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M Daudon

Publications and source records attributed to M Daudon.

At least 55 records · Page 3Linked to original sources
PubMed1997

An in vitro comparison of urease-induced encrustation of JJ stents in human urine.

OBJECTIVE: To report the results of a comparative study of in vitro encrustation of five different types of JJ stents in human urine. MATERIALS AND METHODS: Samples of five JJ stents (polyurethane, silicone, Percuflex, C-Flex and hydrogel-coated C-Flex) were immersed for 24 h at 37 degrees C in fresh human urine supplemented with urease, and the surface photographed and dried. The crystals formed on the stents were dissolved in hydrochloric acid and the calcium and magnesium concentrations determined. RESULTS: Large crystals were deposited on the surface of the hydrogel-coated C-Flex stent and significantly higher levels of calcium and magnesium salts were obtained after acidic dissolution. There were no differences in crystal deposition among the remaining stents. CONCLUSION: Hydrogel-coated stents have an higher risk of becoming encrusted in vitro than do uncoated stents made of the same substrate polymer or made of different materials. These results emphasize the need for the regular follow-up of patients with hydrophilic stents in place.

Crystallization↗
PubMed1997

New aspects of urolithiasis in France. GERBAP: Groupe d'Evaluation et de Recherche des Biologistes de l'Assistance Publique des Hôpitaux de Paris.

OBJECTIVE: To confirm epidemiological studies showing a continuous progression of calcium oxalate nephrolithiasis in western countries, we investigated some aspects of the evolution of stone disease in France. METHODS: Calculi collected from 1977 to 1993 in 10,438 adult French patients were analyzed by infrared spectroscopy. Only 8,631 well-documented cases were available. The anatomical location, the removal mode of calculi, and the time evolution of stone composition were studied. RESULTS: The stones were more often retained in the upper urinary tract in females than in males and needed urological removal. Uric acid stones were more frequently observed on the left side in both sexes (p < 0.0001). Extracorporeal shock wave lithotripsy seems to have been used for a time in calculi which would have been spontaneously discharged. Calcium oxalate stones were preponderant, but their proportion did not change in both sexes. A significant decrease of the proportion of calcium phosphate stones was observed in females (p < 0.0001), probably responsible for the increase of the male/female sex ratio from 1.7 to 2.4. CONCLUSIONS: From our observations and from the evolution of dietary habits in France, it can be deduced that urolithiasis trends to a plateau.

Adult↗
PubMed1997

[Primary hyperoxaluria: Tunisian experience apropos of 24 pediatric cases].

We report on 24 children (10 girls) presenting with primary hyperoxaluria. The mean age at diagnosis was 6.3 years (range: 3 months-14.8 years). The mean interval between initial symptom and diagnosis was 1.3 year. The average follow-up period was 22 months (range: 1-60 months). At the time of diagnosis the renal function was normal in 6 children, moderately altered in 1 and severely in 17. During the follow-up the renal function remained stable in 6 patients, improved in 2, deteriorated in 4. The 12 patients with end-stage renal disease at diagnosis remained unchanged. Urolithiasis were present in all patients older than 2 years, and in 1 among the 5 infants. Medullary nephrocalcinosis was observed in 3 patients in whom the renal function was preserved. Diffuse nephrocalcinosis was present in all patients with end-stage renal failure. Improvement of renal function was secondary to stone removal in 2 patients. Extracorporeal shock wave lithotripsy performed in 7 patients was efficient only in 3. In 10 patients oxalate bone disease was correlated with both renal function and dialysis duration, whereas retinal involvement noted in 6 patients was not.

Adolescent↗
PubMed1997

[Urolithiasis in children in West Algeria].

We analyzed a series of 61 stones from children aged 3 to 14 years old using Fourier transform infrared spectroscopy. The calculi were collected from urology departments of the University Hospitals of Oran, Sidi-Bel-Abbès and Mostaganem in West Algeria. This series is the first investigation concerning the composition of stones in children based on infrared analysis. Calculi were more frequent in males (75.4%) and mainly localized in the bladder (55.8%). Upper urinary tract calculi were more frequent in children over the age of 10 years, and the sex ratio was about 1. Calcium oxalate monohydrate was present in 70.5% of stones and was the main component in 50.8% of cases both in whole stones and nuclei. In contrast, calcium oxalate dihydrate was the main component in only 9.8% of calculi although it was present in 75.4% of stones. Ammonium urate was detected in 29.5% of stones and was always the main component of nuclei. Uric acid, observed in 31.1% of calculi, was the major constituent in 14.7% of stones and 19.7% of nuclei. Magnesium ammonium phosphate was observed in 24.6% of stones as a consequence of urinary tract infection by urea-splitting bacteria. Our observations emphasized that the anatomical location of stone and their composition were in accordance with those previously reported in other countries.

