Biomedical subjects

J A Fried

Publications and source records attributed to J A Fried.

3 recordsLinked to original sources

PubMed1977

Neuronal transport in salamander nerves and its blockade by colchicine.

Neuronal transport and the effects of colchicine on it has been studied in salamander spinal nerves. Cholinesterase (ChE) accumulation above the cut region of a nerve at 12.5 degrees C was shown to depend upon two processes. One caused a transient increase which declined to zero by 24 h; the other was explained by axoplasmic transport. At 22 degrees C the transient change was not observed, but the rate of accumulation attributable to transport increased. The Q10 for this transport over the range 12.5 degrees C--22 degrees C is approximately three. The ChE accumulation in the sensory component of the mixed nerve was about equal to that in the motor. The rate of fast axoplasmic transport of labeled leucine was 56 mm/day at 22 degrees C; if ChE moves at the same rate, then only 7% of the total enzyme is carried by fast axoplasmic transport. The transport of ChE was reduced by at least 50% when nerves were bathed in a 75 mM solution of colchicine for 30 min; this treatment is known not to cause subsequent degeneration of these nerves. The rate of slow flow of labeled material after bathing the nerve trunk in tritiated colchicine was found to be approximately 0.5 mm/day.

Animals↗

PubMed1977

The production of denervation-like changes in rat muscle by colchicine, without interference with axonal transport or muscle activity.

1. Rat extensor digitorum longus (EDL) muscles were examined after colchicine treatment of the sciatic nerve. Colchicine was applied in one of two ways: (i) a single sub-epineural injection; (ii) a chronically implanted silicone cuff. 2. After the sub-epineural injection, the entire membrane of muscle fibres became sensitive to iontophoretically applied acetylcholine and the muscle action potentials became resistant to tetrodotoxin. However, the majority of these fibres were found to be normally innervated. 3. These effects were not restricted to the EDL muscle of the colchicine injected side but were also found in the EDL muscle of the contralateral side, indicating that the action of colchicine was systemic. 4. In the treated sciatic nerve there was a partial block of axonal transport of 3H-labelled proteins, which correlated with a partial paralysis of the ipsilateral leg. However, axoplasmic transport was found to be normal in the contralateral sciatic nerve and the contralateral limb was not paralysed despite the supersensitivity of the investigated muscle on that side. 5. When colchicine was applied with a silicone cuff, denervation-like changes were confined to the ipsilateral EDL muscle. However, impulse conduction block at the level of the cuff was usually observed. 6. It is concluded that (i) colchicine can produce denervation-like changes in normally active muscle without blocking axoplasmic transport, through an action probably exerted directly on the muscle membrane, and (ii) that colchicine-cuff experiments failed to provide unambiguous evidence in support of the existence of neurotrophic influences on the muscle membrane.

Acetylcholine↗

PubMed1975

The indirect hemagglutination test for malaria. Evaluation of antigens prepared from Plasmodium falciparum and Plasmodium vivax.

Soluble antigens were prepared from Plasmodium falciparum and P. vivax and were evaluated in the indirect hemagglutination test. These antigens, attached to aldehyde-fixed type "O" erythrocytes, detected antibodies in more than 91% of infections with the homologous Plasmodium species. Detection rates in infections caused by the heterologous species ranged from 72% to 76%. Positive reactions occurred in less than 2% of sera from persons without malaria infection.

Animals↗