Erythropoietin alters the pharmacokinetics of organic anions mainly eliminated by the kidney in rats.

Erythropoietin (EPO) is a cytokine originally used for its effects on the hematopoietic system, and is widely prescribed around the world. In the present study, the effects of EPO administration on p-aminohippurate (PAH, a prototype organic anion) pharmacokinetics and on the renal expression of PAH transporters were evaluated. Male Wistar rats were treated with EPO or saline (control group). After 42 h, PAH was administered, and plasma samples were obtained at different time points to determine PAH levels. PAH levels in renal tissue and urine were also assessed. The renal expression of PAH transporters was evaluated by Western blotting. EPO-treated rats showed an increase in PAH systemic clearance, in its elimination rate constant, and in urinary PAH levels, while PAH in renal tissue was decreased. Moreover, EPO administration increased the expression of the transporters of the organic anions evaluated. The EPO-induced increase in PAH clearance is accounted for by the increase in its renal secretion mediated by the organic anion transporters. The goal of this study is to add important information to the wide knowledge gap that exists regarding drug-drug interactions. Owing to the global use of EPO, these results are useful in terms of translation into clinical practice.

Time evolution of methotrexate-induced kidney injury: A comparative study between different biomarkers of renal damage in rats.

Methotrexate (MTX) is commonly used in the treatment of malignant diseases and autoimmune and chronic inflammatory disorders. Along with its effective therapeutic power, MTX has adverse effects on the kidneys. Discovery of new biomarkers is required to improve the early detection of renal damage and optimize the effectiveness of treatments. The aim of this study was to evaluate the time course of MTX-induced nephrotoxicity and to compare the urinary excretion of the organic anion transporter 5 (uOat5) with alterations in other markers of renal function, and to elucidate the possible molecular mechanisms involved in uOat5. Animals were exposed to a unique dose of MTX (80 mg/kg body weight, intraperitoneal). Experiments were carried out at days 2, 4, 8 or 14 after MTX administration. Markers of renal damage, such as creatinine and urea plasma levels, urinary activity of alkaline phosphatase, microalbuminuria, urinary excretion of neutrophil gelatinase-associated lipocalin (uNGAL) and histopathology, were evaluated. Renal organic anion transporter 5 (Oat5) expression and its presence in different urine fraction were assessed by western blotting. uOat5 was significantly increased 2 days after MTX treatment, before than any alteration in other parameters of kidney injury or renal morphology occurred. uNGAL showed an inverted pattern of urinary excretion compared to uOat5. Exosomal pathway is involved in the urinary excretion of Oat5 and depends on the degree of damage induced by MTX. These experimental data allow proposing uOat5 as a potential non-invasive biomarker for early detection of MTX-induced nephrotoxicity.

Time course effects of methotrexate on renal handling of water and electrolytes in rats. Role of aquaporin-2 and Na-K-2Cl-cotransporter.

Methotrexate (MTX) is a derivate of folic acid, commonly used as an anchor drug for the treatment and management of malignant diseases and autoimmune disorders. However, nephrotoxicity is an important drawback of MTX therapy. Unfortunately, there are not enough studies reporting the nature of the renal failure induced by MTX. Thus, the aim of this study was to evaluate the time course of renal handling of water and electrolytes in male Wistar rats, after the exposure to a unique dose of MTX (80 mg/kg b.w.). Experiments were carried out at day 2, day 4, day 8 and day 14 after MTX administration. Several parameters of kidney function related to water and electrolytes handling were evaluated. Renal expression and urinary excretion of aquaporin-2 (AQP2) and Na-K-2Cl-cotransporter (NKCC2) were determined by Western blotting. MTX produced alterations on water handling on the second day after treatment, showing a significant increase in solute free water reabsorption which might be mediated by the increased expression of AQP2 in apical membranes. On the other hand, MTX produced alterations on electrolytes handling on the fourth day after treatment, showing a significant decrease of sodium chloride excretion, mediated at least in part, by the increase renal expression of NKCC2. These results provide valuable information to clinical practice in order to be able to find therapeutic targets that diminish adverse effects and health deterioration. Moreover, MTX treatment altered AQP2 and NKCC2 urinary excretion allowing postulating these transporters as potential biomarkers of MTX induced nephrotoxicity.

Renal expression and urinary excretion of Na+/dicarboxylate cotransporter 1 (NaDC1) in obstructive nephropathy: a candidate biomarker for this pathology.

