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At least 1,657 records · Page 92Linked to original sources
PubMed1998

Monoclonal antibodies to Toxoplasma gondii strain 119 identify recently isolated Danish strains as one group.

Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain-restricted markers. Strain restriction extended beyond discrimination of the 119 and RH strains, as demonstrated on a further six T. gondii reference strains [BK and GT1 (group A), NTE and 561 (group B), and NED and C56 (group C)]. The bradyzoite-specific mAb, 4.3, reacted to the GT1, NTE and 561 strains, but not to the BK, NED or C56 strains. The tachyzoite-specific mAb, 4.25, reacted to all strains tested except the RH strain, while mAb 5.1 reacted to tachyzoites of strains NTE and 561, but not to those of the BK, GT1, NED or C56 strains. Monoclonal antibody 5.15 reacted with the same strain restriction as monoclonal antibody 5.1, but to bradyzoites as well as tachyzoites. A T. gondii strain collection representative for a small geographic area (Denmark) was established within a short time span from a variety of animal species. Using the mAb as typing reagents to this Danish strain collection, all 36 animal and two human strains were identified as having the same reaction pattern as strains 119, NTE and 561.

Animals↗
PubMed1991

Thermospray liquid chromatography-mass spectrometry for the characterisation of sulphate ester conjugates.

Formation of polar conjugates is a well documented metabolic pathway for xenobiotics containing phenolic hydroxyl groups. This paper describes the analysis of two sulphate ester conjugates by fast atom bombardment mass spectrometry and thermospray liquid chromatography-mass spectrometry. Thermospray liquid chromatography-mass spectrometry proved the more successful technique for obtaining the molecular weight of the intact conjugate, but only by removal of the buffer from the high-performance liquid chromatography eluent.

Albuterol↗
PubMed2002

Cell surface phenotyping and cytokine production of Epstein-Barr Virus (EBV)-transformed lymphoblastoid cell lines (LCLs).

Epstein-Barr Virus-transformed B lymphoblastoid cell lines (EBV-LCLs) are routinely used for the in vitro expansion of T cells. However, these cell lines are reported to produce the cytokine IL-10, which is inhibitory for T cells. We, therefore, characterized a panel of 37 EBV-LCLs for a variety of cell surface markers, for secretion of various cytokines including IL-10 and for immunoglobulin production. These cell lines were derived from normal donors or patients with nonsmall cell lung cancer, acute myelogenous leukemia, melanoma or colon cancer. Overall, 26 lines were positive for CD19 and CD20, and 11 were negative for both. All of the lines were strongly HLA-DR+, while CD40 expression was variable. Twenty-four (65%) were both CD23+ and secreted immunoglobulin, and 33 expressed kappa and/or lambda light chains. Additionally, all of the EBV-LCLs were negative for T cell (CD3), NK cell (CD16, CD56), monocyte (CD14) and granulocyte (CD66b) surface markers. Some level of IL-10, IL-6, IL-12p40 and TNF-alpha cytokine production was detected in 33, 18, 19 and 12 EBV-LCLs, respectively. Together, these data reflect the heterogeneity of EBV-LCLs, which cautions their use nondiscriminately in various immunologic assays.

Animals↗
PubMed2001

Demyelination and axonal damage in a non-human primate model of multiple sclerosis.

The demyelinating plaque is the paradigmatic lesion of multiple sclerosis (MS), but only recently attention has been given to axonal damage and to its role in the pathophysiology of disease. Albeit the possible relevance of axonal loss in MS and its experimental models, the amount and timing of axonal sufferance has been addressed only in experimental autoimmune encephalomyelitis (EAE) of rodents. In this report we observed that, in the marmoset model of EAE, axonal damage occurs early during the demyelinating process as assessed by immunoreactivity for amyloid precursor protein (APP) and non-phosphorylated neurofilaments (SMI-32 positive) detected mostly in early active lesions compared to late active and normal appearing white matter. The rare occurrence of morphological features of axonal transection, such as APP or SMI-32 positive spheroids and swellings, as well as an increase of neurofilament density in the demyelinated axons without accumulation of electron dense organelles or osmiophilic bodies, at electron microscopy, suggests that early axonal damage may be, at least in part, a reversible process. These findings are of relevance for the development of therapies, which can protect axons and enhance their function and survival.

