Nonhuman primates are relevant models for research in hematology, immunology and virology

Nonhuman primates have been used for biomedical research for several decades. They have proved to be models that are relevant to humans because of the high level of gene homology which underlies physiological and biochemical similarities. The similarity of monkeys to humans has been used to investigate pathophysiological mechanisms in hematology, immunology and virology. New therapeutic procedures can be assessed in primates by using materials, in particular pharmacological reagents, and methods designed for humans. The relevance of these models also relies on the use of species-specific pathogens and the availability of recombinant, homologous cytokines. The introduction of more and more sophisticated cell and gene therapy protocols in hematopoietic cell transplantation and immunotherapy requires the development of preclinical trials similar to clinical settings. For several decades now, baboons and cynomolgus/rhesus monkeys have been the most useful primate models in experimental hematology, and this has contributed to numerous therapeutic advances. Primate models of AIDS have been developed to study the pathogenesis, transmission and immune responses to infection, and to test vaccines and drugs. Primate research should be restricted in quantity, and mainly designed with the aim of removing uncertainty as to the safety and clinical benefit to the patient, of new biomedical protocols.     

Secnidazole vs. paromomycin: Comparative antiprotozoan treatment in captive primates

The antiprotozoan activity of secnidazole was studied in Cercocebus t. torquatus, Cercopithecus campbelli, Erythrocebus patas (Cercopithecidae), and Gorilla gorilla (Pongidae) compared with that of paromomycin in Cercocebus t. lunulatus (Cercopithecidae), E. patas, and G. gorilla (Pongidae) by coprological analysis. The antiprotozoan activity of both drugs depended on the parasite species and the host species. The drugs acted in a similar way on Entamoeba coli parasitising C. t. torquatus, and E. patas. This activity was different from that observed on I. buestchlii from the same host species. Nevertheless, E. coli parasitising cercopithecids and pongids responded to drugs differently.     

The origin of phage virology.

The history of bacteriophage (phage) had its start in 1915, when Twort isolated an unusual filterable and infectious agent from excrete of patients struck by diarrhoea; this discovery was followed by an analogous, and probably independent, finding of d'Hérelle in 1917. For several years phage research made scant progress but great attention was paid to the question of phage nature, which saw the contrast between d'Hérelle and Bordet's views (living against chemical nature, respectively). This situation changed with the independent discovery of lysogeny, in 1925, thanks to Bordet and Bail: this phenomenon was considered of genetical origin, a view that Wollman interpreted by assimilating the properties of phage to those of gene (according to a previous idea of Muller). In the 1930s, Burnet's work opened a new era by demonstrating the occurrence of several species of phages and their antigenic property. In the same period, the physical and chemical characteristics of these viruses were disclosed thanks, in particular, to the work of Schlesinger, who first demonstrated that a virus (phage) was constituted of nucleoproteins. The peculiarity of phage was finally shown after the invention of electron microscope: H. Ruska, in 1940, and Anderson and Luria in the next years, obtained the first images of tailed phages, a finding that strongly helped the investigation on the first steps of the infection process. The decisive impulse to phage virology came from Delbrück, a physicist who entered biology giving it a new arrangement. The so-called "phage group" assembled brilliant minds (Luria, Hershey and Delbrück himself, and later a dozen of other scientists): this group faced three fundamental questions of phage virology, i.e., the mechanisms of attack, multiplication and lysis. In ten years' time, phage virology became an integrant part of molecular biology, also thanks to the discovery of the genetical properties of DNA: in such scientific context, Delbrück, Luria and Hershey's works emerged for the absolute excellence of their results, which led such scientists to Nobel prize. Lysogeny was however neglected by the phage group: this singular property shared by bacteria and phages was instead investigated by Lwoff's group, in Paris, and explained in its fundamental features during the 1950s. The "phage's saga" has gone on being an important division of molecular biology till today, and its history is far from being over.     

Comparative normal levels of serum triiodothyronine and thyroxine in nonhuman primates.

Normative values were obtained for triiodothyronine and thyroxine from four species of Old World primate (chimpanzees, rhesus monkeys, African green monkeys and talopoin monkeys) and a single species of New World primate (squirrel monkeys) represented by two subspecies, Colombian and Bolivian. The Bolivian squirrel monkeys exhibited the lowest values for both triiodothyronine and thyroxine. Male talapoins had the highest levels of thyroxine. Significant differences were found in levels of triiodothyronine and thyroxine between males and females of the same species and between the two subspecies of squirrel monkeys. Triiodothyronine:thryroxine ratios were consistently lower in the males of all species examined.     

Comparative anatomy of the tongue of Pan troglodytes (Blumenbach, 1799) and other primates. II. Findings in other primates

This 2nd part of our studies shows that the papilla foliata is fully developed in Pan, Cebus, and Macaca; in Prosimians the papilla foliata is well developed in Lemur and Chirogaleus. In Galago crassicaudatus, this papilla is missing. Among 3 individuals of Microcebus, the papilla foliata was differently developed: in 2 cases, the tongue exhibited only 2 on both sides and a very low folia. Taste buds were found in the epithelium of only one side of each folium. In the 3rd case, the folia of the papilla were developed only on one side of the tongue, whereas, on the other side, a typical papilla was missing. Instead of the papilla, the tongue of the same animal exhibited a hillock-like structure; it is a gustatory hillock which exhibited many taste buds. There were 3 gustatory hillocks in all of the specimens of Tupaia glis; they are situated on both sides of the tongue.     

