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PubMed1975

The retinal pigment epithelium and photoreceptor cells. Light- and electron microscopic studies on monkey eyes.

In the perifoveal retina of the monkey, Cercopithecus aethiops, the melanin granules are accumulated in apical cytoplasmatic protrusions of the pigment epithelial cells, facing the end of the cones. The rods are inserted deeper into the pigment epithelium than the cones; they reach the bottom of the infoldings of the apical surface membrane of the pigment epithelial cells. No melanin granules or other inclusions are situated at the end of the rods. The outer extremity of the rods is considerably inclined and in sections often appears as groups of rod discs which are incompletely or completely separated from the main part of the outer segments. This separation is regarded as an artifact caused by the inclination of the rods, and it is therefore not considered to represent phagocytosis of the outer segments by the pigment epithelium. The inclusions of the pigment epithelial cells are classified in five categories which seem to be related to each other owing to their shared structural characteristics. It is suggested that melanin granules are produced, modified and destroyed by the pigment epithelial cells of the adult. Because of the relations between the photoreceptors and the melanin granules it is suggested that light scattered by the melanin granules may pass backwards through the outer segments of the cones, but not of the rods.

Animals↗
PubMed1981

Detection of G-C rich heterochromatin by 5-azacytidine in mammals.

A new effect of 5-ACR (5-azacytidine), observed in fibroblast or kidney cell cultures is described in the calf (Bos taurus) and in some selected primates (Cebus capucinus, Erythrocebus patas, and Cercopithecus cephus). This cytidine analogue, used at low doses during the last late S phase, prevents the condensation of R-band positive heterochromatin (G-C rich segments). Thus, 5-ACR treatment can be used as a simple method for the detection of G-C rich heterochromatin.

Animals↗
PubMed1984

Conservation of the human COL1A1-TK-GAA synteny and homoeologous assignment in the African green monkey and the baboon (Cercopithecoidae).

The pro alpha 1 (I) collagen structural gene (COL1A1), the acid alpha-glucosidase (GAA), and the thymidine kinase (TK) genes, known to be closely linked in man (HSA) and mapped to HSA17, were found syntenic in two Cercopithecoidae species, the baboon (Papio papio, PPA) and the African green monkey (Cercopithecus aethiops, CAE) and assigned to homoeologous chromosomes, PPA16 and CAE19, respectively. The assignment of COL1A1 was obtained using two human cDNA probes. Hind III restriction sites found in man were present in the two species. The particular CAE individual used in the experiment showed a polymorphism for one DNA fragment.

Animals↗
PubMed1989

Variations in genome fragments coding for RNA polymerase in human and simian hepatitis A viruses.

The genome of hepatitis A virus (HAV) isolated from spontaneously infected African vervet monkey (Cercopithecus aethiops) has been cloned and partially sequenced. Comparison of genome fragments (1248 and 162 bp) from the 3D (RNA polymerase) region with the corresponding parts of human HAV genomes revealed a high degree of heterogeneity: there were altogether 257 nucleotide changes leading to 44 substitutions in predicted amino acid sequence, i.e. 89% amino acid identity. This divergence is considered to be significantly greater than genomic variations usually found among human HAV strains, where amino acid identity in the 3D region is over 98%.

Amino Acid Sequence↗
PubMed1987

Seasonal variation of serum lipids in the vervet monkey.

Seasonal variation of serum lipids has been observed in man, primates and other species. We are presenting data on serum lipid variation in Vervet monkeys (Cercopithecus aethiops). The monkeys (54 males, 33 females) were fed control diets (commercial pellets, fruit, vegetables) and data were pooled and grouped by season. Data having been obtained in South Africa, the seasons were: summer (December, January, February); fall (March, April, May); winter (June, July, August); and spring (September, October, November). Data presented are based on multiple samplings. Total serum cholesterol (mg/dl) and beta-lipoprotein cholesterol (mg/dl) varied significantly with season, peak values being observed in the fall months. Triglyceride and alpha-lipoprotein cholesterol levels showed seasonal variation which was not statistically significant. However, when data were analyzed by weight group (less than 3.3 kg; 3.3-4.3 kg; 4.4-5.3 kg; greater than 5.4 kg) only triglyceride and alpha-lipoprotein levels varied significantly with season. Significant interactions between diet, sex, weight, and season have also been observed. These observations can be used in planning future studies.

