Fetal blood sampling in baboons (Papio spp.): important procedural aspects and literature review.

BACKGROUND: The baboons (Papio cynocephalus) have similarities with human placentation and fetal development. Fetal blood sampling allows investigators to assess fetal condition at a specific point in gestation as well as transplacental transfer of medications. Unfortunately, assessing fetal status during gestation has been difficult and fetal instrumentation associated with high rate of pregnancy loss. Our objectives are to describe the technique of ultrasound guided cordocentesis (UGC) in baboons, report post-procedural outcomes, and review existing publications. METHODS: This is a procedural paper describing the technique of UGC in baboons. After confirming pregnancy and gestational age via ultrasound, animals participating in approved research protocols that required fetal assessment underwent UGC. RESULTS: We successfully performed UGC in four animals (five samples) using this technique. Animals were sampled in the second and third trimesters with fetal blood sampling achieved by sampling a free cord loop, placental cord insertion site or the intrahepatic umbilical vein. All procedures were without complication and these animals delivered at term. CONCLUSIONS: Ultrasound guided fetal umbilical cord venipuncture is a useful and safe technique to sample the fetal circulation with minimal risk to the fetus or mother. We believe this technique could be used for repeated fetal venous blood sampling in the baboons.

Trisomy of chromosome 18 in the baboon (Papio hamadryas anubis).

Trisomy 18 is usually a lethal chromosomal abnormality and is the second most common autosomal trisomy in humans, with an incidence of 1:8000 live births. It is commonly associated with abnormalities of the lower and upper extremities, having the frequency of 95% and 65%, respectively. A newborn female olive baboon (Papio hamadryas anubis) was diagnosed with intrauterine growth retardation and severe arthrogryposis-like congenital joint deformities. Cytogenetic analysis including G-banding and fluorescence in situ hybridization (FISH) revealed that the congenital abnormalities were associated with chromosomal mosaicism for trisomy 18. Genetic analysis with microsatellites from chromosome 18 confirmed the maternal origin of the extra chromosome 18. This is the first report of trisomy 18 in the baboon, which may be a promising animal model of human disease.

Amplification of simian retroviral sequences from human recipients of baboon liver transplants.

Investigations into the use of baboons as organ donors for human transplant recipients, a procedure called xenotransplantation, have raised the specter of transmitting baboon viruses to humans and possibly establishing new human infectious diseases. Retrospective analysis of tissues from two human transplant recipients with end-stage hepatic disease who died 70 and 27 days after the transplantation of baboon livers revealed the presence of two simian retroviruses of baboon origin, simian foamy virus (SFV) and baboon endogenous virus (BaEV), in multiple tissue compartments. The presence of baboon mitochondrial DNA was also detected in these same tissues, suggesting that xenogeneic "passenger leukocytes" harboring latent or active viral infections had migrated from the xenografts to distant sites within the human recipients. The persistence of SFV and BaEV in human recipients throughout the posttransplant period underscores the potential infectious risks associated with xenotransplantation.

In vitro maturation of baboon oocytes retrieved at the time of cesarean section.

OBJECTIVE: To investigate the feasibility of oocyte retrieval at the time of cesarean delivery and the potential of such oocytes to undergo nuclear maturation in vitro using a baboon model and an established culture system. DESIGN: Randomized, controlled animal study. SETTING: Research foundation and university research laboratory. ANIMAL(S): Mature pregnant baboons. INTERVENTION(S): In vitro culture of aspirated oocytes with or without epidermal growth factor (EGF). MAIN OUTCOME MEASURE(S): Oocyte yield, germinal vesicle breakdown, polar body extrusion. RESULT(S): A total of 246 oocytes were retrieved (mean, 35; range, 14-67). Eighty-seven oocytes (35%) underwent germinal vesicle breakdown and 72 oocytes (29%) extruded a polar body. A chi2 analysis revealed no significant effect of EGF on outcome parameters. No effect of gestational age or maternal age on oocyte yield or development was observed. CONCLUSION(S): A sizeable proportion of oocytes obtained from puerperal primates exhibited the capacity to undergo nuclear maturation in vitro.

Outbreak of Orthoreovirus-induced meningoencephalomyelitis in baboons.

