The use of non-human primates as animal models for the study of hepatitis viruses

Hepatitis viruses belong to different families and have in common a striking hepatotropsin and restrictions for propagation in cell culture. The transmissibility of hepatitis is in great part limited to non-human primates. Enterically transmitted hepatitis viruses (hepatitis A virus and hepatitis E virus) can induce hepatitis in a number of OLD World and New Worls monkey species, while the host range of non-human primates susceptible to hepatitis viruses transmitted by the parenteral route (hepatitis B virus, hepatitis C virus and hepatitis delta virus) is restricted to few species of Old World monkeys, especially the chimpanzee. Experimental studies on non-human primates have provided an invaluable source of information regarding the biology and pathogenesis of these viruses, and represent a still indispensable tool for vaccine and drug testing.

Parallel pathways in the retina of old and new world primates

Old-world simians are all trichromats, but in most new-world primates there is a polymorphism; males are dichromats but most females are trichromats. In the old world simian, luminance and red-green chromatic channels defined by psychophysical experiments have as a basis parasol ganglion cells of the magnocellular (MC) pathway and midget ganglion cells of the parvocellular (PC) pathway respectively. Small bistratified ganglion cells provide a basis for a blue-yellow chromatic channel, which should probably be considered a separate entity. In both dichromatic and trichromatic new-world animals, the MC pathway and the small bistratified, blue-yellow system seem anatomically and physiologically similar to those in their old-world relatives. The midget ganglion cells of the parvocellular pathway in trichromats are anatomically and physiologically similar to the old-world pattern. In dichromatic animals, they are anatomically similar and physiologically resemble those of trichromatic animals, except for the lack of chromatic opponency. We conclude that these three systems may form a basic pattern for the visual pathway of primates. However, the results from dichromats indicate that the evolution of trichromacy may be found to be more complex than presently supposed.

Filogenia de los piojos (Insecta: Anoplura) de los monos del Viejo Mundo (Catarrhini) / Phylogeny of lice (Insecta: Anoplura) of the Old World Monkey (Catarrhina)

The genera Pediculus and Pthirus were studied cladistically, although the genus Pedicinus was also taken into account. Morphological characters from the literature, and some established through direct study were analyzed. Using five methods of cladistic analysis, one most parsimonious tree with a c.i.=0.84 and a length of 38 was obtained ((Pedicinus)+(Paenipediculus+(Parapediculus+(Pediculus humanus capitis+Pediculus humanus humanus). A novelty of this study is the inclusion of the subgenus