Adolescent↗
PubMed1997

Validation by image analysis of a turbidimetric method to study calcium oxalate crystallization.

Numerous studies of calcium oxalate crystal formation have been carried out in the past two decades. In the present study, experiments were carried out to validate a turbidimetric method allowing to assess the calcium oxalate crystallization process. This method is quick and reproducible and can be used to quantify the inhibition of calcium oxalate crystal growth by various compounds. An experimental method of validation has been developed, which consisted in filtering solutions pure or containing modifiers at given crystallization times, photographing the filters used on scanning electron microscopy and analyzing the images using mathematical methodology. The results obtained through image analysis, namely crystal density (mean particle number per unit volume) and mean area, were correlated with the turbidimetric parameters. This finding was consistent with the qualitative examination of the photographs. Moreover, the morphological differences in crystals observed on the photographs were confirmed by the calculated length/width ratio. One can therefore assume that inhibition of calcium oxalate crystal growth is at least, partly explained by surface adsorption phenomena, which may add to complex formation.

Calcium Oxalate↗
PubMed1996

Fourier transform infrared microscopy identification of crystal deposits in tissues: clinical importance in various pathologies.

The presence of crystal deposits in tissues is associated with various pathologies. Sometimes their identification is useful for understanding the etiology or the mechanism of the disorder. The authors applied Fourier transform infrared microscopy (FTIRM) to the molecular characterization of crystal deposits in tissue and compared the results with those provided by histologic studies using polarized light microscope and histochemical reactions. Twenty-five biopsies were investigated. In 10 cases, the results were in good agreement. In 15 cases only FTIRM could precisely identify the crystals. In three cases, this technique allowed to characterize dihydroxyadenine crystals revealing an adenine phosphoribosyltransferase deficiency previously undiagnosed in patients presenting severe chronic renal failure. In three cases, crystal deposition was related to drug therapy. In other cases, crystal identification was useful to understand the mechanism of the pathology responsible for tissue damage and crystal deposition.

Adenine↗
PubMed1996

Management of oxalosis.

Oxalosis is the final stage of primary hyperoxaluria type I (PHI) when reduction of GFR produces oxalate accumulation. It involves bones, arteries, eyes, heart, nerves, etc. The management of oxalosis starts with prevention of nephrocalcinosis and renal failure by diluting urine and by inhibiting oxalate crystal formation either by increasing the urinary citrate or the urinary pyrophosphate. At endstage renal disease (ESRD) there is no dialysis modality for avoiding the progression of oxalosis. Combined liver/kidney transplantation (LKT) represents the most effective approach. The European PHI transplant registry recently reported 64 LKT with a five-year patient survival of 80% and progressive healing of oxalosis. Four children who received LKT in our unit are reported, all of whom are alive with a follow-up of three months to five years. Bone disease completely healed in one case after three years, but retinal deposits persisted despite improvement of visual acuity. A special perioperative protocol must be applied for protecting the graft from oxalate released from the stores. Laboratory follow-up including oxalemia and urinary crystal volume helps to adjust the individual prescriptions. This intensive management must be continued as long as oxalate stores persist.

Combined Modality Therapy↗
PubMed1996

Proteins and bioprosthetic calcification in the rat model.

BACKGROUND AND AIM OF THE STUDY: The mechanism of valvular bioprostheses calcification is still unknown, but early studies showed increased Gla-protein content in calcified valves. Using an experimental model, which reproduces the clinical process, we therefore analyzed the role of minerals and proteins in bioprosthetic valvular calcification. METHODS: Glutaraldehyde pretreated porcine valves were studied before and after implantation in rats by X-ray, calcium (Ca) and phosphorus (P) measurement, Fourier Transform Infrared (FTIR) spectroscopy, SDS-PAGE and 45Ca ligand blotting of the extracted proteins. RESULTS: Before implantation, there was no X-ray calcification with very little Ca and P content. After implantation, X-ray calcifications appeared on day seven with increased Ca and P up to day 35 (p < 0.05, ANOVA). FTIR revealed structural proteins alone before implantation, plus minor proportions of lipids on day two, which always preceded Ca and P appearance. Ca and P increased up to day 35, first as amorphous and changed in carbapatite over time. SDS-PAGE before implantation revealed two proteins (66-kD and 54-kD) alone, which were sustained up to day 35. The 66-kD had 45Ca affinity. On day two, many other proteins appeared on SDS-PAGE, four of which (52, 45, 14 and below 14-kD) with 45Ca affinity. Protein pattern did not change from day two to 35. CONCLUSIONS: Valvular bioprosthesis calcification is associated with progressive increase in Ca and P content and at least five calcium-binding proteins: one intrinsic valvular protein, pre-existing to implantation, plus four other, extrinsic valvular proteins adsorbed within the tissue after implantation.