Animals↗
PubMed1988

Hepatic estrogen-binding proteins in male and female vervet monkeys.

Hepatic cytosols from male and female vervet monkeys (Cercopithecus pygerythrus) were found to contain the same levels of high affinity estrogen-binding proteins. Multipoint saturation analyses revealed that male liver cytosols contain two distinctly different binding components: a high affinity (HAEB) and a low affinity estrogen binder (LAEB). Female livers appeared to contain only the HAEB. Sucrose density gradient (SDG) analyses, however, clearly established the presence of a 3.8 S as well as an 8.1 S estrogen-binding component in the hepatic cytosols of both sexes. The 3.8 S binding component appeared to be more prominent in male SDG profiles. Cytosols, prepared in the presence of sodium molybdate (cyt +) exhibited significantly lower (50%) levels of specific estrogen-binding than cytosols prepared in the absence of the oxyanion (cyt-). SDG analyses, however, indicated that in cyt+ the 8.1 S binding component was stabilized at the cost of the 3.8 S binder. This phenomenon was observed in both sexes. Large excess levels of cortisol did not have any effect on specific estrogen binding by hepatic cytosols. The hepatic estrogen-binding proteins displayed a lower relative binding affinity for diethylstilbestrol than for its native ligand and higher affinities for estriol and estrone than expected.

Animals↗
PubMed1986

The suitability of East African primates as animal models of visceral leishmaniasis.

The susceptibility of four East African primate species to experimental infection with Leishmania donovani was investigated. Vervet monkeys (Cercopithecus aethiops), Sykes monkeys (C. mitis) and baboons (Papio cynocephalus) all supported low grade infections for periods ranging between four and eight months and subsequently showed evidence of self-cure. Greater bushbabies (Galago crassicaudatus) remained completely refractory throughout the course of the experiment. The significance of hepatic histiocytic nodules in the infected primates, similar to those observed in asymptomatic human visceral leishmaniasis, and the susceptibility of Old World primates to experimental infection are discussed.

Animals↗
PubMed1992

Spondyloarthropathy as an Old World phenomenon.

The presence of spine and sacroiliac involvement and the nature and distribution of erosive lesions allowed definitive diagnosis of spondyloarthropathy in the great apes (Gorilla and Pan [chimpanzee]), the lesser ape (Hylobates), and Old World monkeys (Theropithecus, Papio, Cercopithecus, Macaca, Colobus, Presbytis, and Erythrocebus). Analysis of lesional character, distribution, radiological appearance, and sex ratios showed a picture indistinguishable from human spondyloarthropathy. This contrasts with orangutans (Pongo), who lack reactive bone or sacroiliac involvement. A different pathophysiology, as yet undefined, is implied for their erosive arthritis. Limited individual susceptibility to spondyloarthropathy in humans (1% to 4%), Old World monkeys (2.4%), and lesser apes (2.4%) contrasts with the high frequency of disease in the great apes (20% to 28%). The wide geographic distribution of this phenomenon suggests an African and perhaps Asian "panendemic." This natural disease state provides a unique model for in-depth analysis of the contribution of genetic and environmental factors to disease pathophysiology.

Animals↗
PubMed1992

Frequency and intensity discrimination in Mongolian gerbils, African monkeys and humans.

