Discrete reduction patterns of parvalbumin and calbindin D-28k immunoreactivity in the dorsal lateral geniculate nucleus and the striate cortex of adult macaque monkeys after monocular enucleation

We analyzed the immunohistochemical distribution of the two calcium-binding proteins, parvalbumin (PV) and calbindin D-28k (CB), in the primary visual cortex and lateral dorsal geniculate nucleus (dLGN) of monocularly enucleated macaque monkeys (Macaca fascicularis and Macaca nemestrind) in order to determine how the expression of PV and CB is affected by functional inactivity. The monkeys survived 1-17 weeks after monocular enucleation. The distribution pattern of each of the proteins was examined immunocytochemically using monoclonal antibodies and compared with that of the metabolic marker cytochrome oxidase (CO). We recorded manually the number of immunostained neurons and estimated the concentration of immunoreactive staining product using a computerized image-acquisition system. Our results indicate a decrease of approximately 30% in the labeling of PV-immunoreactive (ir) neuropil particularly in those layers of denervated ocular-dominance columns receiving the geniculocortical input. There was no change in the number of PV-ir neurons in any compartment irrespective of the enucleation interval. For CB-ir, we found a 20% decrease in the neuropil labeling in layer 2/3 of the denervated ocular-dominance columns. In addition, a subset of pyramidal CB-ir neurons in layers 2 and 4B, which are weakly stained in control animals, showed decreased labeling. In the dLGN of enucleated animals, PV-ir and CB-ir were decreased only in the neuropil of the denervated layers. From these results, we conclude that cortical interneurons and geniculate projection neurons still express PV and CB in their cell bodies after disruption of the direct functional input from one eye. The only distinct decrease of PV and CB expression is seen in axon terminals from retinal ganglion cells in the dLGN, and in the axons and terminals of both geniculocortical projection cells and cortical interneurons in the cerebral corte

Bacterial Causes of Empyema in Children, Australia, 2007–2009

Most infections were caused by non–7-valent pneumococcal conjugate vaccine serotypes

Expression of glycine and the glycine transporter Glyt-1 in the developing rat retina

Previous studies show that glycine transporter-1 (glyt-l) is a consistent membrane marker of adult retinal neurons that are likely to release glycine at their synaptic terminals (Pow, 1998; Vaney et al., 1998; Pow & Hendrickson, 1999). The current study investigated when glyt-l immunoreactivity appeared in the postnatal rat retina, and whether all glycine-containing neurons also labelled for glyt-1. Ganglion cells, horizontal cells, and photoreceptors showed transient labelling. Many cells in the ganglion cell layer are immunoreactive for both glycine and glyt-1 at postnatal day (Pd) 1 but both are minimal by Pd5. Transient immunoreactivity for both glyt-1 and glycine was observed in presumptive horizontal cells between Pd5 and Pd10. At Pd1 many cells in the outer part of the retina which resembled immature photoreceptors were heavily labelled for glycine, but did not express glyt-1; these disappeared at older ages. These findings suggest diverse mechanisms and transient roles for glycine in the developing rat retina. In the adult rat retina, a subpopulation of amacrine cells are prominently immunoreactive for both glycine and glyt-1. These cells labelled for glycine at Pd1, but did not express significant levels of glyt-1 until Pd5. Processes from these amacrine cells did not reach the inner half of the inner plexiform layer until Pd10-14. Bipolar cells became glycine-IR between Pd10 and Pd14, but consistently lacked any glyt-1 immunoreactivity. This temporal pattern of labelling strongly indicates that bipolar cells label for glycine when gap junctions become functional between glycine/glyt-1 immunoreactive amacrine cells and cone bipolar cells

Distribution of the glycine transporter glyt-1 in mammalian and nonmammalian retinae

We have examined the distribution of the glycine transporter glyt-1 in retinae of macaques, cats, rabbits, rats, and chickens. In all species, all glycine-containing amacrine cells expressed immunoreactivity for glyt-1, though the intensity of immunoreactivity for glyt-1 did not appear to directly correlate with the intensity of immunoreactivity for glycine in individual cells. A small subpopulation of glycine-immunoreactive displaced amacrine cells or ganglion cells also expressed glyt-1 in retinae from macaques, cats, chickens, and rats but not in retinae from rabbits. In addition, in all species examined, some displaced amacrine cells also contained glycine but did not express glyt-1. In monkeys, cats, and rats, populations of cells which we interpret as being glycine-containing interplexiform cells expressed glyt-1; these cells lacked a content of glutamate, suggesting they are not bipolar cells. The glycine-containing bipolar cells did not express glyt-1, suggesting that these cells probably acquired their content of glycine by other means such as via gap junctional connections with glycine-containing amacrine cells

Distribution of short-wavelength-sensitive cones in human foetal and postnatal retina: early development of spatial order and density profiles