Animals↗
PubMed1996

[Uronic-acid-rich protein: a new glycoprotein inhibiting the crystallization of calcium oxalate in vitro].

During about ten years, nephrocalcin was considered the main calcium oxalate crystal growth inhibitor. Today, it appears only a urinary protein inhibitor among other ones such as non polymerized Tamm-Horsfall protein, uropontin or crystal matrix protein (CMP), a protein derived from prothrombin. All these molecules are able to inhibit either crystal growth or aggregation of calcium oxalate in urine. Another protein, named renal lithostathine, was also reported to be a potent inhibitor of secondary nucleation and growth of calcium carbonate crystals. A new urinary inhibitor of calcium oxalate formation was isolated from the urine of healthy subjects using chromatographic procedures. It is a macromolecule with a molecular weight (MW) of approximately 35 kDa as estimated by polyacrylamide gel electrophoresis. Its carbohydrate content represents an average of 8.5% of its MW. Glutamic and aspartic acids represent 24% of total amino acids. This protein is called Uronic-Acid-rich Protein (UAP) because of its uronic acid content. The same protein isolated from the urine of stone formers showed less inhibitory activity than that purified from the urine of healthy subjects. Structural modifications may explain this diminution of its inhibitory activity. This protein was also purified from rat urine using same procedures. Human and rat UAP exhibit similar biochemical characteristics and strongly inhibit calcium oxalate crystallization in vitro. Partial amino acid sequence analysis showed a homology with inter-alpha-trypsin inhibitor (ITI), confirmed by the immunological results on Western blot. Nevertheless, various chemical and enzymic treatments revealed that UAP and ITI are not identical molecules. Consequently, urine contains several macromolecular substances belonging to ITI superfamily which are involved in the inhibition of calcium oxalate crystallization. UAP takes place among the most efficient macromolecular substances known as inhibitors in calcium oxalate nephrolithiasis.

Animals↗
PubMed1995

[Evaluation of the lithogenic risk in renal lithiasis. Value of urine density measurement].

OBJECTIVE: Measuring specific gravity of urine is a simple means of self-monitoring for urolithiasis patients. METHODS: We evaluated the reliability of two test strips (N-Multistix and Combur-Stix) and determined the relationship between urine specific gravity and crystal formation in first morning urine in 179 patients with calcium oxalate lithiasis. Urine hydrometry was used as the reference method. RESULTS: There was a good correlation between urine density read on the test strips and hydrometry (r = 0.733 for N-Multistix and 0.697 for Combur-Stix). Hydrometry showed little pH effect but the test strips gave results correlated with urine pH (r = 0.764 and 0.813 respectively). When urine pH was below 6.5, the specific gravity of the urine was overestimated; inversely for pH > 7, it was underestimated. Correction factors were obtained by comparing test strip values with specific gravity measurements for pH level between 4.5 and 8. There were crystals in 66% of the urine samples with a density > or = 1012 g/l. In contrast, 75% of the samples below this value were crystal free. There was a close relationship between 24-hour urine volume and specific gravity (n = 124; r = 0.778): a specific gravity of 1.012 corresponded to 2100 ml urine output. For 24% of the patients, specific gravity of the morning urine was > or = 1.012 despite a 24-h urine output > or = 2100 ml, indicating insufficient urine dilution during the night. CONCLUSION: Measurement of specific gravity with test strips with correction for pH can be a simple way to measure the specific gravity of urine and assess whether urine dilution is sufficient to reduce the risk of crystal formation, the main risk factor in urolithiasis patients.

Humans↗
PubMed1995

Analysis of the soluble organic matrix of five morphologically different kidney stones. Evidence for a specific role of albumin in the constitution of the stone protein matrix.