Amyloid beta-Protein Precursor↗
PubMed1986

A putative non-cholinergic mechanism in urinary bladders of New but not Old World primates.

The effects of atropine on bladder contractions evoked by sacral ventral root stimulation were investigated in two species of New World monkey (marmoset and cebus) and in paraplegic man. The findings were then compared to those previously obtained for the cat and two species of Old World monkey (rhesus and baboon). The results show the marmoset and cebus to represent a transitional stage between the complete sensitivity of the bladders of Old World monkeys to atropine and the relative insensitivity of the cat bladder. The bladder response is shown to comprise two components, an atropine sensitive component which is slow in onset and an atropine resistant component which is easily fatigued. The experiments in paraplegic people confirm that the parasympathetic innervation of the bladder of man is, like that of Old World monkeys, exclusively cholinergic. A behavioural interpretation is tentatively offered to explain the two types of innervation.

Animals↗
PubMed1998

A comparison of sensory nerve function in human, guinea-pig, rabbit and marmoset airways.

We have investigated the role of sensory nerves in regulating airway smooth muscle function in the guinea-pig, marmoset, rabbit and man. Tissue levels of the sensory neuropeptides CGRP and substance P in the airways of the guinea-pig were significantly greater compared with the rabbit and marmoset. The relative order of tissue content was guinea-pig >>> rabbit = marmoset. Marmoset bronchial and tracheal preparations responded weakly to exogenously administered substance P and neurokinin A but contracted to methacholine and demonstrated atropine-sensitive cholinergic responses. In marmoset, rabbit and human airway preparations, capsaicin mediated weak contractile responses to exogenously administered capsaicin. However, high concentrations of capsaicin elicited a relaxation response that was epithelium-independent, cyclo-oxygenase-insensitive, not involving nitric oxide and not dependent on the activation of capsaicin-sensitive afferents. These results suggest that rabbit and marmoset airways respond functionally in a similar way to human airway preparations and maybe more relevant than guinea-pig airways with regard to understanding the role of sensory neuropeptides in airways.

Animals↗
PubMed2002

[3H]-SB-269970 radiolabels 5-HT7 receptors in rodent, pig and primate brain tissues.

The selective 5-HT7 receptor antagonist radioligand, [3H]-SB-269970, has been reported to radiolabel the human cloned 5-HT7(a) receptor and 5-HT7 receptors in guinea pig cortex (thomas et al, 2000). Saturation analysis of [3H]-SB-269970 binding to mouse forebrain, rat cortex, pig cortex, marmoset cortex and human thalamus membranes was consistent with labelling a homogenous population of binding sites in each tissue. K(D) values for [3H]-SB-269970 binding in these tissues ranged from 0.9 to 2.3 nM, being similar to those reported for the human cloned and guinea pig cortex 5-HT7 receptors (1.3 and 1.7 nM, respectively). Bmax values for [3H]-SB-269970 binding to the mouse, rat, pig, marmoset and human brain membranes were 20, 30, 31, 14 and 68 fmoles x mg x protein(-1), respectively. For each species the profile of inhibition of [3H]-SB-269970 binding, using a number of 5-HT7 receptor agonists and antagonists, correlated well with that reported for the human cloned 5-HT7(a) receptor (correlation coefficients were 0.95, 0.94, 0.92, 0.95, 0.97 versus the mouse, rat, pig, marmoset and human tissues, respectively). In conclusion, [3H]-SB-269970 has been shown to radiolabel 5-HT7 receptors in rodent, pig and primate brain and represents a valuable tool with which to further characterise the distribution and function of 5-HT7 receptors in native tissues and elucidate their potential role in disease states.

Algorithms↗
PubMed2000

The 5-HT1A antagonist, WAY 100 635, alleviates cognitive impairments induced by dizocilpine (MK-801) in monkeys.

