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J Vilar

Publications and source records attributed to J Vilar.

At least 19 recordsLinked to original sources
PubMed2003

Spatiotemporal distribution of insulin-like growth factor receptors during nephrogenesis in fetuses from normal and diabetic rats.

Exposure to hyperglycemia in utero impairs rat nephrogenesis. The effect of maternal diabetes on insulin-like growth factors and their receptors in the fetal kidney is associated with an increase in both mRNA and protein of the insulin-like growth factor II/mannose 6-phosphate receptor. However, this receptor has never been localized in the fetal kidney. The spatial and temporal distribution of the three insulin-like growth factor receptors (insulin-like growth factor I receptor, insulin-like growth factor II/mannose 6-phosphate receptor and insulin receptor) in rat metanephros during both normal and streptozotocin-induced diabetic renal development was investigated using in situ hybridization and immunohistochemistry. All receptors were found in the fetal kidney from the start of nephrogenesis. Insulin-like growth factor I receptor expression was ubiquitous and continuously present during metanephric development. Insulin receptor expression was developmentally regulated during kidney maturation with an enhanced expression in proximal tubules at the late stages of development. Insulin-like growth factor II/mannose 6-phosphate receptor expression was ubiquitous in the early stages of development and was dramatically decreased at the late stages of normal kidney development. Insulin receptor and insulin-like growth factor I receptor expressions were unchanged in diabetic metanephroi. Although the spatial expression of insulin-like growth factor II/mannose 6-phosphate receptor was unaffected by hyperglycemia, its expression was not downregulated in the mesenchyme of the nephrogenic zone of diabetic fetuses on gestational day 20. This study suggests a crucial role of insulin-like growth factor II/mannose 6-phosphate receptor in the pathogenesis of the impaired nephrogenesis in fetuses of diabetic mothers.

Animals↗
PubMed2001

Utility of intrarenal Doppler ultrasound in the diagnosis of renal artery stenosis.

PURPOSE: To determine the utility of intrarenal Doppler parameters and waveform analysis in a hypertensive population screened for renal artery stenosis (RAS). MATERIALS AND METHODS: Sixty five patients were studied (122 kidneys) with intrarenal Doppler sonography. Doppler waveforms of three different areas from each kidney were obtained (superior, middle and inferior level). Waveform morphology, acceleration time (AT), acceleration (Ac) and resistive index (RI) were evaluated in each kidney, comparing retrospectively the Doppler findings with the angiographic results. RESULTS: Arteriography demonstrated 33 (27.2%) renal arteries with stenosis (18 with RAS>75%). Statistically significant differences for AT and Ac were found among the patients with RAS>75% and the other groups (P<0.01). An AT>80 ms and an Ac< or =1 m/s(2) showed a sensitivity of 89% and a specificity of 99%, for the diagnosis of RAS>75%. Better results were obtained in patients less than 50 years old (100% of sensitivity and specificity). The morphologic analysis of the Doppler waveform had poor results but the detection of a waveform grade 0 had a high specificity (98%). An additional comparison of both kidneys didn't improve the results. CONCLUSION: Intrarenal Doppler waveform analysis using quantitative measurements (AT and Ac) is an adequate technique for the diagnosis of severe RAS in previously selected patients, especially in younger patients (<50 years).

Adolescent↗
PubMed2001

N-phenacylthiazolium bromide decreases renal and increases urinary advanced glycation end products excretion without ameliorating diabetic nephropathy in C57BL/6 mice.

AIMS: Advanced glycation end products (AGE), which form from the non-enzymatic reaction of proteins and sugars, have been implicated in the pathogenesis of diabetic nephropathy. Recently, a compound [N-phenacylthiazolium bromide (PTB)] has been described which cleaves alpha,beta-dicarbonyl compounds. In the present study we used diabetic C57BL/6 mice to determine if PTB altered renal AGE levels and reduced diabetic glomerulosclerosis. METHODS: Mice with stable hyperglycaemia induced by streptozotocin were given daily subcutaneous injections of either PTB (10 microg/g) or saline for 12 weeks. Renal-collagen bound AGE and urinary AGE-peptides were measured by ELISA using an anti-AGE-RNase antibody. Renal collagen-released Nepsilon(carboxymethyl)lysine (CML) and pentosidine were determined by high pressure liquid chromatography (HPLC). Glomerular lesions (volume and mesangial/total surface area) were evaluated by computer-assisted image analysis. We determined urinary protein/creatinine ratio as a functional parameter. AGE localization was examined by immunohistochemistry using the anti-AGE-RNase antibody. RESULTS: Renal collagen-bound AGE were decreased and urinary AGE excretion was increased in PTB-treated diabetic mice. However, collagen-released CML and pentosidine were similar in both groups. Glomerular histology and morphometric analysis revealed also no differences between PTB-and saline-treated diabetic mice. The urinary protein/creatinine ratio was unaffected by PTB-treatment. AGE staining by anti-AGE-RNase antibody was present in Bowman's capsules, glomerular basement membranes and cortical tubules. It was decreased in all structures in PTB-treated diabetic mice. CONCLUSION: In summary, PTB decreased renal AGE accumulation but did not ameliorate glomerular lesions or proteinuria. Thus, cleavage of AGE by PTB is not sufficient to prevent development of diabetic nephropathy in C57BL/6 mice.

