老化对猕猴中颞视区细胞早期方向选择性的影响

中颞视区(middle temporal area、MT/V5)在视觉运动处理过程中起着重要作用。MT区神经元对物体运动方向具有强选择性,而这种细胞的方向选择性被认为是运动方向知觉的神经基础,且已有实验表明方向选择性由于受到注意影响,而在时间进程上分为2个阶段。该研究组先前的实验发现麻醉猕猴(Rhesus macaque)MT区细胞的方向选择性发生了衰退,但该衰退是整个时间进程上平均的结果,并不能在时间进程上揭示其神经机制。因此,为了进一步探索运动方向感知能力下降的神经机制,该实验采用单细胞技术在麻醉猕猴的MT区研究了在正常老化过程中MT区细胞的早期方向选择性变化(early stage direction selectivity,esDB),结果表明老年猕猴MT区细胞早期方向选择性显著降低,具有强早期方向选择性的细胞显著减少。该结果进一步揭示了MT区细胞方向选择性在早期发生的衰退可能介导了视觉运动感知能力的下降。     

The formation of relationships based on socio-spatial proximity in a free-ranging colony of rhesus monkeys

This study attempted to describe the pattern of social affiliations in a colony of free-ranging rhesus monkeys (Macaca mulatta) on Key Lois Island, Florida. Monkeys arrived to Key Lois in nine distinct groups that were held in a 50×100 ft enclosure for between 30 and 60 days and then released. The data consisted of observations of groups of monkeys seen together at various times in various locations. The study tested the hypothesis that monkeys that were in the same quarantine group would more frequently be seen together in the free-range than monkeys from different quarantine groups. The hypothesis was confirmed in seven of the nine groups. Chi-square =2137.1 (p<.001),Cohen’s kappa =.38 (p<.001) (1960). Prior common group membership was found to be predictive of future social affiliations. Explanations of residual kin structure from India, the effect of a primary social experience in a new environment, and the possibility of in-group versus out-group forces between the successively introduced groups were advanced as possible reasons for the findings.     

Circulation of Campylobacter spp. in rhesus monkeys (Macaca mulatta) held in captivity: a longitudinal study

Campylobacteriosis is an extremely important zoonosis, circulating freely in the environment. In nonhuman primates kept in open facilities and bred for experimental purposes, the presence of Campylobacter spp. could cause severe damage to the production and interfere with the results of scientific research. In this paper, we assessed the circulation of Campylobacter spp. in a colony of clinically healthy rhesus monkeys (Macaca mulatta) destined to research. The analysis was carried out during seven non-consecutive years. Data showed that despite several changes made in animal management along the studied years in order to control this zoonosis, reduction of bacterial charge did not occur. Significant differences among the age groups and sex were observed. Infants showed higher susceptibility than adult animals. In general males were more infected than females. Modifications adopted in the handling techniques need to be reviewed with the intent of improving the production, reducing bacterial infection of the stock and avoiding undesirable cross reactions in the research carried out with these animals. Therefore, this paper alerts professionals that work directly with captive rhesus monkeys about the risks of Campylobacter spp. infection and possible interference on the experimental procedures.     

Species discrimination and concept formation by rhesus monkeys (Macaca mulatta)

There are 19 species in genusMacaca and some of them are living in sympatry (Fooden, 1980). Although inter-specific hybrids are relatively easy to produce under artificial conditions, hybridization does not occur naturally. What is preventing that among the species of genusMacaca? Three rhesus monkeys acquired a discrimination between pictures with rhesus monkeys and without rhesus monkeys. All subjects showed positive transfer of this discrimination to new pictures with rhesus monkeys and without rhesus monkeys. A further test showed that these monkeys could discriminate between pictures of rhesus monkeys and pictures of Japanese monkeys. The results suggest that rhesus monkeys recognize rhesus monkeys as a class, independent of the actual stimuli such as a picture or an individual monkey. The ability to recognize members of their own species and the opportunities for such learning may be an important factor preventing hybridization among the species of genusMacaca.     