Central glutamate neurotransmission is modulated by an upregulatory cholinergic influence and an inhibitory serotonergic influence. In Alzheimer's disease, cognitive decline is associated with loss of both glutamatergic and cholinergic neurones (Francis et al., 1992, Progress in Neurobiology 39, 517-545). While therapeutic strategies for alleviating this cognitive decline have concentrated on restoring cholinergic tone, we suggest that 5-HT1A antagonists also have the potential to alleviate the cognitive symptoms of Alzheimer's disease. Previous studies have shown that dizocilpine (MK-801), a glutamatergic antagonist acting at the NMDA receptor, produces learning impairments in the common marmoset, a non-human primate. Specifically, it impairs the acquisition of shape discrimination and visuospatial conditional tasks, at doses that do not affect locomotor behaviour or coordination (Harder et al., 1998, Society for Neuroscience Abstracts 23(1), 219). In the present study we investigated the effects of WAY 100 635, a 5-HT1A antagonist, on the cognitive deficits induced by dizocilpine. The number of trials required to learn each type of task under combined treatment with dizocilpine and WAY 100 635 was significantly lower than under dizocilpine treatment alone, and did not differ significantly from the number of trials required under saline, demonstrating that the cognitive effects of glutamatergic blockade can be overcome by treatment with a 5-HT1A antagonist.

Animals↗
PubMedDate not supplied

Taste quality and intensity: lessons from the Morrison technique.

The nontoxic and nonshock Morrison operant technique was used to evaluate taste quality in rat and marmoset: response to a tastant test solution in pursuit of a pellet reward was dependent on making a choice between two bars that had been linked in discrimination training to qualitatively different stimulus pairs (NaCl versus either HCl, QHCl, or NH(4)Cl). The percentage distribution of bar-press responses to test stimuli showed: (1) stability of quality across 0.069-0.3 M NaCl, 0.003-0.1 M HCl, and 0.0001-0.003 M QHCl; (2) for LiCl, a quality change consistent with human reports of a "sour" to "salty" shift; (3) a suggestion that the "salty-like" quality of NH(4)Cl and NaCl are not perceptually equivalent; (4) NaNO(3) shares NaCl-like, QHCl-like, and NH(4)Cl-like components; (5) CaCl(2), KCl, and MgCl(2) share QHCl-like and NH(4)Cl-like components; and (6) responses to HCl and QHCl were not hedonically driven in the rat. Comparison of rank order correlations of single-unit firing rates to the distribution of bar-press responses for the same test stimulus concentration revealed that (7) no single level of the gustatory pathway exclusively accounts for the operant response distribution pattern to either simple or complex tastants, and (8) discriminations between tastants, one of which may be qualitatively complex, are not necessarily mediated only at levels proximal to the solitary nucleus. Thus, the Morrison discrimination technique effectively yields statements about gustatory quality without use of negative reinforcers and largely uninfluenced by tastant hedonics.

Animals↗
PubMed1998

Possible involvement of transforming growth factor-beta 1 and transforming growth factor-beta receptor type II during luteinization in the marmoset ovary.

The expression of transforming growth factor-beta 1 (TGF-beta 1), and transforming growth factor-beta receptor type II (T beta R-II), were evaluated in periovulatory marmoset ovaries. Histochemical methods were used, in particular double-labelling techniques, in order to correlate growth factor/receptor expression with proliferation (Ki 67), apoptosis (TUNEL method) and luteinization (3 beta-hydroxysteroid dehydrogenase (3 beta-HSD)). The latter was used as a luteinization marker. Periovulatory ovaries are especially suited for studying all aspects since they typically consist of small non-luteinized follicles, large luteinizing follicles and corpora lutea accessoria (Clas), which have developed from large luteinizing follicles. TGF-beta 1 and T beta R-II expression was found in luteinizing theca cells of large periovulatory follicles and in all luteal cells of Clas. Non-luteinized theca cells, including those of small follicles were always devoid of any immunostaining. Granulosa cells of small follicles were immunopositive for T beta R-II. Large follicles with granulosa cell immunoreactivity of both antibodies coexisted with non-reactive follicles of comparable size. The highest activity of the luteal marker enzyme 3 beta-HSD was co-localized in the same cells that expressed TGF-beta 1 and T beta R-II. The double-labelling experiments revealed that TGF-beta 1 and T beta R-II expression is not correlated with proliferation or apoptosis of follicular cells. Our results indicate that TGF-beta 1 and T beta R-II participate in differentiation processes, i.e. luteinization, rather than proliferation. In particular, the dynamics of T beta R-II expression appear highly related to the process of luteinization.

