A review of chronic inhalation studies with mainstream cigarette smoke, in hamsters, dogs, and nonhuman primates.

This paper is the continuation of previously published work, a review limited to studies on rats and mice. This paper makes an identical evaluation as before, but, restricting the species being evaluated to representative studies of smoke-exposed hamsters, dogs (both by tracheostomy and by direct inhalation), and nonhuman primates. As was seen previously, no statistically significant increase in the incidence of malignant tumors of the respiratory tract was found in any of the 3 species, even though very long exposures and high doses of smoke were used. All 5 of the species of laboratory animals commonly used to evaluate carcinogenic potential produce results with mainstream cigarette smoke that are at variance with the epidemiological evidence in smokers.     

Selective myocardial cell necrosis in nonhuman primates

A retrospective study was performed to describe the histologic stages of selective myocardial cell necrosis (SMCN) in nonhuman primates, and to compare the incidence of SMCN in two groups of nonhuman primates. Myocardial tissues taken at the time of autopsy from 50 primates at an experimental center were compared with similar tissues from 50 primates housed in a breeding colony. SMCN was confirmed in 20% of the experimental primates and 30% of the breeding primates, proportions that were not significantly different. The incidence and histologic characteristics of SMCN in nonhuman primates were similar to those described in humans, and resembled the lesion produced in experimental primates by administration of catecholamines of by hypokalemia.     

Effects of HOXB4 overexpression on ex vivo expansion and immortalization of hematopoietic cells from different species

Overexpression of the human HOXB4 has been shown to induce the expansion and self-renewal of murine hematopoietic stem cells. In preparation for clinical studies, we wished to investigate the effects of HOXB4 on cells from other species, in particular preclinical large animals such as dogs and nonhuman primates. Thus, we transduced CD34(+) cells from nonhuman primates, dogs, and humans with a HOXB4-expressing gammaretroviral vector and a yellow fluorescent protein-expressing control vector. Compared with the control vector, HOXB4 overexpression resulted in a much larger increase in colony-forming cells in dog cells (28-fold) compared with human peripheral blood, human cord blood, and baboon cells (two-, four-, and fivefold, respectively). Furthermore, we found that HOXB4 overexpression resulted in immortalization with sustained growth (>12 months) of primitive hematopoietic cells from mice and dogs but not from monkeys and humans. This difference correlated with increased levels of retrovirally overexpressed HOXB4 in dog and mouse cells compared with human and nonhuman primate cells. The immortalized cells did not show any evidence of insertional mutagenesis or chromosomal abnormalities. Competitive congenic transplantation experiments showed that HOXB4-expanded mouse cells engrafted well after 1 or 3 months of expansion, and no leukemia was observed in mice. Our findings suggest that the growth promoting effects of HOXB4 are critically dependent on HOXB4 expression levels and that this can result in important species-specific differences in potency. Disclosure of potential conflicts of interest is found at the end of this article.     

Comparative expression and distribution of c-fos, estrogen receptoralpha (eralpha), and p38alpha in the uterus of rats, monkeys, and humans

The uterine cellular expression and distribution of c-fos, ERalpha and p38alpha was compared in humans, nonhuman primates, and rats using immunohistochemistry. ERalpha and c-fos were present in the glandular (GE) and luminal epithelial cells (LE) of humans and nonhuman primates, with differing expression patterns evident between proliferative and secretory cycle phases. In rats, the highest and lowest expression of c-fos was present during proestrus and estrus, respectively, in the LE and GE. The most intense ERalpha staining in rats was observed during proestrus in the GE, while the least intense staining was seen in the LE during proestrus. Strong LE and GE expression of p38alpha was present in rats in all stages of the estrous cycle and during the proliferative phase in both humans and nonhuman primates. No p38alpha expression was observed during the secretory phase in either humans or nonhuman primates. Our work suggests that c-fos, ERalpha and p38alpha (a) are primarily expressed during the proliferative phase, but not the secretory phase and exhibit interspecies expression variability, and (b) rats exhibit cyclic changes in the expression of c-fos and ERalpha.     

Comparison of nonhuman primate antibodies against Haemophilus influenzae type b polysaccharide with human antibodies in oligoclonality and in vivo protective potency.

