Low density lipoprotein kinetics in African Green monkeys showing variable cholesterolaemic responses to diets realistic for westernised people.

African Green (vervet) monkeys were fed either an atherogenic Western diet (WD), a prudent diet (PD), or a high carbohydrate diet (HCD) for various lengths of time. Monkeys differed greatly in their response to the WD, and a strong negative correlation was observed between the fractional catabolic rates (FCR) of low density lipoprotein (LDL) and the total plasma cholesterol concentrations (r = -0.83 P = 0.0029). Similarly the individual synthetic rates (SR) of LDL plotted against the total plasma cholesterol concentrations showed a correlation coefficient of r = 0.94 P = 0.01 for WD animals. There was no correlation for PD or HCD animals for either SR or FCR and the total plasma cholesterol concentrations. The aortic lesion scores correlated with the SRs (r = 0.66 P = 0.040) but not with the FCRs. LDL turnover was also studied using 125I-labelled native LDL and methylated 131I-labelled LDL in African Green monkeys showing high or low cholesterolaemic response to an atherogenic Western diet. Measurements after 4 weeks and again after 6 months on the diet showed a decrease in both total and non-receptor mediated clearance of LDL. Receptor-mediated catabolism was significantly lowered in the hyperresponding group (P = 0.0011) and not in the hyporesponding group with a resultant significant difference between the two groups being P = 0.0355 after 6 months. Non-receptor mediated catabolism of LDL was similarly affected in that there was no significant difference between the two groups at 4 weeks but the clearance of methylated LDL was markedly lowered at 6 months, for the hyporesponding group P = 0.0003 and for the hyperresponding group P = 0.0184. Furthermore the hyperresponding group was depressed to a significantly greater extent when compared to the hyporesponding group (P = 0.0241).

Atherogenic effects in a non-human primate of Fusarium moniliforme cultures added to a carbohydrate diet.

Adding less than 0.5% w/w of culture material of strain MRC 826 of the fungus Fusarium moniliforme to a carbohydrate diet low in fat resulted in an atherogenic plasma lipid profile in a non-human primate. Simultaneously increased plasma fibrinogen and activity of blood coagulation factor VII could enhance atherogenesis. This unique potential for promotion of atherosclerosis was probably secondary to chronic hepatotoxicity as indicated by liver fibrosis and elevated cholesterol, albumin and the enzymes AST, ALT, LD, GGT and ALP in serum. The cholesterol and enzymes responded in proportion to the calculated doses of fumonisin mycotoxins in the F. moniliforme MRC 826 cultures. Fumonisins are water soluble and heat stable. Thrombotic, hepatotoxic, carcinogenic and cerebral effects of MRC 826 culture material and fumonisins are well known in non-primates. The estimated fumonisin concentrations tested fall within a range due to natural contamination of human foods. The results suggest that all maize grain products should be analysed for fumonisins.

Toxicity of culture material of Fusarium verticillioides strain MRC 826 to nonhuman primates.

We conducted a chronic feeding study in vervet monkeys (Cercopithecus aethiops) over 13.5 years. The experimental design consisted of two dietary treatment groups, each including males and females, fed varying levels of culture material of Fusarium verticillioides (Sacc.) Nirenberg (= F. moniliforme Sheldon) strain MRC 826 mixed into their daily food ration. Two females were included as treatment controls. We conducted blood chemical analyses bimonthly and recorded all clinical signs during the course of the experiment. We took liver biopsies at various stages during the initial phase of the experiment. Several monkeys were terminated in extremis during the experiment. Detailed feed intake profiles were determined 5 years after the experiment began, and the fumonisin B (FB) mycotoxin content of the feed was determined during the final stages of the experiment. The apparent FB consumption patterns were related to changes observed in the biochemical parameters in the blood and urine, including the liver function enzymes and creatinine clearance as well as differential blood counts and sphingolipid levels in the serum and urine. An apparent no-effect threshold for kidney and liver damage is estimated to be between 0.11 and 0.18 mg FB/kg body weight (bw)/day, which corresponds to a feed contamination level of between 8.21 and 13.25 mg FB/kg bw diet. Apart from the effects on the liver and kidney, a wide variety of parameters, including cholesterol and creatine kinase, were also adversely affected. Several blood parameters, including white and red blood cells, also significantly decreased in the treated animals. The serum sphinganine level and the sphingosine/sphinganine ratio, monitored toward the end of the experiment, significantly increased in both the low-dose and high-dose animals. The present study provides important information about the diversity of lesions induced by culture material of F. verticillioides in vervet monkeys and the dosage levels of fumonisins to be used in long-term studies in nonhuman primates.

Increased peripheral lymphocytes, lymphoid hepatitis and anaemia in African vervet monkeys seropositive to retroviruses.

