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PubMed2003

Pterygodermatites nycticebi (Nematoda: Rictulariidae): accidental detection of encapsulated third-stage larvae in the tissue of a white-fronted marmoset.

Twin, white-fronted marmosets (Callithrix geoffroyi) born and raised in a zoo in Japan died at 7 mo of age. Several encapsulated nematode larvae were detected in the intestinal wall, as well as a few in the mesenteric lymph nodes of 1 of the twins. In the other marmoset, no encapsulated nematode larva was detected in the organs, but many adult Pterygodermatites nycticebi were found in the intestinal lumen. In the past 5 yr, 5 primates kept in the same zoo, i.e., 1 squirrel monkey (Saimiri sciureus), 2 Pygmy marmosets (Cebuella pygmaea), 1 Senegal galago (Galago senegalensis), and 1 cotton-top tamarin (Saguinus oedipus), died from heavy infestation with the same nematode. A few migrating larvae of the rictulariid were also identified histologically in the intestinal wall and liver of the cotton-top tamarin. Although no other primate currently held in the same zoo was infected with the rictulariid, German cockroaches (Blattella germanica) collected with traps near marmoset cages had encapsulated P. nycticebi larvae, indicating latent perpetuation of the life cycle of this rictulariid species in the zoo premises. Our results indicated that encapsulation or migration of third-stage larvae of P. nycticebi might occur accidentally in the organs of callithrichid primates.

Animals↗
PubMed2001

Molecular evolution of GH in primates: characterisation of the GH genes from slow loris and marmoset defines an episode of rapid evolutionary change.

Pituitary growth hormone (GH), like several other protein hormones, shows an unusual episodic pattern of molecular evolution in which sustained bursts of rapid change are imposed on long periods of very slow evolution (near-stasis). A marked period of rapid change occurred in the evolution of GH in primates or a primate ancestor, and gave rise to the species specificity that is characteristic of human GH. We have defined more precisely the position of this burst by cloning and sequencing the GH genes for a prosimian, the slow loris (Nycticebus pygmaeus) and a New World monkey, marmoset (Callithrix jacchus). Slow loris GH is very similar in sequence to pig GH, demonstrating that the period of rapid change occurred during primate evolution, after the separation of lines leading to prosimians and higher primates. The putative marmoset GH is similar in sequence to human GH, demonstrating that the accelerated evolution occurred before divergence of New World monkeys and Old World monkeys/apes. The burst of change was confined largely to coding sequence for mature GH, and is not marked in other components of the gene sequence including signal peptide, 5' upstream region and introns. A number of factors support the idea that this episode of rapid change was due to positive adaptive selection. Thus (1) there is no apparent loss of function of GH in man compared with non-primates, (2) after the episode of rapid change the rate of evolution fell towards the slow basal level that is seen for most mammalian GHs, (3) the accelerated rate of substitution for the exons of the GH gene significantly exceeds that for introns, and (4) the amino acids contributing to the hydrophobic core of GH are strongly conserved when higher primate and other GH sequences are compared, and for coding sequences other than that coding for hydrophobic core residues the rate of substitution for non-synonymous sites (K(A)) is significantly greater than that for synonymous sites (K(S)). In slow loris, as in most non-primate mammals, there is no evidence for duplication of the GH gene, but in marmoset, as in rhesus monkey and man, the putative GH gene is one of a cluster of closely related genes.

Animals↗
PubMed2004

Cloning of oestrogen receptor beta from Old and New World primates: identification of splice variants and functional analysis.

