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Biomedical subjects

B G Livett

Publications and source records attributed to B G Livett.

118 records · Page 7Linked to original sources
PubMed1969

Immunohistochemical localizatio of protein components of catecholamine storage vesicles.

1. The distribution of specific proteins in sympathetic neurones has been examined by immunofluorescent histology using antibodies prepared against soluble protein components of the catecholamine storage vesicles of the adrenal medulla.2. Two antigen preparations were separated by ion exchange chromatography of the soluble proteins released on osmotic lysis of catecholamine storage vesicles which had been isolated by centrifugation from homogenates of sheep adrenal medulla. One fraction (AgDH) had high dopamine-beta-hydroxylase activity, while another (AgCB), consisting of the bulk of the protein, had some capacity to bind catecholamines. On disk gel electrophoresis the antigens ran as single bands with very different mobilities.3. Antisera (AsDH) and (AsCB) produced in rabbits to the two antigens were shown to react specifically with their antigens by immunodiffusion and electrophoresis in agarose.4. Indirect immunofluorescent staining of tissue sections was achieved by layering first the rabbit anti-sera, followed by goat anti-rabbit globulin serum which had been conjugated with fluorescein isothiocyanate.5. The adrenal medulla and the cell bodies of sympathetic ganglia showed the most intense green fluorescence with the immune rabbit sera, and hardly stained when pre-immune serum from the same animal was used. The reactivity of the antisera could be abolished by incubation with the corresponding antigen.6. The preterminal and terminal axons of sympathetic nerves also stained specifically but less intensely with both antisera. When the nerves were ligated for up to 24 hr, the portion immediately proximal to the constriction showed an enhanced reaction to the antisera.7. The results provide evidence that sympathetic neurones contain proteins immunologically identical to those involved in the synthesis and storage of noradrenaline in the adrenal medulla, and support the concept that granular vesicles are synthesized in the perikaryon of the neurone and are transported somatofugally in the axon.

Adrenal Medulla↗
PubMedDate not supplied

Evidence against a generalized membrane defect in dystrophic mice platelets.

The response of the membrane-bound enzyme AChE to changes in temperatures was investigated to test the applicability of the "generalized membrane defect" hypothesis proposed for human myotonic and Duchenne muscular dystrophies to the two forms of muscular dystrophy expressed in mice. For intact platelets from homozygous normal and dystrophic mice of both strains, a break (Tc) occurred in the Arrhenius plot of AChE activity at approximately 22 C. Solubilization of membrane-bound AChE by Triton X-100 produced a nonlinear Arrhenius plot over the temperature range (7.7 C to 37 C) in normal and dystrophic mice of both strains. However, in the presence of phospholipase A2 + C and Triton X-100, a linear Arrhenius plot was produced indicating that the membrane-bound enzyme is normally modulated by a bulk lipid domain as well as by a tightly bound (immobilized) phospholipid domain. The temperature response of platelet AChE from normal and dystrophic mice of both strains was not significantly different. These results showing normal temperature kinetics of AChE do not lend support to the theory of a membrane defect in the platelets of dystrophic mice.

Acetylcholinesterase↗
PubMedDate not supplied

Acetylcholinesterase molecular forms in C57BL/6J dystrophic mice.

Acetylcholinesterase (AChE) was extracted from normal and dystrophic C57BL/6J mouse hindlimb muscles and its molecular forms fractionated by sucrose density gradient ultracentrifugation. In the soleus muscles from 6- to 7-week-old mice an increase in the 3 Svedberg unit (S) and a decrease in the 16S AChE molecular forms was observed in dystrophic animals compared to controls. At 12-13 weeks of age, no major significant differences in the relative proportions of AChE molecular forms were noted. In the extensor digitorum longus (EDL) muscles of 6- to 7-week-old dystrophic mice a significant decrease in the proportion of the 10S AChE molecular form and an increase in the 3S and 5S forms was observed. At 12-13 weeks, the dystrophic EDL muscles again displayed a decrease in the 10S form; however, the increase in the 3S and 5S AChE forms, while still apparent, was not significant. These results provide evidence for a biochemical abnormality in the distribution of specific AChE molecular forms, and a differential expression of this abnormality in the soleus and EDL muscles.

Acetylcholinesterase↗
PubMedDate not supplied

Inhibition of angiotensin converting enzyme by N-terminal fragments of substance P.

A range of N-terminal fragments of substance P (SP) were evaluated for inhibitory activity against angiotensin converting enzyme (ACE) from rat lung and brain (striatum). SP inhibited the enzyme from both sources in a concentration dependent manner (IC50 30 microM). The N-terminal fragments SP[1-7], SP[1-6], SP[1-4] and SP[3-4] were equipotent with SP for both sources of the enzyme. However, SP[1-3] showed a difference in its activity, being more active than SP (IC50 10 microM) in inhibiting the brain enzyme, but inactive against lung ACE. These results suggest that the inhibitory action of SP on ACE resides in the N-terminus of the peptide. The difference in reactivity towards SP[1-3] lends support to the idea that lung and brain ACE are different isozymes.

Angiotensin-Converting Enzyme Inhibitors↗