Nonhuman primates are often used as a model for studying vaccines for humans. However, it is not always clear how closely the antibody responses in these species mimic human responses. Recent studies have characterized the human antibody response to Haemophilus influenzae type b (Hib) in great detail. In this study, we have compared the antibody response to Hib of humans with those of other primates. Studies of isoelectric points and V kappa subgroup usage show that, like humans, nonhuman primates produce oligoclonal antibodies. Also, monkey antibodies to the Hib polysaccharide are as protective as human antibodies in an in vivo model of Hib infection. Thus, we conclude that nonhuman primates produce antibodies to Hib polysaccharide that are structurally and functionally similar to human antibodies and are a good model for testing human vaccines.     

Relationships between antibodies against human soluble complement receptor 1 (hsCR1) from various species

The relationships between antibodies against human soluble complement receptor 1 (hsCR1) were studied in rodents, dogs, nonhuman primates, and humans. An antibody response occurred in all species except humans. The anti-hsCR1 antibodies from the various species were characterized to determine if they recognize similar epitopes on the hsCR1 molecule. Dog and monkey sera, positive for hsCR1 binding, were used as blocking antibodies against mouse anti-hsCR1 monoclonal antibodies as well as mouse and rat anti-hsCR1-positive sera. Human sera (blood group antisera: anti-Knops, anti-McCoy, anti-Knops/McCoy, anti-Swain-Langley) and serum from one burn patient (who became seropositive despite ever receiving treatment with hsCR1) were also used to test blocking of mouse, rat, dog, and monkey anti-hsCR1. Characterization of anti-hsCR1 antibodies from different species demonstrated that hsCR1 causes divergent antibody responses among animals. While mouse, rat, and dog antibodies cross inhibit binding by approximately 50%, monkey antibodies recognize primarily different epitopes of the hsCR1 molecule. Moreover, human antibodies binding hsCR1 are completely different from the animal antibodies, including monkey. This study indicates that although hsCR1 is immunogenic in animals, there is a difference in response between species, particularly between nonprimates and primates, and finally, that this antibody response is not predictive for humans.     

Genomic DNA insertions and deletions occur frequently between humans and nonhuman primates

Comparative DNA sequence studies between humans and nonhuman primates will be important for understanding the genetic basis of the phenotypic differences between these species. Here we compare approximately 27 Mb of human chromosome 21 with chimpanzee DNA sequences identifying 57 genomic rearrangements (deletions and insertions ranging in size from 0.2 to 8.0 kb) between the two species. These rearrangements are distributed along the entire length of chromosome 21, with approximately 35% found in genomic intervals encoding genes (genic intervals), and have occurred in the genomes of both humans and chimpanzees. Comparison of approximately 9 Mb of human chromosome 21 with orangutan, rhesus macaque, and woolly monkey DNA sequences identified a combined total of 114 genomic rearrangements between humans and nonhuman primates. Analysis of these rearrangements revealed that they are randomly distributed with respect to genic and nongenic intervals and identified one deletion that has likely resulted in the inactivation of a gene (beta1,3-galactosyltransferase) in the woolly monkey. Our data show that genomic rearrangements have occurred frequently during primate genome evolution and significantly contribute to the DNA differences between these species. These DNA rearrangements are commonly found in genic intervals, and thus provide natural starting points for focused investigations of qualitative and quantitative gene expression differences between humans and other primates.     

PIB binding in aged primate brain: Enrichment of high-affinity sites in humans with Alzheimer's disease

Aged nonhuman primates accumulate large amounts of human-sequence amyloid β (Aβ) in the brain, yet they do not manifest the full phenotype of Alzheimer's disease (AD). To assess the biophysical properties of Aβ that might govern its pathogenic potential in humans and nonhuman primates, we incubated the benzothiazole imaging agent Pittsburgh Compound B (PIB) with cortical tissue homogenates from normal aged humans, humans with AD, and from aged squirrel monkeys, rhesus monkeys, and chimpanzees with cerebral Aβ-amyloidosis. Relative to humans with AD, high-affinity PIB binding is markedly reduced in cortical extracts from aged nonhuman primates containing levels of insoluble Aβ similar to those in AD. The high-affinity binding of PIB may be selective for a pathologic, human-specific conformation of multimeric Aβ, and thus could be a useful experimental tool for clarifying the unique predisposition of humans to Alzheimer's disease.     

