Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Primates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,603 records · Page 89Linked to original sources
PubMed2006

Correlation of cerebral metabolites with functional outcome in experimental primate stroke using in vivo 1H-magnetic resonance spectroscopy.

BACKGROUND AND PURPOSE: Ensuring the translatability of primate stroke models is critical for preclinical testing of cerebroprotective strategies, and such models would benefit from further characterization of the experimental ischemic tissue. Our purpose was to examine the cerebral metabolic response to stroke in baboons with MR spectroscopy and to correlate metabolite levels with functional neurologic outcomes. METHODS: Seven baboons underwent 1 hour of middle cerebral artery occlusion. At 3 and 10 days, each animal was imaged with traditional MR imaging and multivoxel proton (1)H-MR spectroscopy, and a neurologic examination was performed. Spectra obtained from the infarcted hemisphere of each animal were compared with the contralateral hemisphere, and metabolite levels were correlated with neurologic outcome scores. RESULTS: Spectra obtained at 3 days postischemia revealed prominent lactate (LAC) resonances and attenuated N-acetylaspartate (NAA) peaks in infarcted hemispheres. Ten-day spectra showed persistence of these findings in animals with large strokes (>30% of the hemisphere), with partial normalization of the spectra in animals with small strokes (<30% of the hemisphere). Mean area under the curve from LAC spectra had a negative correlation with functional outcome by 2 different scoring systems (r(2) = 0.72 and 0.73), whereas NAA showed a positive correlation (r(2) = 0.79 and 0.62). CONCLUSIONS: The metabolic alterations observed in our primate model of reperfused ischemia by (1)H-MR spectroscopy recapitulate those seen in clinical stroke. Furthermore, correlations between LAC and NAA peaks with functional outcome further suggest that MR spectroscopy may play a role in outcome prediction following cerebral infarction in higher primates.

Animals↗
PubMed1991

Conservation of the most JH proximal Ig VH gene segment (VHVI) throughout primate evolution.

The human VHVI gene segment, the sole member of the VHVI gene family, is remarkable in that it is the most D-proximal VH gene segment and is apparently nonpolymorphic. Here we report that the VHVI gene segment has been remarkably preserved in primate evolution. We were unable to detect RFLP among several primates, and nucleotide sequences of several VHVI gene segments showed remarkable conservation. No differences were detected in the nucleotide sequences of the VHVI gene segment from three unrelated chimpanzees. These findings suggest that the VHVI gene segment has been strongly selected for during primate evolution, suggesting an important immunologic role.

Amino Acid Sequence↗
PubMed1991

Modular organization of projection neurons in the matrix compartment of the primate striatum.

It is well known that the striatum has a chemical architecture dividing it into striosomes and matrix, and that these compartments have different input-output connections. However, striatal afferent-fiber systems also form vividly patchy terminal fields in the matrix, and studies in the past year have uncovered instances of nonstriosomal clustering of striatal output neurons. In the experiments reported here, we systematically investigated this output-neuron clustering in the primate, using the striatopallidal system as a model. Our goals were to determine whether the modular organization is a general characteristic of projection neurons in the striatal matrix, whether the modularity occurs independent of striosomal boundaries, and whether the output modules are systematically organized. We studied the distribution of striatopallidal projection neurons in 9 adult squirrel monkeys by centering deposits of the retrograde tracer HRP-WGA in either the external segment or the internal segment of the globus pallidus. Following injections of each type, many retrogradely labeled neurons appeared in the striatal matrix in clusters and bands having cross-sectional diameters of 0.2-0.8 mm. Comparisons with adjoining sections stained to demonstrate striosomes established that the local groups of striatal output neurons sometimes abutted striosomes but often did not. The retrogradely labeled clusters and bands appeared both in the caudate nucleus and in the putamen. Their arrangements were regular and often periodic. These findings suggest that the large matrix compartment of the primate striatum, which is the primary site of origin of striatal outputs to the pallidum and the reticular part of the substantia nigra, contains systematic mosaics of projection neurons. We propose that this output-neuron modularity of the striatal matrix in the primate could serve as the template for redistribution of the massive afferent-fiber systems of the striatum into specialized striatopallidal output channels.