We analysed spatial density and distribution of short-wavelength-sensitive photoreceptors (S-cones) in developing and adult human retinae using antibody against short-wavelength-sensitive opsin. Statistical tests indicate that before 20 weeks of gestation (WG) the S-cone mosaic is not distinguishable from a random distribution, but by 20 WG is significantly different from a random distribution in the perifoveal region, as reported previously for adult retina. Changes in spatial density during development are consistent with displacement of the photoreceptor population towards the incipient fovea so that prior to 20 WG, peak S-cone density is >1.7 mm from the fovea, but is within 800 μm of the fovea by 20 WG

Differential distribution of fibroblast growth factor receptors (FGFRs) on foveal cones: FGFR-4 is an early marker of cone photoreceptors

Purpose: Relatively little is known of the expression and distribution of FGF receptors (FGFR) in the primate retina. We investigated expression of FGFRs in developing and adult Macaca monkey retina, paying particular attention to the cone rich, macular region. Methods: One fetal human retina was used for diagnostic PCR using primers designed for FGFR1, FGFR2, FGFR3, FGFR4, and FGFR like-protein 1 (FGFrl1) and for probe design to FGFR3, FGFR4, and FGFrl1. Rat cDNA was used to synthesize probes for FGFR1 and FGFR2 with 90% and 93% homology to human, respectively. Paraffin sections of retina from macaque fetuses sacrificed at fetal days (Fd) 64, 73, 85, 105, 115, 120, and 165, and postnatal ages 2.5 and 11 years were used to detect FGF receptors by immunohistochemistry and in situ hybridization. Results: PCR showed each of the FGF receptors are expressed in fetal human retina. In situ hybridization indicated that mRNA for each receptor is expressed in all retinal cell layers during development, but most intensely in the ganglion cell layer (GCL). FGFR2 mRNA is reduced in the adult inner (INL) and outer (ONL) nuclear layers, while FGFrl1 mRNA is virtually absent from the adult ONL. FGFR4 mRNA is particularly intense in fetal and adult cone photoreceptors. Immunoreactivity to FGFR1-FGFR4 was detected in the interphotoreceptor matrix in what appeared to be RPE microvilli associated with developing photoreceptor outer segments, and generally is high in the GCL and low in the INL. Different patterns of FGFR3 and FGFR4 immunoreactivities in the outer plexiform layer (OPL) suggest localization of FGFR3 to horizontal cell processes, with FGFR4 being expressed by both horizontal and bipolar cell processes. FGFR1, FGFR3, and FGFR4 immunoreactivities are present in the inner segments and somata of adult cone. The pedicles of developing and adult cones are FGFR1 and FGFR3 immunoreactive, and the basal, synaptic region is FGFR4 immunoreactive. FGFR4 labels cones almost in their entirety from early in development and is not detected in rods. The fibers of Henle are intensely FGFR4 immunoreactive in adult cones. Conclusions: The results show high levels of FGF receptor expression in developing and adult retina. Differential distribution of FGF receptors across developing and adult photoreceptors suggests specific roles for FGF signalling in development and maintenance of photoreceptors, particularly the specialized cones of the fovea

The role of opsin expression and apoptosis in determination of cone types in human retina

In primates, short wavelength sensitive cones (S cones) and medium- or long-wavelength-sensitive cones (L/M cones) are two separate populations. Each cone type has a different developmental timecourse, contributes to different intra-retinal circuits, an

VEGF Expression by Ganglion cells in Central Retina before formation of the Foveal Depression in Monkey retina: Evidence of Developmental Hypoxia

In macaque monkeys the foveal depression forms between fetal day (Fd) 105 and birth (Fd 172 of gestation). Before this, the incipient fovea is identified by a photoreceptor layer comprising cones almost exclusively, a multilayered ganglion cell layer (GCL), and a "domed" profile. Vessels are absent from the central retina until late in development, leading to the suggestion that the GCL in the incipient fovea may be transitorily hypoxic. Vascular endothelial growth factor (VEGF), expressed by both glial and neuronal cells and mediated by the hypoxia-inducible transcription factor (HIF)-1, is the principal factor involved in blood vessel growth in the retina. We examined VEGF expression in macaque retinas between Fd 85 and 4 months postnatal. Digoxygenin-labeled riboprobes were generated from a partial-length human cDNA polymerase chain reaction fragment, detected using fluorescence confocal microscopy, and quantified using Scion Image. High levels of VEGF mRNA were detected in astrocytes associated with developing vessels. We also detected strong expression of VEGF mRNA in the GCL at the incipient fovea prior to Fd 105, with peak labeling in the incipient fovea that declined with distance in nasal and temporal directions. By Fd 152 peak labeling was in two bands associated with development of the inner nuclear layer (INL) capillary plexus: in the inner INL where Müller and amacrine cellsomas are located, and in the outer INL where horizontal cells are found. The findings suggest that at the incipient fovea the GCL is hypoxic, supporting the hypothesis that the adaptive significance of the fovea centralis is in ensuring adequate oxygen supply to neuronal elements initially located within the avascular region