Search Results
You are looking at 1 - 3 of 3 items for
- Author: M. E. EDWARDS x
- Refine by access: All content x
Search for other papers by B. A. EDWARDS in
Google Scholar
PubMed
Search for other papers by M. E. EDWARDS in
Google Scholar
PubMed
In earlier studies it was shown that oxytocin and vasopressin were broken down by peptidases present in the neurohypophyses of the rat, pig and ox (Edwards, 1971a, b; Pliška, Thorn & Vilhardt, 1971). The present work was carried out to determine the subcellular localization of this enzymic activity with special interest in the lysosomes whose function as a mechanism of controlling excess hormone in the anterior pituitary has been suggested by Smith & Farquhar (1966).
Separation of the various subcellular fractions was carried out using a differential centrifugation procedure suggested by A. Livingston (personal communication). Four fractions were prepared: A (1000 g for 10 min), B (5000 g for 10 min), C (25 000 g for 20 min) and D (the final supernatant). Each fraction was analysed for vasopressin (hormonal marker), cathepsin (lysosomal marker), fumarase (mitochondrial marker) and lactate dehydrogenase (cytoplasmic marker). Complete separation into discrete fractions was not
Search for other papers by R. M. LEONE in
Google Scholar
PubMed
Search for other papers by R. E. SILMAN in
Google Scholar
PubMed
Search for other papers by R. J. L. HOOPER in
Google Scholar
PubMed
Search for other papers by M. D. A. FINNIE in
Google Scholar
PubMed
Search for other papers by S. J. CARTER in
Google Scholar
PubMed
Search for other papers by R. EDWARDS in
Google Scholar
PubMed
Search for other papers by I. SMITH in
Google Scholar
PubMed
Search for other papers by P. TOWELL in
Google Scholar
PubMed
Search for other papers by P. E. MULLEN in
Google Scholar
PubMed
SUMMARY
5-Methoxytryptophol (ML) is found in the pineal gland and is known to have biological activity especially as an antigonadotrophic agent, but methods have been lacking for its measurement in the circulation. A gas chromatography–mass spectrometry assay using a trimethylsilyl derivative has been developed for the routine measurement of ML in plasma. The assay is of great specificity and has a sensitivity of 20 pmol/l. Studies on the levels of pineal indoles in the circulation, however, have been hampered by the possibility that extraneous compounds are being cross-measured. Thus the specificity of the routine assay has been further validated by comparing it with an alternative assay system where all the major parameters were changed, i.e. derivatizing reagent, internal standard and mass number. Results that were obtained using both assay systems were closely comparable.
Search for other papers by M. A. KUMAR in
Google Scholar
PubMed
Search for other papers by E. SLACK in
Google Scholar
PubMed
Search for other papers by A. EDWARDS in
Google Scholar
PubMed
Search for other papers by H. A. SOLIMAN in
Google Scholar
PubMed
Search for other papers by A. BAGHDIANTZ in
Google Scholar
PubMed
Search for other papers by G. V. FOSTER in
Google Scholar
PubMed
Search for other papers by I. MacINTYRE in
Google Scholar
PubMed
SUMMARY
(1) Calcitonin preparations from acetone-dried thyroid were administered to rats by various routes.
(2) Intravenous administration, especially by infusion, produced a much greater fall in plasma calcium than s.c. or i.p. injection.
(3) The log dose-effect curves after i.v. injection or infusion showed no evidence of non-linearity over a 100-fold dose range and had highly significant slopes.
(4) The potency ratio of two preparations was estimated by means of a (2+2) assay design using both i.v. infusion and single i.v. injection. There was satisfactory agreement.
(5) The i.v. injection method is recommended for the routine assay of calcitonin. A simple assay schedule is given in the Appendix.
(6) A unit of calcitonin activity is defined in terms of a standard preparation.