Animals↗
PubMed1976

Nonhuman primate-associated viral hepatitis type A. Serologic evidence of hepatitis A virus infection.

Since 1961, viral hepatitis has been recognized as an occupational hazard among handlers of newly imported chimpanzees and other nonhuman primates. To determine whether previously reported cases were caused by human viral hepatitis type A, we tested paired serum samples from two outbreaks for antibody to hepatitis A antigen (anti-HA) by immune adherence hemagglutination (IAHA), recently available test. In both outbreaks, one of hepatitis transmitted from chimpanzee to man (Michigan, 1964), the second from chimpanzee to chimpanzee, man, and woolly monkey (Connecticut, 1971), serologic data documented recent hepatitis A virus infection among contacts-human and nonhuman primate-of implicated chimpanzees. This confirms serologically a previously noted epidemiologic association between nonhuman primate-associated hepatitis and human viral hepatitis, type A.

Animals↗
PubMed1991

Distribution and fine structural analysis of undifferentiated cells in the primate subependymal layer.

The subependymal layer (SEL) of the postnatal marmoset, a simian primate, has been investigated by histological and electron microscopic techniques. Although well documented in rodents, little is known about this layer in primates. The distribution of the SEL in marmosets is most extensive at birth around the anterior lateral ventricles, where the layer is generally 5-10 cells deep; however, there is considerable regional variation. With age the size of the SEL decreases dramatically, becoming very poorly demarcated in adult animals. Ultrastructurally, many subependymal cells in neonatal and young brains display the features of undifferentiated cells, although neurons and glia are also present. Cells displaying features intermediate between astrocytes and undifferentiated SEL cells are occasionally encountered. In adults undifferentiated cells are seen rarely and the former SEL is composed primarily of glial and neuronal processes. Thus the layer in primates probably represents a site of continued cellular differentiation in the postnatal brain and as such must play an important role in the final stages of cortical development.

Aging↗
PubMed1990

Genetically distinct cell populations in naturally occurring bone marrow-chimeric primates express similar MHC class I gene products.

The cotton-top tamarin (Saguinus oedipus) is a naturally occurring "A" + "B"----"A" bone marrow-chimeric species. These primates usually are born as dizygotic twins and, due to placental vascular anastomoses, develop sharing each others' bone marrow elements. Strikingly, almost 50% of the PBL of a member of a twin pair are derived from the hematopoietic stem cells of its cotwin. To clarify the mechanisms underlying the maintenance of tolerance in these stable chimeras, MHC gene products have been biochemically characterized in cloned, genetically distinct, male and female lymphocytes from two male/female cotton-top tamarin twin pairs. Extensive MHC class II sharing between the genetically distinct cell populations was not seen in the two twin pairs. This was consistent with the MHC class II polymorphism seen in the species. However, the MHC class I gene products expressed by one member of a twin pair were almost identical to those expressed by its cotwin. A human minisatellite probe demonstrated restriction fragment length polymorphism in DNA from these animals, indicating extensive polymorphism. Thus, MHC class I sharing did not occur due to inbreeding in these animals. Additionally, another bone marrow-chimeric primate species, the common marmoset (Callithrix jacchus), expresses MHC class I molecules with low levels of variation. These studies suggest that the stable chimerism of bone marrow-chimeric primates may be facilitated by MHC class I similarity between the genetically distinct bone marrow derived-cell populations in their circulation.

Animals↗
PubMed1990

Metabolic processing and carcinogenicity of heterocyclic amines in nonhuman primates.