Differential cross-reactivity of monoclonal antibody OPD4 (anti-CD45RO) in macaques

Immunologic research in nonhuman primates is occasionally limited by the availability of reagents that cross-react in nonhuman primates. One major limitation has been the lack of a monoclonal antibody to CD45RO. Although the monoclonal antibody UCHL-1 is used to detect CD45RO isoforms in humans, it does not react with nonhuman primates, mandating the use of alternative strategies to define "memory" T cell responses in nonhuman primates. The current study examined the reactivity and specificity of another antibody against CD45RO, clone OPD4, in macaques. Here we demonstrate that OPD4 specifically labels memory CD4+ T cells in approximately 44% of rhesus macaques (Macaca mulatta) of Indian but not Chinese origin. In contrast, tissues from pigtail macaques (Macaca nemestrina) react with this clone, indicating that OPD4 may be useful for examining memory CD4+ T cells in certain macaques, but its utility may be limited in other species or even among individual macaques.     

Multi-region hemispheric specialization differentiates human from nonhuman primate brain function

The human behavioral repertoire greatly exceeds that of nonhuman primates. Anatomical specializations of the human brain include an enlarged neocortex and prefrontal cortex (Semendeferi et al. in Am J Phys Anthropol 114:224–241, 2001), but regional enlargements alone cannot account for these vast functional differences. Hemispheric specialization has long believed to be a major contributing factor to such distinctive human characteristics as motor dominance, attentional control and language. Yet structural cerebral asymmetries, documented in both humans and some nonhuman primate species, are relatively minor compared to behavioral lateralization. Identifying the mechanisms that underlie these functional differences remains a goal of considerable interest. Here, we investigate the intrinsic connectivity networks in four primate species (humans, chimpanzees, baboons, and capuchin monkeys) using resting-state fMRI to evaluate the intra- and inter- hemispheric coherences of spontaneous BOLD fluctuation. All three nonhuman primate species displayed lateralized functional networks that were strikingly similar to those observed in humans. However, only humans had multi-region lateralized networks, which provide fronto-parietal connectivity. Our results indicate that this pattern of within-hemisphere connectivity distinguishes humans from nonhuman primates.     

Lifespan in captive baboons is heritable

The effects of aging are evident in multiple organ systems, tissues, cell types, and molecules; all complex phenotypes affected by multiple shared and unique environmental factors and genes, which makes identifying the role of genetics in human aging difficult. Researchers have used yeast, nematodes, fruit flies, and mice to search for genes that influence the aging process. Given the phylogenetic distance and anatomic and physiologic dissimilarities of these organisms from humans, directly extrapolating these results to our species is problematic. However, nonhuman primates have a high degree of genetic, anatomic and physiologic similarity with humans and, thus, they may assist in the detection, characterization, and identification of genetic and environmental influences on human aging. Our goal is to demonstrate that effects of genes on variation in lifespan, a surrogate measure of aging, can be detected in a nonhuman primate species. Using variance component analysis, heritability of age at death was estimated to be 0.23+/-0.08 (P=0.0003) in 674 baboons from the Southwest Foundation for Biomedical Research (SFBR). This research demonstrates that lifespan is under partial genetic control. Given these findings, we believe that the baboon has potential as a model of human aging.     

Comparative and evolutionary dimensions of the energetics of human pregnancy and lactation

