Biologies administrative route changes

Hyoscyamine.—Hyoscyamine (103) is a member of a large family of alkaloids in which a pyrrolidine ring is derived from ornithine. The biosynthetic pathway to hyoscyamine shown in Scheme 22 is supported by a wealth of evidence from past work.68 It is noteworthy that the route from ornithine to (102) parallels exactly the corresponding sequence (path b, Scheme 16) by which lysine is converted to A -piperideine in the currently favoured route to sedamine. Further support69 for this sequence has come from the administration of ATa-methyl-ornithine (101) to Datura stramonium plants. The precursor was multiply labelled with 14C as indicated and the activity was incorporated specifically into the corresponding positions of the alkaloid, without change in isotopic ratio. In contrast, the JV -methyl isomer of ornithine was biologically inert. 

Dioxins and dioxin-like PCBs induce a broad spectrum of toxic responses, such as loss of body mass, hepatotox-icity, immunotoxicity, epidermal changes, embryotoxicity and carcinogenicity. In addition, they can act as endocrine disrupters, thereby mimicking or interfering with the action of endogenous hormones and other molecules of the endocrine system. Besides their interference with the reproductive system, there are indications of their role in thyroid hormone (TH) metabolism and function. The toxic and biological effects of these PHAHs depend on several factors, such as doses, route of administration, species, age, strain and sex of the animals (Safe, 1986). 

In conclusion, the macromolecular properties of polymers and their interactions with cell surfaces result in a specific pharmacokinetic behaviour of polymers. The routes of parenteral administration are far from being equivalent, e.g. the intraperi-toneal application often used cannot substitute the intravenous administration. Molecular parameters of the polymer circulating in the coitral compartment are changed in time not necessarily by a direct biological modification of the polymer but as a consequence of a selective processing of different fractions. The intracellular accumulation in secondary lysosomes is the only proven mode of persistence of a soluble polymer in tissues. Variations in the chemical structure of the polymer may result in a different pattern of polymer distribution in the body as a consequence of a different rate of cellular accumulation. 

Whereas the biological effect of some hormones, c.ff., adrenalin, insulin, pitocin, pitressin, and intermedin, becomes apparent very shortly after their administration, sex hormones act differently. There is a marked time interval between the administration of the sex hormones and their first perceptible effect. The duration of this period cannot be shortened either by changing the route of administration or the solvent or by increased dosages. 

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