The potential for human exposure to heterocyclic amine (HAA) mutagens derived from cooking food prompted an evaluation of the disposition and carcinogenicity of three of the HAAs in nonhuman primates, especially cynomolgus monkeys. The three HAAs currently under study are 2-amino-3-methylimidazo [4, 5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx) and 2-amino-1-methyl-6-phenylimidazo [4,5,b]pyridine (PhIP). These three HAAs were selected on the basis of several factors including structure, mutagenic activity in vitro, concentration in cooked meat, activity in rodent carcinogenicity tests and availability. Studies on the disposition of IQ demonstrated that it was extensively metabolized in monkeys and excreted in urine and feces as metabolites. These metabolites represent predominantly detoxification products of IQ. The extent of in vivo activation of IQ and PhIP was assessed by measuring DNA adducts in various tissues and white blood cells of monkeys following administration of the compounds. Both compounds form high levels of DNA adducts in a number of organs, particularly the liver, kidney, and heart. The carcinogenicity of IQ, 8-MeIQx and PhIP in nonhuman primates has been under study for 5 years, 24 months, and 7 months, respectively. Thus far, IQ has induced hepatocellular carcinoma in 3 of 20 monkeys at doses of 10 mg/kg daily, 5 days/week and in 10 of 20 monkeys at 20 mg/kg on the same schedule. Thus, IQ is a potent liver carcinogen in nonhuman primates and a potential carcinogen for humans.

Animals↗
PubMed1990

Clinical and parasitologic aspects of cryptosporidiosis in nonhuman primates.

Eighty-one cases of acute cryptosporidiosis were diagnosed among 157 (52%) infant primates, predominantly Macaca nemestrina, housed in the nursery unit of the Washington Regional Primate Research Center. The mean age at onset of oocyst passage was 38 +/- 25 days. The outbreak was confined to the nursery and no cases were detected among juvenile or adult primates housed in other rooms within the colony. All but one animal manifested symptoms of enteric infection, including severe diarrhea and dehydration. Infected animals excreted oocysts for a mean of 36 days (range 7-78 days). No reinfections occurred. Cryptosporidium was the second most common enteric pathogen detected in the population, after Campylobacter jejuni. The risk of infection was related to the length of time the animal was housed in the nursery and to social interaction with other monkeys. These findings are relevant to the understanding of the epidemiology of cryptosporidiosis among human infants and children in environments with close social interactions and minimal learned personal hygiene practices.

Animals↗
PubMed1990

Nerve growth factor infusion in the primate brain reduces lesion-induced cholinergic neuronal degeneration.

NGF is a protein that promotes survival, differentiation, and process extension of selected neuronal populations during development and, in some cases, in the mature organism. Previous lesion and aging studies in the rat have shown that intracerebroventricular NGF infusions can prevent degenerative changes in basal forebrain cholinergic neurons. We sought to determine whether salutory effects of NGF occur in the primate brain. Cholinergic fibers of the septohippocampal projection in the primate were surgically transected, followed by infusion of either a vehicle or an NGF solution into the ventricular system for a 4-week period. Quantification of cholinergic neurons in the medial septal nucleus at the end of the infusion period demonstrated that only 45 +/- 5% of cholinergic neurons could be identified after fornix lesions in vehicle-infused animals, whereas 80 +/- 6% of neurons were visible in NGF-treated animals. Thus, NGF substantially reduced lesion-induced cholinergic neuronal degeneration in the adult primate brain. This finding may be relevant to the hypothesis that NGF has potential use as a cholinergic "neurotrophic-factor therapy," given that loss of basal forebrain cholinergic neurons is common in Alzheimer's disease.

Acetylcholinesterase↗
PubMed1990

Anti-LPS antibodies reduce endotoxemia in whole body 60Co irradiated primates: a preliminary report.

