Short duration anaesthesia with medetomidine and ketamine in cynomolgus monkeys

Cynomolgus monkeys were anaesthetized with either intramuscular ketamine (10 mg/kg or intramuscular ketamine 2 mg/kg and medetomidine 50 microg/kg. Various physiological measurements were made once the animals were safe to handle and again 10 min later. Cardiovascular and respiratory function were well maintained with both regimens but the heart rate was lower and arterial-alveolar carbon dioxide gradient was higher in the animals that received medetomidine. In those animals that received medetomidine, atipamezole was given to reverse the medetomidine but there was no difference in recovery times between the two regimens. Anaesthesia was not entirely reliable with medetomidine/ketamine and we recommend caution when using this mixture.     

Effects of repeated anaesthesia with ketamine/medetomidine and of pre-anaesthetic administration of buprenorphine in rats

Two groups of rats were anaesthetized at weekly intervals for 6 weeks with either ketamine/medetomidine alone (60 mg/0.4 mg/kg i.p.) or ketamine/medetomidine (45 mg/0.3 mg/kg i.p.) one hour following buprenorphine (0.05 mg/kg s.c.). Animals that received buprenorphine had longer periods of surgical anaesthesia (P = 0.04) and a greater depression of both mean pedal withdrawal score (P < 0.01) and mean respiratory rate (P = 0.014). Mean total duration of anaesthesia was also greater in the buprenorphine group on day 1. Sleep times reduced with successive doses of anaesthetic in the buprenorphine group (P = 0.024). Two animals in the buprenorphine group died. Repeated anaesthesia with ketamine/medetomidine alone was not associated with anaesthetic mortality. These results indicate that although buprenorphine has a clear anaesthetic-sparing effect, its use with ketamine/medetomidine may be associated with an increased risk of anaesthetic-related mortality.     

Effects of daily management stress on haematology and blood rheology of the gilthead seabream

Haematological and haemorheological responses against a moderate management stress, applied for 2 weeks, have been studied in the gilthead seabream ( Sparus aurata ). The stress application leads to a significant reduction in circulating erythrocytes, which caused decreased blood viscosity. Although erythrocyte osmotic fragility showed a trend inversely related to the duration of management stress, no significant change in cell dimensions, aggregation and deformation indices was observed. Consequently, the decrease in oxygen transport capacity attributable to haematocrit reduction, is not compensated by a qualitative change in the microrheological behaviour of erythrocytes, since the blood viscosity decreases as a direct result of the decline in red blood cell number.     

Effects of heated hydrotherapy on muscle HSP70 and glucose metabolism in old and young vervet monkeys

Increasing heat shock protein 70 (HSP70) in aged and/or insulin-resistant animal models confers benefits to healthspan and lifespan. Heat application to increase core temperature induces HSPs in metabolically important tissues, and preliminary human and animal data suggest that heated hydrotherapy is an effective method to achieve increased HSPs. However, safety concerns exist, particularly in geriatric medicine where organ and cardiovascular disease commonly will preexist. We evaluated young vervet monkeys compared to old, insulin-resistant vervet monkeys (Chlorocebus aethiops sabaeus) in their core temperatures, glucose tolerance, muscle HSP70 level, and selected safety biomarkers after 10 sessions of hot water immersions administered twice weekly. Hot water immersion robustly induced the heat shock response in muscles. We observed that heat-treated old and young monkeys have significantly higher muscle HSP70 than control monkeys and treatment was without significant adverse effects on organ or cardiovascular health. Heat therapy improved pancreatic responses to glucose challenge and tended to normalize glucose excursions. A trend for worsened blood pressure and glucose values in the control monkeys and improved values in heat-treated monkeys were seen to support further investigation into the safety and efficacy of this intervention for metabolic syndrome or diabetes in young or old persons unable to exercise.     

Rank,relationships, and responses to intruders among adult male vervet monkeys

We examined the influences of dyadic relationships among captive adult male vervet monkeys (Cercopithecus aethiops sabaeus) on behavior directed toward caged “intruder” males placed inside subjects' enclosures. Subjects were all 9 adult male residents from three stable social groups, each of which contained 3 adult males, at least 3 adult females, and their immature offspring. Every male was observed in two 3-hour sessions, each time with one of the 2 other adult males from his group. Observation sessions consisted of six consecutive 30-min stages in which group composition and the presence of the intruder were manipulated. All groups exhibited a stable, linear male dominance hierarchy prior to and throughout the study. In each group, there was one pair of males, when together, in which each member exhibited higher rates of intruder-directed approach and aggressive behaviors than when either animal was paired with the third male of his social group. Such pairs were also distinguished by high levels of within-pair agonistic interactions. The higher-ranking member of each dyad was the most aggressive male toward the intruder in his social group, although only one of these animals was the dominant male of his group. Mutual facilitation of aggression against intruding males is interpreted as cooperative behavior benefitting both males by increasing the likelihood of repelling a potential competitor for resident females. Such cooperation provides further evidence in nonhuman primates for cohesive male-male dyads between animals whose social interactions are characterized by agonism. © 1993 Wiley-Liss, Inc.     

