Corticotropin releasing factor: basic studies and clinical applications

Corticotropin releasing factor (CRF) is a newly sequenced peptide first isolated from sheep hypothalami and thought to be an important modulator of both the pituitary-adrenal axis and the sympathetic nervous system. We administered intravenous, intramuscular, and intracerebroventricular CRH to non-human primates and measured plasma ACTH, beta endorphin, cortisol, GH and PRL responses to CRF. In addition, we determined the pharmacokinetic properties of I125 in these primates. We administered CRF as an intravenous bolus or as a continuous infusion to normal volunteers and as an intravenous bolus to patients with disorders of the hypothalamic-pituitary-adrenal axis, such as Cushing's syndrome and adrenal insufficiency, and patients with endogenous depression and mild hypercortisolism, and assessed their plasma ACTH, cortisol, GH and PRL responses. In addition, we determined the pharmacokinetic properties of CRF in man by measuring CRF immunoreactivity in plasma. CRF given intravenously to primates or man is a slowly metabolized, long-acting, secretagogue of ACTH, beta-endorphin and cortisol. When given intracerebroventricularly to primates it stimulates the hypothalamic-pituitary-adrenal axis without escaping into the plasma and it is actively cleared in the CNS. It does not cross the blood brain barrier appreciably when given intravenously. CRF given to primates and men as an intravenous continuous infusion has only mild ACTH stimulating effects and this may be due to an intact cortisol negative feedback system. Finally, CRF causes characteristic plasma hormone responses in patients with Cushing's disease, adrenal insufficiency and depression.     

Participation of precentral neurons in somatically and visually triggered movements in primates

Monkeys were trained to perform somatically and visually triggered wrist flexion-extension (F-E) movements. Extracellular unit recordings were made in the contralateral precentral forelimb area. These neurons were identified as being best related to particular single forelimb joints by their responses to passive somatosensory stimulation and to the determining effects of local intracortical microstimulation. It was found that almost 60% of single-joint related cells participated in both somatically and visually triggered movements. All wrist (F-E) neurons responded reciprocally while non-wrist (F-E) neurons had reciprocal as well as bidirectional responses to the opposite directed visual and somatic perturbations. Somatically related responses and visually related responses were both uniformly distributed throughout the vertical layers of precentral cortex. With respect to horizontal spatial arrangements, multiple clusters of reciprocally and bidirectionally responsive neurons were intermingled. This latter finding supports the concept of a context-sensitive organization for motor control within precentral cortex.     

Mapping genomic rearrangements in titi monkeys by chromosome flow sorting and multidirectional <Emphasis Type="Italic">in-situ</Emphasis> hybridization

We developed chromosome painting probes for Callicebus pallescens from flow-sorted chromosomes and used multidirectional chromosome painting to investigate the genomic rearrangements in C. cupreus and C. pallescens. Multidirectional painting provides information about chromosomal homologies at the subchromosomal level and rearrangement break points, allowing chromosomes to be used as cladistic markers. Chromosome paints of C. pallescens were hybridized to human metaphases and 43 signals were detected. Then, both human and C. pallescens probes were hybridized to the chromosomes of another titi monkey, C. cupreus. The human chromosome paints detected 45 segments in the haploid karyotype of C. cupreus. We found that all the syntenic associations proposed for the ancestral platyrrhine karyotype are present in C. cupreus and in C. pallescens. The rearrangements differentiating C. pallescens from C. cupreus re one inversion, one fission and three fusions (two tandem and one Robertsonian)that occurred on the C. cupreus lineage. Our results support the hypothesis that karyological evolution in titi monkeys has resulted in reduction in diploid number and that species with higher diploid numbers (with less derived, more ncestral karyotypes)are localized in the centre of the geographic range of the genera, while more derived species appear to occupy the periphery     

Divergence and convergence of thalamocortical projections to premotor and supplementary motor cortex: a multiple tracing study in the macaque monkey

