Dopamine release and uptake dynamics within nonhuman primate striatum in vitro. (65/878)

The putamen of the human striatum is a heterogeneous nucleus that contains the primary site of loss of dopamine (DA) in Parkinson's disease (PD). Furthermore, different functional domains of the putamen are heterogeneously susceptible to DA loss, and yet the dynamic regulation of extracellular DA concentration ([DA](o)) and comparison between domains has not been explored in the primate brain. In these studies, DA was measured in real time using fast-scan cyclic voltammetry at a carbon-fiber microelectrode in vitro in striatal sections from the common marmoset (Callithrix jacchus). [DA](o) released by a single stimulus pulse varied threefold along a ventromedial-dorsolateral axis. DA uptake was via the DA transporter (GBR12909 sensitive, desipramine insensitive). On the basis of data modeling with simulations of Michaelis-Menten kinetics, rate maximum, V(max), varied with region: both [DA](o) and V(max) were greatest in regions most vulnerable in PD. These differences were reflected in part by regional variation in DA content. [DA](o), V(max), and regional variation were two- to threefold greater than in rodent caudatoputamen. In addition, steady-state [DA](o) at physiological firing rates in primate striatum was controlled by depolarization frequency, uptake, and presynaptic autoreceptors. Furthermore, regulation of [DA](o) by these mechanisms differed significantly between limbic- and motor-associated domains. These data indicate interspecies heterogeneity in striatal DA dynamics that must be considered when extrapolating behavioral and drug responses from rodent to the primate brain. Moreover, the heterogeneity demonstrated within the primate putamen in the availability and dynamic regulation of DA may be central to understanding DA function in health, cocaine abuse, and disease.  (+info)

Determining the role of the Epstein-Barr virus Cp EBNA2-dependent enhancer during the establishment of latency by using mutant and wild-type viruses recovered from cottontop marmoset lymphoblastoid cell lines. (66/878)

Epstein-Barr virus (EBV) nuclear antigen (EBNA) 2 (EBNA2) is involved in upregulating the expression of both EBNAs and latency-associated membrane proteins. Transcription of the six EBNA genes, which are expressed in EBV-immortalized primary B cells, arises from one of two promoters, Cp and Wp, located near the left end of the viral genome. Wp is exclusively used to drive EBNA gene transcription during the initial stages of infection in primary B cells; induction of transcription from Cp follows. We previously have mapped an EBNA2-dependent enhancer upstream of Cp (M. Woisetschlaeger et al., Proc. Natl. Acad. Sci. USA 88:3942-3946, 1991) and, more recently, have demonstrated that deletion of this enhancer results in EBV-immortalized lymphoblastoid cell lines (LCLs) that are heavily biased toward the use of Wp to drive transcription of the EBNA genes (L. Yoo et al., J. Virol. 71:9134-9142, 1997). To assess the immortalizing capacity of this mutant EBV and to monitor the early events after infection of primary B cells, B cells isolated from cottontop marmosets were used to generate LCLs immortalized with the Cp EBNA2 enhancer deletion mutant virus. As previously reported, all EBV-infected marmoset LCLs examined could be triggered to produce significant levels of virus. Infection of human B cells with wild-type or Cp EBNA2 enhancer mutant viruses recovered from marmoset B-cell lines demonstrated that (i) the Cp EBNA2 enhancer mutant virus immortalizes primary human B cells nearly as efficiently as wild-type virus and (ii) the Cp EBNA2-dependent enhancer plays an important role in the induction of Cp activity during the early stages of infection. The latter is consistent with the phenotype of LCLs immortalized with the Cp EBNA2 enhancer mutant EBV. Finally, using an established LCL in which EBNA2 function is regulated by beta-estradiol, we showed that the loss of EBNA2 function results in an approximately 4-fold decrease in the steady-state levels of Cp-initiated transcripts and a concomitant increase in the steady-state levels of Wp-initiated transcripts. Taken together, these results provide strong evidence that EBNA2 plays an important role in regulating Cp activity. These results also demonstrate that diminished induction of Cp activity does not appear to affect the ability of EBV to immortalize primary B cells in cultures. Finally, as shown here, infection of marmoset B cells with immortalization-competent mutants of EBV provides a convenient reservoir for the production of mutant viruses.  (+info)

Differential vasoconstrictor activity of human urotensin-II in vascular tissue isolated from the rat, mouse, dog, pig, marmoset and cynomolgus monkey. (67/878)