Maternal protectiveness and response to the unfamiliar in vervet monkeys

Vervet monkeys (Cercopithecus aethiops sabaeus) show individual differences in approach-avoidance behavior when faced with an unfamiliar and potentially threatening situation. Prior research from our colony demonstrated that juveniles who had experienced high levels of early maternal protectiveness were more cautious in response to novelty, compared to juveniles who had had less protective mothers. The research reported here was designed to verify this result in a paradigm that experimentally varied maternal protectiveness through the introduction of new breeding adult males. Mothers responded to the presence of new males by increased maternal protectiveness toward infants born in the year following the introductions. Individual differences in response to the unfamiliar were later evaluated by measuring the latency to approach within 1 m of novel food containers placed into the home enclosure of four naturally composed social groups. Infants approached with the same latency and in the same order as their mothers. Juveniles approached sooner than, and independent of, their mother's current behavior, but their latency to approach could be predicted by the experimentally induced variation in maternal protectiveness they had experienced as infants. Immatures who had been born in New Male years, when maternal protectiveness was high, were more cautious and had significantly longer latencies to approach the novel stimulus compared to immatures who had been born in Resident Male years. © 1993 Wiley-Liss, Inc.     

An antigen resembling HL-A7 on the leukocytes of vervet monkeys.

Human leukocyte typing sera of known specificities were used to test the leukocyte antigens of vervet monkeys. The results suggest that these leukocytes contained an antigen resembling the HL-A7 antigen of human leukocytes. This is similar to a previous observation with leukocytes from baboons. These findings are consistent with the suggestion that the 4a/4b complex is the precursor substance from which the other specificities have evolved.     

Effects of speed on forelimb joint angular displacement patterns in vervet monkeys (Cercopithecus aethiops)

Shoulder, elbow and wrist joint angular displacement patterns were analyzed for five vervet monkeys across increasing speed. Within symmetrical gaits, the peak positions of the pattern for each joint tended to decrease with increasing speed as did the yield angle of the elbow (more "yielding"). Across the walk(run)-gallop transition there were no notable changes in the displacement patterns, but there was a consistent decrease in the range of elbow movements and an increase in the yield angle. Across symmetrical gaits, there was also a tendency for some of the peak positions to decrease. These results are compared with those available for cats and dogs, and are interpreted relative to functional and neurological aspects of forelimb movements in primates.     

Determinants of fecundity and reproductive success in captive vervet monkeys

Between 1975 and 1983, adult female vervet monkeys (Cercopithecus aethiops sabaeus) over 3.5 years of age, living in two undisturbed social groups in a captive colony in Sepulveda, California, have averaged 1.0 births per female year with a mean interbirth interval of 10.7 months. Increased fecundity did not result in decreased survival rates of offspring in this population. Fecundity was influenced by the mother's age and dominance rank. The primary factor in the age-fecundity relationship was the age at first birth, which varied from three to five years. High-ranking females contributed the most to the high rate of fecundity, with significantly shorter interbirth intervals, more births per female year, and more surviving infants compared to low-ranking females.     

Effects of age,rearing, and separation stress on immunoglobulin levels in rhesus monkeys

The study reported here examined the effect of different rearing conditions and psychological stress on immunoglobulin levels in rhesus monkey infants. In the first experiment, 24 rhesus neonates were placed in one of the three following rearing conditions: Separated from their mothers and reared in the laboratory nursery; kept with their biological mothers; or removed at birth from their biological mothers and cross-fostered to adoptive rhesus mothers. Plasma samples were obtained from the nursery-reared infants immediately after birth and at weekly intervals for the next 30 days. Samples were also obtained from mother-reared and foster-reared infants on days 15 and 29. All samples were tested for IgG and IgM levels. The results indicated that neither rearing nor diet affected Ig levels. IgG levels were highest at birth and decreased progressively for the first 30 days, suggesting that placental transfer of maternal IgG is the critical determinant of IgG levels in primate infants as in humans. IgM changes were also similar to those in human infants: Low levels at birth, a significant increase from birth to day 15, and a moderate decline from day 15 to day 30. When IgG levels and IgM levels were correlated across the first month, many significant correlations were found which were consistent with human data relating both infant IgG and IgM levels to infant maturation. In the second experiment, 11 of the previously tested nursery infants were subjected to four consecutive social separations from peer groups at 6 months of age. Plasma samples were obtained before and after the first and fourth weeks of separation and tested for IgG and IgM levels. Small but significant decreases in both immunoglobulins were detected after 4 days of separation, particularly on the fourth week.     