BACKGROUND AND PURPOSE: Spontaneous viral encephalitis is rare in the baboon; yet, during a 13-month period (1993-1994), eight juvenile baboons (Papio cynocephalus spp.) developed acute, progressive nonsuppurative meningoencephalomyelitis caused by an unknown agent. Clinical signs of disease included disorientation and truncal ataxia that rapidly progressed to hemiparesis or paraparesis. Clinicopathologic findings were not remarkable and appreciable gross lesions were not seen at necropsy. Microscopic examination revealed CNS lesions that were characterized by lymphoplasmacytic perivascular cuffing, microglial nodules, demyelination, axonal degeneration, vacuolization, and hemorrhage. Subsequently, a novel syncytium-inducing mammalian orthoreovirus was isolated from the brain tissue of five baboons with clinical signs of infection. METHODS: To confirm the etiologic role of the orthoreovirus, two juvenile baboons were inoculated with the virus, then were monitored for 6 weeks. RESULTS: Lesions similar to those seen in spontaneous cases were found in the CNS, and orthoreovirus was isolated from the brain of both animals. CONCLUSION: Analysis of the outbreak indicated juvenile baboons were most susceptible to disease and the virus had a possible incubation time of 46 to 66 days, but did not indicate a source of the virus or mode of transmission.

Blood-sucking lice may disseminate Trypanosoma cruzi infection in baboons.

Trypanosoma cruzi (Schyzotrypanum, Chagas, 1909), and Chagas disease are endemic in captive-reared baboons at the Southwest Foundation for Biomedical Research, San Antonio, Texas. We obtained PCR amplification products from DNA extracted from sucking lice collected from the hair and skin of T. cruzi-infected baboons, with specific nested sets of primers for the protozoan kinetoplast DNA, and nuclear DNA. These products were hybridized to their complementary internal sequences. Selected sequences were cloned and sequencing established the presence of T. cruzi nuclear DNA, and minicircle kDNA. Competitive PCR with a kDNA set of primers determined the quantity of approximately 23.9 +/- 18.2 T. cruzi per louse. This finding suggests that the louse may be a vector incidentally contributing to the dissemination of T. cruzi infection in the baboon colony.

Cortical sulcal areas in baboons (Papio hamadryas spp.) with generalized interictal epileptic discharges on scalp EEG.

Brain MRI studies in people with idiopathic generalized epilepsies demonstrate regional morphometric differences, though variable in magnitude and location. As the baboon provides an excellent electroclinical and neuroimaging model for photosensitive generalized epilepsy in humans, this study evaluated MRI volumetric and morphometric differences between baboons with interictal epileptic discharges (IEDs) on scalp EEG and baboons with normal EEG studies. Seventy-seven baboons underwent high-resolution brain MRI and scalp EEG studies. The scans were acquired using an 8-channel primate head coil (Siemens TRIO 3T scanner, Erlangen, Germany). After spatial normalization, sulcal measurements were obtained by object-based-morphology methods. One-hour scalp EEG studies were performed in animals sedated with ketamine. Thirty-eight (22F/16M) baboons had normal EEGs (IED-), while 39 (22F/17M) had generalized IEDs (IED+). The two groups were compared for age, total brain volume, and sulcal areas (Hotelling's Trace) as well as between-subjects comparison of 11 individual sulcal areas (averaged between left and right hemispheres). There were no differences between IED- and IED+ groups with respect to age or total brain (gray or white matter) volume, and multivariate tests demonstrated a marginally significant decrease of sulcal areas in IED+ baboons (p=0.075). Tests of between-subjects effects showed statistically significant decreases in the intraparietal (p=0.002), central (p=0.03) and cingulate sulci (p=0.02), and marginal decreases involving the lunate (p=0.07) and superior temporal sulci (p=0.08). Differences in sulcal areas in IED+ baboons may reflect global developmental abnormalities, while decreases of areas of specific sulci reflect anatomical markers for potential generators or cortical nodes of the networks underlying spontaneous seizures and photosensitivity in the baboon.

Gastroesophageal reflux disease in baboons (Papio sp.): a new animal model.