Frequency (delta F) and intensity (delta I) difference limens were directly compared in Mongolian gerbils (Meriones unguiculatus), Old World African Monkeys (Cercopithecus mitis, Cercocebus albigena), and humans. Methods employed a repeating background AX discrimination procedure, and positive (food) reinforcement for animals. For delta I, there were small quantitative differences between the species. At 1 kHz, 70 dB SPL, DLs averaged 2.82 dB for gerbils, 2.29 dB for monkeys, and 0.75 dB for humans. For delta F, there were larger differences between the species. At 1 kHz, 60 dB SPL, frequency DLs were highest for gerbils, averaging 108 Hz. DLs were lower for monkeys, averaging 32.6 Hz, similar to recently reported DLs for other Old World monkeys (Prosen et al., 1990). Human DLs, averaging 2.27 Hz, were markedly lower than those of either monkeys or gerbils. These results suggest that animals provide better models of human delta I than delta F.

Acoustic Stimulation↗
PubMed1998

Prediction of percutaneous absorption from physicochemical data: a model based on data of in vitro experiments.

Correlations between in vitro percutaneous absorption data and physicochemical properties of industrial chemicals are evaluated in order to develop predictive mathematical models based on said properties. Percutaneous diffusion of 16 pounds of occupational interest, eight of which were polycyclic aromatic hydrocarbons (acenaphthene, anthracene, benzo(a)anthracene, chrysene, phenanthrene, fluorene, naphthalene, pyrene), six organophosphorus insecticides (acephate, chlorpyrifos, dimethoate, fenitrothion, methamidophos, omethoate) and two phenoxycarboxylic herbicides (2,4-D, MCPA), were tested in vitro using monkey (Cercopithecus aetiops) skin. The test apparatus consisted of nine static diffusion cells with normal saline, gentamycin sulphate and 4% bovine serum albumin as receiving solution. Test compounds were applied at various concentrations in 30 microliters of acetone solution and determined, in the receiving phase, by chemical analysis. Values for ln Kow (octanol/water partition coefficient) were correlated with experimentally determined values of the permeability constant Kp (r = 0.90, P < 0.001) and lag time (r = 0.81, P < 0.01). Analysis of variance in a model of multiple linear regression between Kp, ln Kow and water solubility [water] of the compounds, showed that the data had a highly significant fit (P < 0.0001). A more general model which also included molecular weight (MW) and vapour pressure was evaluated as well, but the two variables made no substantial difference. Multiple regression analysis between lag time, ln Kow and [water] was significant (P < 0.0001), whereas introduction of vapour pressure and MW as independent variables did not significantly improve the predictive effect on lag time. Our experimental system, therefore, enables the values of Kp and lag time to be predicted with reasonable precision on the basis of ln Kow and [water] values, using the algorithm derived from the multiple linear regression equation.

Animals↗
PubMed2000

Causal cognition in a non-human primate: field playback experiments with Diana monkeys.

Crested guinea fowls (Guttera pucherani) living in West African rainforests give alarm calls to leopards (Panthera pardus) and sometimes humans (Homo sapiens), two main predators of sympatric Diana monkeys (Cercopithecus diana). When hearing these guinea fowl alarm calls, Diana monkeys respond as if a leopard were present, suggesting that by default the monkeys associate guinea fowl alarm calls with the presence of a leopard. To assess the monkeys' level of causal understanding, I primed monkeys to the presence of either a leopard or a human, before exposing them to playbacks of guinea fowl alarm calls. There were significant differences in the way leopard-primed groups and human-primed groups responded to guinea fowl alarm calls, suggesting that the monkeys' response was not directly driven by the alarm calls themselves but by the calls' underlying cause, i.e. the predator most likely to have caused the calls. Results are discussed with respect to three possible cognitive mechanisms - associative learning, specialized learning programs, and causal reasoning - that could have led to causal knowledge in Diana monkeys.

Animals↗
PubMed1976

The influence of traumatic intrusion of primary teeth on their permanent successors. A radiographic and histologic study in monkeys.

