Antigenic variation is employed by a number of different protozoan parasites. Trypanosoma brucei (the model for study of protozoan antigenic variation) and Plasmodium falciparum are some of the most well studied examples of protozoan parasites that exhibit antigenic variation.ntigenic variation is the expression of various alternative forms of antigen on the cell surface. Whereas phase variation is the phenotypic switch that is usually reversible and is referred to as an ON-OFF switch.
NO: Amitriptyline is a tricyclic antidepressant for depression and some forms of anxiety, sometimes used for chronic pain or migraine. Xanax is a triazolobenzodiazepine or a benzodiazepine with an extra triazole ring structure. It is quite addicting and has a short half-life.
CLINICAL PHARMACOLOGY. Amitriptyline HCl is an antidepressant with sedative effects. Its mechanism of action in man is not known. It is not a monoamine oxidase inhibitor and it does not act primarily by stimulation of the central nervous system.Amitriptyline inhibits the membrane pump mechanism responsible for uptake of norepinephrine and serotonin in adrenergic and serotonergic neurons.adioactivity of the plasma was practically negligible, although significant amounts of radioactivity appeared in the urine by 4 to 6 hours and one-half to one-third of the drug was excreted within 24 hours. Amitriptyline is metabolized by N-demethylation and bridge hydroxylation in man, rabbit, and rat.