The responses of growth hormone, cortisol, and prolactin to symptomatic hypoglycaemia during an intravenous insulin tolerance test were measured in 20 massively obese subjects and six lean volunteers. In 11 subjects, who had been obese since early childhood, an impaired growth-hormone response and an absent prolactin response were found. In the nine other obese subjects, however, the growth-hormone and prolactin responses were not significantly impaired. Seven of these subjects had become obese either as a teenager or during adult life. These findings suggest the existence of two types of human obesity similar to those found in rodent models. In one the disorder of hypothalamic function may be due to a basic, possibly genetic abnormality, while in the other it is acquired.
Resistance to antimalarial drugs arises when spontaneously occurring mutants with gene mutations or amplifications which confer reduced drug susceptibility are selected, and are then transmitted. Simultaneous use of two or more antimalarials with different modes of action and which therefore do not share the same resistance mechanisms will reduce the chance of selection, because the chance of a resistant mutant surviving is the product of the parasite mutation rates for the individual drugs, multiplied by the number of parasites in an infection that are exposed to the drugs. The artemisinin derivatives are very active antimalarials, which produce large reductions in parasite biomass per asexual cycle, and reduce malaria transmissibility. To date no resistance to these drugs has been reported. These drugs therefore make particularly effective combination partners. This suggests that antimalarial drugs should not be used alone in treatment, but always in combination, as in the treatment of tuberculosis or HIV, and that the combination should include artemisinin or one of its derivatives.
