Serum protein binding of lead in vitro in amyotrophic lateral sclerosis patients and controls

In vitro lead cation-hyaluronic acid interaction

It is the purpose of this investigation to study the in vitro spontaneous interaction lead-hyaluronic acid using the equilibrium dialysis technique. The following working conditions were used: membrane retention capacity starting from 12000 D; solvent was an aqueous buffer solution (pH 7.4); relation of internal-external volume of 0.5 : 25 mL: dialysis time 24 hours; lead concentration in dialyzing solution 4 micrograms/mL (always outside the bag); temperature 4 degrees C; concentrations of hyaluronic acid 0.3, 1.2, 2.1 and 3.0 mg/mL; concentration of plasma proteins 1.5 mg/mL; lead was determined in the internal solution of the bag, and was measured quantitatively by atomic absorption spectrometry. Testing separately hyaluronic acid and plasma proteins both types of marcromolecules turned out to bind lead. As the concentration of hyaluronic acid increases, the amount of lead retained increases as well, although this relation is only approximately linear. At the normal concentrations of plasma proteins and hyaluronic acid in synovial fluid, the proteins solution bound more lead than hyaluronic acid solution 16.2 +/- 2.1 and 5.7 +/- 0.4 micrograms/mL respectively (P < 0.0001). What these data show ist that both, hyaluronic acid and proteins are involved in the in vitro lead retention. The effect of both ligands must be synergistic, because when the two molecules are present, a higher amount of lead is retained compared to the amount bound separately, suggesting that lead can replace calcium by complexation with mucopolysaccharides; this explains the lead accumulation in synovial fluid since this fluid is rich in hyaluronic acid and proteins.

Determination of cerebrospinal fluid and serum lead levels in patients with amyotrophic lateral sclerosis and other neurological diseases

In a total of 62 samples of cerebrospinal fluid (CSF) and an equal number of serum samples obtained from 16 patients suffering from amyotrophic lateral sclerosis, 22 patients suffering from miscellaneous neurological diseases, and 24 controls, lead was measured by atomic absorption spectrophotometry. No statistical difference in lead concentration was found between the above three groups.

[Electrophysiological study of neuromuscular function in a population poisoned by lead]

A comprehensive electrophysiological examination of the peripheral nervous system was carried out in 12 patients who proved to be toxicated with lead (high lead blood levels, and diminished activity of the delta-aminolevulinate dehydratase, ALA D, in erythrocytes). Maximal motor nerve conduction velocities and terminal latencies were investigated in the median, radial and deep peroneal nerves. Also the amplitude of the evoked muscle response (M wave) was measured in thenar, extensor longus and extensor digitorium brevis muscles. Sensory conduction velocity and amplitude of the nerve compound action potential were measured at the median nerve. Tibialis anterior muscle responses to deep peroneal nerve repetitive stimulation were also explored. Conventional needle electromyogram was performed in the deltoid and tibialis anterior muscles. Slight diminished motor and sensory conduction velocities were found as well as a reduction of the amplitude of the evoked muscle response of the compound sensory action potential. Four out of the 12 patients tested showed either decremental or incremental amplitude of the muscle response with nerve repetitive stimulation. A electromyographical diminished interference pattern was found in all patients tested. Most of the remaining motor unit potentials were fragmented or polyphasic. Just one patient disclosed potentials of enhanced duration and amplitude. No relationship was found between blood lead levels or ALA D erythrocytes concentration and the different electrophysiological tests performed, except between reduced ALA D concentration and diminished amplitudes of the M wave and of the sensory compound action potential, and also between ALA D and diminished radial motor conduction velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Filterable plasma concentration, glomerular filtration, tubular balance, and renal clearance of heavy metals and organic substances in metal workers