BACKGROUND: Gastroesophageal reflux disease (GERD) is increasingly prevalent in the human population. Current animal models require surgical or other manipulation to produce symptoms. An animal model that exhibits spontaneous GERD would provide the opportunity for much-needed research examining the susceptibility, diagnosis, and treatment of GERD. METHODS: Eight baboons (Papio hamadryas sp.) were diagnosed with GERD histopathologically using biopsies or postmortem tissues. RESULTS: The disease was characterized by a spectrum of symptoms comparable with that found in the human population. Some subjects had no gross signs of clinical disease, but were diagnosed by histopathological examination. Almost all subjects presented with at least one clinical sign of the disease. Regurgitation was the most common. CONCLUSIONS: The baboon may be a superior animal model for GERD research because it is a naturally occurring model and is anatomically and physiologically similar to humans.

Barbiturate euthanasia solution-induced tissue artifact in nonhuman primates.

BACKGROUND: Barbiturate euthanasia solutions are a humane and approved means of euthanasia. Overdosing causes significant tissue damage in a variety of laboratory animals. METHODS: One hundred seventeen non-human primates (NHP) representing 7 species including 12 fetuses euthanized for humane and research reasons by various vascular routes with Euthasol, Sodium Pentobarbital, Fatal Plus, Beuthanasia D, or Euthanasia 5 were evaluated for euthanasia-induced tissue damage. Lungs and livers were histologically graded for hemolysis, vascular damage, edema, and necrosis. Severity of tissue damage was analyzed for differences on the basis of agent, age, sex, dose, and injection route. RESULTS: Severity of tissue damage was directly related to dose and the intracardiac injection route, but did not differ by species, sex, and agent used. CONCLUSIONS: When the recommended dose of agent was used, tissue damage was generally reduced, minimal, or undetectable. Barbiturate-induced artifacts in NHPs are essentially the same as in other laboratory species.

Alteration of the menstrual cycle in baboons placed on tethering devices and moved to individual housing--a stress model for a follicular phase defect.

BACKGROUND: During an attempt to identify endocrine characteristics in the baboon that would more precisely predict ovulatory status for assisted reproductive techniques, we observed severe alterations in the menstrual cycle length upon introducing an environmental stress. This environmental stress involved moving animals from their baseline gang cage environment to individual indoor caging and placing them on a tethering apparatus. METHODS: Five adult female baboons were followed for changes in sex skin indicative of menstrual cycle timing and move from outdoor gang gages to individual indoor cages during the early follicular phase of their cycle. A tether device including a surgically implanted cannula was then installed to facilitate daily blood draws without sedation. Radioimmuonoassays were performed to monitor serum estradiol levels and lapraroscopic surveillance was used to confirm time of ovulation. RESULTS: Complete data sets were collected from four of the female baboons. In each case, a prolongation of the menstrual cycle was noted either during the cycle during which the females were moved to indoor caging or during the cycle immediately following the move. This prolongation was isolated to the follicular phase of the affected cycle. CONCLUSIONS: We conclude that otherwise normal handling procedures, including movement to new caging, and/or installation of a tether device, can impart a stress effect on reproductively cycling adult female baboons, such that folliculogenesis is delayed.

Cross-sectional growth standards for captive baboons: II. Organ weight by body weight.

We present the first cross-sectional organ weight by body weight reference standards for captive baboons (Papio hamadryas). Organ weight data were obtained from necropsy reports for 634 healthy, pedigreed, captive female and male baboons. From summary statistics we calculated and fit cross-sectional sex-specific percentile curves for: adrenals, brain, eyes, heart, kidneys, liver plus gall bladder, lungs, pancreas, pituitary gland, spleen, and thyroid gland in three kilogram body weight intervals and cross-sectional summary statistics by sex for each organ in one kilogram body weight intervals.

Cross-sectional growth standards for captive baboons: I. Organ weight by chronological age.

We present the first cross-sectional organ weight reference standards for captive baboons (Papio hamadryas). Organ weight data were obtained from necropsy reports for 634 healthy, pedigreed, captive female and male baboons. From summary statistics we calculated and fit cross-sectional, sex-specific percentile curves for: adrenals, brain, eyes, heart, kidneys, liver plus gall bladder, lungs, pancreas, pituitary gland, spleen, and thyroid gland in two year age class intervals and summary statistics by sex for each organ in one year age classes.

