[Epidemiology of monoclonal gammopathy in a general hospital and a university internal medicine department]. / Epidémiologie descriptive des gammapathies monoclonales. Expérience d'un centre hospitalier général et d'un service de médecine interne de centre hospitalier et universitaire.

PURPOSE: Monoclonal gammopathy are common in the general population. We describe biological features and etiology of monoclonal gammopathy diagnosed during more than a ten year period in the Internal Medicine Department of Rennes University Hospital and in all the medical departments of General Hospital of Blois. METHODS: Patients were identified by immunofixation registry of Biochemistry Laboratories in both hospital (from 1990 in Rennes and from 1980 in Blois). RESULTS: Internal Medicine Department of Rennes University Hospital: 1051 monoclonal gammapathies were identified: 514 men and 537 women. Median age was 71. Isotypes repartition was: IgG 42.8% (450 cases), IgM 31.9% (335), IgA 8.9% (94) biclonal gammopathy 9.8% (103). Sixty-nine monoclonal light chains (6.6%) were identified. Median concentration of monoclonal protein was 14 g/l (1.8-104.4). All department of General Hospital of Blois: 1282 monoclonal gammapathies were identified: 700 men and 582 women. Median age was 79. Isotypes repartition was: IgG 59.7% (765 cases), IgM 27.5% (329), IgA 11.8% (151). Thirty-four monoclonal light chains (2.7%) were identified. Median concentration of monoclonal protein was 5.6 g/l (0.5-96.6). Most frequent diagnosis were: monoclonal gammopathy of undetermined significance or MGUS (77.6% in Blois and 64.1% in Rennes), multiple myeloma (11.9% and 12.7%), Waldenström's macroglobulinemia (4.4% and 8.7%). CONCLUSION: Monoclonal gammopathy are common in clinical practice. MGUS account for more than 60% of monoclonal gammopathy. Given their frequency, diagnostic and follow-up strategies must be costless and simple.

[Multisite validation of CDT measurement by the %CDT TIA and the Tina Quant %CDT kits]. / Validation multicentrique du dosage de la CDT par les méthodes %CDT TIA et Tina Quant %CDT.

The measurement of CDT (Carbohydrate Deficient Transferrin) is an essential biological tool in the diagnosis and follow-up of alcohol abuse. It is also employed as a marker of abstinence for the restitution of driving licences. However, the precision of measurement, and the between laboratory homogeneity of the results are still discussed. The ion exchange followed by immunodetermination of CDT is available in two products, the Tina Quant %CDT (Roche, Mannheim, Germany) and the %CDT TIA (Bio-Rad, Hercules, United States). This multicentre study was undertaken: 1) to evaluate the analytical characteristics of these kits and the homogeneity of the results from one laboratory to another, independently of the method used, 2) to validate the differences between the proposed normal values of both kits, 3) to study the possibility of using commercial control sera as external quality control. Four analytical systems were included in the study (Roche Modular/Hitachi 717, Beckman Coulter Immage and LX20, Dade Behring BNII). Determinations were carried out on pools of sera, commercial control sera, kit controls, and 30 serums of patients. These latter were also analyzed in capillary electrophoresis in order to establish correlations between the techniques. The calibrations were stable over one 2 weeks period. The repeatability of measurements spread out from 3,1% to 24,7%, for a mean value lower than 10%. The commercial control sera provided reliable results, with values adapted to a routine quality control use. The results of the Bio-Rad applications were lower by approximately 20% than those of the Roche application, which justifies the difference of the normal values (2,6% versus 3%), and an identical classification of the patients in at least 27 of the 30 samples. We conclude that the analytical quality of the compared techniques, even if it could be improved, is sufficient to guarantee a good reliability of the results. An external quality control could be proposed by using the control sera that we tested.

Fluoride ion toxicity in rabbit kidney thick ascending limb cells.

BACKGROUND AND OBJECTIVE: Some halogenated agents, especially methoxyflurane, because of a higher level of fluoride production, induce a renal concentrating defect that could be related to an ascending limb impairment. We investigated the mechanisms of fluoride toxicity on an immortalized cell line. METHODS: Cells were cultured for 2, 6 or 24 h in the presence of fluoride. Toxicity evaluation was based on: cell numbers, protein content, leucine-incorporation, lactate dehydrogenase (LDH) and N-acetyl-beta-glucosaminidase (NAG) releases, Na-K-ATPase and Na-K-2Cl activities, electron microscope studies. Infrared analysis and fluoride microdetermination allowed crystal components. RESULTS: At 5 mmol after 24 h, fluoride decreased cell numbers (-14%, *P < 0.05), protein content (-16%*), leucine incorporation (-54%*), Na-K-2Cl activity (-84%*), increased LDH (+145%*) and NAG release (+190%*). Na-K-ATPase was more sensitive and impaired from 1 mmol for 24h and after 2 h at 5 mmol. Crystal formation in mitochondria occurred after 6 h at 5 mmol. Infra-red analysis and fluoride microdetermination established that crystals contained sodium, phosphate and fluoride. CONCLUSIONS: The results suggest that the Na-K-ATPase pump is a major target for fluoride toxicity in Henle's loop.