Intrusion of maxillary central primary incisors was performed in 18 green vervet monkeys (Cercopithecus aethiops) with the purpose of studying early and late histologic changes in odontogenesis of permanent tooth germs and the effect of treatment of primary tooth injury. Immediate changes were studied in five monkeys where both maxillary central primary incisors were intruded. The monkeys were sacrificed 10-15 min after intrusion. The immediate changes in the permanent tooth germ consisted of contusion and displacement of the reduced enamel epithelium and slight displacement of the hard dental tissue in relation to the cervical loop, or Hertwig's epithelial root sheath. Late changes and effect of treatment were studied in 13 monkeys where both maxillary central incisors were intruded. One central primary incisor was removed 1 hour after intrusion while the other incisor was allowed to remain in the jaw. The monkeys were sacrificed 6 weeks after injury and the anterior portion of the maxilla was examined histometrically. The late changes consisted of metaplasia of the reduced enamel epithelium into a stratified squamous epithelium and, in most cases, changes in morphology of the dentin and enamel matrices. On the side where the injured tooth was preserved, significantly larger areas of epithelial metaplasia of the reduced enamel epithelium were present compared with the extraction side. Changes in morphology of the enamel matrix and dentin were found with the same frequency in the two groups, but tended to be less severe in the extraction group. It is concluded that more studies are needed on the effect of metaplasia of the reduced enamel epithelium on complete mineralization of the enamel before an optimal treatment of intruded primary incisors can be determined.

Animals↗
PubMed1978

Periodontal and pulpal healing of monkey incisors preserved in tissue culture before replantation.

The effect of delayed replantation and tissue culture as a prevention against root resorption was examined in green Vervet monkeys (Cercopithecus aethiops). Extracted incisors were kept in tissue culture medium (Eagle's medium) for 5--14 days before replantation. The extra-alveolar dry period before tissue culture ranged from to 0 to 60 min. Incisors not subjected to tissue culture served as controls. The animals were sacrificed 8 weeks after replantation. The following histologic parameters were registered for each tooth: surface resorption, inflammatory resorption, replacement resorption (ankylosis), downgrowth of pocket epithelium, and periapical inflammatory changes. The evaluation of the pulp included the extent, recorded in mm, of pulp survival. Histometric evaluation showed that teeth immediately placed in tissue culture medium for 5--14 days showed improved periodontal healing, exhibiting significantly less inflammatory resorption than control teeth immediately replanted. Also the extent of pulp survival was significantly increased in teeth replanted after tissue culture. Teeth bench-dried for 60 min and thereafter placed in tissue culture medium also showed a significant reduction in the amount of inflammatory resorption and increased amount of pulp survival compared with control teeth replanted after the 60-min dry extra-alveolar period. Replacement resorption (ankylosis) was found in all teeth in both groups.

Animals↗
PubMed1980

Further studies on tissue ingrowth into intrabony porous ceramic implants.

Porous ceramic Al2O3 implants with pore size of 100-750 micrometers were placed intrabony in the maxillary tuberosity of eight Cercopithecus monkeys. All implants healed primarily. Vital staining of mineralizing tissue was attempted using intravenous injections of tetracycline and calcein. The implants were retrieved after implantation times of 3, 5, 10, 11 and 12 months. Infiltration of fibrous tissue and bone was found in all impants, but the amounts of tissue observed were not significantly greater after the longest implantation times as compared to the 3- and 5-month results.

Aluminum Oxide↗
PubMed1989

Metal release from plates used in jaw fracture treatment. A pilot study.

This study investigated the occurrence of corrosion associated with the use of metallic implants to stabilize jaw fractures. Three different types of plates, Co-Cr and Ni-Cr alloys and Titanium, were connected in vivo to the mandibular bone surface of monkeys (Cercopithecus aethiops). The animals were killed after 3 and 6 months. The mucous membrane and bone tissue were analysed for concentrations of Co, Cr, Ni, Mo, Al, and Ti by atomic absorption spectrophometry and a radiochemical neutron activation technique. With the exception of Ti, higher concentrations of all the above elements were found in the tissue near the implants when compared with contralateral controls. However, no signs of corrosion, macroscopic or microscopic, were observed on the surface of the implants.

Animals↗
PubMed1989

Isolation of human immunodeficiency virus-related simian immunodeficiency viruses from African green monkeys.