The premotor cortex of macaque monkeys is currently subdivided into at least six different subareas on the basis of structural, hodological and physiological criteria. To determine the degree of divergence/convergence of thalamocortical projections to mesial [supplementary motor area (SMA)-proper and pre-SMA] and lateral (PMd-c, PMd-r, PMv-c and PMv-r) premotor (PM) subareas, quantitative analyses were performed on the distribution of retrograde labelling after multiple tracer injections in the same animal. The results demonstrate that all PM and SMA subareas receive common inputs from several thalamic nuclei, but the relative contribution of these nuclei to thalamocortical projections differs. The largest difference occurs between subareas of SMA, with much greater contribution from the mediodorsal (MD) and area X, and a smaller contribution from the ventral lateral anterior (VLa) and ventral part of the ventral lateral posterior (VLpv) to pre-SMA than to SMA-proper. In PM, differences between subareas are less pronounced; in particular, all receive a significant contribution from MD, the ventral anterior (VApc) and area X. However, there are clear gradients, such as increasing projections from MD to rostral, from VLa and VLpv to caudal, and from dorsal VLp (VLpd) to dorsal premotor subareas. Intralaminar nuclei provide widespread projections to all premotor subareas. The degree of overlap between thalamocortical projections varies among different PM and SMA subareas and different sectors of the thalamus. These variations, which correspond to different origin and topography of thalamocortical projections, are discussed in relation to functional organizations at thalamic and cortical levels.     

Oesophagostomum bifurcum in non-human primates is not a potential reservoir for human infection in Ghana

In northern Togo and Ghana, human infection with the parasitic nematode Oesophagostomum bifurcum is of major health importance. Elsewhere, oesophagostomiasis is considered a zoonotic infection, non-human primates being the natural host. We examined 349 faecal samples of the olive baboon, mona monkey and black and white colobus monkey from two geographically distinct areas in Ghana, outside the region endemic for O. bifurcum in humans. Using both microscopy and species-specific PCR, we found a high prevalence of O. bifurcum (75-99%) in olive baboons and mona monkeys. The majority of the test-positive faecal samples contained large numbers of larvae after copro-culture (>100). No O. bifurcum was detected in the faeces of the black and white colobus monkeys. Observational studies on the behaviour of the non-human primates, focusing on defecation, food consumption and the sharing of habitat with the local human population, indicated favourable conditions for zoonotic transmission. Given that no human infection with O. bifurcum has been reported from either study area, the present findings support the hypothesis that O. bifurcum from humans in the north of Ghana, and O. bifurcum from olive baboons and/or mona monkeys are distinct.     

Parastrongylus cantonensis in a nonhuman primate, Florida

Parastrongylus (= Angiostrongylus) cantonensis is a parasitic nematode of Norway rats throughout tropical regions. This parasite is neurotropic and causes disease and death in humans and other mammals. We report the first identification of P. cantonensis as the cause of a debilitating neurologic disease in a captive primate in Florida.     

Rhesus offspring produced by intracytoplasmic injection of testicular sperm and elongated spermatids

OBJECTIVE: To establish pregnancies in rhesus monkeys using testicular sperm and elongated spermatids injected into oocytes. DESIGN: Comparative animal study. SETTING: Regional Primate Research Center. ANIMAL(S): Prime, fertile rhesus monkeys. INTERVENTION(S): Oocytes collected by laparoscopy from gonadotropin-stimulated female rhesus monkeys were injected with testicular sperm or elongated spermatids obtained from the testis of males. Cleavage stage embryos were transferred to surrogate females. MAIN OUTCOME MEASURE(S): Fertilization, embryo cleavage, and the establishment of pregnancies. Fertilization failures were fixed and processed for the detection of microtubules and chromatin configurations. RESULT(S): Fertilization, assessed by the presence of two pronuclei within 15 hours after injection, was 60% for intracytoplasmic sperm injection with testicular sperm and 47% for elongated spermatid injection. Fertilized zygotes co-cultured in Connaughts Medical Research Labs (CMRL) medium on a Buffalo Rat Liver cell monolayer resulted in hatched blastocysts after testicular sperm extraction-intracytoplasmic sperm injection and elongated spermatids. Embryos transferred at the 4- to 8-cell stage gave rise to three pregnancies: 2/3 from testicular sperm and 1/1 from an elongated spermatid. Three healthy infants were delivered by cesarean. Oocytes that failed to fertilize typically remained arrested in metaphase of meiosis. CONCLUSION(S): Testicular sperm and elongated spermatids can be used for fertilization in the rhesus monkey resulting in live births.     