3-Hydroxysteroid Dehydrogenases↗
PubMed1998

Blockade of the hypothalamic-pituitary-testicular axis with a GnRH antagonist in the neonatal marmoset monkey: changes in Leydig cell ultrastructure.

Little is known of the cell biology of Leydig cells during the neonatal activation of the hypothalamic-pituitary-testicular (HPT) axis. The current study examined the effect of blockade of the HPT axis with a GnRH antagonist (antide) on the neonatal population of Leydig cells in the new world primate, the common marmoset. Three sets of twins, age 7 weeks, were studied: in each pair one twin was used as a control, while the other received treatment with GnRH antagonist from the day of birth to suppress pituitary gonadotrophin secretion. Leydig cells of treated animals were dramatically different from those of controls. The cells were atrophic and exhibited very irregular nuclei. The organelles involved in steroid synthesis were reduced to the extent to being barely evident. The smooth endoplasmic reticulum (SER) was greatly diminished in quantity and distribution. The usual form of the SER (anastomosing tubules) was not evident, but, instead, the SER was relatively unbranched. Peroxisomes, organelles involved in transfer of cholesterol to the mitochondria, were greatly reduced in number. Mitochondria were relatively sparse and exhibited a non-typical morphology, as tubular elements of the cristae were rarely evident. Thus, the central apparatus in steroid production, the SER, mitochondria and peroxisomes, was essentially shut down in the GnRH-antagonist-treated animals. Storage of cholesterol, the precursor of steroid biosynthesis, was also not in evidence, as lipid droplets were extremely rare. Two prominent features of control in neonatal marmoset Leydig cells, the membranofibrillar inclusion (MFI) and basal laminae, remain prominent in the Leydig cells of treated animals. Evidence of apoptosis was not observed. These results provide strong support that the gonadotrophic hormones are the primary regulator of neonatal Leydig cell development in primates, and also suggest cell regression, rather than apoptosis, being the mechanism of this inhibition.

Animals↗
PubMed2003

Long-term, low-level exposure of guinea pigs and marmosets to sarin vapor in air: lowest observable effect level.

Realistic scenarios for low-level exposure to nerve agents will often involve exposures over several hours to extremely low doses of agent. In order to expose animals to the lowest controllable concentrations of agent and to increase exposure times until a lowest observable effect level (LOEL) becomes measurable, a validated system was developed for exposing conscious animals to 0.05-1.0 microg/m(3) (8-160 ppt) of sarin and other nerve agents. Based on cold trapping of sarin from the exposure air, the concentration could be measured semicontinuously, at 4-min time intervals by means of gas chromatography. We found that the LOEL upon a 5-h whole body exposure of guinea pigs and marmosets to sarin vapor corresponds with the measurement of an internal dose by means of fluoride-induced regeneration of sarin from phosphylated binding sites in plasma, mostly BuChE. For guinea pigs the LOEL was observed at Ct = 0.010 +/- 0.002 mg/min/m(3), whereas a Ct of 0.04 +/- 0.01 mg/min/m(3) was established for the LOEL in marmosets. These levels are several orders of magnitude lower than those based on classical measurement of depressed cholinesterase activities. At low exposure levels of guinea pigs and marmosets (< or =1 microg/m(3)), a reasonable linearity was observed between exposure dose and internal dose. The data were addressed in the light of the recently recommended occupational exposure limits to sarin for workers without respiratory protection, which suggests that the exposure limits should be reconsidered if the slightest inhibition of cholinesterases should be prevented.