To estimate "filterable" plasma concentration (FPx), glomerular filtration, tubular balance, and renal clearance of heavy metals and organic substances, the authors examined the regressions of the 24-hr urinary excretion on glomerular filtration rate [GFR, 24-hr endogenous creatinine (Cn) clearance] in 19 gun-metal foundry workers with blood lead (Pb) concentrations of 25-59 micrograms/dl. It was estimated that the proportion of FPx to total plasma concentration was on average 15, 7, 3, 0.6, 0.06, and 0.008% for Pb, cadmium (Cd), manganese (Mn), zinc (Zn), chromium (Cr), and copper (Cu), respectively. The estimated FPx value was 2.8 X 10(2), 4, 0.08, and 2.8 X 10(4) micrograms/dl for hippuric acid (HA), delta-aminolevulinic acid (ALA), coproporphyrin (CP), and total urinary solutes (TUS), respectively. The estimated glomerular filtration was significantly greater than the zero level for all substances but inorganic mercury (Hg). Similarly, the estimated net tubular secretion was significantly greater than the zero level for Cr, Cu, and TUS; the net tubular reabsorption was significantly greater than the zero level for Pb, ALA, and CP. The renal clearance of "filterable" plasma substance was significantly greater than GFR for Cr, Cu, and TUS and was significantly smaller for Pb, ALA, and CP. Thus the renal excretory mechanisms of substances were classified into four major categories: glomerular filtration for Cd, Mn, Zn, HA, and Cn; glomerular filtration and net tubular secretion for Cr, Cu, and TUS; glomerular filtration and net tubular reabsorption for Pb, ALA, and CP; and no glomerular filtration, i.e., suspected tubular secretion, for Hg.

Lead concentrations in blood, plasma, erythrocytes, and cerebrospinal fluid in amyotrophic lateral sclerosis

The purpose of the investigation was to elucidate the repeatedly discussed relationship between chronic lead intoxication and ALS. The following mean lead concentrations were determined in 9 patients with ALS: 8.65 +/- 3,91 micrograms/100 ml in the blood, 0.97 +/- 0.78 microgram/100 ml in the plasma, 19.15 +/- 5.0 micrograms/100 ml in the erythrocytes, and 0.89 +/- 0.44 microgram/100 ml in the cerebrospinal fluid. These values did not differ appreciably from the controls with 7.91 +/- 3.83 micrograms/100 ml (n = 14) in the blood, 1.13 +/- 0.46 microgram/100 ml (n = 10) in the plasma, 18.96 +/- 12.63 micrograms/100 ml (n = 10) in the erythrocytes, and 0.85 +/- 0.91 microgram/100 ml (n = 15) in the cerebrospinal fluid. These findings do not support the assumption of lead poisoning as a pathogenetic factor in ALS.

Further studies on the erythrocyte uptake of lead in vitro in amyotrophic lateral sclerosis (ALS) patients and controls. Abnormal erythrocyte fragility in ALS

Following our earlier observations on increased plasma concentrations of lead in amyotrophic lateral sclerosis (ALS), the erythrocyte uptake of lead from plasma has been studied in vitro. Whole-blood from ALS patients and controls was incubated after the addition of lead (0.6 mumol/l whole-blood) and plasma lead concentrations were repeatedly determined. Incubation was continued until haemolysis developed. Fairly stable plasma lead concentrations were established at, on the average, 0.5-0.6 mumol/l after 10-30 min and persisted throughout the incubation with no significant difference between ALS- and control samples. Unexpectedly, it was also observed that haemolysis occurred significantly earlier in the ALS- than in the control samples. Plateau levels in plasma lead concentration of the same order as in the present experiments have been observed both in ALS- and control samples in previous experiments with the same technique, where the lead dose added was twice as high, and these plateau levels were about 10 times higher than those observed in vivo in ALS patients and controls. It is therefore suggested that the final plasma lead concentrations in vivo is established by factors other than the erythrocyte uptake and it is improbable that the differences between ALS patients and controls in plasma lead concentration are associated with differences in the degree of lead uptake by the red cells. The increased plasma lead concentrations in ALS patients may instead be caused by increased fragility of the erythrocytes, as manifested by the earlier occurrence of haemolysis in the present experiments. The observation of increased red cell fragility is, however, also of interest as a possible manifestation of a generalized membrane defect.