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M Daudon

Publications and source records attributed to M Daudon.

At least 91 records · Page 5Linked to original sources
PubMed1991

[Analytical methods of calculi and urinary crystals].

Numerous methods can be used for the analysis of urinary stones, but few of them provide information on the structure, chemical composition and crystal phases of these stones. In a good urinary stone analysis the stone is first examined through a binocular magnifying glass, for instance, to detect its structural features including umbilication. Randall's plaque, bracketing faces and individualized or non-individualized nucleus. Morphological typing is important as it points to one pathology or another irrespective of composition. Composition must be determined quantitatively, with differentiation of crystal phases, and this requires global physical methods such as X-ray microdiffractiometry or infrared spectrophotometry. Urinary crystals can be identified by polarized light microscopy supplemented, if necessary, by infrared microscopy when the crystals are few and of unusual morphology. Studying crystalluria is a simple and efficient means of following up lithiasic patients, provided their urine is collected and stored under adequate conditions. In interpreting the results various criteria, and particularly the nature, abundance, size, facies, aggregation and frequency of crystals, must be taken into account.

Chemistry Techniques, Analytical↗
PubMed1991

[Hepatic and renal transplantation in the treatment of type I hyperoxaluria].

Hyperoxaluria type I (HPI) is a metabolic disorder secondary to liver alanine glyoxylate aminotransferase deficiency. Renal failure occurs due to the excessive production and precipitation of oxalate in the kidney. Combined liver-renal transplantation is the correct treatment for this condition when end-stage renal failure occurs as with renal transplantation alone the risk of recurrence of the same pathology in the transplanted kidney would be high. We report the case of a 4 year-old child with HPI suffering from terminal renal failure in whom a hepato-renal transplantation was performed: six months later, creatinine clearance was 62 ml/min/1.73 m2 and liver function tests were normal.

Actuarial Analysis↗
PubMed1991

Investigation of urinary crystals by Fourier transform infrared microscopy.

Although crystalluria is generally considered a normal finding, sometimes it gives evidence of renal disturbance. Thus, detection and identification of urinary crystals may provide useful data for understanding the etiology of mechanism of the disorder. Light microscopy may be not sufficient to accurately identify the crystals. We investigated the ability of Fourier transform infrared microscopy (FTIRM) to identify isolated crystals of clinical interest. Twenty-five urine samples presenting crystalluria were tested because of their unusual aspect. We successfully identified 16 compounds and showed that crystals with the same apparent morphology can be composed of different substances. Moreover, an unexpected structure may be an insoluble phase of a drug metabolite. We conclude that FTIRM is a good technique for investigating urinary crystals of clinical interest.

Crystallization↗
PubMed1990

[Should fragments of stone expelled after extracorporeal lithotripsy always be analyzed?].

The morphological and constitutional analysis of renal stone fragments expelled after extracorporeal shock wave lithotripsy enables the structure and morphological type of stones to be reconstructed in 92.8 per cent of the cases as regards surface and section and in 74.5 per cent of the cases down to the core. A study of the molecular and crystalline composition of such fragments demonstrated the preponderance of whewellite in both sexes (men 85.4 per cent; women 72.4 per cent). The frequency of weddellite was 1.6 times higher in men (73.8 per cent) than in women (44.8 per cent), and the frequencies of struvite and ammonium urate were 2.8 and 2.6 times respectively higher in women than in men, despite a significant fall in frequency as compared to a previous series. Correlations between morphological type of stone and biochemical data (when available) could be established in 84 per cent of the cases. This made it possible to initiate treatments aimed at preventing recurrences, the cost of these treatments in the long term being lower than that of the curative urological treatments, including extracorporeal shock wave lithotripsy.

Adult↗
PubMed1990

[In vitro test of piezoelectric lithotripsy with ultrasound detection using an EDAP LT 01 lithotripser].

200 in vitro shots were performed with an EDAP LT 01 system in order to test the sensitivity of the various urinary stones to lithotrity and to study the action of the various shot parameters. All calculi do not have an equally favorable reaction to lithotrity. The deciding factor is neither their hardness, nor their chemical composition, nor their crystallizing shape, but rather the architecture ruling the arrangement of the crystallins forms in the calculus. The most important shot parameter is the power of the system, which conditions its efficiency. However, the shooting method, and more specifically the setting of the shot rate, allows adjusting the shots according to the desired results. The lithotriters will only be improved, ie. made more effective and less traumatic, if these experiments are continued.