Animals↗
PubMed2003

Toxicokinetics of the nerve agent (+/-)-VX in anesthetized and atropinized hairless guinea pigs and marmosets after intravenous and percutaneous administration.

In continuation of our investigations on the toxicokinetics of the volatile nerve agents C(+/-)P(+/-)-soman and (+/-)-sarin, we now report on the toxicokinetics of the rather nonvolatile agent (+/-)-VX. A validated method was developed to determine blood levels of (+/-)-VX by means of achiral gas chromatography at blood levels > or =10 pg/ml. The ratio of the two enantiomers of VX in blood could be measured at levels > or =1 ng/ml by using chiral HPLC in combination with off-line gas chromatographic analysis. In order to obtain basic information on the toxicokinetics of (+/-)-VX, i.e., under conditions of 100% bioavailability, the blood levels of this agent were measured in hairless guinea pigs at iv doses corresponding with 1 and 2 LD50. The derived AUCs indicate a reasonable linearity of the toxicokinetics with dose. Also, the toxicokinetics in marmoset primates was studied at an absolute iv dose corresponding with 1 LD50 in the hairless guinea pig which led to approximately the same levels of (+/-)-VX in blood as observed at 2 LD50 in the hairless guinea pig. Finally, the toxicokinetics of (+/-)-VX were measured in hairless guinea pigs via the most relevant porte d' entrée for this agent, which is the percutaneous route at a dose corresponding with 1 LD50 (pc). Large variations were observed between individual animals in the rate of penetration of (+/-)-VX and in concomitant progression of AChE inhibition in blood of these animals. Blood levels of (+/-)-VX increased gradually over a 6-h period of time. After a 7-h penetration period, the total AUC corresponded with 2.5% bioavailability relative to iv administration. In contrast with the G-agents C(+/-)P(+/-)-soman and (+/-)-sarin, stereospecificity in the sequestration of the two enantiomers of (+/-)-VX is not a prominent phenomenon. It appears that (+/-)-VX is substantially more persistent in vivo than the two G-agents. This persistence may undermine the efficacy of pretreatment with carbamates of percutaneous intoxication in particular due to gradual replacement of carbamate on AChE by (+/-)-VX, whereas classical treatment of intoxication with oximes is hampered by the short persistence of oximes relative to the agent.

Acetylcholinesterase↗
PubMed2003

Comparison of tamarins and marmosets as hosts for GBV-B infections and the effect of immunosuppression on duration of viremia.

GBV-B virus is a close relative to hepatitis C virus (HCV) that causes hepatitis in tamarins, and thus, is an attractive surrogate model for HCV. In this study, we demonstrate that the host range of GBV-B extends to the common marmoset with an infection profile similar to that observed for tamarins. Marmoset hepatocytes were susceptible to in vitro infection with GBV-B. Virus was efficiently secreted into the medium, and approximately 25% of hepatocytes were positive for NS3 staining. In an attempt to induce persistent infections, tamarins were immunosuppressed with FK506 and inoculated with GBV-B. Although no chronic infections were induced, the duration of viremia was increased in most animals. In one animal, the duration of viremia was extended to 46 weeks, but viral clearance occurred 18 weeks after stopping FK506 therapy. The greater availability of marmosets in comparison to tamarins will greatly facilitate future research efforts with this model.

Animals↗
PubMed2001

Compensatory changes in eye growth and refraction induced by daily wear of soft contact lenses in young marmosets.

