42% women. Inulin clearance 13-244 ml/min/1,73m). Bland-Altman diagrams were drawn and mean bias and standard deviation of the formulae were compared with inulin clearance, as were sensitivity and specifity for diagnosing reduced renal function. RESULTS: All formulae underestimated glomerular filtration rate (GFR), with CGF and MDRD formulas giving the best results. These formulae had a mean bias of -16.2 (SD 24.8) and -18.2 (SD 25.6) ml/min/1,73m (2) , respectively. All creatinine-based formulae showed a high sensitivity and specifity for diagnosing a GFR below 60 ml/min/1,73m (2). CONCLUSION: None of the estimating formulae can replace inulin clearance with adequate accuracy. In our patients the cystatin C formula of Larsson et al showed no advantage. But the MDRD formula, which can be calculated without knowing body weight, is as accurate and precise as CGF.

Digoxin transport by renal proximal tubule cells is enhanced by adhesive synthetic RGD peptide.

INTRODUCTION: The dialyzer apparatus has been widely used as an artificial kidney in medical treatment. However, side effects such as amyloidosis have occurred during long-term treatment. Therefore, we focused on developing a hybrid artificial kidney with a filtration and reabsorption apparatus, but it was found that cells spread extensively and it is difficult to maintain a uniform monolayer with a regular cell shape on a collagen-coated substrate. The purpose of this study was to improve cell adhesion, uniform stable monolayer formation and active transport function by immobilization of arginine-glycine-aspartic acid (RGD) on the culture substratum. MATERIALS AND METHODS: Polycarbonate semipermeable membranes were coated with collagen, fibronectin, laminin and synthetic polypeptide, including RGD (Pronectin F). Cell adhesion and digoxin transport were estimated using a renal proximal tubule cell line that overexpressed the P-glycoprotein gene. RESULTS AND DISCUSSION: Under initial and confluent conditions, immobilized cell density in Pronectin F-coated wells was higher than that under other conditions. Transepithelial electrical resistance and digoxin transport activity on Pronectin F-coated membranes were the highest of all conditions. This might have been caused by uniform cell morphology and high cell density.