Quantitative genetics of relative organ weight variation in captive baboons.

Anthropoid phylogeny has been characterized by dramatic increases in relative brain size. Given the importance of genetic mechanisms in evolution, quantitative genetic analyses of the biological concomitants of relative brain size variation should greatly augment our understanding of this phylogenetic phenomenon. In humans the brain is often linked metabolically with three other organs--heart, kidneys, and liver--that together account for most of the total basal metabolic rate. Because the weights of these four organs are proportional to their individual organ metabolic rates, their summed weights have been used by previous researchers as a proxy measure for their composite organ metabolic rate. We have conducted a quantitative genetic analysis of variation in the relative weights of these four organs in a population of captive baboons from the Southwest Foundation for Biomedical Research. These analyses were performed on loge-transformed organ weights available for 601 animals, 307 of which were assigned to 25 pedigrees containing 2 to 49 members; the remaining 294 animals were treated as independent individuals. Moderate but statistically significant (p < 0.005) heritabilities were estimated for all four organ weights: h2brain = 0.409 +/- 0.147, h2heart = 0.386 +/- 0.184, h2kidneys = 0.468 +/- 0.152, and h2liver = 0.600 +/- 0.160. Significant (p < 0.05) additive genetic correlations were estimated between brain and liver weights (rho G = 0.568) and between liver and kidney weights (rho G = 0.858). Significant (p < 0.05) environmental correlations were identified for heart and kidney weights (rho E = 0.551) and for liver and kidney weights (rho E = 0.684). Our results clearly demonstrate that the four organ weights have substantial heritable components that, because of their similar magnitudes, are probably equally susceptible to selection. However, the patterns of intercorrelation revealed by our analyses of the genetic and environmental correlation matrices indicate that, of the four organs composing the proxy measure of organ metabolic rate, only the liver and the kidneys are likely to exhibit correlated responses to selection for increased relative brain size such as that observed in the anthropoid fossil record.

Spontaneous pancreatic islet amyloidosis in 40 baboons.

Spontaneous amyloidosis occurs in many nonhuman primate species but remains difficult to diagnose and treat. Nonhuman primates continue to offer promise as animal models in which to study amyloidosis in humans. Amyloidosis was not diagnosed clinically but was found histologically in four male and 36 female baboons. The baboons averaged 18 years of age at death (range, 7-28 years). Clinical signs, if present, were hyperglycemia and cachexia. Blood glucose values were elevated in 12 of 30 baboons with available clinical pathology data. Four baboons had been clinically diagnosed as diabetic and three were treated with insulin. Amyloid was found in the islets of Langerhans of the pancreas in 40 baboons; 35 baboons had amyloid only in the islets of Langerhans. Amyloid was found in nonislet tissue of baboons as follows: five, nonislet pancreas; four, intestine and adrenal; three, kidney; two, prostate and spleen; and one each, lymph node, liver, gall bladder, stomach, tongue, urinary bladder, and salivary gland. Sections of paraffin-embedded tissues were evaluated for amyloid with hematoxylin and eosin (HE) and congo red (CR) staining, and using immunohistochemistry for human islet amyloid polypeptide (IAPP), calcitonin gene-related peptide (CGRP), glucagon, pancreatic polypeptide (PP), somatostatin (SS), and porcine insulin. Islet amyloid was positive with HE in 40 baboons, with CR in 39 baboons, and with IAPP and CGRP in 35 baboons. IAPP and CGRP only stained islet amyloid. PP, SS, glucagon, and porcine insulin did not stain amyloid. Islet amyloidosis in the baboon appears to be difficult to diagnose clinically, age-related, and similar to islet amyloidosis in other species. The baboon may be a good model for the study of islet amyloidosis in humans.

Clinical parameters of the normal baboons (Papio species) and chimpanzees (Pan troglodytes).