Advantage of zero-crossing-point first-derivative spectrophotometry for the quantification of calcium oxalate crystalline phases by infrared spectrophotometry.

The main component of urinary calculi in industrialized countries is calcium oxalate. Its detection in stones is easily performed by infrared spectrophotometry. However its two crystalline forms calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD), which are linked to different aetiologies, provide similar patterns, with overlapping vibrations leading to difficulties in differentiation and quantitation of both the phases in mixtures. Some minor but characteristic bands of each crystalline species are emphasized for analytical purposes. The method of zero-crossing-point first-derivative spectrophotometry was applied to calcium oxalate species quantitation and revealed to be easy, accurate, precise and very well adapted to routine laboratories.

Crystalline phase differentiation in urinary calcium phosphate and magnesium phosphate calculi.

UNLABELLED: Phosphates are encountered as the main components in about 15% of urinary calculi. Except for struvite, no specific correlations have been found between the crystalline phase of the phosphates and the cause of nephrolithiasis. OBJECTIVE: The relationship between aetiological factors and crystalline phases or carbonate rate in calcium phosphate stones were assessed. MATERIAL AND METHODS: From a series of 1148 phosphate calculi, we investigated the relationship between composition and aetiological factors. RESULTS: Carbapatite was the most frequent crystalline phase (74.0%). It was associated with many possible causes, including hypercalciuria, hypocitraturia, primary hyperparathyroidism, tubular acidosis, medullary sponge kidney and chronic urinary tract infection. The carbonate rate of carbapatite may be of clinical interest because carbonate rates above 15% are frequently related to urinary tract infection with urea-splitting bacteria. Conversely, the carbonate rate was commonly less than 10% in cases of carbapatite induced by metabolic disorders. Among other phosphates, brushite was found in hypercalciuric states and primary hyperparathyroidism and whitlockite in cases of urinary tract infection by non-urease-producing bacteria. CONCLUSION: Identification of crystalline phases and measurement of carbonate rate in calcium phosphate calculi is of clinical interest for identifying stone aetiology.

Foscarnet-induced crystalline glomerulonephritis with nephrotic syndrome and acute renal failure after kidney transplantation.

Foscarnet nephrotoxicity has been reported to be associated with acute tubulointerstitial nephritis. Crystals in glomerular capillary lumens have also been observed in patients with acquired immunodeficiency syndrome who were treated with foscarnet for cytomegalovirus disease. We describe a kidney transplant recipient who developed a nephrotic syndrome with microscopic hematuria and nonoliguric acute renal failure within 15 days after starting foscarnet therapy for cytomegalovirus infection. A kidney biopsy specimen showed the presence of crystals in all glomeruli and in proximal tubules. Fourier transform infrared microscopy analysis demonstrated that crystals were made from several forms of foscarnet salts: mixed calcium and sodium salts, and unchanged trisodium foscarnet salts. Renal function and proteinuria spontaneously improved, and a second transplant biopsy performed 8 months after the first one revealed fibrotic organization of half of the glomeruli and of interstitial tissue, and crystal vanishing. We were thus able to provide proof of the possible precipitation of foscarnet in a transplanted kidney.

Irreversible glomerular lesions induced by crystal precipitation in a renal transplant after foscarnet therapy for cytomegalovirus infection.

AIMS: Foscarnet is an antiviral agent used to treat cytomegalovirus infection in AIDS patients and in transplant recipients. In most cases, foscarnet induces reversible tubulo-interstitial lesions which can be avoided by correct hydration. We report the first case of crystal foscarnet precipitation within glomerular capillaries in a renal transplant. METHODS AND RESULTS: The recipient, a 49-year-old man, developed a nephrotic syndrome with haematuria and an acute renal failure after foscarnet therapy for cytomegalovirus (CMV) infection. The polarization examination of the first graft biopsy revealed the presence of birefringent crystals within glomeruli and tubules. Infrared analysis attested to the presence of trisodium foscarnet salts and mixed sodium calcium salts coloured by Von Kossa's reaction. A second biopsy showed glomerular sclerosis, interstitial fibrosis, tubular atrophy and crystal vanishing. Polymerase chain reaction (PCR) in situ applied to this biopsy confirmed the diagnosis of cytomegalovirus infection. CONCLUSIONS: These adverse effects might be the result of a toxic synergy between foscarnet and other drugs. In cases with crystalline precipitation, graft biopsy remains the best mean of diagnosis and follow-up of glomerular damage.