Animals↗
PubMed2000

Association analysis of drug metabolizing enzyme gene polymorphisms in HIV-positive patients with co-trimoxazole hypersensitivity.

The use of co-trimoxazole in HIV-positive patients has been associated with a high frequency (40-80%) of hypersensitivity reactions. This has been attributed to the bioactivation of the sulphonamide component, sulphamethoxazole (SMX), to its toxic hydroxylamine and nitroso metabolites. The aim of this study was to determine whether functionally significant polymorphisms in the genes coding for enzymes involved in SMX metabolism influence susceptibility to SMX hypersensitivity. HIV-positive patients with (n = 56) and without (n = 89) SMX hypersensitivity were genotyped for allelic variants in CYP2C9, GSTM1, GSTT1, GSTP1 and NAT2 using polymerase chain reaction (PCR) and/or PCR-restriction fragment length polymorphism analysis. The CYP2C9*2/*3 genotype and CYP2C9*3 allele frequencies were nine- and 2.5-fold higher in the hypersensitive group compared to non-sensitive patients, respectively, although they were not statistically significant when corrected for multiple testing. There were no differences in the frequencies of the GSTM1 and GSTT1 null genotypes, and the slow acetylator genotype, between hypersensitive and non-sensitive patients, while GSTP1 frequency was lower (although non-significant) in the hypersensitive group [21% versus 32%, odds ratio (OR) = 0.5, Pc = 0.24]. Comparison of the genotype frequencies in HIV-positive and -negative patients showed that the NAT2 slow acetylator genotype frequency in the HIV-positive patients (74%) was significantly (Pc = 0.0003, OR = 2.3) higher than in control subjects (56%). Our results show that genetic polymorphisms in drug metabolizing enzymes are unlikely to be major predisposing factors in determining individual susceptibility to co-trimoxazole hypersensitivity in HIV-positive patients.

Acetylation↗
PubMed1999

Role of retinoids in renal development: pathophysiological implication.

Vitamin A closely modulates nephron endowment at birth. It is also required for the development of renal vasculature. Fetal vitamin A status may thus be responsible for most of the variations in nephron number found in the general population, and may play a major role in the intrauterine programming of chronic renal disease and hypertension.

Animals↗
PubMed1999

Adverse effects of hyperglycemia on kidney development in rats: in vivo and in vitro studies.

Congenital malformations occur more frequently in the offspring of diabetic mothers. These in vivo and in vitro studies investigate the potential adverse effects of hyperglycemia on kidney development in the rat. Female rats were made hyperglycemic throughout gestation with a single injection of streptozotocin (STZ) on day 0 of gestation, or for a short period encompassing the early stage of renal organogenesis by infusing glucose from gestational days 12-16. Kidney development in the pups was assessed by determining the total number of nephrons formed in the kidney. The number of nephrons was significantly reduced (10-35%) in the pups from STZ-treated dams, as a function of hyperglycemia. There were also fewer nephrons in pups from dams given glucose infusion whose hyperglycemia was transiently higher on day 13 of gestation. The in vitro experiments were done on metanephroi removed from 14-day-old fetuses and grown for 6 days in medium containing 0, 6.9, 13.8, or 27.5 mmol/l glucose. The development of explants grown in 0, 13.8, and 27.5 mmol/l glucose was impaired compared with that of explants grown in the 6.9 mmol/l control medium, showing that the glucose concentration must be closely controlled to ensure optimum in vitro metanephros development. Thus, exposure to hyperglycemia in utero can cause a nephron deficit, which in turn may have renal consequences later in life.

Aging↗
PubMed1998

Mild vitamin A deficiency leads to inborn nephron deficit in the rat.

