Cardiac allograft pathology in Rhesus monkeys

Orthotopic, allogeneic heart transplantations were performed in 26 randomly selected rhesus monkeys to study the effect of immunosuppressive treatment on survival and cardiac morphology. The histological picture of the acute and chronically rejected hearts was similar to that described for acute and chronic cardiac allograft rejection in man. As seems to be the case in man, an obliterative arteritis of the coronary arteries appears to be the limiting factor in cardiac allograft survival in the rhesus monkey. Immunosuppressive treatment with either Imuran and ALS or Imuran, ALS, and Prednisone could not prevent the occurrence of obliterative arteritis of the coronary arteries. Contrary to the observation in man, no atherosclerotic changes were found in the affected parts of the coronary arteries or in the non-diseased parts.     

Night observations of free-ranging Rhesus monkeys

The nocturnal distribution and behavior of individually marked Macaca mulatta were studied at the La Parguera, Puerto Rico, colony of the Caribbean Primate Research Center. The new image intensifier was used successfully to identify 399 monkeys in 185 sleeping clusters. Monkeys moved into mangrove trees close to favorite feeding areas usually 35 minutes after sunset. The group condensed to less than one-half the daytime spread, vocalizations increased and grooming ceased. Movements and vocalizations ceased several hours after sunset, although bursts of activity occurred throughout the night. Activity resumed 40 minutes before sunrise. Activity was higher during full moon, when I observed feeding, play and sexual behavior. Fights at night were twice as frequent during the breeding season. Monkeys slept in clusters of one to four, 58% of which were of two. Sixty-three percent were composed of maternal relatives, 33% were mother-infant pairs. Mature males clustered with non-related males, slept alone or with females (in the breeding season). Yearlings slept with their mothers or with older siblings. Distribution of monkeys in a group at night reflects daytime associations.     

Behavior of an all-juvenile group of Rhesus monkeys

The behavior and organization of a group of 33 juvenile rhesus monkeys removed from a single free-ranging group were found to parallel closely intact rhesus social groups. Dominance ranking among the juveniles was 95% predictable from prior knowledge of mothers' ranks. Grooming, sitting close together, sitting touching, and play were found to occur much more frequently between matrilineal kin than expected from random selection of partner. Some estrous behavior was observed, including two instances of peri-menstrual estrus. One lengthy homosexual interaction between two two-year-old females was observed. The basis of much of the behavior and organization shown by the juveniles was found to be the matrilineal kin bonds brought from their natal group.     

The timing of fission among free-ranging Rhesus monkeys

Behavioral observations were carried out on a large group of free-ranging rhesus monkeys (Macaca mulatta) on Cayo Santiago from January 1968 to December 1969 and from October through December 1970. During this period, social group A divided. The 24-month study period can be classified into five stages which represent the different phases in the process of group fission. Two criteria for fission were established: the cessation of grooming between adult females of different sub-groups of the main group and the stabilization of the adult female population. The criteria were based on established information on group dynamics and inter-group behavior on Cayo Santiago. Several points became clear from the chronological analysis. Group fission is a long process. The duration of the process of fission and the specification of the season in which fission begins and is completed depends upon the definition applied. For purposes of this analysis, fission was defined as beginning with the onset of spatial fragmentation and corresponded to the initial part of the breeding season. The fission was completed during the breeding season. The duration of the process of fission was 18 months.     

Male blue monkeys alarm call in response to danger experienced by others

Male blue monkeys (Cercopithecus mitis stuhlmanni) of Budongo Forest, Uganda, produce two acoustically distinct alarm calls: hacks to crowned eagles (Stephanoaetus coronatus) and pyows to leopards (Panthera pardus) and a range of other disturbances. In playback experiments, males responded to leopard growls exclusively with a series of pyows and to eagle shrieks predominantly with hacks. Responses to playbacks of these alarm call series matched the responses to the corresponding predators, suggesting that the calls conveyed something about the nature of the threat. When responding to a series of hacks, indicating an eagle, males responded predominately with hacks, but produced significantly more calls if their group members were close to the playback stimulus than far away, regardless of their own position. When responding to a series of pyows, indicating a range of disturbances, males responded with pyows, but call rates were independent of the distance of other group members. The results suggest that males took into account the degree of danger experienced by other group members.     

Immune responses during measles infection in immunosuppressed Rhesus monkeys.

Rhesus monkeys immunosuppressed with horse anti-human thymocyte gamma-globulin (ATG) were infected with measles and simultaneously inoculated with sheep erythrocytes (SRBC), a thymus-dependent antigen, and with pneumococcal polysaccaride type III (SSS-III), a thymus-independent antigen. ATG treatment alone suppressed SRBC antibody production, had no effect on SSS-III antibody production, and effectively eliminated circulating T cells compared to nonsuppressed monkeys. ATG treatment of measles-infected monkeys resulted in delayed virus clearance and delayed antibody production compared to nonsuppressed infected monkeys. After cessation of ATG treatment, measles antibodies and T cells reached normal levels, and measles virus was eliminated. Thus, immune clearance of measles virus is T cell-dependent, but the relative roles of cellular- and humoral-mediated immunity in vivo could not be clearly separated. Also, measles infection was associated with a decreased T cell mitogen responsiveness of circulating lymphocytes but not of lymph node lymphocytes, suggesting an altered circulating pattern of the cells responsible for delayed hypersensitivity. Also, measles infection had no effect on T-dependent antibody production to SRBC.     

