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Inadequacy of APUD concept in explaining production of peptide
hormones by tumours.Lancet.
1983 Jan 15;1(8316):118-9.
The amine
precursor uptake and decarboxylation (APUD) system of cells has been
claimed to derive from the embryological neural crest. This assertion
has been uncritically accepted. There is much contradictory evidence,
especially about the origin of the gastrointestinal and respiratory
APUD cells. There is further evidence that the embryological
derivation of a particular cell does not relate to the possibility of
ectopic peptide hormone synthesis by malignant tumours arising from
that cell type. There are many reports of APUD activity by
endodermally and mesodermally derived tumours, and of "APUDomas" with
endodermal microscopic features. It seems that the concept of
dedifferentiation explains the observed data much more satisfactorily
and that the presence of double minute chromosomes may denote gene
amplification and cellular production of peptides.
The diffuse
neuroendocrine (APUD) system.Biomed
Pharmacother. 1983;37(7):322-8.
The bulk of
experimental evidence indicates that the APUD series of cells is a
distinct system based upon common pathophysiological features. The
diffuse nature of this system with elements in the central and
peripheral nervous system suggests a more complex interaction of the
body's homeostasis than has been established. It is probable that as
radioimmunological and radioenzymatic assays become more widely
available and standardized, other apudomas will be described. Finally,
an understanding of the APUD concept, with its peculiar pluripotential
for the production of biogenic amines and peptides, the multicentric
nature of the disease and the possibility of multiple cell
involvement, is of key importance in managing patients. Studies of the
apudomas will also advance the understanding of the normal physiologic
interrelationships of the APUD cells.
Physiology of the APUD system.Semin
Surg Oncol. 1993;9(5):362-7.
The
characteristic biochemical pathway of the APUDoma cell, namely amine
precursor uptake and decarboxylation, are illustrated by the examples
of serotonin and catecholamine metabolism. Increasing understanding of
the origins of APUDomas as well as the biochemistry and physiology of
the hormones they produce, has led to improved methods of detection,
imaging and treatment of afflicted patients.
The APUD system and
its apudomas.Int
Adv Surg Oncol. 1981;4:255-76.
As sensitive
radioimmunoassays for the detection of polypeptide hormones are
developed, the exciting discovery of a diffusely distributed system of
interrelated endocrine cells has begun a new era of endocrinology.
This system, although anatomically disassociated, is bound together by
a number of common features such as its biosynthetic mechanism,
histochemical and ultrastructural features, and embryologic origin
(Table I). The most prominent feature, however, is their biosynthetic
pathways for hormone production, from which the acronym APUD has been
derived. These are the capacity for Amine Precursor Uptake such as
DOPA and then subsequent Decarboxylation, resulting in the synthesis
of bioactive amines or polypeptide hormones. Hyperplasias or neoplasms
of these cells are defined as apudomas. In the last ten years a great
deal of research has rapidly altered the original concepts of this
system, especially in terms of its embryologic origin, physiologic
interrelationships, classification, as well as the addition of many
new APUD cell members. These will be reviewed, and the origin,
diagnosis, and treatment of each recognized apudoma will be
synthesized in light of its membership within the APUD system.
Pancreatic apudoma.Chirurg.
1980 Jun;51(6):380-8
Endocrine
tumors of the pancreas apparently develop from a premature stem-cell,
possibly originating from the ectodermal neural crest. These tumors
belong to the APUD-cell system, which is identical with the "Helle-Zellen-system".
Following a description of the various forms of appearance there is a
discussion of the different syndromes. The present-day differentiated
diagnostic procedures are described. Finally, details and problems of
treatment, especially regarding surgical intervention, are discussed.
Cases from the author's own clinic are considered.
Hormonally active
pancreatic tumors (apudomas). A review.Zentralbl
Chir. 1986;111(4):177-87.
Hormonally
active pancreas tumours have ceased to be rare cases, and by means of
up-to-date methods they are now more frequently diagnosed than they
used to be in the past. An account, based on the authors' own
experience, is given in this paper of diagnostic and surgical problems
relating to the various hormone-producing tumours of the pancreas.
Particular reference is made to the treatment of malignant apudomata
and to new concepts which have resulted from the introduction of H2
receptor blockers.
APUD cells and the
apudomas. A concept relevant to anaesthesia and endocrinology.Anaesthesia.
1977 Oct;32(9):879-88.
A variety of
cells found in the pituitary and pineal glands, sympathetic nervous
system and adrenal glands, the gut, pancreas, thyroid (C-cells),
chemoreceptors (type I-Cells), lungs (P-cells), skin (melanocytes) and
the urogenital tract have a common origin from the neural crest. These
cells are programmed for neuro-endocrine function and, as a group, can
be regarded as one of the physiological control systems. They secrete
a variety of amine and peptide hormones and have common cytochemical
characteristics from which the term APUD cell is derived. Tumours of
these cells are referred to as 'apudomas' and may synthesise not only
their own hormones but also those which are normally produced by other
APUD cells. The relevant physiological properties of some of the
peptides which have been described relatively recently are discussed
and the principal clinical syndromes produced by the APUDomas are
described.
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