BACKGROUND: Vitamin A plays a critical role in fetal organogenesis, and its severe deficiency during pregnancy is known to result in malformations of several organs, including the kidney. However, the consequences of mild vitamin A deficiency (VAD) has received little attention. In the present study, we examined the effect of in utero exposure to mild VAD on renal organogenesis. METHODS: A rat model of mild VAD compatible with normal gestation was developed. Plasma retinol was determined by reverse phase HPLC in mothers and fetuses. Nephron counting was performed in kidneys of fetuses and pups issued from control and VAD mothers. Metanephroi explanted from 14-day-old fetuses from both groups were cultured in the presence or absence of retinoic acid (RA), and growth and differentiation were assessed. c-ret expression was analyzed from fetuses exposed in utero to VAD or to normal vitamin A status and also in metanephroi grown in culture with or without RA using RT-PCR. RESULTS: The 50% reduction in circulating vitamin A levels induced by vitamin A deprivation in pregnant rats did not affect the overall fetal development. However, the number of nephrons was reduced by 20% in 21-day-old VAD fetuses. The number of nephrons was closely correlated with circulating vitamin A level in both VAD and control fetuses. Metanephroi taken from VAD fetuses developed to a lesser extent in vitro, but their capacity to respond to exogenous retinoic acid was not altered. Finally, we found that the expression of the proto-oncogene c-ret was modulated according to the retinoid environment. CONCLUSION: We conclude that vitamin A supply to the fetus is critical in determining the number of nephrons. Data available thus far on the frequency of mild VAD during pregnancy and on the long-term consequences of inborn nephron deficit highlight the clinical relevance of the present study.

Animals↗
PubMed1998

The inheritance of glomerulosclerosis in mice is controlled by multiple quantitative trait loci.

BACKGROUND: Glomerulosclerosis, the common terminal event in chronic glomerular diseases such as diabetic nephropathy or IgA nephropathy, leads to end-stage renal disease. The considerable variation in both the risk of developing glomerulosclerosis and the rate of progression in individual patients suggest a role for genetic factors which have not been identified so far. In this study we sought to examine the mode of inheritance of glomerulosclerosis in mice. METHODS: F1 animals of a mating between glomerulosclerosis-prone ROP-Os/+ male and non-sclerotic C3H female mice were backcrossed to the ROP strain. We took advantage of the radiation-induced mutation oligosyndactylism (Os) to identify glomerulosclerosis at the age of 3 months. Kidneys were perfused in situ with PBS/Formalin 10%. The extent of glomerulosclerotic lesions was evaluated on PAS stained paraffin sections using computer-aided morphometry. RESULTS: F1 mice did not show any glomerulosclerosis. In the backcross offspring, we found a wide distribution of glomerular lesions between individual animals, ranging from normal to very severe. We calculated that at least 8-10 loci determine the severity of glomerulosclerosis in mice. CONCLUSIONS: Our data show that glomerulosclerosis is inherited in a recessive fashion involving at least 8-10 loci.

Animals↗
PubMed1998

Regulation of c-ret expression by retinoic acid in rat metanephros: implication in nephron mass control.

Vitamin A and its derivatives have been shown to promote kidney development in vitro in a dose-dependent fashion. To address the molecular mechanisms by which all-trans-retinoic acid (RA) may regulate the nephron mass, rat kidneys were removed on embryonic day 14 (E14) and grown in organ culture under standard or RA-stimulated conditions. By using RT-PCR, we studied the expression of the glial cell line-derived neurotrophic factor (GDNF), its cell surface receptor-alpha (GDNFR-alpha), and the receptor tyrosine kinase c-ret, known to play a major role in renal organogenesis. Expression of GDNF and GDNFR-alpha transcripts was high at the time of explantation and remained unaffected in culture with or without RA. In contrast, c-ret mRNA level, which was low in E14 metanephros and dropped rapidly in vitro, was increased by RA in a dose-dependent manner. The same is true at the protein level. Exogenous GDNF barely promotes additional nephron formation in vitro. Thus the present data establish c-ret as a key target of retinoids during kidney organogenesis.

Amino Acid Sequence↗
PubMed1997

Birth-related changes in energy metabolism enzymes and Na-K-ATPase in kidney proximal convoluted tubule cells.

In the proximal convoluted tubule (PCT) of rat kidney, reabsorption is known to take place during fetal life, but no data on Na-K-ATPase and mitochondrial energy metabolism enzymes in this epithelium were available at fetal and neonatal stages. With use of the quantitative histochemistry approach, Na-K-ATPase, citrate synthase (tricarboxylic acid cycle), 3-ketoacid CoA-transferase and thiolase (ketone body oxidation), beta-hydroxyacyl-CoA dehydrogenase (fatty acid oxidation), and acetylcarnitine transferase (acetyl-CoA transport through mitochondrial membrane) were microassayed in PCT and metanephric mesenchyme of fetal and newborn rat kidney. The data indicate that, during fetal life, PCT differentiation involves concomitant increases in Na-K-ATPase and oxidative enzyme activities, supporting the hypothesis that mitochondria could play an active role in cellular ATP turnover when reabsorptive functions develop. Birth resulted in marked increases in the activities of Na-K-ATPase and of fatty acid and ketone body oxidation enzymes in the PCT, whereas no changes in enzyme activities occurred in the metanephric mesenchyme between the fetal and the newborn stage.