Oestrogens have a major impact on reproductive function in both males and females. Two oestrogen receptor genes known as ERalpha (ESR1NR3A1) and ERbeta (ESR2NR3A2) have been cloned. Splice variant isoforms of the ERbeta gene have been identified in human, bovine and rodents and it has been suggested that the existence of these forms can influence oestrogen responsiveness. In the human, splicing of an alternative eighth exon results in the formation of a C-terminal variant called hERbetacx, or hERbeta2, but this isoform has not been identified in other species. The aim of the present study was to clone ERbeta cDNAs from primates so as to determine how closely they resembled the ERbeta isoforms found in the human. The two species studied were the stump-tailed macaque (Macaca arctoides), an Old World primate, and the common marmoset (Callithrix jacchus jacchus), a New World primate. Full length ERbeta (wild type, ERbeta1) cDNAs were cloned from macaque and marmoset; they encoded proteins of similar size to those found in human (59 and 54 kDa, long and short forms respectively) and shared significant sequence homology (97.5% in macaque and 93.8% in marmoset) with the human peptide sequence. Full length cDNAs homologous to the hERbeta2 variant were identified in both primates. Marmoset ERbeta2 was slightly shorter than that of human ERbeta2 (54 kDa compared with 55 kDa) and did not contain the peptide sequence used to raise an anti-hERbeta2 antibody. All the macaque ERbeta2 cDNAs contained 56 bp of intronic sequence which included an in-frame stop codon resulting in translation of a truncated protein ( approximately 35 kDa). In all three species, truncated, alternatively spliced mRNAs lacking exon 5 were isolated on multiple occasions from all tissue extracts. In transient transfection assays, ERbeta2-containing constructs were unable to induce transcription of an oestrogen response element (ERE) reporter plasmid in the presence of oestradiol. ERbeta1 from human, macaque and marmoset exhibited minor differences in their ability to induce transcription of the ERE reporter when incubated with different ligands (oestradiol, PPT, DPN, 5-alpha-androstane-3-beta, 17beta-diol (3betaAdiol), genistein) and this may be due to amino acid substitutions within their ligand binding domains. In conclusion, we have identified and cloned wild type ERbeta (ERbeta1) from macaque and marmoset and demonstrated that splice variant mRNAs homologous to hERbeta2 are formed in both species. The marmoset monkey, therefore, provides a suitable animal model in which to investigate the impact of ERbeta variant expression on tissue responsiveness to oestrogens.

Alternative Splicing↗
PubMed1984

Ovulation in the marmoset monkey: endocrinology, prediction and detection.

Circulating progesterone, oestrogens and LH were measured in female marmosets (Callithrix jacchus) over the periovulatory period. Progesterone concentrations increased in all animals within 1 day of the estimated day of ovulation, confirming the usefulness of this hormone for retrospective detection of ovulation. Oestradiol-17 beta and LH both showed a preovulatory rise, but due to the large quantity of plasma required (oestradiol: 0.2 ml) and the length of time taken for the assay (LH: 2-3 days), measurement of these hormones is not practical for the prediction of ovulation. There were no preovulatory changes in unconjugated oestrone, but a rise in total (i.e. conjugated plus unconjugated) oestrone was used to time the collection of recently ovulated oocytes. Levels of oestrone-3-sulphate showed an increase at least 1 day before the expected day of ovulation in four out of five animals. This preovulatory rise can be measured easily by a rapid direct assay, thereby providing a practical method for predicting ovulation in this species.

Animals↗
PubMed1989

Control of inhibin production by primate granulosa cells.

In-vitro data from experiments on rats implicate granulosa cells as primary sites of hormone-dependent ovarian inhibin biosynthesis, but no equivalent data exist for primates. We have used the common marmoset (Callithrix jacchus) to investigate inhibin biosynthesis in primate granulosa cells in vitro and to determine its relationship to preovulatory follicular development. To relate the production of immunoactive inhibin to follicular maturity, we studied primary granulosa cell cultures from follicles at progressive stages of preovulatory development. Granulosa cells from 'large' (greater than or equal to 2.0 mm diameter) follicles expressed high rates of inhibin production and steroidogenesis (progesterone), and were positively regulated by human (h)LH in vitro. Less mature granulosa cells from 'medium' (1.1-1.9 mm) and 'small' (less than or equal to 1.0 mm) follicles expressed proportionately lower rates of inhibin production and steroidogenesis, but each parameter was stimulated in a dose- and time-dependent manner by hFSH in vitro. The stimulatory action of hFSH on immunoreactive inhibin was augmented by the presence of testosterone or oestradiol; testosterone (but not oestradiol) also augmented the steroidogenic response to hFSH. Marmoset luteal tissue also produced inhibin in vitro and expressed an approximately 1.5 kb inhibin alpha-subunit mRNA, confirming the corpus luteum as a source of ovarian inhibin in primates. These results provide direct experimental evidence that primate granulosa cells produce inhibin. They suggest that production of inhibin by immature granulosa cells is initially induced by FSH and subject to modulation by follicular steroids.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Inhibin secretion during the ovulatory cycle and pregnancy in the common marmoset monkey.