We have isolated lentivirus strains that are related to the human immunodeficiency virus (HIV) from African green monkeys (Cercopithecus aethiops; AGM). Although immunologically related, these SIVagm are clearly distinct from other simian immunodeficiency virus (SIV) isolates, including isolates from Macaca mulatta (SIVmac) or even from other AGM. The SIVagm strains described in this communication grow well in a limited number of human T-lymphoma lines. Virus density, morphology, and reverse transcriptase activity are characteristic of the lentivirus group. SIVagm exhibits the following pattern of major virus proteins: p18, p28, gp45, p64, gp140. They appear to bind to the target cell via the CD4 or its primate analogue. Four virus isolates have already been molecularly cloned for detailed genomic analysis and within this SIV agm group they exhibit the genomic variability that is typical of lentiviruses. AGMs infected with this virus apparently remain healthy and therefore SIVagm not only provides a virus model for vaccine studies but also allows investigation of the defense mechanisms (immunological and others) that keep the AGMs healthy. Furthermore, precise genomic analysis of these and other SIV strains will lead to a better understanding of the evolution and pathogenicity of human lentiviruses like HIV.

Animals↗
PubMed1990

Isolation and characterization of simian immunodeficiency viruses from two subspecies of African green monkeys.

Cercopithecus aethiops (African Green monkey), a nonhuman primate species distributed throughout subsaharan Africa, has been shown to have high seroprevalence rates of antibodies to simian immunodeficiency virus (SIV), and therefore, has been proposed as a natural reservoir for immunodeficiency viruses. Our laboratories have isolated SIV-like viruses from two East African subspecies of C. aethiops designated grivet and vervet monkeys. Analysis of the structural proteins based on the molecular weights and immunologic cross-reactivity to the prototypic SIV(MAC), HIV-1, and HIV-2 isolates suggests that these viruses are distinctly different. Heterogeneity was observed in the molecular weights of the gag, pol, and env gene products between SIV isolates from vervets [SIV(AGM(VER))] and grivets [SIV(AGM(GRI))]. Phenotypically, SIV(AGM(VER)) isolates were distinguishable from SIV(AGM(GRI)) isolates by the apparent size difference of the major core antigen p24. All SIV(AGM(GRI)) and SIV(AGM(VER)) isolates were found to encode a transmembrane protein of approximately 40 kD (gp40) in contrast to gp32 of SIV(MAC). Furthermore, the transmembrane protein was shown to be encoded by the entire env open reading frame, unlike gp32 of SIC(MAC) or gp36 of SIV(AGM(TYO-1)). These data indicate that viruses from C. aethiops share common features with SIV(MAC) and HIV-1, but represent diverse SIV-like viruses which may vary according to subspecies and geographic location.

Amino Acid Sequence↗
PubMed1976

Serum lipid and lipoprotein responses of six nonhuman primate species to dietary changes in cholesterol levels.

The response of serum lipids and lipoproteins to different levels of cholesterol in the diet was studied in chimpanzee (Pan troglodytes), rhesus (Macaca mulatta), green (Cercopithecus aethiops), patas (Erythrocebus patas), squirrel (Saimiri sciurea) and spider (Ateles sp.) monkeys. Five animals of each species were fed increasing amounts of dietary cholesterol (0.05% to 1.5% W/W) for 3-week periods; between each experimental diet, the animals were fed a basal diet without cholesterol for a similar period. Serum cholesterol response of different species measured in terms of response index (area under the time-concentration curve above basal value) varied with the dietary cholesterol content and showed a significant interspecies difference at 0.5% dietary cholesterol (1.8 mg/kcal) level. The overall response for the different diets allowed ranking of the species as follows: squirrel greater than green greater than spider approximately equal to rhesus approximately equal to patas greater than chimpanzee. The serum lipoprotein response was reflected not only in an increase in beta-lipoprotein but also in alpha-liprotein with significant differences among species in the amount of cholesterol transported in the lipoprotein classes. Challenging the animals with dietary cholesterol seems to be an essential step for determining inter- and intraspecies differences.

Animals↗