Acepromazine-ketamine anesthesia in the rhesus monkey (Macaca mulatta).

Six adult male rhesus monkeys (Macaca mulatta) were anesthetized using a combination of acepromazine maleate and ketamine hydrochloride administered by intramuscular injection. This combination produced a smooth induction to anesthesia requiring less than 5 minutes. The average duration of anesthesia was slightly less than 1 hour and was safely prolonged with additional doses of ketamine. The depth of anesthesia was sufficient for minor surgical procedures and for precise radiological studies. No deleterious side effects were noted, and animals recovered completely in a short time.     

Fetal sex ratio in the rhesus (Macaca mulatta).

Fetal sex ratio was determined in several hundred timed Macaca mulatta pregnancies terminated by hysterotomy between 75 and 179 days' gestation. From 75 to 149 days' gestation a greater number of females occurred in utero, while after 150 days a greater number of males was observed. However, this difference was not statistically significant.     

Menetrier's disease in a rhesus monkey (Macaca mulatta).

Gross and microscopic features closely resembling those found in Menetrier's disease in man are described in a 20-month-old rhesus monkey. The gastric lining was characterized by greatly enlarged rugae caused by mucosal hypertrophy and hyperplasia along with outfolding of the muscularis mucosa and the submucosa. The mucosa and submucosa were infiltrated with inflammatory cells, mainly lymphocytes and plasma cells.     

Flexible fiberoptic bronchoscopy of the rhesus monkey (Macaca mulatta).

Using a flexible fiberoptic bronchoscope, 10 rhesus monkeys were bronchoscoped 30 times without complication. The bronchoscopic anatomy was found to be similar to that of the human except for the presence of a right cardiac lobe in the monkey.     

Seasonal weight changes in male rhesus monkeys (Macaca mulatta)

Adult male rhesus monkeys lose weight during the breeding season and regain it during the nonbreeding season. The annual pattern of maximum weight gain just prior to the onset of breeding resembles the seasonal “fattening” seen in squirrel monkeys, but the period of weight gain is less discrete. The magnitude of weight change is less in younger males, in that sexually immature males gain weight in both seasons, but significantly less during the breeding season. Females do not lose weight during the breeding season. Post hoc analyses revealed no significant correlations between male testosterone levels, dominance ranks, weights, or weight changes. The heaviest animals as juveniles were predictably the heaviest as adolescents. The timing of seasonal changes in testosterone did not correlate with the timing of changes in weight; weight losses followed the rise in testosterone, and weight gains continued until early in the breeding season after testosterone levels had already begun to rise. It is suggested that seasonal hormonal changes may influence activities in individuals and that changes in the activities of particular group members may alter the activity patterns of other group members. This alteration of activity patterns due to group influences on individuals as well as individual influences on the group may explain why hormonal regulation of seasonal weight appears to be indirect and why individuals (juveniles) experiencing no seasonal hormonal changes nonetheless show differences in activity patterns and seasonal weight changes.     

Amniocentesis and antenatal sex determination in the rhesus monkey (Macaca mulatta).

Antenatal sex was correctly identified in 87.5% of the rhesus monkeys studied by evaluation of sex chromatin bodies in the exfoliated cells present in amniotic fluid. Fluid samples were obtained by either amniocentesis, amnioscopy, or by cesarean section at 80--120 days of gestation. Amniotic fluid concentrations of progesterone, total estrogen, and testosterone were correlated with fetal sex. Concentrations of these hormones decreased over the time period examined. Amniocentesis is a simple procedure which provides for routine fetal sex determination.     

Biochemical studies on the aqueous humour of rhesus monkeys (Macaca mulatta).

Aqueous humour of rhesus monkey eye contains lower concentration of glucose and excess of sodium and chloride irons in comparison to constituents of serum of the same animals.     

Accidental methyl methacrylate inhalation toxicity in a rhesus monkey (Macaca mulatta).

A rhesus monkey (Macaca mulatta), accidentally exposed to vapors of methyl methacrylate for 22 hours was found in a comatose condition. Attempts to revive the animal were unsuccessful. Necropsy revealed a diffusely mottled liver, pulmonary edema, and atelectasis. The thoracic cavities each contained 30 ml of clear yellow fluid. Histopathologic review of the tissues showed central lobular liver necrosis, pulmonary edema, pulmonary emphysema, and atelectasis. Analysis of a blood sample obtained from the monkey 1.5 hours prior to death showed a normal hemogram, but elevated values for serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, lactate dehydrogenase, phosphohexose isomerase, blood urea nitrogen, and serum sodium. The pathologic findings, laboratory results, and clinical history suggested a diagnosis of methyl methacrylate poisoning.     

Comparison of kidney weight and volume to selected anatomical parameters in the adult female rhesus monkey (Macaca mulatta).