Improved equipment and advanced progressive techniques by scientists using baboons and chimpanzees in biomedical research have resulted in improved clinical laboratory data. The use of state-of-the-art clinical laboratory instruments, methodologies with improved accuracy, and an increased variety of individual tests routinely requested and performed has necessitated the comparison of current data with prior data produced in our laboratory and with those values reported in the literature. In addition to an expanded hematologic profile, including red blood cell distribution width and mean platelet volume, and a more comprehensive chemical profile of 28 individual tests, additional data collected included values for coagulation profiles, arterial blood gases, serum protein electrophoresis, and urine osmolalities. Samples for evaluation were obtained from clinically normal sedated adult baboons (Papio species) and chimpanzees (Pan troglodytes) and processed conventionally according to Good Laboratory Practice Act standards. Arithmetic means were calculated, values of 3 standard deviations or greater were eliminated, and means were recalculated to include 2 standard deviations. All data correlated well with prior in-house values, and no remarkable differences from established data were detected, thus indicating the reliability of past and present data. Data compared favorably with normal clinical values established for humans.

Glioblastoma multiforme in three baboons (Papio spp).

Glioblastoma multiforme is the most malignant astrocytic neoplasm and the most common brain neoplasm of humans. Spontaneous neoplasms of the brain are rare in nonhuman primates. This report describes three glioblastomas in adult captive-reared baboons. The animals exhibited a range of clinical signs, including depression, weight loss, weakness, and blindness. All three neoplasms were located in the cerebrum, with extension into the pons in one case. Histologically, the tumors were similar and were characterized by cellular pleomorphism, multinucleated cells, areas of necrosis, microvascular proliferation (glomeruloid bodies), and palisading of neoplastic cells around blood vessels and areas of necrosis. Two baboons exhibited gemistocytic differentiation, and in one baboon, the neoplastic cells were predominantly spindle shaped with a fascicular growth pattern. Immunohistochemical staining for glial fibrillary acidic protein, vimentin, and S-100 protein was positive, whereas immunostaining for synaptophysin and chromogranin A was negative. Positive staining for the cell proliferation marker Ki67 ranged from 8.2% to 13.9%. Terminal deoxynucleotidyl transferase mediated dVTPnick end labeling (TUNEL) staining ranged from 1.8% to 5.7%. These baboon glioblastomas share many features with those of humans.

Record review of baboons with histologically confirmed endometriosis in a large established colony.

Spontaneous endometriosis was diagnosed in 43 baboons over a 14-year period. Thirty-seven have died; five remain alive; one was sold and lost to follow-up. The average age at diagnosis was 17.2 years; 29 (67%) were between 12 and 21 years of age. Fifteen (35%) were diagnosed by biopsy and received surgical excision of the endometriotic tissue; four of these were identified during caesarian section, confirming one prior report of endometriosis in pregnant animals. Twenty-eight (65%) were diagnosed at or shortly preceding necropsy. When diagnosed by a palpable abdominal mass, there was a significantly greater likelihood the animal died or was killed as a result of complications of endometriosis. When diagnosis was at necropsy, there was a significantly greater likelihood that the animal died from causes unrelated to endometriosis. Early identification with surgical removal appears to provide a benefit for both survival and delivering offspring after diagnosis. In twenty-one baboons (49%), endometriosis affected multiple sites within the peritoneal cavity. In the remaining baboons, lesions were more localized. Ovarian involvement was seen in sixteen (37%) of these baboons. This paper is the first to describe significant ovarian involvement in baboons, previously considered a limitation of the usefulness of this species as an animal model. We also describe the first reported endometriosis seeding of an abdominal surgery scar in a baboon. Many of these baboons were middle aged, had few or no offspring, or had evidence of a long duration of uninterrupted menstrual cycles, consistent with risk factors for women. Endometriosis was an incidental finding in 17 (40%) of these baboons, consistent with previous reports of minimal endometriosis as a common asymptomatic finding in baboons and in women. Overall, endometriosis in baboons presents a spontaneously occurring animal model that shares important features with the disease in women and the rhesus macaque.

Direct fetal glucocorticoid treatment alters postnatal adaptation in premature newborn baboons.