The purpose of this article is to compare the energetics of reproduction for human and other primates in order to evaluate the extent to which human reproductive energetics are distinct from other primates and other large‐bodied placental mammals. The article also evaluates the energetics of human and primate gestation and lactation using data from a variety of different populations living under different environmental circumstances. Energetics refers to energy intake and expenditure, and changes in body fat stores. Human and nonhuman primates have longer periods of gestation and lactation and slower prenatal and postnatal growth than other mammals of similar size. This reduces daily maternal energy costs. The development of sizable fat stores is not unique to humans, but fat stores are typically greater in human females and may play a greater role in reproduction. The strategies used to meet the energy costs of pregnancy vary among populations of humans and nonhuman primates and among humans interindividual variability is high. In pregnancy, some increase energy intake but others apparently do not. Increases in metabolic efficiency are evident in some human populations, whereas decreases in physical activity occur, but are not seen in all human or primate populations. Lactation is more energetically costly on a daily basis among humans and nonhuman primates, but has not been as well studied. It appears that both nonhuman and human primates tend to increase energy intake to meet in part the cost of lactation. They also use other strategies such as relying on body tissue stores, reductions in physical activity, and/or increases in metabolic efficiency to meet the remainder of the cost. It is also clear that human females in different populations and different women in the same population use a different combination of strategies to meet the cost of lactation. Am. J. Hum. Biol. 14:584–602, 2002. © 2002 Wiley‐Liss, Inc.     

Characterization of monkey enteropathogenic Escherichia coli (EPEC) and human typical and atypical EPEC serotype isolates from neotropical nonhuman primates

Enteropathogenic Escherichia coli (EPEC) has been associated with infantile diarrhea and mortality in humans in developing countries. While diarrhea is also a major problem among primates kept in captivity, the role of E. coli is unclear. This study was designed to characterize diarrheagenic E. coli recovered from the feces of 56 New World nonhuman primates, primarily marmosets (Callithrix spp.). Seventeen of the 56 primates had signs of diarrhea and/or enteritis. E. coli recovered from feces from these animals was tested by PCR for genes encoding virulence factors of diarrheagenic E. coli and for patterns of adherence to HeLa cells. In addition, isolates were characterized by the fluorescence actin staining test and by their ability to induce attaching and effacing lesions. PCR for the eae gene was positive in 10 of the 39 (27%) apparently healthy animals and in 8 of the 17 (47%) animals with diarrhea and/or enteritis. Colonies of eae(+) E. coli were serotyped and examined by PCR for genes encoding EPEC virulence markers. The eae(+) E. coli isolates recovered from both healthy and sick nonhuman primates demonstrated virulence-associated attributes similar to those of EPEC strains implicated in human disease and are designated monkey EPEC. The results presented here indicate that EPEC may be a significant pathogen for nonhuman primates, deserving further investigation. The similarities between the affected animals investigated in this study and human EPEC infections suggest that marmosets may represent an important model for EPEC in humans.     

Effects of formaldehyde gas on the respiratory tract of rhesus monkeys. Pathology and cell proliferation.

Formaldehyde is a nasal carcinogen in rats but it remains to be determined what cancer risk this chemical poses in humans. Molecular dosimetry studies of formaldehyde and cellular proliferative responses to formaldehyde-induced cytotoxicity have been studied in the rodent and are important components of the authors' ongoing research, which has now been extended to nonhuman primates, a species more analogous to humans. The present study was designed to characterize formaldehyde injury in the respiratory tract of nonhuman primates to provide a direct comparison to the toxic effects of formaldehyde in rodents. Groups of three rhesus monkeys were exposed to room air, or 6 ppm formaldehyde for 5 days per week for 1 or 6 weeks, and the respiratory tract was assessed for nature and extent of histologic responses, and changes in epithelial cell proliferation rate. Lesions were characterized by mild degeneration and early squamous metaplasia confined to specific regions of the transitional and respiratory epithelia of the nasal passages and the respiratory epithelium of the trachea and major bronchi. There was minimal progression of histologic changes between 1 and 6 weeks; however, the percent of nasal surface area affected significantly increased in the 6-week exposure group. Formaldehyde-induced lesions were associated with increases in cell proliferation rates up to 18-fold over controls, which remained significantly elevated after 6 weeks of exposure. Histologic lesions and increases in cell proliferation were most extensive in the nasal passages and were minimal in the lower airways, whereas the maxillary sinuses exhibited no evidence of a response to formaldehyde exposure. Based on the extent of lesions and cell proliferation data, it appears that the monkey is more sensitive than the rat to the acute and subacute effects of formaldehyde at 6 ppm. The absence of response in the maxillary sinuses in the monkey suggests that combining tumors of the nasal cavity and sinuses in epidemiologic studies may not be appropriate for formaldehyde cancer risk assessment. Results of this study also have provided important information for tissue sample site selection in the monkey respiratory tract for ongoing molecular dosimetry studies.     

