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The following will be discussed in this chapter: Hormonal regulation of male reproductive function, hpg axis, mechanism and effects of testosterone activity, male secondary sex characteristics, female reproductive anatomy,...
Thyroid hormone receptors (TRs) play a major role in animal physiology.
TRs are important and very interesting regulators of diverse aspects, including
brain development, hearing, bone growth, morphogenesis, metabolism, intestine,
and heart rate in vertebrates (Fig. 1). Aberrant functions of TRs induce
tremendous defects in these pathways. For example, the human disease of
Resistance to Thyroid Hormone (RTH) (see Chapter 8 by Yoh and Privalsky)
is a genetically autosomal dominant inherited syndrome that is caused by mutations
in the gene encoding the TRβ.
Histidine-containing protein (HPr) is a central metabolic sensor in low-GC
Gram-positive bacteria and plays a dual role in sugar uptake by the phos-phoenolpyruvate–sugar phosphotransferase system and in transcriptional
control during carbon catabolite repression. The latter process is mediated
by interaction between HPr and the carbon catabolite repression master
transcription regulator, carbon catabolite protein A (CcpA), a member of
the LacI-GalR family of DNA-binding proteins.
The ubiquitin ligase RING finger protein 13 gene (RNF13) was first identi-fied in a screen for genes whose expression is regulated by myostatin in
chicken fetal myoblasts. In this study, we demonstrate that theRNF13gene
is broadly expressed in many chicken tissues.
Recent expansion of biomedical knowledge on the interactions between the
fetus, placenta, and the mother have transformed our view of pregnancy in
general. Recent basic and clinical investigations have improved significantly our
understanding on how hormones affect the pregnancy, and on how pregnancy
affects the fetal and maternal hormones. Because pregnancy may be seen as the
ultimate hormonally mediated event, the topic of endocrinology of pregnancy is
Malonyl-CoA, a potent inhibitor of carnitine pamitoyl
transferase-I (CPT-I), plays a pivotal role in fuel selection in
cardiac muscle. Malonyl-CoA decarboxylase (MCD) cata-lyzes the degradation of malonyl-CoA, removes a potent
allosteric inhibition on CPT-I and thereby increases fatty
acid oxidation in the heart. Although MCDhas several Ser/
Thr phosphorylation sites, whether it is regulated by AMP-activated protein kinase (AMPK) has been controversial.
We therefore overexpressed MCD(Ad.MCD) and consti-tutively active AMPK (Ad.
In haem-regulated phosphodiesterase (PDE) fromEscheri-chia coli(EcDOS), haem is bound to the PAS domain, and
the redox state of the haem iron regulates catalysis by the
PDEdomain.We generatedmutants ofAsp40, which forms
a hydrogen bondwithHis77 (a proximal haemaxial ligand)
via twowater molecules, and a salt bridge withArg85 at the
protein surface. The redox potential of haem was markedly
increased from67 mVvs. the standardhydrogenelectrode in
the wild-type enzyme to 95 mV and 114 mV in the Ala and
Asn mutants, respectively. ...
To sustain life mammals have an absolute and continual
requirement for oxygen, which is necessary to produce
energy for normal cell survival and growth. Hence, main-tainingoxygen homeostasis is a critical requirement and
mammals have evolved a wide range of cellular and phy-siological responses to adapt to changes in oxygen avail-ability. In the past few years it has become evident that the
transcriptional protein complex hypoxia-inducible factor
(HIF) is a key regulator of these processes.
The expression of the six types of human Hb subunits over time is cur-rently considered to be regulated mainly by transcription factors that bind
to upstream control regions of the gene (the ‘extrinsic’ component of regu-lation).
As the key regulator of reproduction, gonadotropin-releasing hormone
(GnRH) is released by neurons in the hypothalamus, and transported via
the hypothalamo-hypophyseal portal circulation to the anterior pituitary to
trigger gonadotropin release for gonadal steroidogenesis and gametogene-sis.
Arachidonic acid and its lypoxygenated metabolites play a fundamental
role in the hormonal regulation of steroidogenesis. Reduction in the expres-sion of the mitochondrial acyl-CoA thioesterase (MTE-I) by antisense or
small interfering RNA (siRNA) and of the arachidonic acid-preferring
acyl-CoA synthetase (ACS4) by siRNA produced a marked reduction in
steroid output of cAMP-stimulated Leydig cells.
Pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play central roles in regulating gametogenesis and the production of gonadal hormones, in fish as in other vertebrates. Pituitary gonadotropins are composed of two non-covalently associated polypeptide subunits, which must be glycosylated, folded, and assembled as a heterodimer to be biologically active.
Osteoporosis and fractures may increase due to hypoestrogenism in menopause and
cytochrome P450 inducing AEDs. Recent studies suggest lower bone mineral density (BMD)
in adults and children with epilepsy, irrespective of AED treatment.
Both idiopathic epilepsy and symptomatic epilepsy are associated with reduced BMD, with
the greatest reduction in symptomatic generalized epilepsy (Sheth & Hermann, 2008).
However, the pathophysiological underlying mechanisms are far from understood and likely
The peptide hormones of the anterior pituitary are essential for the regulation of growth and
development, reproduction, responses to stress, and intermediary metabolism. Their synthesis and
secretion are controlled by hypothalamic hormones and by hormones from the peripheral endocrine
organs. A large number of disease states as well as a diverse group of drugs also affect their
The food we eat has a major effect on our physical health and psychological wellbeing.
An understanding of the way in which nutrients are metabolized, and hence of the
principles of biochemistry, is essential for an understanding of the scientific basis of
what we would call a prudent or healthy diet.
My aim in the following pages is to explain both the conclusions of the many
expert committees that have deliberated on the problems of nutritional requirements,
diet and health over the years and also the scientific basis on which these experts have
reached their conclusions.
FOR NEARLY 30 YEARS after the discovery of auxin in 1927, and more than 20 years after its structural elucidation as indole-3-acetic acid, Western plant scientists tried to ascribe the regulation of all developmental phenomena in plants to auxin. However, as we will see in this and subsequent chapters, plant growth and development are regulated by several different types of hormones acting individually and in concert. In the 1950s the second group of hormones, the gibberellins (GAs), was characterized.
THE FORM AND FUNCTION of multicellular organism would not be possible without efficient communication among cells, tissues, and organs. In higher plants, regulation and coordination of metabolism, growth, and morphogenesis often depend on chemical signals from one part of the plant to another. This idea originated in the nineteenth century with the German botanist Julius von Sachs (1832–1897). Sachs proposed that chemical messengers are responsible for the formation and growth of different plant organs.
Inadvertent fetal exposure to contraceptive hormones is common, with a USA study
estimating that approximately 70 000 fetuses are exposed to oral contraceptives annually.23
Most of the data on fetal outcomes relate to COC. The CEU found no studies that specifically
assessed exposure through quick starting contraception. Studies are often limited by their
observational nature, potential confounding factors and small sample size. Reassuringly there
have been no consistent findings of specific fetal abnormalities.
Medical advances have been occurring at breathtaking speed, with diagnostic and treatment
options becoming available for conditions for which none previously existed. However, several
aspects of health care remain the same. Patients continue to rely heavily on clinicians for help in
understanding the burgeoning evidence in medical research and for providing optimal health
care. Clinicians remain steadfast in their quest to meet the needs of their patients and to encourage
innovation in meeting those needs.