Persistent adrenocortical activation in female rhesus monkeys after new breeding groups formation

Persistent elevated adrenocortical responsiveness to ACTH has been demonstrated in female rhesus monkeys as long as 13 weeks after relocation into new single male breeding groups. Measures of immediate responses to psychosocial stress of grouping such as aggressive interaction and circulating plasma cortisol levels were highest immediately after grouping, but tended to decline to lower levels after the first month. In a retrospective comparison of such 'new' breeding groups (less than one year) versus established breeding groups (more than two years), stress-related morbidities such as trauma (wounding) and loose stools were higher for as long as six months after new group formation. The actual and potential adverse effects of regrouping stress on colony health and reproduction are relevant to cost-benefit assessment of such colony management procedures.     

Chylothorax in rhesus monkeys with intravenous catheters.

Chylothorax associated with the use of indwelling intravenous catheters was diagnosed in 13 Macaca mulatta. Clinical signs were marked respiratory embarrassment or sudden death. Lesions at necropsy included large quantities of sterile pleural fluid, pulmonary atelectasis and chronic fibrinous pleuritis. Lipid was present in the effusion and in tissue sections of visceral pleura.     

Long-term mortality and cancer risk in irradiated rhesus monkeys.

Continuous, 24-year observations on a group of 358 rhesus monkeys reveal that life shortening from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events is influenced primarily by the dose rather than by the energy of radiation. Life shortening in groups exposed to similar surface doses of 138- to 2300-MeV and 32- to 55-MeV protons are not significantly different, but the low-energy protons are associated with more deaths in the early years, while the high-energy protons contribute more to mortality in later years. In males, the most significant cause of life shortening is nonleukemia cancers. In females, radiation increased the risk of endometriosis (an abnormal proliferation of the lining of the uterus) which resulted in significant mortality in the years before early detection and treatment methods were employed. Animals exposed to 55-MeV protons had a high incidence of malignant brain tumors with latent periods ranging from 13 months to 20 years. The first fatal cancer among nonirradiated controls occurred 18 years after the study began. Analysis of the dose-response data supports the 1989 guidelines of the NCRP for maximum permissible radiation exposures in astronauts (NCRP, Guidance on Radiation Received in Space Activities, Report No. 98, National Council on Radiation Protection and Measurements, Bethesda, MD, 1989).     

The problem of age estimation: a study using rhesus monkeys (Macaca mulatta)

Accurate estimation of chronological age for animals of unknown birth date is important in a variety of circumstances. This is particularly true for non-human primates and especially true for rhesus monkeys. Data, useful for this purpose, have been organized in a variety of ways. The purpose of this paper is to duplicate some of these methods and to check their accuracy. In general, three methods of organizing data were used. The parameters for each method were estimated from one group of rhesus monkeys. Accuracy of age estimation was determined from a closely related, second group which had been raised under approximately the same conditions and from a third group of unrelated monkeys raised under different conditions. Some methods provided better estimations than others, but none was absolutely accurate. The analyses indicate that the degree of inaccuracy of a method should be determined on a sample which is independent of the one from which the parameters were estimated.     

Resident bacteria in a mixed population of rhesus macaque (Macaca mulatta) monkeys: a prevalence study

Background  Microflora populations residing in oropharyngeal and gastrointestinal sites defend against pathogenic bacterial colonization. Perturbations in these microbial communities may allow opportunistic pathogenic bacteria to establish themselves and cause morbidity and mortality from sepsis particularly after stressful experimental procedures. This study determined the prevalent facultative bacteria in a resident population of Macaca mulatta prior to use in experimentally induced immunosuppressive radiation studies.
Methods  Standard microbiological methods were used to assess prevalent facultative bacteria in the oropharynx and rectum of 24 male M. mulatta .
Results  The majority of the bacteria isolated from the oropharyngeal and rectal sites were gram-positive cocci. Species of Staphylococcus and Streptococcus predominated in all samples. Few gram-negative bacteria were isolated.
Conclusions  Bacteriological assessment is recommended to identify predominant bacterial species to be prepared to provide appropriate antimicrobial therapy in non-human primates that are expected to undergo stressful immunocompromising procedures.     