Long periods in space may expose astronauts to the potentially harmful effects of ionizing radiation. We have used a primate model to evaluate any role of lipopolysaccharide (LPS, endotoxin) in radiation sickness. Vervet monkeys, which had been whole-body 60Co irradiated with an LD100 exposure, had periodic blood samples taken for the determination of LPS, anti-LPS IgG antibodies and bacteriological studies. On day 2 post-irradiation, primates were treated i.m. with either sterile 0.9% saline, or equine anti-LPS hyperimmune plasma (Anti-LPS), or orally with tripotassium-dicitrato-bismuthate ("Denol"). Gram positive bacteria were evident in blood samples of all animals as early as 2 d post-irradiation. Gram negative bacteria were found in the blood of saline- and Denol-treated primates by days 5 and 8, respectively, but first appeared on day 13 in the anti-LPS-treated animals. The saline controls and Denol-treated animals showed insignificant rises in plasma LPS on day 3, which increased further thereafter achieving significance on day 8 (p less than 0.01). These elevated levels persisted until death. However, in anti-LPS-treated monkeys, LPS concentrations remained below baseline until day 9, after which they rose significantly until death, but, were significantly less than the concentrations in both other groups (p less than 0.001). The anti-LPS-treated animals survived significantly longer than both the other groups (p less than 0.005). Since LPS may cause nausea, vomiting, diarrhea, anorexia and headaches, Anti-LPS administration may be of value in reducing plasma LPS concentration in humans and improving their performance and survivability.

Animals↗
PubMed1990

Molecular history of gene conversions in the primate fetal gamma-globin genes. Nucleotide sequences from the common gibbon, Hylobates lar.

Comparative and phylogenetic analyses of homologous sequences from closely related species reveal genetic events which have happened in the past and thus provide considerable insight into molecular genetic processes. One such process which has been especially important in the evolution of multigene families is gene conversion. The fetal gamma 1 and gamma 2-globin genes of catarrhine primates (humans, apes, and Old World monkeys) underwent numerous gene conversion events after they arose from a gene duplication event 25-35 million years ago. By including the gamma 1- and gamma 2-globin gene sequences from the common gibbon, Hylobates lar, the present work expands the gamma-globin data set to represent all major groups of hominoid primates. A computer-assisted algorithm is introduced which reveals converted DNA segments and provides results very similar to those obtained by site-by-site evolutionary reconstruction. Both methods provide strong evidence for at least 14 different converted stretches in catarrhine primates as well as five conversions in ancestral lineages. Features of gene conversions generalized from this molecular history are 1) conversions are restricted to regions maintaining high degrees of sequence similarity, 2) one gene may dominate in converting another gene, 3) sequences involved in conversions may accumulate changes more rapidly than expected, and 4) certain elements, such as polypurine/polypyrimidine [Y)n) and (TG)n elements, appear to be hotspots for initiating or terminating conversion events.

Amino Acid Sequence↗
PubMed1990

Hippocampal damage associated with prolonged glucocorticoid exposure in primates.

In the laboratory rat and guinea pig, glucocorticoids (GCs), the adrenal steroids that are secreted during stress, can damage the hippocampus and exacerbate the hippocampal damage induced by various neurological insults. An open question is whether GCs have similar deleterious effects in the primate hippocampus. In fact, we showed that sustained and fatal stress was associated with preferential hippocampal damage in the vervet monkey; however, it was not possible to determine whether the excessive GC secretion that accompanied such stress was the damaging agent. The present study examines this possibility. Pellets of cortisol (the principal GC of primates) were stereotaxically implanted into hippocampi of 4 vervet monkeys; contralateral hippocampi were implanted with cholesterol pellets as a control. One year later at postmortem, preferential damage occurred in the cortisol-implanted side. In the cholesterol side, mild cell layer irregularity was noted in 2 of 4 cases. By contrast in the cortisol-exposed hippocampi, all cases had at least 2 of the following neuropathologic markers: cell layer irregularity, dendritic atrophy, soma shrinkage and condensation, or nuclear pyknosis. Damage was severe in some cases, and was restricted to the CA3/CA2 cellfield. This anatomical distribution of damage, and the cellular features of the damage agree with that observed in instances of GC-induced toxicity in the rodent hippocampus, and of stress-induced toxicity in the primate hippocampus. These observations suggest that sustained GC exposure (whether due to stress, Cushings syndrome or exogenous administration) might damage the human hippocampus.

