Tissue growth promoters

To promote tissue growth, a biologically active agent can be added. This may be either a hard or soft tissue promoting substance or combinations thereof. Suitable tissue growth promoting agents are shown in Table 8.10. 

Calorimetry shows that the rates of metabolism of plant tissues vary widely with species, with cell types, and with environmental conditions. This provides a means of exploring the mechanisms by which various agents influence the health of a plant community. Studies are being done on beneficial agents such as growth promoters and detrimental ones such as atmospheric pollutants. For example, a correlation has been found between the metabolic heat rates and the extent of damage to pine needles by ozone. 

The testes and adrenal glands produce 90% and 10%, respectively, of circulating testosterone. Testosterone enters prostate cells, where predominantly type II 5a-reductase activates testosterone to dihydrotestosterone, which combines with a cytoplasmic receptor. The complex enters the nucleus and induces changes in protein synthesis which promote glandular tissue growth of the prostate. Thus, 5a-reductase inhibitors (e.g., finasteride and dutas-teride) directly interfere with one of the major etiologic factors of BPH. 

A closely related challenge is the design of materials that interact with cells or living tissues to promote desired biological responses. Such responses might be cell attachment, cellular differentiation and organization into functional tissue, or promotion of in-growth of bone into an artificial prosthesis such as an artificial hip. 

A major function of hGH is the promotion of anabolic activity, that is, bone and tissue growth due to increase in metabolic processes. Other biological effects of hGH are stimulation of protein synthesis, elevation of blood glucose level, and improvement of liver function. 

Hormones are intercellular messengers insulin is used to treat diabetes, while growth hormone promotes bone and tissue growth. 

Sex hormones control tissue growth and reproduction. Male sex hormones are testosterone and Sa-dibydrotestosterone, also known as androgens, which are secreted by the testes. The primary male hormone, testosterone, is responsible for the development of secondary sex characteristics during puberty. They also promote muscle growth. The two most important female sex hormones are oestradiol and oestrone, also known as oestrogem estrogens). They are responsible for the development of female secondary sex characteristics. 

Oleandomycin is a macrolide antibiotic produced by Streptomyces antibi-oticus. Oleandomycin and its triacetylated form, troleandomycin, are less effective than erythromycin against staphylococcal infections. They are usually administered orally or intravenously intramuscular administration is avoided because of the pain and tissue irritation it induces. Oleandomycin is also used in intramammary treatments and as a feed additive for growth promotion purposes. 

Oxytetracycline has a long history in human and veterinary medicine for the treatment and control of a wide variety of bacterial infections, and for its growth-promoting properties. It may be administered by any of the normal routes. It is readily absorbed from the intestine by most mammals but intestinal absorption in poultry is restricted. Oxytetracycline is most useful in that it readily disperses throughout the body, attaining therapeutic levels in most tissues and fluids within a short time. 

---