Acetyl-CoA C-Acetyltransferase↗
PubMed1997

Glomerulosclerosis, arteriosclerosis, and vascular graft stenosis: treatment with oral heparinoids.

At present there is no known treatment for established glomerulosclerosis or atherosclerosis. Since the principal lesion in glomerulosclerosis involves mesangial cells, a vascular smooth muscle cell, we searched for new therapeutic approaches affecting vascular smooth muscle function, especially with respect to modifying the turnover of extracellular matrix. We used mice transgenic for bovine growth hormone (bGH), since these mice develop end-stage renal disease due to progressive glomerulosclerosis. We previously showed that the subcutaneous injection of a non-anticoagulant heparin reduced glomerulosclerosis in bGH mice. Since injectable drugs are not a practical means of controlling glomerulosclerosis in humans, we assessed oral heparin-like compounds and found that oral pentosan polysulfate (PPS) reduced glomerulosclerosis in bGH mice at non-toxic doses. Because the positive therapeutic response in the bGH model could have been principally hormone-mediated, we examined other models of non-immune mediated glomerulosclerosis, including ROP Os/+ non-diabetic and diabetic mice. We found that an oral PPS (Elmiron), which is approved for other indications in humans, reduced sclerosis in all of these forms of chronic, progressive glomerulosclerosis. Based on the similarity of the cellular events in glomerulosclerosis and arteriosclerosis, we assessed the effect(s) of PPS in congenital (Watanabe rabbits) and induced (New Zealand White lipid-fed rabbits) models of arteriosclerosis. The extent and severity of the lesions was significantly reduced in both models by PPS treatment. Finally, we asked whether the proliferative and sclerotic lesion, which is the cause of vascular graft stenosis, might also respond to PPS treatment. To do this we cultured cells from the materials removed from stenotic arteriovenous grafts in hemodialysis patients. We found that PPS inhibits the proliferation and matrix production in a dose-dependent manner.

Animals↗
PubMed1996

Rat metanephric organ culture in terato-embryology.

The development of the permanent mammalian kidney, or metanephros, depends on mesenchymal-epithelial interactions, leading to branching morphogenesis of the ureteric bud that forms the collecting ducts and to conversion of the metanephric mesenchyme into epithelium that forms the nephrons. Rat metanephric organ culture in which these interactions are maintained is a valuable in vitro model system for investigating normal and abnormal renal organogenesis. Methods were designed to evaluate either the capacity of the ureteric bud to branch or that of the mesenchyme to form nephrons. Both are based on specific staining of the ureteric bud and the glomeruli with lectins. Using this approach, we have shown that retinoids are potent stimulating factors of nephrogenesis, acting through an increase in the branching capacity of the ureteric bud. On the other hand, several drugs such as gentamicin and cyclosporin A were found to reduce the number of nephrons formed in vitro. While gentamicin affects the early branching pattern of the ureteric bud, cyclosporin may affect the capacity of the mesenchyme to convert into epithelium. This methodology therefore appears a potentially useful tool for toxicological studies of new drugs.

Animals↗
PubMed1996

Metanephros organogenesis is highly stimulated by vitamin A derivatives in organ culture.

Vitamin A and its metabolic derivatives are known to be key signalling molecules in regulating morphogenetic events in vertebrate development. Here we investigated their possible involvement during mammalian kidney development using paired rat metanephros organ culture. Metanephroi were explanted from 14-day-old embryos and cultured for six days in a chemically defined medium containing a retinoid at a dose of 10(-11) to 10(-4) M. Retinol, all-trans and 9-cis retinoic acid were able to promote metanephros growth and differentiation in vitro. A significant increase in the number of nephrons was observed from 10(-8) M of retinol and 10(-10) M of all-trans retinoic acid, before any change in growth parameters. A threefold increase in the number of nephrons was obtained at a dose of 10(-6) M. At low retinoid concentrations, there was a modulating effect of triiodothyronine on retinoid-stimulated nephrogenesis since the absence of triiodothyronine in the medium enhanced the nephrogenic stimulation. Exposure of metanephroi from 13-day-old embryos to all-trans retinoic acid (10(-7) M) led to a sixfold increase of nephron formation. Finally, we analyzed the branching pattern of the ureteric bud and showed that within 48 hours of culture, it was significantly more developed upon retinoid exposure. In conclusion, this study demonstrates that retinoic acid is a key regulator of renal organogenesis in controlling nephrogenic induction processes and ureteric bud patterning, and that the younger the metanephros, the greater the effect.