Animals↗
PubMed1985

The histologic and functional characterization of enzymatically dispersed intestinal mast cells of nonhuman primates: effects of secretagogues and anti-allergic drugs on histamine secretion.

Despite the apparent involvement of gastrointestinal mast cells in hypersensitivity reactions in the mucosa, remarkably little information is available concerning the characteristics of these cells from man and higher animals. To study the characteristics of gastrointestinal mast cells from nonhuman primates, a previously described technique which uses a combination of mechanical and enzymatic methods to obtain mast cells from the tissues of rodents required modification to permit the successful dispersion of normal gastrointestinal tissues of higher animals. This modified procedure, as described in this report, appears to be relatively selective for mast cells located in the mucosal site, and typically yields ca 9 X 10(5) mast cells per gram of tissue. The mucosal mast cells obtained comprised ca 2% of the total nucleated cells, contained approximately 1 pg of histamine per cell, and stained metachromatically with toluidine blue only at low pH. The cells exhibited a dose-dependent release of histamine on challenge with goat anti-human IgE or the ionophores A23187 and Br-x537A but were refractory to the action of compound 48/80. IgE-mediated histamine release from monkey intestinal mast cells differed from that observed from rat intestinal mast cells in that release was inhibited not only by quercetin but also by theophylline. Disodium cromoglycate gave variable results. The data indicate that viable nonhuman primate mucosal mast cells can be obtained for study, and that these cells, although sharing some characteristics of mucosal mast cells from lower species, have distinct and unique properties. The availability of this nonhuman primate model for the study of mast cell function in higher animals should contribute to the understanding of mast cell-mediated diseases in man.

Animals↗
PubMed1986

Mast cell heterogeneity in higher animals: a comparison of the properties of autologous lung and intestinal mast cells from nonhuman primates.

The issue of mast cell heterogeneity has been investigated in nonhuman primates by a comparative examination of lung and intestinal mast cells. These cells were obtained in parallel from the respective tissues of individual monkeys by an identical enzymatic dispersion technique. Mast cells derived from the lungs differed from those derived from the intestine in that the majority of the former cell type could be stained with toluidine blue at pH 4 to 5, whereas the intestinal mast cells in the dispersed preparations required a more acidic pH (less than 1) to display metachromasia. In addition, the lung cells exhibited an increased content of the mast cell mediator histamine. Nonhuman primate lung mast cells were also quantitatively more responsive to an immunologic challenge than their intestinal counterparts in that they released a higher percentage of cellular histamine and generated more leukotriene C4 on stimulation. Considerable inter-animal variation was observed between the magnitude of mediator release from both mast cell types after anaphylactic activation, but evidence for the presence in nonhuman primates of the phenomenon of releasability was not obtained. The responsiveness of both cell types to a range of potential nonimmunologic secretagogues and anti-allergic agents, including compound 48/80, substance P, theophylline, and isoprenaline, was essentially similar. We conclude that mast cell heterogeneity in higher animals may be reflected more by cytochemical rather than by functional differences between mast cell classes.

Animals↗
PubMed1978

The role of fibrin formation in the pathogenesis of bacteremic shock in the primate.

In this study, an attempt was made to elucidate further the role of intravascular fibrin formation in the pathogenesis of sepsis in the primate. It was found that injected live Escherichia coli caused death in primates within four to 11 hours as a result of microcirculatory failure and acidosis. Pretreatment with Arvin did not prolong the survival rate, probably because of an overloading of the reticuloendothelial system with fibrin degradation products. This study does not support an obligatory role for intravascular coagulation or fibrin formation in primate sepsis and coincides with an earlier report (6) from this laboratory on cats. Vascular damage and malfunction, secondary to mediators released by platelets, leukocytes, red cells or Hageman factor, are not ruled out.

Ancrod↗
PubMed1989

Reversibility of GnRH agonist-induced inhibition of testicular function: differences between rats and primates.