Changes in plasma concentrations of immunoreactive inhibin in the reproductively cyclic, pregnant and ovariectomized female marmoset monkey (Callithrix jacchus) were measured with a heterologous radioimmunoassay. The pattern of inhibin secretion in five marmosets studied individually during four consecutive cycles was shown to resemble that of progesterone. In these animals, data were pooled according to stage of cycle on the basis of plasma progesterone concentrations. Mean values for inhibin were 5465 and 4972 U/l during the early and late follicular phase. Concentrations rose during the luteal phase to 8431, 12,246 and 12,557 U/l for the early, mid- and late luteal phase respectively. The hormonal profile of inhibin during the normal cycle is similar in both marmoset and stumptailed macaque; however, the marmoset has a 28-fold greater level of inhibin during the luteal phase. In six marmosets in which pregnancy occurred, inhibin concentrations showed no decline at the end of the conceptual cycle and remained increased with respect to the follicular phase throughout the subsequent gestation. Inhibin levels were non-detectable (less than 1000 U/l) in ovariectomized and acyclic marmosets. These results suggest that the corpus luteum is the major source of inhibin in this New World monkey, in common with man and the Old World primates.

Animals↗
PubMed1992

Effects of oestradiol-17 beta on FSH-stimulated steroidogenesis in cultured marmoset granulosa cells.

A role for oestradiol in ovarian follicular development is well recognized. However, a number of disparate effects have been reported for the action of oestradiol in the primate ovary. To investigate this further, we have examined the effects of oestradiol on the differentiation of granulosa cells isolated from small (0.5-1 mm) antral follicles obtained from the ovaries of prepubertal marmoset monkeys (Callithrix jacchus). Granulosa cells were co-cultured with oestradiol and human FSH (hFSH) for 48 h, or were pretreated with oestradiol for 48 h before addition of gonadotrophin for a further 48 h. Oestradiol (0.01-100 nmol/l) had no effect on basal or hFSH-stimulated progesterone accumulation and aromatase activity when the hormones were added concurrently. Furthermore, oestradiol did not influence the ability of hFSH to induce LH/human chorionic gonadotrophin (hCG) responsiveness in immature granulosa cells. The absence of synergism between oestradiol and hFSH in the induction of marmoset granulosa cell differentiation was independent of the presence of phenol red in culture medium. However, gonadotrophin-stimulated steroidogenesis was attenuated when cells were cultured in the presence of phenol red compared with in its absence; this effect was more pronounced for gonadotrophin-stimulated aromatase activity but was evident for LH/hCG-stimulated progesterone accumulation at higher doses of hCG (10 and 100 ng/ml). An effect of phenol red on basal steroidogenesis was less obvious.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

Immunolocalisation of oestrogen receptor-alpha within the testis and excurrent ducts of the rat and marmoset monkey from perinatal life to adulthood.

The sites of action and the physiological role of oestrogens in the male reproductive tract are poorly understood. We have undertaken a systematic study of the immunoexpression of oestrogen receptor-alpha (ER alpha) in the male rat from late fetal life through to adulthood and compared the findings with results obtained in the marmoset monkey (Callithrix jacchus) from neonatal to adult life. The testes, rete testis, efferent ducts and epididymis were examined from normal male rats (aged 4, 8, 10, 15, 20, 25, 38, 48 and 90 days) and from male rat fetuses on days 17.5 and 18.5 of gestation; comparable tissues were examined from neonatal, infantile, peripubertal and adult marmosets aged 8, 18-24, 54-62 and 92-112 weeks respectively. Immunolocalisation of ER alpha used antigen retrieval and a monoclonal antibody directed to the N-terminus, which had proved superior to six other antisera tested. ER alpha was immunoexpressed in interstitial cells, including the fetal/ neonatal generation of Leydig cells, in both the rat and marmoset. In the rat, the adult generation of Leydig cells were also immunopositive for ER alpha whereas the comparable cells in the marmoset were only weakly immunopositive. ER alpha was not expressed in Sertoli cells, peritubular myoid cells, blood vessels or germ cells at any time in either species. In late fetal life in the rat, ER alpha was immunoexpressed in cells surrounding the mesonephric tubules, whereas postnatally it was expressed in the epithelium of the rete testis and efferent ducts at all ages from 4 to 90 days; this immunoexpression was most pronounced in the efferent ducts. In the marmoset, the efferent ducts, but not the rete testis, also showed intense immunoexpression of ER alpha. Apart from sporadic immunostaining for ER alpha in the epididymal duct of the rat in the neonatal period, the caput, corpus and cauda epididymis were negative for immunoexpression of ER alpha at all ages in both species. These findings suggest that the main actions of oestrogens in the male reproductive tract, mediated by ER alpha, are related to the development and function of the efferent ducts and the Leydig cells. In consideration of data from this and previous studies of oestrogen binding, we predict possible sites of expression of other oestrogen receptors (e.g. ER beta) in Sertoli cells and the epididymis. Interactive effects, related to the relative levels of androgens and oestrogens, could be physiologically important in the excurrent ducts of the adult testis.