Obstructive nephropathy is characterized by alterations in renal function that depends on the degree and type of obstruction. To increase the knowledge about the physiopathological mechanisms involved in the renal damage associated with bilateral ureteral obstruction (BUO), we studied the renal expression and function (as urinary citrate excretion) of sodium-dependent dicarboxylate cotransporter (NaDC1) in rats. In addition, we evaluated the urinary excretion of NaDC1 as a candidate biomarker for this pathology. Male Wistar rats underwent bilateral ureteral obstruction for 1 (BUO1), 2 (BUO2), 5 (BUO5), and 24 (BUO24) h or sham operation. After 24 h of ureteral releasing, traditional parameters of renal function and citrate levels were determined, and NaDC1 levels were evaluated in total renal homogenates, apical plasma membranes, and urine by electrophoresis and Western blotting. Traditional parameters of renal function were only modified in BUO5 and BUO24. The renal expression of NaDC1 was decreased in BUO5 and BUO24, with a concomitant increase in urinary excretion of citrate. Moreover, the urinary excretion of NaDC1 increased after short times of ureteral obstruction (BUO1 and BUO2) and was positively correlated with the time elapsed after obstruction. The results obtained from the renal expression of NaDC1 could explain an adaptive mechanism to prevent the formation of kidney stones by increasing the levels of citrate, a calcium chelator. The urinary excretion of NaDC1 could be postulated as an early biomarker of obstructive nephropathy that also gives information about the duration of the obstruction.

Impact of the induced organic anion transporter 1 (Oat1) renal expression by furosemide on the pharmacokinetics of organic anions.

AIM: Furosemide is a loop diuretic. Different authors demonstrated that continuous administration of furosemide modulates the expression of organic anion transporters. This study was undertaken to simultaneously evaluate the effects of furosemide pretreatment on organic anion transporter 1 (Oat1) and multidrug resistance protein 2 (Mrp2) renal expressions, on p-aminohippurate (PAH) pharmacokinetics and on renal and urinary PAH levels in rats. METHODS: Male Wistar rats were treated with furosemide (6 mg/100 g body weight per day, subcutaneously, 4 days) (treated group) or saline (control group). On the fifth day, PAH was administered as a bolus infusion in the femoral vein, and plasma samples were obtained from femoral artery at different time points. PAH levels in renal tissue and urine were also assessed. Renal Oat1 and Mrp2 expressions were evaluated by western blotting. RESULTS: Furosemide pretreatment increased both the expression of Oat1 and Mrp2. PAH plasma concentrations decreased following a biexponential function. The furosemide-treated group showed higher PAH plasma levels, a lower systemic clearance and elimination rate constant from the peripheral compartment, indicating that PAH renal elimination was decreased. PAH levels in renal tissue were significantly elevated and in urine appeared to be significantly lower as compared with control animals. CONCLUSIONS: Furosemide pretreatment caused a significant decrease of PAH renal elimination, despite Oat1 and Mrp2 augmented renal expression. The goal of the present study is the addition of important information in the wide gap of knowledge that exists about drug-drug interactions. Because of furosemide worldwide use, the data obtained are interesting and useful in terms of translation to clinical practice.

Wnt/ß-catenin pathway in the prefrontal cortex is required for cocaine-induced neuroadaptations.

Behavioral sensitization is a progressive and enduring enhancement of the motor stimulant effects elicited by repeated administration of drugs of abuse. It can be divided into two distinct temporal and anatomical domains, termed initiation and expression, which are characterized by specific molecular and neurochemical changes. This study examines the role of the Wnt canonical pathway mediating the induction of cocaine sensitization. We found that ß-catenin levels in the prefrontal cortex (PFC), amygdala (Amyg) and dorsal striatum (CPu) are decreased in animals that show sensitization. Accordingly, GSK3ß activity levels are increased in the same areas. Moreover, ß-catenin levels in nuclear fraction, mRNA expression of Axin2 and Wnt7b are decreased in the PFC of sensitized animals. Then, in order to demonstrate that changes in the PFC are crucial for initiation of sensitization, we either rescue ß-catenin levels with a systemic treatment of a GSK3ß inhibitor (Lithium Chloride) or inhibit Wnt/ß-catenin pathway with an intracerebral infusion of Sulindac before each cocaine injection. As expected, rescuing ß-catenin levels in the PFC as well as CPu and Amyg blocks cocaine-induced sensitization, while decreasing ß-catenin levels exclusively in the PFC exacerbates it. Therefore, our results demonstrate a new role for the Wnt/ß-catenin pathway as a required neuroadaptation in inducing behavioral sensitization.

Role of Wnt/ß-catenin pathway in the nucleus accumbens in long-term cocaine-induced neuroplasticity: a possible novel target for addiction treatment.