1. Urotensin-II (U-II) and its G-protein-coupled receptor, GPR14, are expressed within mammalian cardiac and peripheral vascular tissue and, as such, may regulate mammalian cardiovascular function. The present study details the vasoconstrictor profile of this cyclic undecapeptide in different vascular tissues isolated from a diverse range of mammalian species (rats, mice, dogs, pigs, marmosets and cynomolgus monkeys). 2. The vasoconstrictor activity of human U-II was dependent upon the anatomical origin of the vessel studied and the species from which it was isolated. In the rat, constrictor responses were most pronounced in thoracic aortae and carotid arteries: -log[EC(50)]s 9.09+/-0.19 and 8.84+/-0.21, R(max)s 143+/-21 and 67+/-26% 60 mM KCl, respectively (compared, for example, to -log[EC(50)] 7.90+/-0.11 and R(max) 142+/-12% 60 mM KCl for endothelin-1 [ET-1] in thoracic aortae). Responses were, however, absent in mice aortae (-log[EC(50)] <6.50). These findings were further contrasted by the observation that U-II was a 'coronary-selective' spasmogen in the dog (-log[EC(50)] 9.46+/-0.11, R(max) 109+/-23% 60 mM KCl in LCX coronary artery), yet exhibited a broad spectrum of vasoconstrictor activity in arterial tissue from Old World monkeys (-log[EC(50)]s range from 8.96+/-0.15 to 9.92+/-0.13, R(max)s from 43+/-16 to 527+/-135% 60 mM KCl). Interestingly, significant differences in reproducibility and vasoconstrictor efficacy were seen in tissue from pigs and New World primates (vessels which responded to noradrenaline, phenylephrine, KCl or ET-1 consistently). 3. Thus, human U-II is a potent, efficacious vasoconstrictor of a variety of mammalian vascular tissues. Although significant species/anatomical variations exist, the data support the hypothesis that U-II influences the physiological regulation of mammalian cardiovascular function.  (+info)

Herpesvirus saimiri pathogenicity enhanced by thymidine kinase of herpes simplex virus. (68/878)

Herpesvirus saimiri can be used as an efficient gene expression vector for human T lymphocytes and thus may allow applications in experimental leukemia therapy. We constructed recombinant viruses for the functional expression of the thymidine kinase (TK) of herpes simplex virus type 1 (HSV) as a suicide gene. These viruses reliably allowed the targeted elimination of transduced nonpermissive human T cells in vitro after the administration of ganciclovir. To test the reliability of this function under the most stringent permissive conditions, in this study we analyzed the influence of the prodrugs ganciclovir and acyclovir in common marmosets on the acute leukemogenesis induced by either wild-type herpesvirus saimiri C488 or by a recombinant derivative expressing TK of HSV. Antiviral drug treatment did not influence the rapid development of acute disease. In contrast, the presence of the HSV tk gene resulted in a faster disease progression. In addition, HSV TK-expressing viruses showed faster replication than wild-type virus in culture at low serum concentrations. Thus, HSV TK accelerates the replication of herpesvirus saimiri and enhances its pathogenicity. This should be generally considered when HSV TK is applied as a transgene in replication-competent DNA virus vectors for gene therapy.  (+info)

Age-related alteration of taste bud distribution in the common marmoset. (69/878)

Alteration in the number of taste buds on the soft palate (SP), fungiform (FF), foliate (FL) and circumvallate (CV) papillae in the common marmoset at different postnatal ages was examined histologically. After paraffin embedding, complete serial sections at 10 microm thickness were made and stained by HE. Digitized images for each section were examined carefully. The number of FF taste buds at day 1 was 334. While only 20% of all the taste buds at birth possessed a taste pore, 39% of 174 SP taste buds at day 1 possessed a taste pore. The number of taste buds with pores at day 1 was small for the center CV (19 of 59), one side CV (7 of 25), and one side FL (2 of 16). These results suggest that the functional maturation of SP taste buds may precede maturation in other areas of the tongue. The total number of taste buds increased with increasing age, reached a maximum at 2 months of age: FF, 1069; SP, 609; CV-center, 530; CV-side, 390; FL, 201, and decreased thereafter. Almost all taste buds possessed a taste pore after 2 months of age. The decrease in the number of taste buds in the oral cavity with increase in age may change taste sensitivity.  (+info)

Quantitative analysis of spermatogenesis and apoptosis in the common marmoset (Callithrix jacchus) reveals high rates of spermatogonial turnover and high spermatogenic efficiency. (70/878)

Spermatogenesis is characterized by the succession in time and space of specific germ cell associations (stages). There can be a single stage (e.g., rodents and some macaques) or more than one stage (e.g., chimpanzee and human) per tubular cross section. We analyzed the organization of the seminiferous epithelium and quantified testicular germ cell production and apoptosis in a New World primate, the common marmoset (Callithrix jacchus). Tubule cross sections contained more than one stage, and the human six-stage system could be applied to marmoset spermatogenesis. Stereological (optical disector) analysis (n = 5) revealed high spermatogenic efficiency during meiosis and no loss of spermatids during spermiogenesis. The conversion of type A to type B spermatogonia was several-fold higher than that reported for other primates. Highest apoptotic rates were found for S-phase cells (20%) and 4C cells (15%) by flow cytometric analysis (n = 6 animals); histological analysis confirmed spermatogonial apoptosis. Haploid germ cell apoptosis was <2%. Marmoset spermatogenesis is very efficient and involves substantial spermatogonial proliferation. The prime determinants of germ cell production in primates appear to be proliferation and survival of spermatogonia rather than the efficiency of meiotic divisions. Based on the organizational similarities, common marmosets could provide a new animal model for experimental studies of human spermatogenesis.  (+info)