Animals↗
PubMed1995

Thyroid hormones regulate development of energy metabolism enzymes in rat proximal convoluted tubule.

Ketone bodies represent preferred energy substrates in the adult rat proximal tubule. They are abundant in the plasma of suckling rats and might represent an important oxidative substrate for the immature proximal tubule. The postnatal development of two enzymes involved in ketone body oxidation pathway, 3-ketoacid-CoA transferase and acetoacetyl-CoA thiolase, and of citrate synthase and carnitine acetyltransferase was studied in microdissected rat proximal convoluted tubule (PCT) at 1, 8, 16, and 21 days after birth. The enzyme levels in PCT of juxtamedullary and subcapsular nephrons were compared at 8, 16, and 21 days. A role of thyroid hormones in regulating the development of these enzymes was investigated by studying 8- and 21-day-old pups made hypothyroid by propylthiouracyl (PTU) treatment, as well as 21-day hyperthyroid rats. PTU treatment had no effect on enzyme activities on day 8. In contrast, the activity of all mitochondrial enzymes, except acetoacetyl-CoA thiolase, was significantly decreased in 21-day-old hypothyroid pups. In hypothyroid animals, the normal development of 3-ketoacid-CoA transferase, citrate synthase, and carnitine acetyltransferase could be restored after treatment by triiodothyronine (T3). In addition, one single injection of T3 to 8-day-old control pups induced a precocious rise in the activity of 3-ketoacid-CoA transferase, citrate synthase, and carnitine acetyltransferase in juxtamedullary PCT and in the activity of citrate synthase and carnitine acetyltransferase in subcapsular PCT. Altogether, these results point out the importance of the postnatal physiological rise in T3 in triggering the development of some mitochondrial oxidative enzymes in the PCT.

Aging↗
PubMed1995

[Extracorporeal lithotripsy: comparative study with magnetic resonance, ultrasonography, and nuclear medicine of short-term renal changes produced by piezoelectric and electrohydraulic equipment].

Ultrasound, Nuclear Magnetic Resonance (NMR) and Nuclear Medicine (NM) were used to evaluate short-term changes and renal complications (within the first 10 days) induced by extracorporeal lithotrity (ESWL) from two separate lithotripters. To this end, a consecutive prospective study with 18 randomly selected patients, all candidates to ESWL, was conducted. ESWL was performed using a piezoelectric lithotripter in 10 patients and an electrohydraulic equipment in 8 patients. Qualitative evaluation of images was done with ultrasound and NMR (changes in renal morphology: shape, cortico-medullary definition, size, changes in perirenal space), and with isotopic renogram (global renal function); while quantitative evaluation was done with NMR (measurement of signal intensity on cortex, marrow and muscle), and with isotopic renogram (semiquantitative assessment of unilateral renal function and renal excretory function). ESWL with piezoelectric and electrohydraulic lithotripter shows a low short-term complication rate: changes of cortico-medullary differentiation (ultrasound in 27.8% cases, NMR in 5.6%) and perirenal striations (NMR in 11%). No renal function changes were found. These observations have not been quantitatively corroborated; we have not found statistically significant differences between changes produced after ESWL either with piezoelectric or electrohydraulic lithotripters.

Female↗
PubMed1994

[Rounded nodular atelectasis: computerized tomography and magnetic resonance appearances].

Rounded atelectasis is a rare form of lung collapse whose X-ray appearance can be confused with that of tumors, especially nodular forms. We studied 14 such lesions with computerized tomography, finding that all were rounded and subpleural, specifically in the thickened pleura visceralis. The radiological sign that was most useful for diagnosis was the arc of the proximal vessels in the direction of the lesion. Such an arc was present in all the cases we reviewed. Other radiological signs such as brightness of the surrounding parenchyma, loss of volume in the affected lobe and the presence of air bronchogram were found in 10, 7 and 7 patients, respectively. When the X-ray appearance clearly indicates a diagnosis of rounded nodular atelectasis, we recommend that no additional diagnostic procedure be made. Three lesions in our sample were studied by magnetic resonance, which revealed the characteristic hypointense curves in all sequences done on 2 patients. The usefulness of computerized tomography in the diagnosis of this entity relegates magnetic resonance to a second plane.

Adult↗