Amyotrophic lateral sclerosis (ALS) is a progressive and fatal degenerative disorder of motor neurons. The cause of this degeneration is unknown, and different causal hypotheses include genetic, viral, traumatic and environmental mechanisms. In this study, we have analyzed metal concentrations in cerebrospinal fluid (CSF) and blood plasma in a well-defined cohort (n = 17) of ALS patients diagnosed with quantitative electromyography. Metal analyses were performed with high-resolution inductively coupled plasma mass spectrometry. Statistically significant higher concentrations of manganese, aluminium, cadmium, cobalt, copper, zinc, lead, vanadium and uranium were found in ALS CSF compared to control CSF. We also report higher concentrations of these metals in ALS CSF than in ALS blood plasma, which indicate mechanisms of accumulation, e.g. inward directed transport. A pattern of multiple toxic metals is seen in ALS CSF. The results support the hypothesis that metals with neurotoxic effects are involved in the pathogenesis of ALS.
Rabbits were given repeated injections of cadmium chloride. Cadmium- and zinc-containing protein fractions were obtained from the livers of these animals by precipitation procedures and Sephadex G-75 chromatography. The protein thus obtained showed several characteristics similar to those of the earlier described protein metallothionein. Further separation by isoelectric focusing showed two main protein peaks with isoelectric points at 3.9 and 4.5 respectively. Amino acid analysis of these two forms showed similar content of most amino acids [residues per cent.: cysteine (28%), aspartate (8%), threonine (5-6%), serine (12%), glycine (7%), alanine (13%), methionine (2%), isoleucine (2%)] but with a small difference in content of lysine (12 and 13% respectively), proline (9 and 5% respectively) and glutamate (2 and 4% respectively). The two forms of the protein both contained cadmium, but only the one with pI4.5 contained also significant amounts of zinc.
The serum activities or concentrations of aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), alkaline phosphatase (ALP), albumin, y-glutamyl transpeptidase (GGT), bilirubin (BIL), cholic acid (CHOL), chenodeoxycholic acid (CHENO), and transferrin with isoelectric point 5-7, and the urinary excretion of albumin were determined among male current or former house painters (n = 135) and house carpenters (n = 71) who had worked in their trades for at least 10 years before 1970. Workers who showed a value above the 90th percentile among the carpenters in at least one of the tests ASAT, ALAT, GGT, BIL, CHOL, or CHENO were regarded as showing "pos-
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