Wild-caught African Vervet monkeys are commonly infected by Simian T-lymphotropic virus I (STLV1) and Simian immunodeficiency virus (SIV), yet the natural histories of these infections are largely unknown. Seropositivity was associated with increased total, T and atypical lymphocytes. In seropositive females there was mild, normocytic, normochromic anaemia. Lymphoid hepatitis was present in seven seropositive cases. African Vervets used in biomedical research, vaccine production and organ transplantation research are often infected by exogenous retroviruses which can be oncogenic and immunosuppressive in captive monkeys. Elimination of these infections may be possible by breeding Vervets in captivity.

Cholesterol-ascorbic acid interactions in guinea pig liver homogenates, and in the in situ perfused liver: relationship between ascorbic acid status and cholesterol and bile acid synthesis from mevalonate.

Cell free homogenates, and in situ perfused livers were used to study cholesterol synthesis and catabolism in control and latently scorbutic guinea pigs. In the homogenate studies, cholesterol synthesis from (2-14C) mevalonate was significantly depressed in latently scorbutic guinea pigs when compared to controls (0.02 less than p less than 0.05). Synthesis of cholesterol from (1-14C) acetate and n (1-14C) octanoate was minimal in guinea pigs. In the in situ liver perfusions, the synthesis of cholesterol from (2-14C) mevalonate was 40% lower in latently scorbutic guinea pigs than in control animals (p less than 0.005). The synthesis of cholesterol from (1-41C) acetate did not show the same clear cut effect. Bile acid production in the in situ perfused liver was unexpectedly higher in the latently scorbutic animals than in control animals (p = 0.005), although the incorporation of the label from (2-14C) mevalonate into the bile acids from the two groups was not significantly different. This finding led to the latently scorbutic group having a far lower specific activity in the bile acid fraction than the replete group.

Psorergatic acariasis in vervet monkeys.

7 cases of acariasis were discovered amongst a colony of vervet monkeys (Cercopithecus pygerythrus). Lesions were confined to palpebrae and periorbital areas. Skin scrapings and biopsies were taken and the parasite was identified as Psorergates cercopitheci. The skin biopsies showed that the parasite invaded the superficial epidermis only. Skin scrapings taken from other parts of the infested animals' bodies were all negative for mites. Several of the infested animals have had physical contact with conspecifics, the majority of which have remained uninfested. Topical treatment was effective and often eradicated the mite completely after only one treatment.

Semen characteristics of vervet monkeys.

Semen samples (91) from 47 vervet monkeys were collected by electroejaculation over a 2 year period. Seventy-eight of these were from 37 singly caged males of unknown fertility and 13 from 10 breeding males of known fertility. Mean values for semen characteristics of the singly caged males were: volume 0.45 ml, pH 7.8, concentration 184 x 10(6)/ml, forward progression rating 2.95 (scale 0-4), motility 55.4%, live 68% and abnormal morphology 3.5%. Mean values for semen characteristics for the breeding males were: volume 0.86 ml, pH 9.00, concentration 117.15 x 10(6)/ml, forward progression rating 3.00 (scale 0-4), motility 43.6%, live 53.3% and abnormal morphology 6%. Semen volumes in the singly caged males were lower than the volumes reported in other studies.

Folic acid and vitamin B12 status of vervet monkeys used for nutritional research.

Plasma and red blood cell (RBC) folic acid levels, as well as plasma vitamin B12 levels were determined in Vervet monkeys (Cercopithecus aethiops). All the vervets were apparently healthy and without symptoms or lesions typical of folic acid and/or vitamin B12 deficiencies. Competitive protein binding radioassays were used to determine folate and vitamin B12 values in animals fed 4 different diets. The B12 levels for all the groups ranged between 866 and 5867 pg/ml and showed an inverse relationship with the FA measurements. The lowest mean RBC folic acid content in a group fed an atherogenic diet for 3 years was 12.8 ng/ml. For the other 3 diets, mean RBC folic acid levels were 90.7, 132.3 and 152.8 ng/ml, respectively. A megadose of 25.6 mg of folic acid per day for 99 days was given to 3 adult males. No obvious toxic effects were observed in these animals although mean RBC folic acid levels increased to 1013 ng/ml.

Endemic enteric disease in vervet monkeys.

Comprehensive bacteriological investigation indicates Shigellae as the probable aetiological bacteria in one endemic enteric disease situation. One species and four serotypes have been detected. In vitro antibiotic sensitivity spectra have been determined. Epidemiology, pathology and pathogenesis in relation to the experimental animal situation and experimental results are considered. A rationale for treatment and control is suggested.

Voluntary consumption of substances of unknown palatability by vervet monkeys: a refinement.

BACKGROUND: Pure compounds and herbal medicines, had to be administered orally to vervet monkeys for testing. A reliable method was sought to avoid daily gavaging. METHODS: Substances were incorporated into the maize meal based diet of this facility for voluntary consumption. Food intake was monitored. RESULTS: In all but one case, consumption of the treated food was in excess of 90%. In all cases, the purpose of the study was achieved. Habituation was usually only required to the vehicle, and was accomplished by incremental increases to the desired concentration. Aversion was overcome by the addition of a small amount of honey. Plasma concentrations of a compound metabolite could be measured in one case after gavage and food consumption, and were similar for both methods. CONCLUSION: The method enables reliable voluntary consumption of diverse substances. Since stressful gavaging is avoided, it is a valuable contribution to the 3Rs.

