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In mammals, the major factors involved in the regulation of body
growth are known: insulin-like growth factors (IGF) are key
regulators of somatic growth. Growth hormone (GH), secreted by the
pituitary gland, directly regulates circulating levels of IGF-I,
which is the major coordinator of spatio-temporal growth of the
organism. In humans, growth is even more complex, involving a
number of specific characteristics not found in other species.
These include rapid intrauterine growth, deceleration just after
birth, a mid-childhood growth spurt, a second deceleration before
puberty, an adolescent growth spurt, and finally full statural
growth, which is seen somewhat later. The combined knowledge
concerning the endocrine and paracrine aspects of growth have led
to the introduction of treatment regimens, most effective in
GH-deficient children. However, size depends on the combination of
a number of genetic factors, and there remain several aspects of
this complex process still poorly understood.
Multicellular organisms require a means of intracellular
communication to organize and develop the complex body plan that
occurs during embryogenesis and then for cell and organ systems to
access and respond to an ever changing environmental milieu.
Mediators of this constant exchange of information are growth
factors, neurotransmmitters, peptide and protein hormones which
bind to cell surface receptors and transduce their signals from the
extracellular space to the intracellular compartment. Via multiple
signaling pathways, receptors of this general class affect growth,
development and differentiation. Smaller hydrophobic signaling
molecules, such as steroids and non-steroid hormones, vitamins and
metabolic mediators interact with a large family of nuclear
receptors. These receptors function as transcription factors
affecting gene expression, to regulate the multiple aspects of
animal and human physiology, including development, reproduction
and homeostasis.
The aim of this book is to cover various aspects of intracellular
signaling involving hormone receptors.
Growth is a complex process that is essential to life. Not only
does size play an important role in the process of cellular
proliferation, but body size is also a critical factor in
determining which organisms live longer. Evolution has been
characterised by a dramatic increase in an organism's body size,
which is not only limited to the size of the brain.
Endocrinology is a field in which enormous advances have been made
in the last decade; the rate of discovery of new hormones,
hormone-like molecules, receptors, and mechanisms of action is
continually advancing. The development of techniques in immunology
and molecular biology has led to the possibility of describing in
detail the gene structure of many of the compounds involved in
hormonal systems. Remarkable homology has been shown between
oncogene products and various components of the endocrine network,
leading to the asser tion that deregulation of hormonal function is
involved in the generation and/or development of cancer. We now
know that the central nervous system is both a target and a
production site of many hormonal products, and that hormones,
neurotransmitters, growth factors and immunopeptides all act
through similar mechanisms. The only second messenger known ten
years ago was cAMP; today calcium, derivatives of membrane
phospholipids, and protein kinases are also known to be mediators
of hormone action. The very concept of hormonal systems has been
expanded to include not only endocrine secretions but also para-
and autohormones and their mechanisms of action; an understanding
of their functions will be central to the immediate future of
medicine. The discovery of hormonal molecules and endocrine
interactions and the subsequent understanding of hormone related
pathophysiology has led to the development of new strategies in
medical treatment such as fertility control and the management of
diabetes.
The Church of Latter-day Saints renounced the practice of plural
marriage in 1890. In the mid to late nineteenth century, howeverthe
heyday of Mormon polygamyan average of three out of every ten
Mormon women became polygamous wives. Paula Kelly Harline delves
deep into the diaries and autobiographies of twenty-nine such
women, opening a rare window into the lives they led and revealing
their views of and experiences with polygamy, including their
well-founded belief that their domestic contributions would help to
build a foundation for generations of future Mormons. Polygamous
wives were participants in a controversial and very public
religious practice that violated most social and religious rules of
a monogamous America. Harline considers the questions: Were these
women content with their sacrifice? Did the benefits of polygamous
marriage for the Mormons outweigh the human toll it required and
the embarrassment it continues to bring? Polygamous wives faced
daunting challenges not only imposed by the wider society but
within the home, yet those whose writings Harline explores give
voice to far more than just unhappiness and discontent. Following
two or three women simultaneously and integrating their own words
within a lively narrative, Harline focuses on the detail of their
emotional and domestic lives over time, painting a vivid and
sometimes disturbing picture of an all but vanished and still
controversial way of life.
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