In rats, GnRH agonists can induce focal and permanent testicular damage. No such effects have been found in dogs, monkeys and volunteers participating in contraceptive trials. Some of the severe alterations observed in prostatic cancer patients treated with GnRH agonists might be influenced by age and/or disease status. To date no irreversible testicular damage in human and non-human primates, clearly attributable to GnRH agonist treatment has been described. In consequence, the rat appears an unsuitable model for evaluation of the antitesticular effects of GnRH agonists in primates. Thus, non-human primates play an important role in the preclinical evaluation of GnRH analogues.

Animals↗
PubMed1989

Hippocampal damage associated with prolonged and fatal stress in primates.

Sustained exposure to glucocorticoids (GCs), adrenal hormones secreted during stress, can cause neural degeneration in the rat. This is particularly so in the hippocampus, a principal neural target site for GCs, in which GCs can exacerbate the rate of neuron death during normal aging, as well as the severity of neuronal damage after various neurological insults. Thus, stress can be a potent modulator of hippocampal degeneration in the rat. The present report suggests a similar association in the primate. Eight vervet monkeys, housed in a primate center in Kenya, that had died spontaneously from 1984 to 1986, were found at necropsy to have multiple gastric ulcers; a retrospective, neuropathological study was then done of this opportunistic population. Compared with controls euthanized for other research purposes, ulcerated monkeys had marked hippocampal degeneration that was apparent both quantitatively and qualitatively, and both ultrastructurally and on the light-microscopic level. Minimal damage occurred outside the hippocampus. Damage was unlikely to have been due to an agonal or post-mortem artifact. Instead, ulcerated monkeys appear to have been subject to sustained social stress, perhaps in the form of social subordinance in captive breeding groups: most came from social groups, had significantly high incidences of bite wounds at necropsy, and had hyperplastic adrenal cortices, indicative of sustained GC release. Moreover, the specific hippocampal cell fields damaged in ulcerated animals matched those damaged by GCs in the rodent hippocampus. Thus, this represents the first evidence suggesting that sustained stress, via GC hypersecretion, might be neurodegenerative in the primate.

Adrenal Cortex↗
PubMed1988

Characterization of colonic cellular glycoconjugates in colitis and cancer-prone tamarins versus colitis and cancer-resistant primates.

Differences in colonic secretory glycoconjugates (ie, mucin) between normal and ulcerative colitis-prone patients have been noted. Similar differences may occur in a corresponding primate model, the cotton-top tamarin (CTT), Saguinus oedipus, a New World monkey which suffers from spontaneous chronic colitis and colon cancer. Lectin reagents were used to characterize and compare colonic cell surface, cytoplasmic, and secretory glycoconjugates of 9 clinically healthy cotton-top tamarins, 7 colitis-susceptible, cancer-resistant tamarins (Callithrix jacchus, Saguinus fuscicollis), and 8 colitis and cancer-resistant primates (Aotus trivirgatus, Saimiri sciureus, Macaca fascicularis, and Macaca mulatta). Paraffin-embedded colonic sections were labeled with ten different biotinylated lectins and visualized by the avidin-biotin peroxidase (ABC) method. Significant differences were demonstrated in the pattern of lectin staining between the colitis-resistant and colitis-prone groups of primates. The differences were noted with Griffonia simplicifolia-I (GS-I), Dolichos biflorus agglutinin (DBA), peanut agglutinin (PNA) before and after neuraminidase, Ricinus communis agglutinin-I (RCA-I), soybean agglutinin (SBA), Ulex europaeus agglutinin-I (UEA-I), wheat germ agglutinin (WGA), and succinylated WGA (S-WGA). Significant differences between the CTT and phylogenetically related colitis-prone but cancer-resistant tamarins were demonstrated with SBA, UEA-I, and PNA after desialylation with neuraminidase. These results suggest that differences in colonic cellular glycoconjugates between colitis- and cancer-susceptible species versus colitis-susceptible, cancer-resistant species may be associated with risk of cancer.

Animals↗