Infrared analysis of urinary stones: a trial of automated identification.

A Search algorithm included in the Opus software of Bruker (Germany) was evaluated for analysis of urinary stones. Three reference libraries containing respectively 85 (single components), 1,059 (binary mixtures) and 4,565 (ternary mixture) digitized spectra were created and used to identify unknown spectra (n=320), applying the automatic procedure. Identification of the major component was correct in 83% of cases but the percentage of identification significantly decreased for the second and the third components. In cases of identification of the two first components, quantitative assessment was correct within tolerance limits +/- 15%. The computer results are judged unsatisfactory with regard to pathology because computer-aided identification is not sufficiently sensitive and specific to differentiate species with similar spectral pattern, even for the identification of main component, and also to detect minor components. It can be of assistance to guide spectral analysis, but it cannot replace human identification.

Identification of crystals in kidneys of AIDS patients treated with foscarnet.

Three acquired immune deficiency syndrome patients given foscarnet to treat cytomegalovirus retinitis developed renal failure with crystal deposits within the renal glomeruli. We identified these crystals as a mixture of sodium salt, calcium salt, and a mixed salt containing both sodium and calcium ions. This composition has not been previously reported. Foscarnet can complex available ionized calcium and secondarily precipitate in glomeruli. The percentage of complexing depends on calcium concentration in serum and the poor calcium salt solubility.

Unusual morphology of calcium oxalate calculi in primary hyperoxaluria.

Primary hyperoxaluria (PH) is a severe inherited disease induced by an enzymatic deficiency responsible for high endogenous production of oxalate. Oxalate ions are excreted by the kidney where they can form an insoluble salt with calcium ions, thus inducing urinary stones, crystal deposition in the tubular lumen and renal parenchyma leading to nephrocalcinosis and renal failure. Eighty-seven calculi from 63 PH patients with primary hyperoxaluria were analyzed and compared to 24,130 calculi from unselected consecutive stone formers referred to our laboratory between January 1977 and December 1996. All stones were analyzed according to a protocol including morphological examination of both surface and cross-section, and sequential infrared identification of the crystalline phases. A typical aspect of both surface and section corresponding to morphological type Ic according to our proposed classification (Daudon et al. Scanning Microsc 1993, 7:1081-1106) was observed in all patients but two whereas only two type Ic stones were observed among patients without primary hyperoxaluria. The latter two patients suffered from severe inflammatory bowel disease and developed heavy hyperoxaluria following extensive ileal resection. We conclude that evidence of type Ic morphology is a simple, cheap and fast tool to detect diseases with heavy hyperoxaluria such as primary hyperoxaluria.

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.

[Urinary calculi and crystalluria in HIV+ patients treated with indinavir sulfate]. / Calculs urinaires et cristalluries chez les patients VIH+ traités par le sulfate d'indinavir.

OBJECTIVES: Anti-proteases, a new class of anti-HIV drugs used in combination with reverse transcriptase inhibitors have led to spectacular improvement in the patients' clinical status. Since April 1996, indinavir is the most widely prescribed anti-protease in France. PATIENTS AND METHODS: From July 1996 to July 1997, we analyzed 46 spontaneously expulsed stones in 45 HIV+ patients (35 men and 10 women; age range 25 to 64 years) given indinavir in combination with other drugs since one week to ten months. Only six patients were known to have a past history of renal lithiasis. RESULTS: Forty-one calculi contained indinavir monohydrate (INDM) identified by mass spectrometry and infrared spectrophotometry. INDM was the only component excepting proteins in 39/45 calculi. In the 12 others, other compounds were also identified. Among the 114 urine samples collected 2 to 3 hours after an 800 mg dose of indinavir, 38 (33%) monohydrate indinavir crystals, identified by infrared microscopy. Mean urinary pH was significantly higher than in samples without INDM crystals (6.53 +/- 0.68 versus 5.96 +/- 0.71, p < 0.001). CONCLUSION: Two measures could possibly reduce the risk of crystalization: administration of urine acidifiers and increased fluid intake to raise diuresis. Alkalinisation is not indicated. Long-term increased fluid intake should be preferred over acidification which could be reserved solely for the treatment of drug-induced lithiasis.