Changes in follicle-stimulating hormone and follicle populations during the ovarian cycle of the common marmoset. (71/878)

The common marmoset (Callithrix jacchus) belongs to the family Callitrichidae, the only anthropoid primates with a high and variable number of ovulations (one to four). An understanding of folliculogenesis in this species may provide some insight into factors regulating multiple follicular growth in primates. The aims of this study were to characterize in detail changes in the antral follicle population at different stages of the ovarian cycle, to characterize the marmoset FSH profile, and to relate cyclic changes in FSH to changes in follicle sizes and circulating estradiol concentrations. Fifty-five pairs of ovaries were collected (32 of which were at five distinct stages of the cycle) from adult marmosets, and antral follicles were manually excised and separated into four size groups. Daily urinary FSH and plasma estradiol and progesterone concentrations from Day 0 of the follicular phase to 2 days postovulation were measured in 22 marmosets using enzyme immunoassays. The FSH profile revealed two distinct peaks, on Days 2 and 6, during the 10-day follicular phase, with a marginal periovulatory increase on Days 9 and 10. Estradiol levels rose significantly (P: < 0.05) above baseline (Days 1-4) on Day 5 and continuously increased to a peak on the day preceding ovulation (Days 8 and 9). Follicle dissection revealed a high (mean = 68) and variable (range, 14-158) total number of antral follicles >0.6 mm. The number of antral follicles significantly declined (P: < 0.001) with age. The number of preovulatory follicles (>2 mm) was positively correlated with the number of antral follicles (P: < 0. 001) and tended to be negatively related to age (P: = 0.06). The number of antral follicles did not vary significantly with stage of the ovarian cycle, although the follicle size distribution was cycle-stage dependent (P: < 0.05). Follicles >1.0 mm appeared only in the follicular phase, and preovulatory follicles (>2.0 mm) appeared only at the end of the follicular phase (Days 7-9). The Day 2 FSH peak corresponded to emergence of a population of medium-size antral follicles, and the Day 6 peak was consistent with rising estradiol levels and appearance of the preovulatory follicles. These results suggest that some aspects of marmoset folliculogenesis are comparable to those in Old World primates, including the absence of multiple follicular waves and the appearance of an identifiable dominant follicle in the midfollicular phase. However, the midphase FSH peak, multiple dominant follicles, and abundance of nonovulatory antral follicles differ strongly from the pattern in Old World primates and humans. The findings are discussed in relation to the regulation of growth of multiple ovulatory follicles and provide the basis for further studies on factors influencing the dynamics of follicular growth and development in this species.  (+info)

NXY-059, a free radical--trapping agent, substantially lessens the functional disability resulting from cerebral ischemia in a primate species. (72/878)

BACKGROUND AND PURPOSE: NXY-059 is a novel nitrone with free radical-trapping properties that has a considerable neuroprotective effect in rats. We have now examined the efficacy of this drug at reducing long-term functional disability in a primate model of stroke. METHODS: Twelve monkeys were trained and tested on a variety of behavioral tasks used to dissociate and quantify motor and spatial deficits. Five minutes after permanent occlusion of the right middle cerebral artery, monkeys received a 1-mL intravenous infusion of either saline or NXY-059 (28 mg x kg(-1)), and osmotic minipumps, model 2001D, were implanted subcutaneously to provide continuous drug or saline infusion for 48 hours. Drug-filled pumps released NXY-059 at 16 mg x kg(-1) x h(-1). The monkeys were retested 3 and 10 weeks after surgery to assess functional disability. Surgery, behavioral testing, and histology were all done blinded to treatment condition. RESULTS: NXY-059-treated monkeys were significantly better at reaching with their hemiparetic arm than were saline-treated monkeys when retested 3 weeks (P:<0.01) and 10 weeks (P:<0.01) after surgery. Drug treatment also significantly lessened the degree of spatial perceptual neglect (P:<0.01), a debilitating though ameliorating consequence of this infarct. NXY-059 treatment reduced the overall amount of brain damage by >50% of saline-treatment values, with similar levels of protection afforded to both white and gray matter. CONCLUSIONS: This novel drug has a substantial protective effect, lessening the disability caused by an experimentally induced stroke in a primate species. These findings provide considerable encouragement for the clinical development of NXY-059.  (+info)