Age Factors↗
PubMed1997

IGF-I variants which bind poorly to IGF-binding proteins show more potent and prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys.

The relative acute hypoglycaemic potencies of IGF-I and several variants of IGF-I which bind poorly to the IGF-I binding proteins (IGFBPs) have been examined in marmosets (Callithrix jacchus) and the pig. In the marmoset study, IGF-I and des(1-3)IGF-I were compared in anaesthetised and conscious animals in a range of bolus doses from 42 to 270 micrograms/kg body weight. In the pig study, IGF-I was compared with four variants, des(1-3)IGF-I long-IGF-I, R3IGF-I and long-R3IGF-I (LR3IGF-I), which show reduced affinity for the IGFBPs as well as with insulin. Doses in the pig were 20 and 50 micrograms/kg body weight for the IGFs and 3 micrograms/kg for insulin. In each study serial blood samples were taken from 30 min before to 4 h after the bolus injection. Plasma glucose levels were decreased in a dose-responsive manner with the pig more sensitive than either the conscious or anaesthetised marmoset (maximum lowering 4.8, 3.7 and 2.5 mmol/l respectively). The IGF variants were consistently 2- to 3-fold more potent than IGF-I in each animal for lowering of plasma glucose to the nadir, with the potency reflecting the relative affinities for binding to the IGFBPs and the IGF-I receptors. Thus, hypoglycaemic potency was in the order IGF-I < long-IGF-I < R3IGF-I approximately LR3IGF-I < des (1-3)IGF-I. Notably the variants suppressed plasma glucose levels over a much longer period than did IGF-I, the cumulative suppression over four hours showing an approximately 4- to 8-fold increase in the extent of hypoglycaemia. The prolonged suppression was not simply proportional to the hypoglycaemic nadir; at doses equipotent for glucose lowering, the cumulative hypoglycaemic effect for the variants in either species was about 2-fold that for IGF-I. The differential effect of the variants in the marmoset could not be accounted for by correlated changes in plasma insulin, IGF-I or IGFBP levels in plasma. Indirect effects via inhibition of glucagon, or direct effects via hepatic insulin receptors are postulated to account for the results. There was a dose-related reduction in plasma amino acids in the pig but, unlike the case for plasma glucose, only one analogue, LR3IGF-I was more potent than IGF-I. The response to LR3IGF-I was accentuated at the high dosage but on the basis of the other variants tested this effect could not be ascribed to either of the incorporated molecular variations. Despite their more rapid clearance from the circulation, variants of IGF-I which show lower affinity for binding to IGFBPs show proportionately superior potency for sustained hypoglycaemic action. Since our data were obtained in animal models of accepted relevance to humans these results point to the possible superior efficacy of the variants, especially des(1-3)IGF-I, over IGF-I for use as an adjunct to insulin treatment of hyperglycaemic conditions.

Amino Acids↗
PubMed1996

Cutaneous representations of the hand and other body parts in the cuneate nucleus of a primate, and some relationships to previously described cortical representations.