Context affects the numerical semantic congruity effect in rhesus monkeys (Macaca mulatta)

Do monkeys anchor their numerical judgments based on the context in which their choices are presented? We addressed this question by varying the numerical range across sessions while macaque monkeys made ordinal judgments. Monkeys were trained to make a conditional discrimination whereby they were reinforced for ordering arrays of dots in ascending or descending numerical order, dependent on a color cue. Monkeys were tested using two ranges of numerosities that converged on a single pair. Similar to the findings of Cantlon and Brannon (2005), we found a semantic congruity effect whereby decision time was systematically influenced by the congruity between the cue (ascending or descending) and the relative Numerical Magnitude of the stimuli within each range. Furthermore, monkeys showed a context effect, such that decision time for a given pair was dependent on whether it was a relatively small or large set of values compared to the other values presented in that session. This finding suggests that, similar to humans, the semantic congruity effect observed in monkeys is anchored by the context. Thus our data provide further evidence for the existence of a shared numerical comparison process in monkeys and humans.     

Establishing a free-ranging breeding colony of rhesus monkeys. Part I.

The Caribbean Primate Research Center recently contracted with the Food and Drug Administration to establish a free-ranging island breeding colony of rhesus monkeys. The goal of the program is to produce 600 to 800 offspring yearly from 1,000 breeding age females. The initial colony stock will consist of approximately 360 animals from an existing colony that was established on an island off the southwestern coast of Puerto Rico in 1961. Expansion of the colony will be accomplished by the purchase and introduction of rhesus females obtained from the wild. The colony site, reproductive history, composition, and the methodology of our expansion plans are discussed. In addition, anticipated problems are identified and analyzed.     

Hyperthermia in radiofrequency-exposed rhesus monkeys: a comparison of frequency and orientation effects

To compare the effects of exposure to a near-resonant frequency of microwaves at two orientations with a higher frequency exposure, five rhesus monkeys were exposed for 4 hr to 225 MHz, electric field oriented parallel to the long axis of the body (225 MHz-E), and to 225 MHz, magnetic field orientation (225 MHz-H), or to 1290 MHz, electric field orientation. On a separate occasion, the monkeys were exposed at night to 225 MHz-E. Exposures were conducted with the animal chair restrained in an anechoic chamber with rectal temperature continuously monitored. Blood samples were taken hourly during the 225-MHz-E exposures for cortisol analysis. The power densities used were 0, 1.2, 2.5, 5.0, 7.5, 10.0, and 15.0 mW/cm2 for 225 MHz-E (day), 0 and 5 mW/cm2 (225 MHz-E night and 225 MHz-H), and 0, 20, 28, and 38 mW/cm2 (1290 MHz). The monkeys were unable to tolerate exposure at power densities equal to or greater than 7.5 mW/cm2 (5.1 W/kg) at 225 MHz-E for longer than 90 min. The criterion for tolerance was that the rectal temperature would not exceed 41.5 degrees C. Average rectal temperature increases for day exposure to 225 MHz-E were 0.4 and 1.7 degrees C for 4-hr exposures to 2.5 and 5.0 mW/cm2 (1.7 and 3.4 W/kg). No changes in circulating cortisol levels occurred during any exposures to 5 mW/cm2 or less. Night exposures to 5 mW/cm2 (3.4 W/kg) at 225 MHz-E raised mean rectal temperature 2.1 degrees C. Exposure to 5 mW/cm2 (1.2 W/kg) at 225 MHz-H for 4 hr resulted in a 0.2 degree rise in mean rectal temperature. For 4 hr of 1290-MHz exposure to 20, 28, or 38 mW/cm2 (2.9, 4.0, and 5.4 W/kg), the mean body temperature increases were 0.4, 0.7, and 1.3 degrees C, respectively. The degree of hyperthermia caused by radiofrequency (rf) exposure was shown to be frequency and orientation dependent for equivalent power densities of exposure.