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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1440-1797
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary: Fibroblast growth factors (FGF) regulate cell proliferation, migration, differentiation and angiogenesis during morphogenesis in many different tissues. Recent evidence indicates that exogenous FGF-2 stimulates mesenchymal condensation in cultured rat metanephroi, a crucial epithelial-mesenchymal induction event in the developing nephron. the aim of the present investigation was to determine the in vivo distribution of FGF-1 and FGF-2 in developing rat metanephroi at embryonic days 14, 15, 16, 18 and 20. Avidin-biotin enhanced indirect immunohistochemistry was used to demonstrate that both FGF-1 and FGF-2 were co-localized in metanephroi at all ages studied. High levels of FGF-1 and FGF-2 were present in ureteric bud branches and in developing distal tubules. Fibroblast growth factor-1 and FGF-2 were colocalized in developing nephron elements, from vesicles to S-shaped bodies, and in the mesangium of capillary loop and maturing stage glomeruli. Both growth factors were present in the mesenchyme of the nephrogenic zone and in the interstitium of the developing cortex. However, immunostaining for FGF was not evident in mesenchymal condensates, endothelial cells, medullary interstitial cells, or in the thin undifferentiated epithelium of the immature loop of Henle. These findings indicate that the expression of both FGF-1 and FGF-2 is tightly regulated in the embryonic kidney and suggest a role for these molecules in kidney development.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1440-1797
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary: The transforming growth factor-β (TGF-β) family of growth factors regulates cell proliferation, differentiation, extracellular matrix synthesis and angiogenesis in many developing tissues. Transforming growth factor-β1 was recently shown to affect the branching of ureteric epithelium and nephron formation in cultured rat metanephroi. As the TGF-β type II receptor is specific for the TGF-β family, the present study used in situ hybridization to localize mRNA for this receptor in metanephroi from Sprague-Dawley rat embryos. Transforming growth factor-β type II receptor mRNA was located in ureteric duct epithelium, undifferentiated mesenchymal cells in the nephrogenic zone, vesicles, comma-shaped bodies and S-shaped bodies. In some S-shaped bodies, TGF-β type II receptor mRNA was not expressed in the lower limb, which subsequently forms the renal corpuscle. Expression was not observed in capillary loop stage glomeruli and maturing glomeruli, or in proximal tubules and interstitial cells. In adult rat kidney, TGF-β type II receptor mRNA was expressed in cortical collecting ducts and distal tubules but not in glomeruli or proximal tubules. These findings demonstrate that the prominent expression of TGF-β type II receptor mRNA decreases as glomeruli and tubules develop. Expression then remains undetectable in adult glomeruli and proximal tubules. the developmentally-regulated expression of this receptor suggests a key role in glomerular and nephron development.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Although neural progenitor cells (NPCs) may provide a source of new neurons to alleviate neural trauma, little is known about their electrical properties as they differentiate. We have previously shown that single NPCs from the adult rat hippocampus can be cloned in the presence of heparan sulphate chains purified from the hippocampus, and that these cells can be pushed into a proliferative phenotype with the mitogen FGF2 [Chipperfield, H., Bedi, K.S., Cool, S.M. & Nurcombe, V. (2002) Int. J. Dev. Biol., 46, 661–670]. In this study, the active and passive electrical properties of both undifferentiated and differentiated adult hippocampal NPCs, from 0 to 12 days in vitro as single-cell preparations, were investigated. Sparsely plated, undifferentiated NPCs had a resting membrane potential of ≈ −90 mV and were electrically inexcitable. In 〉 70%, ATP and benzoylbenzoyl-ATP evoked an inward current and membrane depolarization, whereas acetylcholine, noradrenaline, glutamate and GABA had no detectable effect. In Fura-2-loaded undifferentiated NPCs, ATP and benzoylbenzoyl-ATP evoked a transient increase in the intracellular free Ca2+ concentration, which was dependent on extracellular Ca2+ and was inhibited reversibly by pyridoxalphosphate-6-azophenyl-2′-4′-disulphonic acid (PPADS), a P2 receptor antagonist. After differentiation, NPC-derived neurons became electrically excitable, expressing voltage-dependent TTX-sensitive Na+ channels, low- and high-voltage-activated Ca2+ channels and delayed-rectifier K+ channels. Differentiated cells also possessed functional glutamate, GABA, glycine and purinergic (P2X) receptors. Appearance of voltage-dependent and ligand-gated ion channels appears to be an important early step in the differentiation of NPCs.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Notes: Alzheimer's disease (AD) is characterized by the presence of extracellular amyloid plaques, which contain a protein referred to as the amyloid or βA4 protein. The βA4 protein is derived from a larger precursor protein (APP). Studies of autosomal-dominant forms of AD have established the central role of APP in the pathogenesis of the disease. Despite considerable research, the function of APP is unknown. APP can be processed by at least two separate routes. The first route involves a protease known as “APP secretase,” which cleaves within the amyloid sequence, thereby mitigating amyloid formation. The second route may result in the production of potentially amyloidogenic fragments. Our studies suggest that following release from the cell membrane, APP interacts with components of the extracellular matrix (ECM) such as the heparan sulfate proteoglycans (HSPG's). The interaction of APP with HSPG's may be important for the function of APP. Substratum-bound APP was found to dramatically increase neurite outgrowth and survival of chick sympathetic neurons in vitro. This effect was dependent upon the presence of substratum-bound HSPG. The results suggest that normally, when bound to the ECM, APP functions to promote neurite outgrowth and/or cell survival. Loss of this normal trophic function might occur in AD, when APP is proteolytically processed via the amyloidogenic pathway.