Abnormalities of premature newborn adaptation after preterm birth result in significant perinatal mortality and morbidity. We assessed the effects of short-term (24 h) fetal betamethasone exposure on preterm newborn baboon pulmonary and cardiovascular regulation and renal sodium handling during the first 24 h after birth. Male fetal baboons (Papio) (124-day gestation, term 185 days) received ultrasound-guided intramuscular injections of saline (n = 5) or betamethasone (0.5 mg/kg; n = 5). Fetuses were cesarean delivered 24 h later, treated with 100 mg/kg surfactant, and ventilated by adjusting peak inspiratory pressures to maintain PCO2 values of 35-50 mmHg for 24 h. Betamethasone- vs. saline-treated mean +/- SE newborn body weights (0.45 +/- 0.02 vs. 0.41 +/- 0.01 kg) were similar. Although prenatal betamethasone did not affect postnatal lung function (PCO2, arterial/alveolar O2 gradient, or dynamic compliance), plasma hormone (cortisol or thyroxine), or catecholamine levels, mean arterial pressure (25 +/- 1 vs. 32 +/- 1 mmHg), plasma sodium concentration (132 +/- 2 vs. 138 +/- 1 meq/l), glomerular filtration rate (0.07 +/- 0.02 vs. 0.16 +/- 0.02 ml.min-1.kg-1), and renal total sodium reabsorption (1.5 +/- 0.5 vs. 16.0 +/- 3.0 mu eq.min-1.kg-1) values were significantly lower in saline-treated than in betamethasone-treated newborns at 24 h. We conclude that despite the fact that there are no pulmonary and endocrine effects, antenatal glucocorticoid exposure alters premature newborn baboon vascular and renal glomerular function and improves sodium reabsorption after preterm delivery.

Ontogenetic changes in genetic regulation of fetal morphometrics in baboons (Papio hamadryas subspp.).

It is known that different genes are expressed during ontogeny; however, it is unclear how variation in that expression is associated with changes in growth patterns. The objective of this study is to assess how genetic variation in fetal morphology changes with ontogeny in baboons. Longitudinal measures of the head and femur (60 to 180 days gestation) were available for 892 pregnancies. We used a genetic model that allowed both the genetic and environmental variances (sigma 2G and sigma 2E) to change with age and estimated genetic and environmental correlations (rho G and rho E) between measurements at different ages. The results indicate a significant increase in the genetic variance for biparietal diameter and femur length but not for head circumference and fronto-occipital diameter. The rho G estimates for all measures decreased as the age between measures increased from 0 to 120 days, indicating that different groups of genes are expressed early in gestation and late in gestation. The rho E estimates dropped rapidly from 1 to 0 for all measures, indicating temporally localized environmental influences on fetal growth. Thus fetal morphometrics are significantly heritable and those genes that influence them show age-specific expression during ontogeny.

Cytogenetic and fertility studies of a rheboon, rhesus macaque (Macaca mulatta) x baboon (Papio hamadryas) cross: further support for a single karyotype nomenclature.

Historically, two different numbering systems have been used to describe the baboon and macaque karyotypes. However, G-banding studies and, more recently, fluorescence in situ hybridization results have shown that the two karyotypes are virtually identical. To confirm this hypothesis, cytogenetic analysis of an unusual animal, a rheboon, was undertaken. The rheboon reported here, an 18-year-old male, is the only long-term survivor of 26 pregnancies resulting from matings between female baboons (Papio hamadryas) and male rhesus macaques (Macaca mulatta). A G-banded karyotype was prepared from the rheboon and compared with the karyotypes of the two parental species. Spectral karyotyping (SKY) was carried out on the rheboon chromosomes, and the results were compared with SKY studies reported for the baboon and with CISS (chromosome in situ suppression) studies in the rhesus macaque. No differences were detected in any of the rheboon's pairs of autosomes, reinforcing the apparent identity of the two parental karyotypes. Based on these results, we argue that a single karyotyping system should be adopted for the two species. Fertility studies were initiated to determine if the rheboon is sterile, as are most hybrid animals. Two semen ejaculates were devoid of sperm. A testicular biopsy revealed hypoplasia of the seminiferous tubules with few Leydig cells and large lumena. Meiotic arrest occurred during meiosis I, resulting in absence of mature spermatozoa. Thus, the testicular and meiotic findings in the rheboon were similar to those observed in other hybrids, even though the parental karyotypes appear identical.