Dynamic properties of primate somatosensory maps are dependent on normal central adjacencies of cutaneous representations. The cuneate nucleus is an important brainstem processing center of cutaneous information. Surprisingly, there are no descriptions of functional representations of the skin in the primate cuneate nucleus; as a result, the relationships of functional representations at the brainstem level and other levels of the somatosensory neuraxis remain obscure. The present neurophysiological study indicates that the main cuneate nucleus of marmoset monkeys (Callithrix jacchus) contains organized representations of cutaneous inputs from the hand, forelimb, and adjacent body between the lateral face and proximal hindlimb. Inputs from the glabrous hand are represented continuously across transverse planes in the cuneate, whereas inputs from the hairy hand are represented discontinuously. Inputs from distal to proximal, and radial to ulnar, parts of the hand are mapped in an organized manner. At rostrocaudal levels where the cuneate nucleus is near its largest transverse area, the map of the hand is about 2600 times smaller than the hand skin area it represents. Cuneate representations of the forelimb and trunk are represented both medial and lateral to the hand representation, and interface with representations in the adjacent gracile and trigeminal nuclei. These findings provide a starting point for understanding functional representations of the skin in the cuneate nucleus of primates. Furthermore, they provide a basis for understanding relationships of cutaneous representations at different levels of the neuraxis. In this regard, comparisons of the present results to previously defined representations in the somatosensory (area 3b) cortex indicate that cuneate hand representations are several times smaller than cortical representations, and that there are similarities and differences in adjacencies of cuneate and cortical representations.

Animals↗
PubMed2005

Oropouche virus isolation, southeast Brazil.

An Oropouche virus strain was isolated from a novel host (Callithrix sp.) in Arinos, Minas Gerais State, southeastern Brazil. The virus was identified by complement fixation test and confirmed by reverse transcription-polymerase chain reaction. Phylogenetic analysis identified this strain as a genotype III isolate previously recognized only in Panama.

Animals↗
PubMed2000

Myelin/oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis in common marmosets: the encephalitogenic T cell epitope pMOG24-36 is presented by a monomorphic MHC class II molecule.

Immunization of common marmosets (Callithrix jacchus) with a single dose of human myelin in CFA, without administration of Bordetella pertussis, induces a form of autoimmune encephalomyelitis (EAE) resembling in its clinical and pathological expression multiple sclerosis in humans. The EAE incidence in our outbred marmoset colony is 100%. This study was undertaken to assess the genetic and immunological basis of the high EAE susceptibility. To this end, we determined the separate contributions of immune reactions to myelin/oligodendrocyte glycoprotein (MOG) and myelin basic protein to the EAE induction. Essentially all pathological features of myelin-induced EAE were also found in animals immunized with MOG in CFA, whereas in animals immunized with myelin basic protein in CFA clinical and pathological signs of EAE were lacking. The epitope recognition by anti-MOG Abs and T cells were assessed. Evidence is provided that the initiation of EAE is based on T and B cell activation by the encephalitogenic phMOG14-36 peptide in the context of monomorphic Caja-DRB*W1201 molecules.

Animals↗
PubMed1998

The zoonotic importance of Mycobacterium tuberculosis: transmission from human to monkey.

A case of zoonotic Mycobacterium tuberculosis infection in a marmoset (Callithrix jacchus) is reported. Genomic typing of the relevant M. tuberculosis isolates strongly suggests that the marmoset, which was kept as companion animal, acquired the disease from an infected member in the household who had been treated for pulmonary tuberculosis 8 years prior to this case.

Animals↗
PubMed2002

Functional domains in dorsal striatum of the nonhuman primate are defined by the dynamic behavior of dopamine.

The dorsal striatum comprises a continuum of distinct functional domains, limbic, associative, and sensorimotor. In the primate it exclusively subdivides further into two nuclei, the putamen and caudate. Dopamine (DA) transmission is differentially affected between these nuclei in neurodegenerative diseases such as Parkinson's and by psychostimulants such as cocaine. Because rodent systems can offer only limited insight into DA systems of the human brain, a fuller appreciation of DA transmission and its role in dysfunction requires direct study in primates. DA behavior was explored in the major functional domains of the caudate nucleus and compared with the putamen, using fast-scan cyclic voltammetry in striatal sections from the marmoset (Callithrix jacchus). There was domain-specific variation in extracellular DA transients [i.e., concentration ([DA](o)) released by a single stimulus and the rate maximum of DA uptake, V(max)]. Across nuclei, functional rather than anatomical regions were differentiated by these dynamics. The largest, fastest DA transients were at motor-associated loci. Evoked [DA](o) at physiological frequencies was differently frequency-sensitive between functional domains but not between anatomical nuclei. In contrast, presynaptic depression was not an index of regional differentiation, recovering with similar kinetics at all loci. Within a given functional domain of dorsal striatum, the dynamics of DA release and uptake are similar for the putamen and the caudate nucleus. Conversely, distinct functional domains are defined by these DA dynamics, in a manner more marked in primates than in rodents. These data from the primate brain highlight differences in DA availability that may be central to DA function and dysfunction in the human.