Occurrence and genetic characterization of Giardia duodenalis from captive nonhuman primates by multi-locus sequence analysis

Giardia is the most common enteric protozoan that can be pathogenic to both humans and animals. Transmission can be direct through the faecal–oral route, or through ingestion of contaminated water or food. Genetic characterization of Giardia duodenalis isolates has demonstrated the existence of seven groups (assemblages A to G) which differ in their host distribution. Assemblages A and B are present in humans and other primates, dogs, cats, rodents, and other species of wild mammals, but the role of the different host animals in the epidemiology of human infection remains unclear. With this preliminary data, we can infer that nonhuman primates (NHP) might be a potential reservoir for zoonotic transmission. This research paper discusses the presence of Giardia in nonhuman primates housed in two Spanish zoological gardens (located in Valencia and Madrid). Twenty faecal samples obtained from 16 different species of NHP were studied; 70% were positives to Giardia, and genetic analyses were performed by sequencing of four genes (SSrRNA, glutamate dehydrogenase, triose phosphate isomerase, and beta-giardin). The assemblage A was the most frequent (63.4%) in the species studied. A sequence from a red ruffed lemur (corresponding to genotype AI) was obtained, and this is the first reported sequence of a gdh gene obtained from this species. The multi-locus sequence analysis was also performed on the samples positive to nested PCR belonging to assemblage B. After amplification using the GDHeF, GDHiF, and GDHiR gdh primers; AL3543, AL3546, AL3544, and AL3545 tpi primers; G7, G759, GBF, and GBR bg primers, amplicons of 432, 500, and 511 bp respectively were obtained. Amplification products were sequenced and the sequence and phylogenetic analyses showed that genotype IV like was the most frequent in the samples belonging to this assemblage.     

Host alloreactive memory T cells influence tolerance to kidney allografts in nonhuman primates

Transplant tolerance, defined as indefinite allograft survival without immunosuppression, has been regularly achieved in laboratory mice but not in nonhuman primates or humans. In contrast to laboratory mice, primates regularly have high frequencies of alloreactive memory T cells (TMEMs) before transplantation. These TMEMs are poorly sensitive to conventional immunosuppression and costimulation blockade, and the presence of donor-reactive TMEMs in primates may account for their resistance to transplant tolerance protocols that have proven consistently effective in mice. We measured the frequencies of anti-donor TMEMs before and after transplantation in a series of rejecting and tolerant monkeys that underwent nonmyeloablative conditioning, short-term immunosuppression, and combined allogeneic kidney/cell transplantation. Transplants were acutely rejected in all the monkeys with high numbers of donor-specific TMEMs before transplantation. In contrast, long-term survival was observed in the recipients harboring lower frequencies of anti-donor TMEMs before transplantation. Similar amounts of TMEM homeostatic expansion were recorded in all transplanted monkeys upon hematopoietic reconstitution; however, only the tolerant monkeys had no expansion or activation of donor-reactive TMEMs after transplantation. These results indicate that the presence of high frequencies of host donor-reactive TMEMs before transplantation impairs tolerance induction to kidney allografts in this nonhuman primate model. Indeed, recipients harboring a low anamnestic reactivity to their donor before transplantation were successfully rendered tolerant via infusion of donor cells and short-term immunosuppression. This suggests that selection of allogeneic donors with low memory responses in recipients may be essential to successful transplant tolerance induction in patients.     

Age-related cerebral atrophy in nonhuman primates predicts cognitive impairments

In humans, but not in nonhuman primates, a clear relationship has been established between age-associated cognitive decline and atrophy of specific brain regions. We evaluated age-related cerebral atrophy and cognitive alterations in mouse lemur primates. Cerebral atrophy was evaluated by in vivo magnetic resonance imaging in 34 animals aged from 1.9 to 11.8 years. The caudate and splenium were atrophied in most older animals, whereas shrinkage of the hippocampus, entorhinal cortex, and septal region was identified in a subgroup of the older animals. The temporal and cingulate cortex also exhibited a severe atrophy, whereas frontal and parietal areas were spared. Measures of cognitive ability in 16 animals studied by magnetic resonance imaging (MRI) showed that both executive functions and spatial memory declined with aging. Impairment of executive functions in older animals was associated with atrophy of the septal region while spatial memory performance was related to atrophy of the hippocampus and entorhinal cortex. Mouse lemurs are the first nonhuman primates in which a clear relationship is established between age-associated cognitive alteration and cerebral atrophy.     

