Growth hormone release requirements

The nervous and endocrine systems are linked by the hypothalamus which contains neurosecretory cells. These, on stimulation by electrical impulses, secrete relatively short chain highly active peptides which pass in special blood vessels directly to the pituitary gland. The hypothalamic hormones include somatostatin, which inhibits growth hormone release, and various hormones that stimulate the release of those anterior pituitary hormones that control the secretion of hormones in various other endocrine glands. For example the secretion of thyroid hormone requires... 

Otfier fiormones accelerate tfie release of free fatty acids from adipose tissue and raise tfie plasma free fatty acid concentration by increasing the rate of lipolysis of the triacylglycerol stores (Figure 25—8). These include epinephrine, norepinephrine, glucagon, adrenocorticotropic hormone (ACTH), a- and P-melanocyte-stimulat-ing hormones (MSH), thyroid-stimulating hormone (TSH), growth hormone (GH), and vasopressin. Many of these activate the hormone-sensitive hpase. For an optimal effect, most of these lipolytic processes require the presence of glucocorticoids and thyroid hormones. These hormones act in a facilitatory or permissive capacity with respect to other lipolytic endocrine factors. 

ENDOCRINE SYSTEM A number of endocrine tissues respond to PGs. In a number of species, the systemic administration of PGE increases circulating concentrations of adrenocorticotropic hormone (ACTH), growth hormone, prolactin, and gonadotropins. Other effects include stimulation of steroid production by the adrenals, stimulation of insulin release, and thyrotropinlike effects on the thyroid. The critical role of PGF in parturition relies on its ability to induce an oxytocin-dependent decline in progesterone levels. PGE works as part of a positive-feedback loop to induce oocyte maturation required for fertihzation during and after ovulation. 

Porous chitosan has recently been evaluated as a protein delivery system by Cardinal et al. (1990). Sustained release was demonstrated for bovine growth hormone, alkaline phosphatase, and BSA. Treatment of dried particles of chitosan with methanol for brief periods extended release duration, with a 10-min treatment increasing the time required for 50% release of BSA from <1 day to 2 weeks. Jamas et al. (1991) have documented preparations of P-glucan microparticles, where time to 50% release ranged from 30min for cytochrome c (MW 14,000) to 200 min for alcohol dehydrogenase (MW 150,000). 

Fluorescent probes (tags) are another option to increase sensitivity in immunodetection systems that have been used in one-, two-, and three-column chromatography strategies. Texas Red (TR)-labeled human growth hormone (hGH) has been used to quantitate anti-human growth hormone (anti-hGH) antibodies in semm [114]. Immunocomplex was captured on a protein G column and then released into a downstream fluorescence detector. TR was the probe of choice because the fluorescence was not quenched at the low pH required for desorption from the protein G column. Labeling hGH with TR enhanced detection of anti-hGH antibodies by at least 10 -fold [115] with a minimum... 

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