The nucleotide sequences of the parathyroid gene in primates (suborder Anthropoidea)

Nucleotide sequences of the parathyroid (PTH) gene of 12 species of primates belonging to suborder Anthropoidea were examined. The PTH gene contains one intron that separates two exons that code the sequence of prepro and PTH, respectively. The intron of the PTH gene in Cebus apella, Callithrix jacchus, and Saguinus oedipus was 102 bp long, whereas a 103-bp intron was observed in the remaining species. Phylogenetic analysis using the nucleotide sequences of PTH revealed that these 12 species of primates of suborder Anthropoidea could be divided into two groups of the infraorder Platyrrhini (C. apella, C. jacchus, and S. oedipus) and the infraorder Catarrhini (Macaca fascicularis, Macaca fuscata, Cercopithecus aethiops, Papio hamadryas, Presbytes obscura, Hylobates lar, Pongo pygmaeus, Pan troglodytes, and Pan paniscus). The latter infraorder could be further subdivided into two subgroups belonging to the superfamily Cercopithecoidea (M. fascicularis, M. fuscata, C. aethiops, P. hamadryas, and P. obscura) and the superfamily Hominoidea (H. lar, P. pygmaeus, P. troglodytes, and P. paniscus). The deduced amino acid sequences of PTH gene between 12 species of nonhuman primates and human revealed no amino acid substitution in mature PTH among orangutans, chimpanzees, and humans. The results indicated that the PTH gene is very conserved among primates, especially between great apes and humans. The apes are the most suitable animals to be used for studying the bone metabolism and applying the knowledge to clinical use in humans.     

Immune Responses Against the Myelin/Oligodendrocyte Glycoprotein in Experimental Autoimmune Demyelination

Myelin/oligodendrocyte glycoprotein (MOG) is a surface-exposed antigen of myelin and an important target for autoimmune responses which mediate inflammatory demyelination in the central nervous system. Experimentally, MOG induces strong pathogenic T cell responses in many strains of laboratory animals. Immunological studies in humans also identify MOG as a surprisingly prevalent antigenic molecule among the myelin proteins. In addition, the encephalitogenic properties of MOG are linked to the induction of antibody responses which have been demonstrated to directly promote central nervous system demyelination, a hallmark neuropathological feature in disorders such as human multiple sclerosis. Factors responsible for autoimmunity to MOG likely include genetic influences as well as other mechanisms, which are the subject of intense investigation. This article reviews experimental data currently available on specificity and pathogenic roles of T cell and antibody responses against MOG, which have implications relevant to multiple sclerosis and related disorders.     

Graphical analysis of 2-[18F]FA binding to nicotinic acetylcholine receptors in rhesus monkey brain

External imaging of nicotinic acetylcholine receptors (nAChRs) using techniques such as PET would help to clarify the roles of these receptors in the physiology and pathology of brain function. Here we report the results of quantitative PET studies of cerebral nAChRs with 2-[(18)F]fluoro-A-85380 (2-[(18)F]FA) in rhesus monkeys. Data from dynamic PET scans were analyzed using graphical methods. Binding potential (BP) values of 2.0, 0.4, 0.3, and 0.03 observed in the thalamus (Th), cortex (Cx), striatum (Str), and cerebellum (Cb), respectively, were consistent with the pattern of alpha(4)beta(2) nAChR distribution in monkey brain. The high value of 2-[(18)F]FA-specific binding in the rhesus monkey Th and low level of that in Cb compared with nonspecific accumulation of radioactivity in these structures allowed use of Cb as a reference region for calculation of BP and volume of distribution of specific binding (VDsb) in Th by graphical methods, both with and without the plasma input function. In contrast, estimation of 2-[(18)F]FA specific binding in low-receptor-density regions such as Cx and Str required assessment of nondisplaceable volume of distribution (VDnd) in a separate study and measurement of nonmetabolized radioligand concentrations in the plasma. For accurate quantitation of 2-[(18)F]FA-specific binding by graphical analysis, PET studies should last up to 7 h due to the slow kinetics of 2-[(18)F]FA brain distribution. Further, to avoid substantial underestimation in measured BP values the doses of administered 2-[(18)F]FA should not exceed 0.1 nmol/kg body weight. The findings suggest that 2-[(18)F]FA is a promising ligand for quantitation of nAChRs in human brain.