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  • 6
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The binding of the amyloid protein precursor (APP) to heparan sulfate proteoglycans has been shown to stimulate the neurite-promoting activity of APP. In this study, proteoglycans that bind with high affinity to APP were characterized. Conditioned medium from cultures of postnatal day 3 mouse brain cells was applied to an affinity column containing a peptide homologous to a heparin-binding domain of APP. A fraction 17-fold enriched in proteoglycans was recovered by elution with a salt gradient. APP bound saturably and with high affinity to the affinity-purified proteoglycan fraction. Scatchard analysis of the binding showed that APP bound to high- and low-affinity sites with equilibrium dissociation constants of 1.4 × 10−11 and 6.5 × 10−10M, respectively. APP, in conjunction with the affinity-purified proteoglycan fraction, promoted neurite outgrowth. The affinity-purified proteoglycan fraction contained a heparan sulfate proteoglycan and a chondroitin sulfate proteoglycan. Digestion of the affinity-purified fraction with heparitinase I revealed a core protein of 63–69-kDa molecular mass, whereas digestion with chondroitinase ABC revealed a core protein of 100–110 kDa. The results suggest that expression of specific APP-binding proteoglycans may be an important step in the regulation of the neurite outgrowth-promoting activity of APP.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: Key words: Fibroblast growth factor ; Kidney ; Immunohistochemistry ; Glomerulus ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The fibroblast growth factors (FGFs) are a family of conserved polypeptides known to regulate cell differentiation and proliferation. We have used avidin-biotin-enhanced indirect immunohistochemistry to localize FGF-1 and FGF-2 in the rat kidney. The most consistent specific immunostaining pattern is found in paraffin sections from kidneys perfusion-fixed with 4% paraformaldehyde in 0.1 M phosphate buffer. Intracellular immunoreactivity for FGF-1 and FGF-2 is co-localized in visceral (podocytes) and parietal (Bowman’s capsule) glomerular epithelial cells, S3 segments of proximal tubules, distal tubules and collecting ducts in the cortex, and thick ascending limbs and collecting ducts in the medulla. Immunoreactivity is also observed within urothelium and the tunica adventitia of large blood vessels. No immunostaining is found in cortical S1 or S2 segments of proximal tubules, in frozen sections prepared from unfixed or 4% paraformaldehyde perfusion-fixed kidneys, or in paraffin sections from Bouin-fixed kidneys. Immersion fixation with 4% paraformaldehyde gives a similar staining pattern in paraffin sections to that achieved with perfusion fixation. However, in paraffin sections fixed with methyl Carnoy’s fixative, immunoreactivity is primarily localized to the tunica media of blood vessels, with little tubular or glomerular immunostaining. Thus, variation in immunolocalization patterns for FGFs can be partially attributed to differences in fixative, preparative technique and antibody specificity.
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  • 9
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Competition between neurons for limited amounts of trophic factors is believed to be the basis for large-scale neuronal death during the normal development of the vertebrate nervous system. In this study, an unbiased stereological counting method, an optical disector/Cavalieri combination, was used to estimate the total number of motor neurons in the lateral motor column of the developing chick and to assess the effects of four growth factors on neuronal numbers. The total number of neurons in lateral motor columns at embryonic day 6 (E6), E8, E10 and E12 were 18,747 ± 1,369 (mean ± SD), 15,037 ± 1,816, 10,245 ± 940, and 8,802 ± 797, respectively. Daily exposure from E6 to E9 to three of the growth factors (basic fibroblast growth factor, bFGF; leukemia inhibitory factor, LIF; nerve growth factor, NGF) had no effect on total neuron number at E10. However, exposure to ciliary neurotrophic factor (CNTF) from E6 to E9 significantly increased (P 〈 0.05) the number of neurons in the lateral motor column (13,610 ± 725, compared with 10,058 ± 204 in normal saline controls). These results are in agreement with previous reports of large scale neuronal death in the developing chick lumbar lateral motor column between E6 and E12 and confirm that exposure to growth factors such as CNTF can mitigate the course of normal ontogenetic cell death. The optical disector/Cavalieri combination is an efficient method for counting neurons: on average, following sectioning and staining, less than 30 min was required to estimate the total number of motor neurons in a lateral motor column with a coefficient of error of approximately 10%.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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