Cocaine addiction is a chronic relapsing disorder characterized by the loss of control over drug-seeking and taking, and continued drug use regardless of adverse consequences. Despite years of research, effective treatments for psycho-stimulant addiction have not been identified. Persistent vulnerability to relapse arises from a number of long-lasting adaptations in the reward circuitry that mediate the enduring response to the drug. Recently, we reported that the activity of the canonical or Wnt/ß-catenin pathway in the prefrontal cortex (PFC) is very important in the early stages of cocaine-induced neuroadaptations. In the present work, our main goal was to elucidate the relevance of this pathway in cocaine-induced long-term neuroadaptations that may underlie relapse. We found that a cocaine challenge, after a period of abstinence, induced an increase in the activity of the pathway which is revealed as an increase in the total and nuclear levels of ß-catenin (final effector of the pathway) in the nucleus accumbens (NAcc), together with a decrease in the activity of glycogen synthase kinase 3ß (GSK3ß). Moreover, we found that the pharmacological modulation of the activity of the pathway has long-term effects on the cocaine-induced neuroplasticity at behavioral and molecular levels. All the results imply that changes in the Wnt/ß-catenin pathway effectors are long-term neuroadaptations necessary for the behavioral response to cocaine. Even though more research is needed, the present results introduce the Wnt canonical pathway as a possible target to manage cocaine long-term neuroadaptations.

The urinary excretion of an organic anion transporter as an early biomarker of methotrexate-induced kidney injury.

Methotrexate (MTX) belongs to a group of medicines known as antimetabolites. It is commonly used in the treatment of malignant diseases and is prescribed in autoimmune and chronic inflammatory disorders. Along with its effective therapeutic power, MTX has adverse effects on several organs, including the kidney. The organic anion transporter 5 (Oat5) is exclusively localized in the renal apical membrane. Oat5 urinary excretion was proposed as an early biomarker in ischemic and nephrotoxic-induced kidney injury and in renal damage due to vascular calcification in preclinical models. The aim of this study was to evaluate Oat5 renal expression and urinary excretion in rats 48 h after the exposure to different doses of MTX, in comparison with traditional markers of renal injury, such as creatinine and urea plasma levels, protein urinary levels, urinary alkaline phosphatase (AP) activity, fractional excretion of water (FEWater) and renal histology. Male Wistar rats were treated with a single intraperitoneal injection of MTX at different dosages: 40-80-120-180-360 mg per kg b.w. (M40, M80, M120, M180, M360, n = 4, respectively) and experiments were carried out 48 h after MTX administration. Oat5 renal expression was evaluated by western blotting and immunohistochemistry. Traditional parameters were only modified at the higher MTX dose (M360). Conversely, Oat5 urinary excretion was elevated at the middle dose of 80 mg per kg b.w. Oat5 renal expression was modified at the highest dose as well, both in homogenates and in apical membranes. These results suggest that Oat5 urinary excretion might serve as an early biomarker of MTX-induced kidney injury.

Effect of a Web-based intervention to promote physical activity and improve health among physically inactive adults: a population-based randomized controlled trial.

BACKGROUND: Many people in Western countries do not follow public health physical activity (PA) recommendations. Web-based interventions provide cost- and time-efficient means of delivering individually targeted lifestyle modification at a population level. OBJECTIVE: To examine whether access to a website with individually tailored feedback and suggestions on how to increase PA led to improved PA, anthropometrics, and health measurements. METHODS: Physically inactive adults (n = 12,287) participating in a nationwide eHealth survey and health examination in Denmark were randomly assigned to either an intervention (website) (n = 6055) or a no-intervention control group (n = 6232) in 2008. The intervention website was founded on the theories of stages of change and of planned behavior and, apart from a forum page where a physiotherapist answered questions about PA and training, was fully automated. After 3 and again after 6 months we emailed participants invitations to answer a Web-based follow-up questionnaire, which included the long version of the International Physical Activity Questionnaire. A subgroup of participants (n = 1190) were invited to a follow-up health examination at 3 months. RESULTS: Less than 22.0% (694/3156) of the participants logged on to the website once and only 7.0% (222/3159) logged on frequently. We found no difference in PA level between the website and control groups at 3- and 6-month follow-ups. By dividing participants into three groups according to use of the intervention website, we found a significant difference in total and leisure-time PA in the website group. The follow-up health examination showed no significant reductions in body mass index, waist circumference, body fat percentage, and blood pressure, or improvements in arm strength and aerobic fitness in the website group. CONCLUSIONS: Based on our findings, we suggest that active users of a Web-based PA intervention can improve their level of PA. However, for unmotivated users, single-tailored feedback may be too brief. Future research should focus on developing more sophisticated interventions with the potential to reach both motivated and unmotivated sedentary individuals. TRIAL REGISTRATION: Clinicaltrials.gov NCT01295203; http://clinicaltrials.gov/ct2/show/NCT01295203 (Archived by WebCite at http://www.webcitation.org/6B7HDMqiQ).