Effects of growth and speed on hindlimb joint angular displacement patterns in vervet monkeys (Cercopithecus aethiops)

Hip, knee, and ankle joint displacement patterns are compared across both age and speed for five immature vervet monkeys sampled approximately every 6 months over a 3 year period. The analysis indicated that, as a group, the animals displayed no consistent changes in joint patterns as they grew. However, individual animals showed consistent patterns. There were also no consistent effects of size across animals at the walk-gallop transition. This is contrary to McMahon's prediction (J. Appl. Physiol. 39:619-627, 1975) based upon his elastic-similarity model of animal scaling. With increasing speed, when symmetrical gaits were used, all of the animals tended to show a decrease in the relative positions of the hip, knee, and ankle maximum values. Furthermore, across the walk-gallop transition, the animals tended to show a decrease in the range of ankle and knee movements.     

Assessment of meaning and the detection of unreliable signals by vervet monkeys

Free-ranging vervet monkeys, Cercopithecus aethiops, who had learned to ignore playbacks of one type of call by an unreliable signaller subsequently also ignored playback of an acoustically different call by the same individual if the calls had similar referents. Such transfer did not occur if either the identity of the signaller changed or if the two calls had different referents. After repeatedly being played an intergroup call in the absence of other groups, vervets also ignored an acoustically different intergroup call given by the same individual. The monkeys did not transfer habituation, however, if the new call was given by a different individual. In tests where the referents of two calls were different, the monkeys also failed to transfer habituation across call types. Vervet monkeys who had learned to ignore an unreliable leopard alarm call did not later ignore an eagle alarm call, even when the signaller remained the same. Results suggest that vervets, like humans, process information at a semantic, and not just an acoustic, level.     

The conflict between vervet monkeys and farmers at the forest edge in Entebbe, Uganda

Forty‐seven property owners in Entebbe, Uganda were questioned about vervet monkey activities on their property. Our main objective was to investigate the interactions between humans and vervet monkeys in an agricultural area adjacent to a forest zone. Other studies have reported that farms located within 300 m of a forested boundary probably incur the greatest risk of crop‐raiding. Two other factors that may influence susceptibility to vervet crop‐raiding were also examined: the types of crops grown and the types of direct preventative measures used. The effect of these two factors on vervet crop‐raiding is not straightforward. However, the distance a property is located from the forest edge is an important factor influencing vervet crop‐raiding. Surveyed gardens 200 m from the forest edge received significantly less crop‐raiding than farms located 100 m or 50 m (P = 0.040, < α = 0.05). We suggest that the development of nonagricultural activities on land directly adjacent to forested areas may reduce vervet crop‐raiding by deterring vervets from travelling greater distances from the forest edge due to increased obstacles or risks.     

The influence of pre-anaesthetic administration of buprenorphine on the anaesthetic effects of ketamine/medetomidine and pentobarbitone in rats and the consequences of repeated anaesthesia

Rats received pentobarbitone (60, 48 and 36 mg/kg i.p.) or ketamine/medetomidine (75/100, 60/80 and 45/60 mg/microg/kg i.p.) alone, or one hour following buprenorphine (0.5 mg/kg s.c.). Animals were anaesthetized once per week for 6 weeks with one of three anaesthetic doses according to a randomized block design. In the pentobarbitone group, animals which received buprenorphine had longer sleep times (236 +/- 22 cf. 204 +/- 21 min) and longer durations of surgical anaesthesia (83 +/- 14 cf. 27 +/- 8 min) (P<0.01), these effects being potentiated with increasing anaesthetic doses (P<0.01). A greater degree of respiratory depression was found in animals that received buprenorphine (P<0.01) although this was judged clinically acceptable in all cases. Unexpectedly high mortality and a high incidence of anaesthetic complications (nine of 16 animals) in the ketamine/medetomidine group made statistical analysis of these data impossible. We conclude that for pentobarbitone, pre-anaesthetic administration of buprenorphine reduces the dose of anaesthetic required to produce surgical anaesthesia, in addition to the presumed benefits of pre-emptive analgesia. In view of the high mortality encountered, we advise caution when considering pre-anaesthetic use of opioids in combination with ketamine/medetomidine in rats.     

Gut microflora of vervet and samango monkeys in relation to diet

The microflora in the gastrointestinal tracts of wild vervet and samango monkeys (Cercopithecus aethiops and C. mitis, respectively) were studied, using fermentation acid analysis, electron microscopy, and culturing methods. The diets of the two species of monkey differ considerably, with that of the samango including a greater proportion of cellulose-rich leaf material, and this is reflected in the microflora. Volatile fatty acid measurements along the gut of both species showed that these end products of bacterial metabolism were concentrated in the cecum and colon. Electron microscopy indicated that morphologically similar bacteria were present in the cecum and colon of both species, but the samango possessed a distinct stomach microflora. Bacteria in the lumina of the four main regions of the gut of the monkeys (stomach, small intestine, cecum, and colon) were plated on a number of anaerobic media (Mann, Rogosa, and Sharp; clostridial basal; and complex media). The cecum and colon were found to contain higher numbers of microbes per gram (wet weight) of gut content than the stomach and small intestine. Microbial isolates were able to catabolize carboxymethyl cellulose and other polymers. This may aid the monkeys, particularly samangos, in the digestion of fibrous dietary components such as leaves.