Our aims were to analyze the protein composition of the organic matrix of urinary stones and to investigate the role of albumin in its constitution. Five different morphological types of stones were studied. Proteins extracted from the stone were submitted to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by immunoblotting with antibodies to 13 urinary proteins. Nine of the 13 proteins were found in all types of stone: human serum albumin (HSA), alpha 1-acid glycoprotein (alpha 1-GP), alpha 1-microglobulin (alpha 1-M), immunoglobulins (Igs), apolipoprotein A1 (apo-A1), transferrin (Tr), alpha 1-antitrypsin (alpha 1-T), retinol-binding protein (RBP) and renal lithostathine (RL). The beta 2-microglobulin (beta 2-M) was present only in calcium oxalate and uric acid stones. In contrast, ceruloplasmin, haptoglobin and Tamm-Horsfall protein (THP) were detected in none of them. Because HSA appeared as the major protein component in all stones, we wondered whether it might play a specific role in the constitution of the stone matrix. Association of HSA with urinary proteins that were present in stones was demonstrated by showing that proteins present in the matrix comigrated with HSA on gel filtration, whereas proteins that were absent did not. Moreover, HSA induced the binding of stone matrix proteins to an albumin-specific affinity column. Finally, we evidenced HSA binding to calcium oxalate monohydrate (COM) crystals in a solution similar to urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1995

Sex- and age-related composition of 10 617 calculi analyzed by infrared spectroscopy.

A series of 10 617 calculi were analyzed by stereomicroscopy and infrared spectroscopy. This first study of French calculi was compared with large series in the literature. That the frequency of pure calculi was the lowest ever observed can be related to the methodology routinely used in our laboratory, which includes microsampling. We described more than 70 components among the 10 617 calculi. The overall sex ratio male to female patients was high (2.27) and increased over the period 1981-1993. Calcium oxalate was the most frequent component (86.48%), followed by calcium phosphate (79.75%) and purines (18.64%). We found a low occurrence of "infection" stones. The sex ratio was related to stone composition and differed according to the main component. For instance, calcium oxalate dihydrate (COD) was more frequent in men than in women, with a sex ratio of 4.97 versus 2.57 for calcium oxalate monohydrate (COM). On the contrary, calcium phosphate was more frequent in female patients (sex ratio 0.72 versus overall ratio). The high frequency of COD calculi (23.17%) suggests that hypercalciuria is particularly frequent in French patients susceptible to stone formation. For each main component, a specific profile was observed in relation to the sex and age of the patients with stones.

Adult↗
PubMed1995

[Etiologic factors of urinary lithiasis in Tunisian children].

Fifty-five Tunisian children with urinary stones, between the ages of 8 months and 15 years, underwent morphological and infrared spectrophotometric analysis of their stones. This study provides an approach to the aetiological profile of urinary stones in Tunisian children. The nucleus of the stones was composed of acidic ammonium urate in 48% of cases with a morphology suggestive of phosphorus deficiency associated with a history of diarrhoea. In 24% of cases, the nucleus contained struvite indicating the presence of urinary tract infection by urease-positive bacteria. The main growth factors of urinary stones were hyperoxaluria and urinary tract infection. In 5 cases, the stones were due to a hereditary lithogenic metabolic disease : cystinuria in 1 case and primary hyperoxaluria in 4 cases.

Adolescent↗
PubMed1994

Reduced inhibitory activity of uronic-acid-rich protein in urine of stone formers.

We recently reported that human urine contains a newly identified urinary glycoprotein acting as a potent inhibitor against calcium oxalate crystallization. This inhibitor is a uronic-acid-rich protein (UAP) with a molecular weight of approximately 35 kDa. In the present study, UAP was isolated from urine of stone formers and of subjects without a stone history, and its inhibitory activity was tested in a calcium oxalate crystallization system in vitro. Our results show a weaker inhibitory activity of UAP extracted from the urine of stone formers than that extracted from the urine of healthy subjects. Preliminary analyses of amino acid and carbohydrate content showed some differences between the two groups. The main difference was the reduction in sialic acid in UAP isolated from the urine of stone formers. We suggest that UAP contributes significantly to total urinary inhibitory activity of calcium oxalate crystallization and that the decrease in this activity in the urine of recurrent stone formers is due, in part, to the weak inhibitory activity of UAP. A structural abnormality of UAP could explain the diminution of its inhibitory activity in the urine of stone formers.

Adult↗
PubMed1994

Chronic renal failure secondary to 2,8-dihydroxyadenine deposition: the first report of recurrence in a kidney transplant.

We report a case of adenine phosphoribosyltransferase deficiency in which the initial presentation was chronic renal failure. Diagnosis was made after infrared microscopy analysis of microcrystalline deposits on a kidney allograft biopsy specimen. This type of presentation is rarely seen, the most frequent manifestation of this disease being urolithiasis. This is the first report of recurrence of the microcrystalline nephritis in a kidney transplant with subsequent loss of allograft function.

Adenine↗