Sexual behavior of laboratory- and wild-born male Rhesus monkeys.

Rearing method has an important influence on the sexual performance of adult male rhesus monkeys. Testosterone levels and sexual behavior of laboratory-born and -reared adult males were compared with those of males born in the wild and brought to the laboratory as adults. The mean sexual performance level of colony-reared animals was significantly below that of males born in the wild but testosterone levels in the two groups did not differ significantly. Not all laboratory-reared males were sexually inadequate but less than 30% ejaculated in tests of sexual behavior. The sexual behavior and testosterone levels of adult males treated prenatally with testosterone propionate were found not to differ from those of untreated males reared in the same way. Conclusions about sexual adequacy based on 10-mm tests of sexual behavior differed very little from those based on 1-hr tests.     

Hormonal and social factors affecting evoked sexual behavior in Rhesus monkeys

Male rhesus monkey sexual behavior occurring spontaneously or evoked by remotely-controlled hypothalamic stimulation was studied in dominant and subdominant males with both dominant and subdominant, estrogen-treated or untreated, ovariectomized females. The behavior was quantified in terms of number and duration of ejaculatory sequences, number of thrusts, and number of mounts per sequence. Little or no spontaneous sexual behavior was observed with an untreated ovariectomized female. However, evoked sexual behavior with the exception of evoked ejaculation could be obtained whether the females were treated or untreated. Spontaneous and evoked sexual behavior was directed towards both dominant and subdominant females. The female chosen by the male was in part determined by the dominance status of the female. Evoked sexual behavior differed from spontaneous behavior in terms of an increased number of thrusts per mount, an increased number of ejaculations per session, and a decrease in latency between ejaculatory sequences.     

Rhesus monkeys correctly read the goal-relevant gestures of a human agent

When humans point, they reveal to others their underlying intent to communicate about some distant goal. A controversy has recently emerged based on a broad set of comparative and phylogenetically relevant data. In particular, whereas chimpanzees (Pan troglodytes) have difficulty in using human-generated communicative gestures and actions such as pointing and placing symbolic markers to find hidden rewards, domesticated dogs (Canis familiaris) and silver foxes (Urocyon cinereoargenteus) readily use such gestures and markers. These comparative data have led to the hypothesis that the capacity to infer communicative intent in dogs and foxes has evolved as a result of human domestication. Though this hypothesis has met with challenges, due in part to studies of non-domesticated, non-primate animals, there remains the fundamental question of why our closest living relatives, the chimpanzees, together with other non-human primates, generally fail to make inferences about a target goal of an agent's communicative intent. Here, we add an important wrinkle to this phylogenetic pattern by showing that free-ranging rhesus monkeys (Macaca mulatta) draw correct inferences about the goals of a human agent, using a suite of communicative gestures to locate previously concealed food. Though domestication and human enculturation may play a significant role in tuning up the capacity to infer intentions from communicative gestures, these factors are not necessary.     

Evaluation of the cardiovascular function of older adult Rhesus monkeys by ultrasonography

OBJECTIVE: To evaluate the cardiovascular structure and function of older adult Rhesus monkey by utrasonography. METHODS: Sixteen monkeys aged from 17 to 20 years and weighing from 8.2 to 15.3 kg, six adults aged 7-8 years and weighing from 8.1 to 9.2 kg. All monkeys were determined to be free from hypertension, hyperglycaemia and cardiac disease. The normal values of index related to heart and blood vessels including structure, haemodynamics and systolic or diastolic function were detected by 2D, M-mode, pulsed Doppler and tissue Doppler echocardiography respectively under ketamine hydrochloride sedation. Meanwhile, blood pressures were also measured by electronic sphygmomanometer. Each monkey underwent repeated detections in 2 weeks and all data were analysed with statistical methods. RESULTS: Compared with young adult monkeys, the older's heart rate (HR), the left ventricular diastolic function and the compliance of big artery including right and left common carotid artery, bulbus caroticus, internal carotid artery and abdominal aorta were decreased and the associated indexes changed significantly (P < 0.05 or P < 0.01). Meanwhile, older monkeys exhibited significant increase in the aorta diameter (AO), amplitude of aortic wall (AAO), left atrial diameter (LAD), end diastolic volume of left ventricle (EDV), stroke volume (SV), left ventricular mass (LVM) (P < 0.05 vs. young adult monkeys); however, cardiac output (CO) only slightly increased but the difference did not reach the statistical significance (P = 0.418, P = 0.644 respectively). CONCLUSIONS: The present results demonstrated the profiles of cardiovascular function and structure in the older Rhesus monkeys. Older monkey is accompanied by diminished left ventricular diastolic function and big artery compliance. Ultrasonography provides a means to non-invasively evaluate the anatomy and function of the heart and blood vessel, and plays an increasingly important role in the drug evaluation against cardiovascular dysfunction.     

Muscle derived serum enzyme accumulation after +Gz acceleration test in Rhesus monkeys exposed to bed rest

It is known that several hours of intensive muscle tension result in accumulation of muscle derived enzymes and structural proteins (see review by Clarkson, 1997). We have assumed that, firstly, acute exposure to hypergravity may induce accumulation of serum creatine phosphokinase (CPK), and, secondly, level of that accumulation may be considerably altered after long term hypokinesia.