In this study, the normal distribution of renal weight and volume was determined and the correlation between the weight and volume and various skeletal measurements taken from radiographs and at necropsy was assessed. Values from 136 female monkeys with complete data (including all bone, radiographic, and kidney measurements) were analyzed. The mean kidney weight was 13 g with a standard deviation (SD) of 2 g. The mean kidney volume was 12 ml, SD 2 ml. The estimation of kidney weight and volume from bone length, age, or body weight was not reliable according to statistical analysis of our data. We did find that all apparently normal adult female rhesus monkeys typically have similar sized kidneys. This information is useful in that it reduces concerns about consistency in experimental subjects.     

Parturition in rhesus monkeys (Macaca mulatta)

During five years of birth season fieldwork, we observed two births and three peri-birth instances of behavior of free-ranging rhesus living in Kathmandu, Nepal. These constitute the first two recorded free-ranging rhesus births, and we compare them to the behavior which has been observed in captivity and expected in the wild. The free-ranging parturition behavior was characterized by a general lack of contact with other troop members and by overall inconspicuousness. In the first birth we observed, the troop moved about 70 m up the hill, leaving the laboring female behind on an open hillside. Two males, a female and a juvenile returned and rested about 20 m from the delivering female. During the second delivery, the female stayed with the troop and seemed to participate normally in most troop interactions, although she avoided physical contact with other troop members. We propose that this near-normal behavior may help to assure successful parturition by allowing the female the needed social isolation and inconspicuousness without any loss of troop protection. It may also partly explain why births have not been observed during previous studies. Observations of rhesus parturition behavior reported from studies of captive monkeys and reports from other free-ranging primate studies are compared with our data.     

Kinship,association, and social relationships in rhesus monkeys (Macaca mulatta)

Data on social interactions with matrilineal kin were collected from two groups of rhesus monkeys for 6 years. All behavioral states, including time within one meter of another, involved kin more often than would be expected by chance. Significant associations were also found between kinship and the frequencies of various forms of agonistic as well as affiliative acts. Frequency of social interaction, however, was not a simple function of time in proximity. Although animals spent more time with kin than nonkin they had more aggressive interactions with kin. Moreover, aggression was biased toward the more serious forms of expression in interactions with kin. Time spent in association was neither predictive of the rate of aggressive interaction nor reduced by high rates of aggressive interaction. Rather than association time influencing rates of interaction, association time may be the consequence of a history of aggressive and affiliative exchanges. Preferential association and high rates of aggressive interaction with kin may be possible due to the existence of compensating social mechanisms nullifying the negative influence of specific aggressive encounters. © 1993 Wiley-Liss, Inc.     

Separation and characterization of plasma lipoproteins of rhesus monkeys (Macaca mulatta).

A group of 14 adult male rhesus monkeys was maintained on a low cholesterol-high fat diet. Periodically, animals were fasted and blood samples were taken for characterization of the plasma lipoproteins. Complete separation of individual plasma lipoprotein classes was not achieved by traditional sequential ultracentrifugation techniques. Rather, initial separation of lipoprotein classes according to size was effected and density centrifugation was used subsequently for further separation. At least six lipoprotein fractions were identified, each of which was unique as defined by the properties of size, density (d), and electrophoretic mobility. These lipoprotein fractions were characterized by determination of chemical compositions and apoprotein patterns. The lipoproteins present in highest concentration in these monkeys were designated as region IV lipoproteins. This fraction had alpha-migration on agarose electrophoresis, 1.063 < d < 1.225, and the size, composition, and apoprotein pattern characteristic of HDL. No fewer than three fractions were identified with densities that overlapped the 1.019 < d < 1.063 range. Of these, the fraction designated as region III lipoproteins was present in highest concentration, had beta-migration by agarose electrophoresis, a predominant B apoprotein, and a chemical composition and size characteristic of LDL. Two larger subfractions, identified as region II lipoproteins, were separated from each other at a density of 1.050 g/ml. Agarose electrophoresis showed that the fraction with d < 1.050 had a migration intermediate between beta and pre-beta. The chemical composition and apoprotein pattern were consistent with the possibility that these lipoproteins were remnants of VLDL catabolism. The fraction with d > 1.050, had pre-beta mobility and a size and composition similar to the Lp(a) lipoprotein in plasma of human beings. At least two VLDL subfractions, identified as region I and IIa lipoproteins, were found although both were present in very low concentrations. Region I lipoproteins were larger and contained relatively more cholesteryl ester and more of the apoproteins that migrated with the mobility of apo-B and arg-rich apoprotein in SDS-polyacrylamide gel electrophoresis. Some of the region I lipoproteins were beta-migrating by agarose electrophoresis. These results suggested the possibility that a beta-migrating VLDL was present in these normal animals.