A population-based randomized controlled trial of the effect of combining a pedometer with an intervention toolkit on physical activity among individuals with low levels of physical activity or fitness.

OBJECTIVES: To examine if receiving a pedometer along with an intervention toolkit is associated with increased physical activity, aerobic fitness and better self-rated health among individuals with low levels of physical activity or fitness. METHODS: The intervention was nested in the Danish Health Examination Survey (DANHES) and carried out in 2008. Participants were randomly assigned to either a pedometer group (n=326) or a control group (n=329). Physical activity, aerobic fitness, and self-rated health were measured at baseline and at 3-month follow-up, and differences were tested by Wilcoxons signed rank tests and Chi-squared tests. RESULTS: At follow-up, no significant differences in physical activity, aerobic fitness and self-rated health were found between the groups. However, the oldest participants in the pedometer group reported significantly more walking time compared to the controls (controls=368 min/week, pedometer group=680 min/week, P=0.05). Among participants who completed the intervention, a significant effect on total walking time was observed (median difference=225 min/week, P=0.04). CONCLUSIONS: The results suggest that receiving a pedometer and along with an intervention toolkit can increase walking time in older individuals, but not in younger individuals. Thus, this type of intervention offers great potential for promoting physical activity in older individuals. TRIAL REGISTRATION NUMBER: NCT01071811.

Canthaxanthin retinopathy: long-term observations.

PURPOSE: To describe the long-term outcome of canthaxanthin retinopathy. METHODS: We identified 13 patients with small golden particles near the macular region among a group of 35 patients with known consumption of canthaxanthin somewhen between 1983 and 1988. One long-term follow-up examination was possible in 5 of 13 cases after 16-24 years. The examinations included determination of visual acuity, the Amsler grid, slit lamp examination, perimetry, electro-oculography, electroretinography, optical coherence tomography and fluorescein angiography. RESULTS: Complete disappearance of the golden particles took approximately 20 years. The patients in our study were asymptomatic and no functional defect related to canthaxanthin could be detected. CONCLUSIONS: Ingestion of canthaxanthin causes no long-term adverse effects.

Contact lens, hyperopia and endothelial changes. A case report.

INTRODUCTION: We report on a 62-year-old healthy woman who suffered from bilateral predescemetic opacities, where the underlying disorder could not be identified. She had bilateral keratopathy with corneal edema, a diffuse predescemetic avascular haze and deszemetic folds. Because of high hyperopia (right +7.50/left +7.75) she weared soft contact lenses for years. METHODS: Removal of contact lenses. Treatment with local steroids and tear substitutes. RESULTS: One year after cessation of contact lenses VA recovered from RE 0.3/LE 0.1 to 0.8/0.63, the deep stromal opacity cleared up, the corneal edema recessed slightly. DISCUSSION: The differential diagnosis concludes either a pure contact lens change that is not completely reversible or a possible posterior polymorphous dystrophy that worsens with long-term contact lens wear and improves on cessation.

Treatment of granular dystrophy with soft contact lenses.

PURPOSE: To prevent recurrence of granular dystrophy by treatment with soft contact lenses. METHODS: After penetrating keratoplasty, a soft contact lens was fitted in a 61-year-old woman patient with granular corneal dystrophy. The lens was worn continuously for 53 months. RESULTS: No recurrence was observed. However, the other eye, which was operated on first and not treated with a contact lens, showed severe recurrence of the underlying disease, with granular deposits in the stroma. CONCLUSIONS: Fitting of a soft contact lens should be considered in this disease after penetrating keratoplasty.

A case of angle-closure glaucoma, cataract, nanophthalmos and spherophakia in oculo-dento-digital syndrome.

BACKGROUND: We report a new case of oculo-dento-digital syndrome. METHODS: Case report. RESULTS: We saw a 34-year-old women with oculo-dento-digital syndrome. Visual acuity was no perception of light (RE) and 1/35 (LE). Biomicroscopy revealed a flat anterior chamber and an advanced cataract. The intraocular pressure (IOP) was 60 mmHg in both eyes. Ultrasonographic biomicroscopy demonstrated a closed chamber angle in both eyes. Measurements of the axial length and of the diameter of the lens were 18.7 mm/6.0 mm for the RE and 18.7 mm/5.8 mm for the LE respectively. In the time following we conducted a cyclodestructive procedure in the RE and a cataract extraction with implantation of an intraocular lens in the LE. This led to a considerable reduction of the IOP in the RE and combined with local therapy to IOP regulation in the LE. CONCLUSION: In this patient nanophthalmos, cataract and spherophakia led to angle-closure glaucoma in both eyes. We recommend early monitoring of IOP, axial length and lens diameter. This case demonstrates that an early cataract extraction might beneficially influence the natural course of the disease.