Animals↗
PubMedDate not supplied

Food avoidance learning in squirrel monkeys and common marmosets.

Using a conditioned food avoidance learning paradigm, six squirrel monkeys (Saimiri sciureus) and six common marmosets (Callithrix jacchus) were tested for their ability to (1) reliably form associations between visual or olfactory cues of a potential food and its palatability and (2) remember such associations over prolonged periods of time. We found (1) that at the group level both species showed one-trial learning with the visual cues color and shape, whereas only the marmosets were able to do so with the olfactory cue, (2) that all individuals from both species learned to reliably avoid the unpalatable food items within 10 trials, (3) a tendency in both species for quicker acquisition of the association with the visual cues compared with the olfactory cue, (4) a tendency for quicker acquisition and higher reliability of the aversion by the marmosets compared with the squirrel monkeys, and (5) that all individuals from both species were able to reliably remember the significance of the visual cues, color and shape, even after 4 months, whereas only the marmosets showed retention of the significance of the olfactory cues for up to 4 weeks. Furthermore, the results suggest that in both species tested, illness is not a necessary prerequisite for food avoidance learning but that the presumably innate rejection responses toward highly concentrated but nontoxic bitter and sour tastants are sufficient to induce robust learning and retention.

Animals↗
PubMed2000

Dopamine release and uptake dynamics within nonhuman primate striatum in vitro.

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.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2000

Distribution of glycine receptor subunits on primate retinal ganglion cells: a quantitative analysis.

This study investigates the distribution of inhibitory neurotransmitter receptors on sensory neurons. Ganglion cells in the retina of a New World monkey, the common marmoset Callithrix jacchus, were injected with Lucifer yellow and Neurobiotin and subsequently processed with antibodies against one (alpha1), or against all subunits, of the glycine receptor, or against the anchoring protein gephyrin. Immunoreactive (IR) puncta representing glycine receptor or gephyrin clusters were found on the proximal and the distal dendrites of all ganglion cell types investigated. For both parasol and midget cells, the density of receptor clusters was greater on distal than proximal dendrites for all antibodies tested. In parasol cells the average density for the alpha1 subunit of the glycine receptor was 0.087 IR puncta/microm of dendrite, and for all subunits it was 0.119 IR puncta/microm of dendrite. Thus, the majority of glycine receptors on parasol cells contain the alpha1 subunit. For parasol cells, we estimated an average of 1.5 glycinergic synapses/100 microm2 dendritic membrane on proximal dendrites and about 9.4 glycinergic synapses/100 microm2 on distal dendrites. The segregation of receptors to the distal dendrites appears to be a common feature of inhibitory neurotransmitter input to parasol and midget cells, and might be associated with the receptive field surround mechanism.

Animals↗
PubMed2001

[Horizontal transmission of live attenuated hepatitis A vaccine virus].

OBJECTIVE: To investigate the horizontal transmission of virus after inoculation with live attenuated hepatitis A vaccine. METHODS: One hundred and ninety nine children aged 4 approximately 7 years without anti-HAV and with normal ALT level have been screened out at two trial fields in Anning, Kunming and divided into vaccine group (82 children) and contact group (117 children) to observe the horizontal transmission of the live attenuated hepatitis A vaccine virus (H2 strain). Four supernatant specimens of HAV positive fecal suspension derived from individual vaccines and contacts were taken and injected intravenousely into 8 common marmoset (Callithrix jacchus) for detecting the virulence level of HAV. RESULTS: The rates of seroconversion were 97.6% (80/82) for vaccine group 6 weeks after inoculation and 13.7% (16/117) for contact group at the ninth week of observation. The detection rates of fecal HAV were 89.5% (34/38) and 70.7% (53/75), respectively. No liver functional abnormality has been found in either groups. The responses of 8 marmosets separately infected with fecal shedding HAV of 2 vaccines and 2 contacts have been examined with neither elevations of serum liver enzyme nor liver histopathological changes but delay seroconversions as well as low titers of anti-HAV. CONCLUSION: The safety and immunogenicity live attenuated hepatitis A vaccine (H2 strain) were good. The vaccine virus could actively propagate but keep the stability of attenuated characteristics in human bodies, and might result in horizontal transmission but not induce hepatitis A in crowd.

Animals↗