Semi-automated determination of the uremic toxin "b4-2".

A semi-automated two-stage chromatographic system is described for use in evaluating neurotoxin b4-2 in body fluids of uremic patients and healthy subjects. The only manual step is the injection, thus decreasing the risk of operator error inherent in the previous manual method (Clin Chem 29: 703-707, 1983) and concurrently improving CV from 9% to 6.4% as measured during a 16-month period.

Drug interaction in middle molecule analysis, with special reference to acetylsalicylic acid.

Concerning the middle molecules in uremia and other diseases, the potential artifact that can impede an accurate quantitation of middle molecules and that is related to the absorption of a very commonly used drug, namely aspirin, is discussed. Peak 7c and peak b 4-2 are two different middle molecules separated by gel permeation chromatography followed by anion-exchange chromatography. Oral ingestion of acetylsalicylic acid modifies the chromatographic pattern of the middle molecule fraction in normal subjects and uremic patients. Peak 7c is increased in the urine of healthy subjects, whereas this is not the case for peak b 4-2: With the b 4-2 technique, ingestion of acetylsalicylic acid produces a higher peak b 5. This is consistent with the previous demonstration that peak 7c was eluted as peak b 5. Structural analogies between salicylate metabolites and orthohydroxyhippuric acid beta-glucuronate (i.e., the main component of peak 7c) could explain this drug-related artifact.

Improved separation and quantification of the "middle molecule" b4-2 in uremia.

The plasma of uremic patients usually contains high concentrations of the so-called middle molecules (molecular mass, 300 to 1500 Da), which exert various toxic effects. Among these numerous substances, only one, named peak b4-2, has been correlated with uremic neuropathy. We describe our improvement of a two-stage chromatographic method, gel permeation followed by anion-exchange chromatography (J. Chromatogr. 146: 55-65, 1978), for separation and quantification of b4-2 in body fluids. In analyzing more than 300 samples from 43 uremic patients and 12 healthy subjects, we found a linear correlation between peak area at 254 nm and b4-2 concentration in the range 0.8 to 32 mg/L. The coefficient of variation, including data acquired during seven changes of columns, was 9%. Analysis time (80 min) was shorter than required with other methods. Our results confirm previous data for urinary b4-2 excretion by healthy subjects and for b4-2 removal rate in uremic patients undergoing hemodialysis or hemofiltration. Patients treated with continuous ambulatory peritoneal dialysis have a higher b4-2 excretion than do healthy subjects, suggesting a higher production of this solute in uremic patients.

[Pleuresies in chronic pancreatitis and in pancreatic pseudocysts. A study apropos of 20 cases]. / Les pleurésies des pancréatites chroniques et des pseudo-kystes du pancréas. Etude à propos de 20 observations

The pleurisies rich in amylase of the chronic pancreatitis and of pancreatic pseudo-cysts, studied in 20 cases, are quite unfrequent (0.5% of pleurisies of all kinds in the medical milieu). A pseudo-cyst was found 12 times out of 20 and a chronic pancreatitis without pseudocyst was found 8 times out of 20. Pleural effusion has a definite diagnostic valve, because in 70% of cases pancreatopathy cannot be recognized before it happens. The pleural liquid is rich in proteins and haemorrhagic in 2/3 of cases and its amylasic activity is either high or very high. Amylase level in pleural liquid is usually superior to amylasemia. The injection of lipiodol in the pleural cavity enables the visualization of a transdiaphragmatic fistula but this examination is not always well tolerated. The preoperatory cystography can opacify the pleura. In the absence of pseudo-cyst, medical treatment can dry the pleurisy in 70% of cases but does not modify the evolution of the pancreatic affection which will require surgery. Where a pseudo-cyst is concerned, surgery will often and quickly be the remedy.

[Mediastinal lymph node calcifications and Hodgkin's disease]. / Calcifications ganglionnaires médiastinales et maladie de Hodgkin (un cas)

If mediastinal lymph-node calcifications are frequent, the "hodgkinian" origin of these calcified adenopathies is unusual; less than 30 cases are reported in the literature. A new observation is described here. These lymph-node calcifications occur most often after radiotherapy; exceptionally "hodgkinian" adenopathies can appear ready-calcified.