Comparative tests of parasite species richness in primates

Some hosts harbor diverse parasite communities, whereas others are relatively parasite free. Many factors have been proposed to account for patterns of parasite species richness, but few studies have investigated competing hypotheses among multiple parasite communities in the same host clade. We used a comparative data set of 941 host-parasite combinations, representing 101 anthropoid primate species and 231 parasite taxa, to test the relative importance of four sets of variables that have been proposed as determinants of parasite community diversity in primates: host body mass and life history, social contact and population density, diet, and habitat diversity. We defined parasites broadly to include not only parasitic helminths and arthropods but also viruses, bacteria, fungi, and protozoa, and we controlled for effects of uneven sampling effort on per-host measures of parasite diversity. In nonphylogenetic tests, body mass was correlated with total parasite diversity and the diversity of helminths and viruses. When phylogeny was taken into account, however, body mass became nonsignificant. Host population density, a key determinant of parasite spread in many epidemiological models, was associated consistently with total parasite species richness and the diversity of helminths, protozoa, and viruses tested separately. Geographic range size and day range length explained significant variation in the diversity of viruses.     

Comparative locomotion of six sympatric primates in Ecuador

Primates exhibit a great variety of arboreal locomotor modes associated with their size and postcranial morphology. The study of sympatric primates is interesting in that it may reveal how primates of different sizes and anatomies move and select for forest structure. This study reports on preliminary data on the locomotion of six non-ateline platyrrhines found in the Yasuni National Park, Napo Province, Ecuador. Pygmy marmosets are confined to the understory using scansorial locomotion and quadrupedalism, preferring large vertical supports. Golden-mantled tamarins, common squirrel monkeys and dusky titis also range in the understory, moving by quadrupedal walk and leap, mainly on small horizontal supports. Monk sakis are found in the main canopy and use quadrupedal walk and less leap on medium-sized horizontal supports. Whitefronted capuchins use the understory and the main canopy equally often, walking quadrupedally and leaping on small and medium-sized oblique supports. In general, smaller species occupy lower strata while larger species tend to spend more time in the upper strata. Small tegulae-bearing monkeys showed the highest proportions of large vertical support use. For all species, leaping was the main gap-crossing mode, though decreasing in proportion with a higher use of the upper forest layers.     

Comparative anatomy of the arterial system of the foot in primates. 1. Macaque

Using stereoscopic angiography, the entire arterial system of the foot of the macaque was analyzed. The arteria saphena, instead of the a. tibialis anterior, reaches the dorsum of the foot, and its branches supply most of the foot. The dorsal arteries are dominant as far as the metatarsal spaces of the lateral four toes. The a. metatarsea dorsalis II showed a tendency to be the single dominant artery and to give rise to even the a. digitalis communis plantaris IV through the catella plantaris distalis. This tendency was observed more clearly in other macaques species than the Japanese monkey. The perforating branch at the second proximal metatarsal space forms the arcus plantaris profundus, which is accompanied by the deep branch of the nervus plantaris lateralis. Beneath the arch, the catella plantaris proximalis is formed on the metatarsal bones among the perforating branches of the aa. metatarseae dorsales. The a. tibialis posterior forms the arcus plantaris superficialis, whose thin branches commonly enter the aa. digitales communes plantares.     

Comparative functional analysis of skull morphology of tree-gouging primates

Many primates habitually feed on tree exudates such as gums and saps. Among these exudate feeders, Cebuella pygmaea, Callithrix spp., Phaner furcifer, and most likely Euoticus elegantulus elicit exudate flow by biting into trees with their anterior dentition. We define this behavior as gouging. Beyond the recent publication by Dumont ([1997] Am J Phys Anthropol 102:187-202), there have been few attempts to address whether any aspect of skull form in gouging primates relates to this specialized feeding behavior. However, many researchers have proposed that tree gouging results in larger bite force, larger internal skull loads, and larger jaw gapes in comparison to other chewing and biting behaviors. If true, then we might expect primate gougers to exhibit skull modifications that provide increased abilities to produce bite forces at the incisors, withstand loads in the skull, and/or generate large gapes for gouging.We develop 13 morphological predictions based on the expectation that gouging involves relatively large jaw forces and/or jaw gapes. We compare skull shapes for P. furcifer to five cheirogaleid taxa, E. elegantulus to six galagid species, and C. jacchus to two tamarin species, so as to assess whether gouging primates exhibit these predicted morphological shapes. Our results show little morphological evidence for increased force-production or load-resistance abilities in the skulls of these gouging primates. Conversely, these gougers tend to have skull shapes that are advantageous for creating large gapes. For example, all three gouging species have significantly lower condylar heights relative to the toothrow at a given mandibular length in comparison with closely related, nongouging taxa. Lowering the height of the condyle relative to the mandibular toothrow should reduce the stretching of the masseters and medial pterygoids during jaw opening, as well as position the mandibular incisors more anteriorly at wide jaw gapes. In other words, the lower incisors will follow a more vertical trajectory during both jaw opening and closing.We predict, based on these findings, that tree-gouging primates do not generate unusually large forces, but that they do use relatively large gapes during gouging. Of course, in vivo data on jaw forces and jaw gapes are required to reliably assess skull functions during gouging.