Several studies have shown that growth of the primate eye responds in a compensatory direction to both positive and negative spectacle lenses--eyes grow more slowly and become hyperopic in response to positive lenses, and eyes grow more rapidly and become myopic in response to negative lenses. On the other hand, extended wear soft contact lenses, whether positively or negatively powered, induce hyperopia (Hung & Smith, 1996. Extended-wear, soft, contact lenses produce hyperopia in young monkeys. Optometry & Vision Science 73, 579-584.). We investigated whether responses in a compensatory direction occurred to soft contact lenses worn on a daily wear basis (8 h per day on an 8:16 h light:dark cycle). Ten infant marmosets (8-13 weeks of age) wore a soft contact lens, in one eye only, for 5-9 weeks. Lens powers used were zero (n = 2), +2 D (n = 1), +2 D followed after 5 weeks of lens wear by +4 D (n = 1) for 4 weeks, +4 D (n = 2), -2 D followed after 5 weeks of lens wear by -4 D (n = 2) for 4 weeks, -4 D (n = 2). At the end of the lens-wear period the positive lens-wearing eyes were more hyperopic relative to the fellow untreated eyes [mean +2.39 +/- 0.24 D (SE)] and the negative lens-wearing eyes were more myopic than the fellow untreated eyes [mean -2.48 +/- 0.91 D (SE)]. Fellow eyes were unaffected by lens wear [mean final refraction +0.45 +/- 0.09 D (SE)]. Plano lenses did not affect eye growth in either marmoset fitted with plano contact lenses.

Analysis of Variance↗
PubMed2001

Overnight lens removal avoids changes in refraction and eye growth produced by plano soft contact lenses in infant marmosets.

Infant marmosets were fitted with zero-powered (plano) soft contact lenses from 4 to 8 weeks of age worn either continuously (24 h per day) (n = 4), for 12 h (n = 4), or for 8 h (n = 3) per day to determine whether limiting the daily duration of lens-wear could significantly reduce or eliminate the effects of continuous lens-wear on ocular growth and refractive state. As in macaques (Hung, L. F., & Smith, E. L. (1996). Extended-wear, soft, contact lenses produce hyperopia in young monkeys. Optometry and Vision Science, 73, 579-584), eyes fitted with contact lenses worn continuously developed more hyperopic refractions (mean +3.22 +/- 1.49 D SE) compared to their fellow untreated eyes, inconsistent changes in vitreous chamber depth (-0.02 +/- 0.09 mm SE) and flatter corneas (mean decrease in corneal power 4.22 +/- 0.39 D SE). Eyes wearing lenses for only 12 h per day showed similar but reduced effects compared to the 24-h group. Most importantly, ocular growth, corneal power and refraction were unaffected in the 8-h group. Future studies using contact lenses in infant primates should employ a reduced daily duration of lens-wear to eliminate the undesirable effect of contact lens-wear per se on ocular development.

Analysis of Variance↗
PubMed1997

Temporal properties of marmoset lateral geniculate cells.

We measured the temporal modulation transfer functions (TMTFs) of cells in the marmoset lateral geniculate nucleus (LGN) at three different luminance levels, and described the responses with a linear model. It was found that qualitatively there are many similarities with the temporal response properties of macaque and marmoset retinal ganglion cells. M-cells displayed stronger attenuation at lower temporal frequencies, and showed more nonlinearities (such as saturation and a contrast gain control) than P-cells. We therefore propose that the temporal properties of the visual system of New and Old World monkeys are similar at least up to the LGN. However, there are some quantitative differences, indicating that response alterations take place at the stage of synaptic transmission in the LGN. The most important are an attenuation of the responses to higher temporal frequencies and the smaller differences between parvo- and magnocellular cell responsivities. Cell responses to square-wave modulation were also measured and compared with predictions from a linear systems analysis. The linear systems analysis gave reasonable predicted responses to square-wave modulation, but these predictions were poor than those for retinal ganglion cells, indicating that additional nonlinearities are introduced at the synaptic transition in the LGN.

Animals↗
PubMed1998

Comparative retinal physiology in anthropoids.

During the last decade it has become clear that colour vision in platyrrhines (New World monkeys) differs from the uniform trichromatic pattern normally found in catarrhines (Old World monkeys, apes and human). Colour vision in most platyrrhine species is polymorphic, with many dichromatic individuals. The comparison of response properties in retinal ganglion cells and lateral geniculate cells between catarrhines and playrrhines elucidates how the evolution of trichromatic colour vision influenced the post-receptoral processing. We find that spatial and temporal processing is very similar in the platyrrhine and catarrhine retina, strongly suggesting that the retinal structure and function, found in living anthropoids, was already present in their common ancestor.

Action Potentials↗