Comparative study of the external auditory canal in humans and large mammals

Given the limited source of human external auditory canal (EAC) skin, animal experiments remain an important approach for studying functional EAC reconstruction. However, differences between humans and animals in terms of the general EAC structure, histological characteristics of EAC skin, and cell markers of its specific glands in cartilaginous EAC skin remain unknown. We compared the characteristics of the EAC between humans and large animals, as a basis for appropriate animal model selection. Temporal bone computed tomography was used to compare the EACs of humans, goats, pigs, and dogs. EAC skin samples were harvested and their histological characteristics evaluated. The skin's ultrastructure and the histological structure of specific glands and cell markers related to cell phenotype and function were further identified. The EAC structure in goats was similar to that in humans in terms of diameter, length, and cartilaginous segment ratio of the EAC, while that of pigs and dogs differed markedly. Furthermore, histological evaluation showed that there were abundant ceruminous and sebaceous glands in the goat's cartilaginous skin, while dogs and pigs showed notably fewer of these glands in cartilaginous skin than humans. Nevertheless, ceruminous glands in all species studied showed similar expression of cell biomarkers and secretion function. Goats might have advantages in terms of surgery and reconstruction of the functional EAC skin compared to dogs and pigs and can be a useful candidate for ceruminous gland cell sources.     

Pharmacology and safety assessment of humanized monoclonal antibodies for therapeutic use.

The humanization of monoclonal antibodies has generated a class of therapeutic products with improved safety, longer half-lives, and greatly diminished immunogenicity. These engineered proteins are highly species specific and in many cases only cross-react in humans. Where there is cross-reactivity in nonhuman primates or other species, it is not always clear that the pharmacologic effects reflect the potential actions in human volunteers or patients. As with other biologic products, the profile of humanized monoclonal antibodies dictates the preclinical strategy. The preclinical programs for the 2 humanized monoclonal antibodies described here, anti-HLA-DR (Hu1D10) and anti-CD3 (HuM291), demonstrate several unique aspects that affected their preclinical development strategy. Hu1D10 binds to a posttranslational form of HLA-DR and recognizes this antigen in some but not all human and nonhuman primates. The second antibody, HuM291, cross-reacts with CD3 only in the chimpanzee, which is not an optimal test species. In addition, a marketed anti-CD3 product exists (OKT3), and in the preclinical development of our antibody during testing of efficacy and safety, we needed to focus on adverse effects that might be similar to those of OKT3. In these studies, the safety, pharmacokinetics, immunogenicity, and pharmacology (B- and T-cell depletion and recovery) of the 2 antibodies were evaluated. The focus in this review is on the safety and pharmacology testing and the current status of each drug.     

Valves in superficial limb veins of humans and nonhuman primates

The venous valves are believed to play an important role in venous function, but their number, position, and spacing in limb veins are reported to be irregular. In this study, the relationship between the number of valves and the length of veins in which they occur was investigated for humans and nonhuman primates. In addition, valve distributions within the superficial veins of the human upper limb were compared with those of the lower limb. Upper and lower limb veins were dissected from adult humans, and forelimb veins were obtained from seven genera of primates. The mean valve index (number of valves per unit length of vein) of the forelimb lateral superficial vein exhibited relatively little variation between humans and primates of a wide range of body sizes and locomotor repertoires. The mean valve index for the lateral superficial vein of the human upper limb is similar to that of the short saphenous vein of the lower limb, and in both veins, the maximum valve index occurs in the most proximal portion of the vein. The relative constancy of the valve index across a range of primate species, and between the upper and lower limbs of humans, may reflect the known constancy of circulatory pressures in mammals. The minimum numbers of valves in superficial veins are only slightly greater than required to limit capillary pressure to below 10 mm Hg, above which pressure the tissue fluid flow would be compromised.