Humans↗
PubMed1989

Relationship between the frequency of piezoelectric shock waves and the quality of renal stone fragmentation. In vitro study and clinical implications.

Nine renal stones were separated into 5 fragments of similar weight and size. One fragment was analyzed chemically and the other 4 fragments were submitted to treatment by piezoelectric shock waves according to the following modalities: 3,000 shock waves at firing frequencies of 1.25, 2.5, 5 and 10 shock waves/s. In the case of hard stones, better quality fragmentation was obtained with low frequencies than with high frequencies. With friable stones, using only 800 shock waves, the result was the same regardless of the frequency used. Treatment of hard stones by shock waves for 20 min at various frequencies revealed that a slightly better result was obtained with a frequency of 5 shock waves/s, although the result was not significantly better. In conclusion, slow frequencies of 1.25 or 2.5 shock waves/s allow better fragmentation of hard stones at the cost of a longer mean treatment than at high frequencies. High frequencies do not give significantly better results than low frequencies when the same firing time is used. In the clinical situation, it is therefore preferable to use low frequencies which allow treatment without anesthesia or analgesia and without admission to hospital.

Humans↗
PubMed1989

Metabolism of metapramine in vitro by chemical model systems and rat liver microsomes.

Metapramine (Timaxel) was oxidised by hepatic microsomes from rat and by biomimetic chemical systems; vanadyl acetylacetonate-iodylbenzene, phthalocyanin-iron II-iodosylbenzene, meso tetraphenyl porphyrine-iron III chloride-iodosylbenzene and Fenton's reagent. The major metabolite in all cases was the monodemethylated product formed by oxydative removal of the methyl group on the endocyclic nitrogen atom.

Animals↗
PubMed1988

[13 cases of drug-induced calculi].

All urinary stones should undergo detailed studies to identify those related to drug therapy. Among 520 stones analyzed by infrared spectrophotometry, we found 13 drug-induced stones (13/520: 2.5%). Drug-induced stones were caused by glafenine in 7 cases, piridoxylate in 4 cases, triamterene in one case and an unknown organic compound in one case. Glafenine stones appear to develop more readily in infected urine. Triamterene stones are often associated with uric acid disorders. Piridoxylate induces the formation of glyoxylate which is responsible for hyperoxaluria and formation of oxalocalcium stones.

Aged↗
PubMed1987

[Principal methods for studying the composition and structure of urinary calculi].

Since stones are the only objective elements of lithiasis, the cause of this disease can only be determined by an accurate analysis of the morphology and composition of the stones. To identify the crystal phases and the distribution of constituents between superficial and central structures such efficient techniques as scanning electron microscopy, X-ray diffraction or infrared spectroscopy are required. At least two complementary techniques must be combined to obtain enough information on the morphology as well as on the molecular and crystalline composition of the stones. The importance of morphological typing for the aetiological evaluation of the disease is demonstrated by examples which clearly show that each stone must first be examined optically. The different techniques used for the study of stones are reviewed and their relative efficiency and adaptability to routine analysis is discussed.

Calcium Oxalate↗
PubMed1987

Piridoxilate-induced calcium oxalate calculi: a new drug-induced metabolic nephrolithiasis.

During the last 4 years we collected 27 specimens of calcium oxalate nephrolithiasis in patients receiving long-term treatment with piridoxilate, a drug composed of an equimolar combination of glyoxylate and pyridoxine. The mean duration of treatment was 3.6 years (range 4 months to 10 years) and the mean daily dose was 580 mg. piridoxilate, which contained 160 mg. glyoxylate. Calculi often recurred, with an average number of 9.9 per patient, and an open operation, shock wave lithotripsy or percutaneous nephrolithotomy was required in 22 patients (81 per cent). Oxalate excretion was 727 +/- 246 mumol. per day while on the drug and 382 +/- 201 mumol. per day after the drug was withdrawn. Whewellite was the major component of calculi in all cases but the stones exhibited a peculiar morphological arrangement, with multiple small indentations and a fine mamillary structure. Freshly voided urine specimens contained unusual crystals, which on infrared spectroscopy were composed of calcium oxalate trihydrate, a variety of crystal never observed previously in human urine. Piridoxilate-induced calcium oxalate nephrolithiasis is a new variety of metabolic drug-induced nephrolithiasis. Our observations suggest that even large doses of pyridoxine may be unable to prevent the excessive production of oxalate from glyoxylate.

Adult↗