Risks associated with environmental enrichment: intestinal obstruction caused by foraging substrate.

Questions are occasionally asked about the safety of enrichment techniques, considering that many novel ways are frequently employed to ensure environmental complexity. A juvenile male vervet monkey was found with a phytobezoar of straw obstructing the sigmoid colon. The straw was foraging substrate, which is used in communal cages. Due to the extent of the resulting necrosis in the sigmoid and descending colon, the monkey had to be killed. This is the only individual to have suffered a harmful effect from the foraging substrate from amongst 120 vervet monkeys, which have been permanently housed on straw for over 5 years.

Breeding vervet monkeys in a closed environment.

A breeding group of vervet monkeys produced 95 offspring over five years. Fetal wastage for 114 pregnancies was 16.7%. Uterine sizes were recorded for 103 pregnancies in various stages of gestation. This enabled diagnosis of pregnancy, estimation of stage of gestation, and prediction of parturition to within two weeks. Detailed observations were made on dental eruption, pelage development, and growth of 57 infants.

Assessment of acrosomal integrity of vervet monkey spermatozoa after cryopreservation.

Cryopreservation of Vervet monkey semen caused a highly significant reduction in the percentage of normal acrosomes and a highly significant increase in the percentage of mildly damaged, severely damaged, and lost acrosomes. This was demonstrated by staining ten post-thaw semen samples, which enabled a visualization of the acrosomal damage. The incidence of post-thaw intact acrosomes in this cryopreservation method was found to be similar to that reported for man and cynomolgus monkey semen.

A mobile cage facilitates periodic social contact and exercise for singly caged adult Vervet monkeys.

A mobile exercise cage that expands the quantity and improves the quality of the space available to singly caged adult Vervet monkey males is described. It was easily fitted into an existing caging system and the addition of a resident consort female made it possible for the males to mate and have regular social contact.

Probable genetic origin for a large number of cataracts among captive-bred vervet monkeys (Chlorocebus aethiops).

During a period of 6 years, uni- or bilateral cataracts occurred in 55 captive-bred vervet monkeys, representing 27.6% of all offspring produced in that time. Fifty-eight percent of all cases were detectable only by ophthalmoscopy. A total of 30% of cases were offspring of wild-caught parents, 40% from first-generation captive-bred parents, 4% from second-generation captive-bred parents, and 26% from parents of which one was wild caught. Cataracts that could be observed macroscopically appeared at about 6-8 mo of age. A sample of juvenile vervet monkeys with cataracts and their parents had no antibodies against rubella virus, herpes simplex virus, or toxoplasma gondi, and all except two wild-caught breeding females had no antibodies against cytomegalovirus. Plasma vitamin D3 (25 [OH] D), calcium, phosphorus, and glucose concentrations of six cataract cases were comparable to a control group of healthy individuals. The exclusion of these extraneous factors, as well as the fact that the majority of all cases were related, was considered evidence of hereditary etiology. Males and females that had either produced offspring with cataracts or were related to individuals with cataracts were replaced. To date, 35 babies have been born, and no new cases have since occurred.

Abnormal morphology of vervet monkey sperm.

Ejaculates of 14 colony-bred and 14 wild-caught vervet monkeys were examined for morphologically abnormal sperm. Sperm head abnormalities were rare in both groups, occurring at rates of 0.01-0.29%. Tail abnormalities predominated, particularly bent midpieces and coiled and folded tails, which all occurred at rates of 3.79-17.18%. Except for the nipple acrosome, there was no difference in the rate at which sperm abnormalities were found in both groups. Three abnormalities were found only in colony-bred and three only in wild-caught individuals. Some common abnormalities, all affecting the tail, were highly variable in consecutive ejaculates from the same individuals.

Horseshoe kidneys in vervet monkeys.

Two cases of horseshoe kidneys in vervet monkeys are described. Apart from the fusion, the rest of the urogenital system was anatomically normal and renal function was apparently not affected by this condition. The microanatomy was normal in both cases.

Torsion of the colon in vervet monkeys: association with an atherogenic Western-type of diet.

The risk of torsion of the colon in adult male vervet monkeys (Cercopithecus aethipos) increased when they were fed with an atherogenic Western-type of diet. No cases occurred in females and rapid diagnosis is necessary to prevent lethal consequences.

Hormonal vaginal cytology of vervet monkeys.

The cellular proliferation and maturation of the vaginal epithelium of adult female Vervet monkeys was examined during their menstrual cycles. At the same time the serum contents of estrogen and progesterone were analysed. Gradual but distinct patterns demarcated the phases of the menstrual cycle cytologically. The karyopyknotic index paralleled the estrogen concentration. Mid-cycle peak maturation produced many anucleate squames, which exfoliated, forming a diagnostic vaginal discharge.